Université d7Otîawa Universiv of Oaawa

National Library Bibliothéque nationale du Canada

Acquisitions and Acquisitions et Bibliagraphic SeMces seMces bibliographiques

395 W d i Street 395. tue Wdlington OrtawaON KIA ON4 OrtawaON K1AONa CaMda CaMda

The a d o r has granted a non- L'auteur a accordé une licence non exclusive licence dowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distriibnte or sell reproduire, prêter, distri3uer ou copies of this thesis m microfonn, vendre des copies de cette thèse sous papa or electronic formats. la forme de microfiche/nlm, de

reproduction sur papier ou sur format électronique.

The author retams ownership of the L'auteur conserve la propriété du copyright m this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantîal extracts fiom it Ni la thèse ni des extraits substantiels may be prhted or othenvise de ceIIeîi ne doivent être Imprimés reproduced wahout the auîhor's ou antrement reproduits sans son permission. autorisation.

Relationships between Composition and Size Distribution of Invertebrates Colonizing Navigation Buoys and Physico-chemid Parameters of the

St Lawrence River, Montreal (Quebec).

0 Vincent Mercier

Acknowledgements

F F h t and foremost 1 would like thank my aipewisors Dn. Antoine Morin and

Chrisime Hudon for their guidance and patience in seeing this work through. 1 would also

particulariy like to thank Chantai VIS who was indispensable for preparing the field sampling

and providing data and information, Dr. Hans Damman for his ben&cid comments, Aline

Sylvestre, Sophie Wong, Kim Desrochers and Thierry Danseradt for their technical assistance

in the field and the Iab. 1 am gratefùl to the laboratones of the Centre Saint-Laurent (Montreal,

Quebec) for providing chernical analyses and field equipment and to Biomedico, Inc., for

conducting f d coliform counts.

Furthmore, I would like to express my gratitude to my f w y and Wends and

paxicularly to the midents &om the Currie, Pick Morin, Chapleau and Moon labs for their

advice and understanding, but most of alI for the fiiendships that we have deveioped over the

iast two years. Special th& to Mylêne, not oniy for proofieading my thesis with a fine

toothed comb, but also for sharing the h e r m o m m of this experience, and seeing me through

the occasionai hstration.

Funding for this project was provided by an N. S E R C . gant to Dr. .Antoine Morin, by

the Ontario Government (O.G.S.) and by the St. Lawrence Cemer of Environment Canada, for

providing labour, equipment and analyses.

Water, algae and invertebrates colonizîng navigational buoys at 18 &es in the Montreal

area of the St. Lawrence River were sampled during the sprins, surnmer and fd of 1995 to

assess which measufes of invertebrate assemblages (de-, biomass, size distriiutioq and

taxonomie composition) best respond to wastewater discharge and to compare invertebrate

responses among sarnphg dates. Increases of up to five orden of magnitude in fecal

coliforms, 2-fold increases in TP and POJ, 20-fold increases in NE& concentration and -3-fold

decreases in water ciarity (Secchi depth, suspended marrer) were found downsaeam of point

sources of urban wastewater discharge. Despite these physico-chernical changes, invertebrate

assemblages were oniy weakiy related to wastewater exposure, since DFA on composition and

N e dimiution only correctly clasnfied 446 1% of mes imo groups based on fecd coliform

concentration for aii four sampling dates. Fecal colifomis were best predicted by

Chironornidae, other Diptera and Nematoda demity in the fàil (mult reg a d j - h . 69,

p<O.OO l), density of invertebrates in the size class 4-8 pg in the fall (adj.*. 65, p<0.00 l), and

total invertebrate density (adj .?=O. 75, p=û.002) in the spring. Penphyton biomass, nispended

matter concentration and m e n t velocity were the main environmental correlates of

invertebrate composition and size dismiution pâttems in the M. The moderate response of

invertebrares sugsest that they are not very us& bioiadicaton of wastewater erposure in the

St Lawrence River at the presexrt range of exponire levels.

In the second chapter, spatio-temporal patterns of buoy invertebrate and alb@ N e

distriibutioos were imrestigated, in relation to trophic -dients in the river. The size

distributions were not significantly related to physico-chernical parameters of the river,

dthough variability in the data may have been too hi@ to detect trophic enects. Size spectra

on buoys, despite the fact that protozoans were not accounted for, had stxiking sïmilarities with

other complete Ne distributions (containing algae, protozoans and invertebrates) fiom meam,

Iake and marine Littoral zones. The results suggest that size distributions, determined over

broad N e ranges, are relative. roblust to ensironmental conditions and are împractical for

assessing ecological degradation because of the labour required t O O btain precise

measurements.

Résumé:

L'eau, ainsi que les aigues et les invertébrés colonisant les bouées de navigation du

fleuve Saint-Laurent, ont été échantillonnés du printemps à l'automne 1995, à dix-huit sites

dans la région de Montréal. Les objectifs du premier chapitre étaient de déterminer quelles

mesures des ensembles d'invertébrés (densité, biomasse, composition taxonomique et structure

en taille) répondaient le mieux aux décharges d'eaux usées et de comparer ces réponses entre

les dates d'échantillonnage. Des au-mentations dant jusqu'à 5 ordres de grandeur en

coliformes fécaw 2x en concentration de PT et de PO4 et 20x en N€&, accompagnées par des

diminutions de - 5 x de la transparence de l'eau (profondeur Secchi et matière en suspension)

ont été trouvées en aval des sources ponctuelles de décharges d'eaux usées municipales.

Maigrés ces chansements physico-chimiques, les ensembles d'invertebrés n'étaient que

faiblement corrélés aux eaux usées, puisque la composition taxonomique et la distribution en

taille n'ont classifiées que 44-6 1% des sites correctement en groupes de coliformes fécaux pour

les quatres dates d'échantillonnage. Les paramètres qui prédisaient le mieux les concentrations

de coIiforrnes f b u x étaient les densités de chironomides, autres diptères et nematodes de

septembre (reg. muit. a d j . h . 6 9 , p<0.00 l), la densité d'invertébrés dans l'intervalle de taille

1-8 pg de septembre ( ad j .h .65 . p<0.00 1) et la densité totale d'invertébrés de mai

( a d j . h . 7 5 , p4.002). La biomasse de périphyton, les matières en suspension et la vitesse du

courant étaient les principaux p aramétres environnementaux expliquant les changements en

composition et de structure en taille. Ces réponses modérées par les imrertébrés suggèrent que

leur utilité comme bioindicateun d'exposition aux eaux usées dans le fleuve Saint-Laurent est

Limitée à l'étendue actuelle des niveaux d'exposition.

Dans le second chapitre, les patrons spatio-temporels des structures en taille des algues

et invertébrés colonisant les bouées, ainsi que leurs changements selon le gradient trophique du

fleuve, dans la région de Montréal, ont été examinés. Les distributions en taille n'étaient pas

significativement corrélées aux paramètres physico-chimiques du fleuve, par contre les niveaux

de variabilité étaient probablement trop élevés pour pouvoir détecter ces effets trophiques, s'ils

existaient. Les distributions provenant des bouées, même sans tenir compte des protozoaires,

avaient une surprenante similarité avec d'autres distributions complètes (celles ayant des

protozoaires, algues et invertebrés) provenant de ruisseaux, lacs et zones littorales marines.

Les résultats suggèrent que les distributions. déterminées pour une _-de étendue de taille

d'organismes. sont relativement robustes aux conditions environnementales. De plus, les

efforts requis pour obtenir des mesures précise rendent les spectres in&caces a l'evduation

d'impacts écologiques.

Contents

Chapter 1: Invertebrate communities on navigation buoys as an indicator of wastewater discharge in the Montreal area of the St. Lawrence River 5

Introduction: ................ ............................................... . .......................................... 6 Methods: . . .. .. . . . . . . . . . . . . . . . . . . . .. . . -. . . . . . -. . . . -. . .. . .. . . . .- -. . . .. - . - .. . . . . . . . . . .. . . . . . . - - . . . .. . . . . . . . . . .. . . . . . 9 Resuits: ...................... ....................................................................................... 15

7 7 Discussion: ..................... ... .......................................................................... - Conciusion ...................................................................................................... 27 Tables and Fi-mes.. .. . . . . . . . . . . . . . . . . . .. . . . .. -. . .- -. . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . - 28

Appendix A: Density of UNertebrate taxa (ïuid-~m'~) of each replicate collecteci on each nwigation buoy for May, June, A u g n and September sampline dates. ..-.-..-.-..-.---. 77

Appendix B: Physicochemicai measurernents made at each navigation buoy for May, June, AuCeust and September samphg dates p-.--.-.-...H---H--p.- 84

Appendir C: Wometric relationships for the conversion of invertebrate len+ghs (mm) to dry mass (p~), couvenion factors for weight measuremems and biomass/dendy caiculations - 89

Appendix D: Invertebraie density (ind-m-3 per N e class (logIo upper limit) for each taxa of each replicate from September, 1993 ..--p--l-**..*....------.. 91

Appendix E: Invertebrate and algal de+ (ind-m-) per N e class (loglo upper limit) for each taxa of each replicate Eom May, June, August and September, 1995--.-..--p 110

Appendix F: Classification and jackknifed classification mamces for the buoys sampled in May, June, August and September based on f d coliform groups ushg density of3 taxa (ioglo ~ansformed) and de- from 3 sire classes (iogio aansformed) from September 113

Appendir G: Component Ioadings of the fim two eigenvecton from the principal component analysis o f the density of al1 taxa (logio transformeci), collecteci in September 1995 ,,.,, 117

List of Figures

Fîg. 1.1. The sampling sites in the Beauhamois Canal (upstream) and the p e n water m a s of .............................................. .......................... the St-Lawrence River in Montreal. .. .28

Fig 1 .2. Average (&SE) total p hosp horous, nispended matter and fecal coliform concentration -- ................................ for three resjons of the St. Lawrence River for each samphg date. 33

F i 1.3. Relative density (94) of dominant taxa throughout the sarnphg season ................... 3 5

Fig. 1.4. PCA factors 1 and 1 showing the ordination of buoys ( ~ 1 8 ) based on d e n e (logio transfomeci) of the 9 învenebrate taxa, sampled in September 1995. ............................. 37

Fie. 1.5. Average N e disfiutions of invertebrates belonging to 3 miter quality groups of buoys, sampled in September 1995. Average relative den* per ske class (%) of the 3 or 1 most dominant taxa of September assemblages, for the 3 water quality goups (iower

..................................................................................................................... panels). 28

Fig. 1.6. Size dimibutions predicted by polynomial mode1 (table 3) for low and high values of ............................................................................ ........................ each parameter. ... 40

Fig. 2.1. Size ranges for dominant poups of or- fond co1onizi.n~ nakiqtion buoy S.

................................................ The Chlorophyceae goup does not include Cladophora. 55

Fis. 1.1. Averase dry biomass (SE, loglo aaosformed) of organisms per N e class (lefi panel) and average biomass of învertebrates (empty bars) and dgae (fïiied bars) per size class (right panel). .................................................................................................................. 56

Fie. 23. Density of invmebates and al- per size c h coIonizing buoys for each samphg .................................................................................................................. date in 1995. 58

Fig. 2.4. Size dimibutions of invenebrates and algae fiom St. Lawrence River buoys and protozoans, aipe and macroinvertebrates f b m Iakes (Cananeo 1983, marine Littoral zones (Schwin&ammer 1981) and temperate streams (Cattaneo 1993) ........................... 59

List of Tables

Table 1.1. Mean ( S D ) phyaco-diemical characteristics for five groups of buoy s by water qudity, meastreci throughout the sampling season Groups are based on fecal coliform

........................................................................................ concentration (UFC/lOO mL). 30

Table 1.2. Pearson correlation co&cients, dons with their p-dues, for the correlations between fecal coliform concentration and the physico-chemid variables, for each of the

......................................................................... ........................... sampline dates. ..... 32

Table 1.3. Multiple regression models predicting f d coliforni concentration (logl* transfomeci) fkom invertebrate taxa dennties for each samphg date and korn size classes

......................................................... ...................... for September assemblages. ..... 36

Table 1 -1. Polynomial regression modei, for September 1995, describing invertebrate density (log10 transformed) per sïze class (indam-) as a function of dry mass (M., in kg dry mass), chlorophyll a (Chla, in pg m-2), suspendeci matter (S, in m-a), current velocity (C, in m se') and ammonia CMIi, in &L) (n=342, h . 6 5 , RMS=0.09). * p < 0.000 1. ............... 4 I

Table 2.1. Poiynomid regression model parameters descn'bin~ invenebrate and algae !oglodensity per N e class (ind. m-') as a fiinctîon of dry Mass ('34, pg ) (adj. ~ ~ 4 8 3 , RMS=I.Z, n=198). Note thar TP and the interaction TP*M were not si-Onificant

.................................................................................................. parameters in the mode1 54

List of abbreviations

AFDW - Ash Free Dv Weight (mg/cm2)

DFA - Discriminant Function Andysis

DM - Dry Miss (w) ESD - Equivalent Spherical Diameter

MüC - Montreal Urban Community

NSD - N o rmalized S ize Distribution (biomass/mass interval) (m@m2)

PCA - Principal Components Analysis

TP - Total Phosphorous (pg)

W C - Units of Fecal Colifonn (ceus/ 100rnl)

General Introduction:

Public concems over the degrading nate of ecosystems have rparked a crifical need for

developing cost-effective tools that enable us to properiy assess and predia anthropogenic

impacts on Our kesh water resources (Schindler 1987, Karr 1 993, Han 1994, Naiman et al.

1995). We are further challenged with the need to use these environmental assessrnent tools

to manage water resources in ways that protect human hedth and ecological integity, while

integating long-term economic development (Courtemanch 1994). One of the moa important

ecological applications ro reappear Iat ely which could meet diese environmental challenges is

arnbient biologicd rnonitorins (Counemanch 1994, Hm 1994). This potentially powerful tool

makes Ulferences about environmental quaiity &ou& the structurai and functiond responses

of individuals. comrnunities or ecosystems to arnbient conditions. In fa- national

biomonitoring protocols were implemented to p i d e management decisions in the Ciniteci-

States (EMAP, U.S. EPA 1990; NA4WQA, Gum 1991; BEST, ETM 1992) and U.K.

(Rn,'PACS, Armitaee et al. 1983), with New-ZeaIand, Canada and rZusPalia in the plannins

stages. For these initiatives to work in improviq resouce manqement, biolo@cal monitoring

mua ren on sound ecolo@cal concepts (Schindler 1987, Hart 1994). Therefore, as academic

biologins, it is essenrial to assume more direct responnbiliaes in using the theory we develop

by bnd-ghg the gaps between basic and applied research (Kart 1994) and by dealin,e directiy

with decision makers (Le. govenunenL environmentai agencies and the senerd public) to

promote our ideas (Schindler 1987, Naiman et al. 1995).

In Canada, one of our moa important naniral resources, which provides us with

indispensable goods and services, is the St. Lawrence River. The river, dong with the Great-

Lakes watershed (ara 1.6 1 million km'), contains 25% of the wodd's fiesh water supply

(Znland Waters Directorate 1990) from which 46% of Quebecers draw their drinking water

(SLC 1996). The watenhed has a nch diversity of habitats which include shallow iakes with

reed beds, deep channels, fieshater, brackish water and saltwater areas, with well over 1645

species of plants, fish. mammais and birds (SLC 1996). From an economical perspective, the

river provides shipping transport (revenue of 51.1 billion in 1990, Ports Canada 199 I),

electricity (1189 MW annual-, SLC 1996), commercial fishing and aquaculture (5200 million

in 1992, Fisheries and Oceans 1992), and tourism and recreation (annual revenue of S3 billion,

SLC 1996). However, these uses corne at the cost of altered basin morphology and hydrologie

conditions. overharvestùig of aquatic species and the release of municipal and industriai

wastewaters (annual con ?). Mon of the socioeconornic activity of the river, dono with the

potential for ecologkal impact, is concentrated in the fluvial section which nretches from

ComwalI to Trois-Rivières, and more precisely in the Metropolitan Montreal area, which has

about 3 million inhabitants (close ro 50% of Quebec's population). In an effort to reduce point

sources of pollution in the St. Lawrence River, the Montreal Urban Community (MX) has

recently ( 1994-95) up-gaded its wastewater treatrnent fâcilities of municipal and indusnial

efnuents (Pureme 1996). To determine whether the ecolo@cal Întegrity of the S t Lawrence

River has been affected and following efforts at reducing pollution caused by MUC

wastewater dischaqes, bioassessmm field midies' were conducted in collaboration with the

St. Lawrence Center, a section of Environment Canada, in Montreal.

' ~ e e vs ( 1997) for cornph- biomomto~g ~fuciy.

The broad objective of the present thesis is to evaiuate cost-effective, easily replicable

biological indicaton of wastewater discharge in the Montreal area that would cornplement

routine physical (e.g. wpended sotids), chernical (e.g. TP) md microbial (e.g. fecal coliforms)

monitoring of wastewater discharge in the St. Lawrence River. ï h e fim chapter specifically

d d s with the development of indicaton uang the responses in composition and size

distribution of invenebrate assemblages colonizing buoys downstream of n o m sewer overflow

and treated effluent discharge into the river. In the second chapter, the spatio-temporal

varïability of size distribution composed of algae and invertebrates colonizing buoys, were

exarnined, dong with their relationships to trophic gradients. Size dinniutions can potentially

provide usefûl cornmunity measures for use in environmental assessments that avoid the

taxonornic expertise normally required for invertebrate identification (Morin et al. 1995) and

that are easily comparable across ecosysterns and among ecoregions (Strayer 199 1, Cattaneo

1993, Poff et ai. 1993).

Chapter 1:

Invertebrate communities on navigation buoys as an indicator of wastewater discharge in the Montreal area of the St. Lawrence River

Introduction:

Water quality monitoring in large rivers bordering on urban aras has become

mandatory in many countries, but remains problematic and coaly because water quaiity is an

encompassing tem. Monitoring activity has thus far generaily been focused on characterizing

the physical (e.g. turbidity), chernical (e.g nutrients and pollutants) andor bacteriological (e-g.

fefal coiiforms) aspects of the water to infer potentiai impact to hurnan health and aquatic life

(Reynoldson and Metcalfe-Smith 1992). This approach is lirnited, however, because

monitoring programs can focus only on a smdl subset of the multitude of possible factors

a . 6 d n g water quality. Moreover, these aspects alone provide little information on the

biologicd impacts of polluted waters. Multiple contamination sources (Le. industrial, municipal

and agricultural (Johnson et al. 1995)) ofien generate a miunire of pollutants (e.g trace metals

and nutrients) that varies in time and space (Sweeting 1994, Cairns et al. 1993, SLC 1996). It

is therefore important to measure biological responses to water quality because organisms

integate these muitiple and cumulative effects (Cook 1976. Cairns et al. 1993).

It has become standard practice to use benthic invertebrates for the bioassessment of

streams and midl rivers. Many characteristics of uivertebrate assemblages have been used as

indicaton of water quality in aquatic habitats (See Armitage et al. 1983, Washington 1984,

Caims et al. 1993, Rosenberg and Resh 1993, Suter 1993. Kerans and Karr 1994). Den* and

biomass of whole assembiqes and/or specific taxa ofien respond to degraded water quality

(e.g tubScid worms and or-dc enrichment (Resh 1995)) and are r o u ~ e l y used in the

muItÏmemcs developed for the United States Environmental Protection A,eency (U.S. EPA)

bioassessment protocols (e-g. Kerans and Karr 1994, Barbour et al. 1996). ~Metrics bas& on

the size dimibution of organisms forming the assemblages have also been proposed to

streamline the process by reducing the taxooomic expertise required (Morin et al. 1995).

However, it is unclear whether these indicators, generally developed for streams and mal1

rivers, are sensitive enough to be usefil in large rivers, where large volumes of water can dilute

poiiutants and narrow pollution _madients.

Indeed previous midies on the use of St. Lawrence River inveriebrates as water quality

indicators have failed to show any clear pollution response patterns (Ferraris 1984, Pinell-

.MIoul et al. 1996. W~llsie and Conan 1996). However, whether this lack of association

between invertebrate assembla~es and water quality is due to the low sigaihoise ratio or

nmply to a lack of response by invenebrates remains unknown. The large sampling variability,

the weak contaminant -zdÏents, and the unaccounted effects of physical factors, such as

curent, seasonality and turbidity, could d l have Ied to low si_oial/noise ratios.

In our study we have attempted to ma>amize the tipai/noise ratio to assess the

refationship between invertebrate community m u m e and exposure to wasrewater dischqes.

We used invertebrates colonking navigation buoys while rna>rimiPns the _=dient of exposure

ro stormwater and municipal wastewaters (as reflected by fecal coliforni concentration,

Geldreich 1978, Purenne 1996). Buoys were selected because they provide a standardized

habitat amone ntes (Rosenbere and Resh 1982), and because the imrertebrate assemblages

developino on buoys are exposed to vexy iocalized physical and chernical water conditions,

integrami over the coionization period (approrcimatdy six months).

The objectives of this study were 1) to quanw .e relationships between

characteristics of the invenebrate assemblages (density, biomass, tavonornic composition and

süe structure) and fecal coliform concentration (used as a proxy for wastewater ewposure), 2)

to describe how these relationships Vary throughout the ice-fke season, and 3) to determine

which environmental characteridcs, other than coliform concentration, are best correlated with

taxonornic composition and size dimibution.

Methods:

Stuc& site

The sampling sites were located in two distinct areas ofthe St. Lawrence River in

Quebec: the Montreal area (45'3 3X,ï3"30'O - 4Sa53W,73 Z 5'0) and the Beauharnois Canai

(45' 13N,73°0!3'0), an area approltimately 20 km upsveam of Montreal (fig. 1.1). M sampling

sites are in the waters of the St. Lawrence River, which drains the Great Lakes watershed and

conaitute roughiy 80% of the discharge downstream of Montrd (7000 m3s-') (Environment

Canada 1996). The water in diis metch of the river is clear (average Secchi depth 3.2 m),

nrongiy mineralized (average conducrivity 266 pSlcm), mesotrophic (average TP 16 pzA) and

~enerally fast fi owine (average current velocity 0.9 m 9'). c.

In the Montreal ares the river receives Iiquid wastes fkom the approximately 2.1 million

people inhabitin3 Montreal Island and its surrounding municipalities, and f?om indumies such

as pulp and paper mills and metallurgicai, petrochernicaL organic inorgank chernicd agi-

food and t&e plants (Sr. Lawrence Action Team 1992. CEILS 1996, 'ynTC 1996, SLC

1996). Ln 1993, the ne Charron wastewater neamient plant seMng the cornrnunity of

Longeuil on the south shore released domesac and industrial effluents at a mean rate of 3

ds-' (CERS 1996) (fie 1.1). The Montreal Urban Community (MUC) discharpi domestic

and industrial ef3luem at the De aux Vaches treatment plant at an averaee of23 rn3s- '~c

1996). Lrntil it was divend to ne aux Vaches in Au-guss 1993, one collecror released

wastewater diredy into Montreal Harbour. Raw wastewater is still periodicaily dischargeci

h o the harbour and dong the south shore from n o m sewer overfiows during rainfall events

(Deschamps et al. 1997). Sampling sites Iocated in the Beauharnois Canai (upnream) are not

impacted by urban wastewater discharge and therefore served as reference sites.

The Montreal Uhan Community has a combined sewer system, whereby, surface

runoff and municipal sewage are transported to the IIe aux Vaches wastewater treatment plant

under normal flow conditions (Purenne 1996). In hi& flow penods, where volumes exceed

marnent plant capacity (i. e. under heavy precipitation), some wastewaters are dic harged into

the Montread harbour from storm sewer collectors. Wast ewater treatment begins wit h chernical

flocculation using femc chioride and an anionic polymer, followed by sedimentation. This

process is designed to reduce suspended solids and total phosphorous discharge.

Consequently, automated monitoring of treated effluents. at the oualow, revealed that total

phosphorous and suspended solid concentrations were 79% and 85% lower than in the original

wastewaters, respectively (hirenne 1996). W C monitoring also measured imponant

concentrations of BOD, COD, alkalinity, co!ifoms (including fecal colifoms), iron, aluminum,

and oils and geases in the outflow (Pureme 1996). Other chemicds which are acpected to be

dischargeci include: nuuients (e.g amrnonia), metals (e.g copper, zinc) (Chambers et ai. 1997)

and orgmic compounds ( e g PCBs and PAHs), which may be toxic and hib* persistent even

at Iow concentrations (Pham and Prouix 1996).

SampIing design md sample processing

hvertebrate sarnpling was conducteci on navigation buoys. These red metdic buoys,

which range fkom 0.8 to 1.4 in in diameter, are placed in the river each spnns in Apd or May,

jus after ice breakup. niey rmain in the water und late tàll when they are retrieved to be

cleaned and repainted over the &ter months. We sampled 9 buoys on May 7&, 17 on June 7&,

18 on A u g ~ a 1- and 18 on September 26&, 1995. Triplicate sarnples of invertebrate

communities were collected from each buoy 20 cm below the water d a c e using a specially

designed sampling apparatus (Vis 1997). The sarnpihg device allowed a nirface of 45.6 cm2 to

be bmshed clean of invertebrates and penphytic aleae and transferred into a gass jar. In the

field. the collecteci material was sonicated for 10 min and aliquots were retained for algal

tôxonomy and chlorophyll a analysis before adding forrnaldehyde for preservation.

In the laboratory, inverrebrates were sorted nom the collected material under a

dissectins microscope at 12 - 25X. Sarnples that contained more than 200 individuals were

divided into mialler fractions using a Folsom plankton spliner, und there remained at least 100

individuals. The invertebrates were categorîzed by broad taxonornic group: Nematoda,

Chironomidae, Diptera Ephemeroptera, Tnchopterq Amphipoda, Copepoda Acarina and

Olieochaeta. Organisms fkom the September sarnpline date were then measured using an image

anaiy sis -stem (a. 0 1 mm). Allomem'c equations were used to estimate individuai dry masses

of Diptera. Chironomidae, Ephemeroptera, and Trichoptera (Smock 1980, Meyer 19891,

. .ph ipoda (Marchant and Hynes 1981), Copepoda (Culver et al. 1985) and Oligochaeta

(Ladle and Bird 1981. Lafont 1987, Lindqaard et al. 1991). .+carina and Nematoda diy m a s

were estimatecl by DM (pz) = 1 L' (mm) (Morin and Nadon 199 1). Density and biomass of

invertebrates were determined by dividing the total number of organisms or thek total mass by

sampling nirfàce (0.0045 m'). Sire distributions of ùivertebrate c o ~ t i e s , fiom each

replicate, were quantifieci by grouping or-pisms imo 19 10,earithmic N e classes of individual

dry mass ran_& &om Y to Y' p g

Penphytic algai biomass on buoys was estimated from chlorophyll a concentrations

(Bergman and Peters 1980). Ash free dry rnass (AFDM) of oqanic maner on buoys was

determined using the methodology of Wetzel and Likens (1 98 l), fiom periphytic samples, once

invertebrates were removed.

PhysicaI und chemical rneanrrernents

At each sampling site and date, a series of physical and chemical measurements were

performed to charaaerize the water. Water temperature, conductivity, and pH were measured

usinp a ponable hydrolab at a constant depth of 20 cm in the water surrounding the buoys.

Current velocity was measured using PVM.2A Montedoro Whitney and Price 622A m e n t

meters. Water transparency was estimated by rneasuring both the light extinction coefficient

using Li-Cor, Li4000 light meter and Secchi depth. Tnplicate water samples were collected 20

cm below the surface to estimate suspended matter, NO2 i NO:, NHi, total phosphorus, PO4

and Si02 concentrations, which were andysed in the St. Lawrence Centre laboratories using

standard methods (Environment Canada 1993). Fecd colifom concentration was estimated

from undenvater agar plate counts at Biomedico labs, within 21 houn of sample coliection

(APHA 1995).

Stutistical analyses a d anddelfitting

Replicate biological, chemical and physicd measurements taken on each buoy and at

each sampiing time were averaged for the statistical anaiyses. When taken within the same site,

these measurements are spatially autocorrelated and wodd violate the assumption of

independence in statistical anaiyses (Legendre 1993).

Groups of buoys assotiated with different concenmtions of feçal coliforms were

characferized using discriminant hnction andysis (DFA) with respect to the tâuonomic

composition and N e d i s t r i i o n of invertebrates found on them. Buoys were separated into

five levels of fecal coliform concentration corresponciing to criteria for drinking water (< 3

UFCll O0 mL). s w i d g and water-contact sports (5-200 UFW100 mL) (MEQ IWO), and

10û-1000,2000-70 000 and > 20 000 UFC/100 mL. DFA ailowed for the cornparison of rwo

sets of variables (size distnibution and tavonomic composition) in discriminating among groups,

to explore the shilarities among groups and to test dtivariate Merences amone those

groups (Wilkinson et al. 1996). We assessed the vaiïdiry of the ~Iassifîcation finaions by

examinin3 the jackknife classification ma& a form of cross-validation which reclassifies the

sites by leaving out one case at a time (Wiilkùison et al. 1996). Three taxa and three Ne classes

only were used to clas* water qualiv groups in each case because of the Iow number of

replicates in mon goups (Wilkinson et al. 1996). The three taxa and ciasses select& for the

analyses, foUowing prelLninary tests, were the ones which discriminateci the moa among water

quality groups based on the F to remove natistic in the DFA output (Widkinson et al. 1996).

The spatial varïabihy in the faxonornic composition of inverrebrates was descnbed

p ~ c i p d componem anaiysis (PCA) on the denskies of the taxa for each of the four

sarnphg dates (Wilkinson et ai. 1996, L W y 1986). Densities were d o m e d pnor to PCA

anaiysis to norrnalize data and to stabiIize vaxïance befween sites. To assess which variables

affect the spatial distribution o f the hertebrates, multiple regression analysis was perfomed,

using PCA factors as dependent variables and the physical/chemical measures of each site as

the independent variables.

The effects of environmental characteristics on the amplitude and shape of the size

dimibution of the invertebrates was assessed by fimng their distributions to polynomial

regession models (Bourassa and Morin 1995). The models include the physical (e.3. currem

velocity in m s"), chernical (e.3. TP. in &L) and biological (e.g chlorophyll a. Ii@m')

parameters of each site. as weil as their tirs order interactions (e.g. TP x current veiocity) and

their interactions with individuai dry mass (IL pg x TP), as the independent variables

predicting density of inverteboles per size class. Since some N e cIasses contained no

orgmisrns, den* was hansformed usÏng logio (density + 167) (se above), which nabilized

residud variance amone sites and size classes. Regession analyses were based on 342

observations for September ( 19 size classes x Z S sites).

.a a a t i d d analyses were done usÏng Systat 6.0 for Wmdows (W~&~IISQ~ et al. 1996)

on IBM-compatiile cornputers.

Wmer q d i t y in the Montreal urea

The discharge of urban wastewater in the Montreai area had a clear effect on water

quality, both spatially and seasonally. There was a graduai decrease in fecal coliform

concentration within the MUC efnuent plume in a downsnearn direction (groups 4 and 5 , table

1.1) and a 5 order of ma-ginide increase between the reference sites and sites located

downstrearn of Montreal (table 1 .1, Bg 1 2). Nutrients (TP) and water clarity (wpended

matter) varieci throughout the season with a -gradud narrowing of environmental -gradients

f?om June to September (fig. 1.2). Improvements in water quality were also apparent with the

diversion of the Iast wastewater coUector 6om Montreal Harbour to the ne aux Vaches

treatment facility in .\u-gs& 1995 (6%. 1.2). In fa- four of the five buoys located in the

harbour had at least an order of ma-qitude decrease in coliforms in September (> 200

LFC/100 mL) (fie. 1.2).

The upstream sires had the lowest fecd coliform concentrations (< 3 UFC/ 100 mL),

lowest nutrient (TP - 10 and ammonia -6 p-SJ) and suspended maner (-1 -1 m-fi)

concentrations and clûarest water (Secchi depth -7.3 m) (table 1.1). Sites Iocated in the St.

Lawrence Seaway and Montreal Harbour (except for September) (group 3) genedy exhîibited

intermediate coliform concentrations (200-2000 WC/ 100 d), mid-range levels of nutrients

(TP - 1 5 and silicates -83 1 pfl) and wpended matter (-3.8 m_@L), and lower water clarity

(Secchi depth -2. I m). The IWO buoys in group 5, located just downstream of the M C o d

(fie 1.1). had the highest levels of coliforms (> 20 000 UFC/100 mL), hi@eest TP and

ammonium (-25 and 135 @,) and suspended matter (4.5 m-a) concentrations and low

water clarity (Secchi depth 3 . 3 m) (table 1.1).

Silicates, total phosphorous, Secchi depth, light transmission coefficient, and suspended

solids were generaily sigificantly CO rrelat ed with f k d CO liform concenvatio n throughout the

season (table 1 2). knmonium was si-enificantly correlated with fecal colifomis in June and

nearly si-gificantiy correlated in Augus and September. By con- current veIocitv.

conductivity, nitratdnitrite. dissolved inorganic phosphorous and measurements of periphyton

biomass on buoys (chIorophy11 a and MDM) were seneally not correlated ~6th coliform

concentration (tabIe 1 2).

Thxonomic cornpsirion and seczso11~1 a&

.4pproximateiy 52 000 invertebrates were collmed and identifid during the four

sampling sessions in 199 3. The densi? of invenebrates increased dramatically fiom May

assemblages (300 r 100 ind./m2) ro those sampled in June (11 800 = I6 600), Aupst (3 2 200

= 12 800) and September (63 100 = 27 300).

.Uthou& the ovedl abundance of inverrebrates did not change si_&camly berween

the Iast three sampling dates, important stiifts in uxonomic composition did occur. May and

June invertebrate assemblages were numericaliy dominated by chironomids wMe nematodes

dominated the September assemblases (5% 1.3). .4uCpust assemblqes had Nnilar abundance

of oligochaetes, nematodes and chiroaomids: aU three made up the bulk of these communities

(6s. 1.5). Except for the pyiv assemblases sampfed in May, ihphipoda, Diptera,

Ephemeroptera, Trichoptera and Copepoda had more or l e s constant Iow relative abundances

throughout the sampling season.

Fecui col i fm group c l ~ f ' c u i ï o n m g size dimSn7htion mtd raronomzc com@on

Invertebrate composition and size distniution codd be roughly related to fecal

coliform contamination Ievel by ushg DFA for each sampling date. Abundance of three tava

could be used to correctly classq 7 out of 9 buoys (78%) for May, 11 out of 17 buoys (82%)

for June and 14 out of 18 buoys (78%) for both August and September. Invertebrate density in

three size classes (0.062, 0.125 and 250 pe) class%ed 15 out of 18 buoys (83%) for September

(see Appendix F for detailed results of DFA).

The =und performance of the DFA in assignhg sites to the proper category of f d

coliform contamination is probably sornewhat Msleading since cross-validation of the

classification yielded Iower accuras.. The jackknife classification matrk indicated that 56% of

buoys in May, 59% in June, 6 1% in Au,eust and 56% in Septernber were corredy classifïed

based on three taxa and that 44% of buoys were corredy classified in September based on N e

classes. .Analyses using more taxa or Ne classes for estimation of classification bct ion

yielded iderior cross-validation resuIts.

A reanalysis of the Septernber clasdication of b u o . with exclusion of the five harbour

sites, was conducteci usin3 taxonomie composition This was done to ver@ that harbour sites

did not mudde DFA dassitication Nice the important reductions in fecal coliform

concentrations in the harbour, in September, created an additionai water quality group @oup

2, table 1 .1). Moreover, invmebrate assemblages observed on harbour buoys in September

may cenainly have been a reflection of the physico-chexnicd conditions pnor to September.

However, the results of the jackknife classification revealed that 62% of buoys were c o r r d y

classifie& which is only slightly higher than the results of the ori_&il DFA for September.

I m e h r a f e Îndicarors of wastauarer discharge

In order to develop usefil models of invertebrate response to wastewater discharge,

direct linear relationships benueen invertebrate abundance and Fecal coliform concentration

were tested using multiple regession anaiysis, for each of the sampling dates (table 1.3).

September invertebrates were found to have the best lin- relationships since rhey had

relatively hi$ adj. R' and Iow residual mean squarecf enor (table 1 3). F e d coiifonn

concentration in September could best be prediaed from nematode, chironomid and other

Diptera density (logio nansformed) and from the density of all invertebrates in the size class 8-

16 pe (logto aandormed). Density of all invertebrates in May also had a mong positive

relationship with coliforms (table I .3), but this relationship was strondy influenced by one

parricdariy low density value.

Environmentai correliztes of imertebrate c o m m n ï ~ m~cture for September

1) TaxomtnÏc composition

hvertebrate assemblages found in September were numencdy dominated by

Nanatoda ( 4 5 000 ind-m**), followed by Cbironomidae (-8000 ind-m-') and Okochaeta

(4000 ind-ni2). Biornass of these comrnunities was mainly composed of Chironomidae

(450 mg D M - ~ * ~ ) , Ephemeroptera (- 120 rns D M - ~ ' ~ ) and -4mphipoda (120 mg DM-~-?.

Periphyton biomass, current velocity, and suspended marrer concentration were the

strongest environmental correlates of taxonornic composition of assemblqe c hanse on buoy S.

The first two orthogonal vectors of a principal cornponent anaiysis of the tâuonornic data

(density of individuais per taxa for each site) explained 59% and 19% of the variability,

respedvely (fig. 1.4; see loading in appendix G). The first vector (factor 1 ), representing

overail invertebrate abundance, was pontivety corretated to periphyton chlorophyll a and

~spended maner (n=18, ?= 0.80, RMS4.2, pc0.001). The second vector (factor î), an index

of taxonomie composition, was positively correlated to current velocity and to suspended

matter (n= 1 8. ?= 0.8 5, RMS=O. 1 5, p<O.OO 1). Therefore? buoys widi higher concentrations of

suspended matter and hi-er current velocity had higher relative abundance of Chironornidae

and Ephemeroptem whereas mes with Iow suspended matter and Iow m e n t velocity had

hi&er relative abundance of Acarina, Amphipoda and Copepoda

.Assemblages fiom upsaearn sites in the Beauhamois Canal (goup 1) were distinct

Eom other groups of buoys and were charaaerited by a Iower invertebrate density and higher

relative abundance of Amphipoda (fig 1.4). Two of the Monacal Maur assernbiaszes - (fK

nght in fio. 1.4) were ais0 distinct f?om the other sites by the very hi& abundance of

nematodes, ,pivins them a higfier score on fiaor 1. The assemblases ffom the odier Montreal

Harbour and Seaway coliform groups did not fonn distinct groupins based on taxonomie

composition and total density. The two buoys located in the W C o u d 3 einuent plume

@oup 5) e?chr'bired a very simiIar abundance and composirion. but are iïke orher wembtages

in their intermediate totd density and higher relative abundance of Chironornidae and

Ephemeroptem

Patterns in invertebrate density and composition for each of the other sampling dates

were al1 si-gificantly correlated to ash bee dry mass of penphyton, according to PCA and

multiple regession analyses.

2) Size distnbzition

Approximately 10 800 invenebrates, collected in September, were rneasured for the

purposes of relating size diaribution to environmental charaaenstks. Invertebrates spanned 19

Logarithmic size classes ranging From 0.016 pg (approhate body lengh of 0.25 mm) to 4 mg

dry mass (- 1 6 mm).

Density in dl size classes tended to be higher at sites with hi&er coliform concentration

(fie. 1.5). Upmearn average ske distribution had very h i e or no invenebrates in the mail size

classes (< 1 pg) and a low peak of invenebrate density (-300 ind.m-'). Buoys located in the

MUC outfidl e£Eiuent plume supporteci an average size distribution with a much higher density

peak (-3 200 ind.niz) and a hi&rr overd density per Ne class than upsneam and Seaway

~roups. except in the very mail body Nes (< 0.1 pg), where Seaway assemblages had higher C

denskies (fie 1 5).

When size dimibutions were separated into average relative abundance (%) of the three

or four mosî dominant taw in each f d coliform p u p , dÏf5erences mono the groups were

fkther highlighted (fig. 1.5). Trichoptera and Arnphipoda, which were numerically important in

the medium and large size classes upstream ( 14000 pg), were gradually replaced in Seaway

and effluent groups by Nematodq which became increasingly dominant in the s m d size classes

(< 2 pg). Oligochaeta, which occupied the s m d to medium size classes (1-8 pg), and

Chironomidae, which essentially dominated the medium to large size classes (4-1 000 pg).

SÏze distriiutions were siyificantly related to periphyton abundance. suspended matter

concentration, cunent velocity and ammonia concentration (table 1.1). Increases in penphyton

biomass were associated with increases in overdl invertebrate abundance and a slight shift in

the p d toward smaller size classes (fig. 1.6). Similarly, hi& suspended matter concentration

was correlateci to higher abundance of invenebrates and a more peaked response in the shape

of the sue disuibution. which flattened under low suspended matter conditions (Be. 1.6).

Invertebrate abundance in d l size classes decreased with increasine curent velocity and

decreasing ammonium concentration (fis 1.6).

Discussion:

St. Lawrence River water quaiity differed spatially and seasonally in 1995 in relation to

effluent discharge (ne aux Vaches and ne Charron) and to n o m sewer overfIow (Montreal

Harbour and south shore). Although f d coliform concentration spanned five orders of

magnitude (< 3 to >20 000 UFC/100 rnL) and generaily exceeded the provincial environment

rninistq pidelines for water consurnption and/or nvimming (c 3 and < 200 L?FC/100 mL.

respectively) (MEQ 1990). coliform levels decreased to < 200 UFC/100 mi. in Montreal

Harbour in September (table 1.1. flg. 1.2). This change in water qudity coincided with Iow

rainfdl and final diversion of collectors fiom the harbour to the MUC treatment piant. Nutrient

!except for PO1 and NOZ + NO:) increases and water clarity (e.g. Secchi depth) demeases,

which were within narrow ranges (e.g. TP 10-25 p-fi), were stron@y correlateci to colifonn

concentration. Thus. fecal CO iiform levels provided a usehl proxy meanire of wastewarer

exposure and a simple critena for eva lua~g water quaIity.

hvertebrate responses to wastewater exponire were similarly weak amone samplin_e

dates according to DFA (jacldnife classification), which classified buoys correctfy 44-6 1% of

the time. Likewise. DFA dassitication on the more mature invertebrate assemblages coiIected

in September yieided only slightly bener clasnfication (62.6) once cornecteci for the shift in

coliform goups in the harbour. DFA classif?cation may also have been less reiiable for May

assemblages because of the low number of sites sampled. In CO- the regession models

predicting coIiform concentration b ased on invertebrate den* sugsests stronger responses

for September assemblages because of die tighter ünear rdarionships. Coincidemally,

invertebrate measurements made in September probabIy offer the mon information since they

integrate the cumulative effects of water pollution events since ice breakup, such as storm

sewer overflows and increased efnuent discharge following rain aorms (Cook, 1976. Cairns et

al. 1993, Rosenberg and Resh 1993).

The degee to which invendrates responded to wastewater exposure was consequent

with the results of VIS (1997). who studied the suitability of using periphyton colonizing buoys

as indicaton of water qudity for the same buoys over the same time penod used in this nudy.

She concluded that natural seasonal variation was much more important in determining

abundance and composition of periphyton than was wastewater discharge in the St. Lawrence

River. The weak responses of invenebrates and periphyton colonizing buoys may cenaidy be a

result of Iow pollution levels in the river. but they rnay also be due to the selective colonizatîon

(Rosenberg and Resh 1982), by more tolerant organisms of these substrates andior unmeasured

contamination in upnream &es reducine the s iga i created by wastewaten.

Strone seasonal changes in the density and composition of invertebates were dso

obvious. The averaze density of invenebrates collecteci frorn buoys placed in the water 1 û-15

days eadier in May was much lower (by two orders of ma-&de) than it was during the other

rnonths. when average d e d e s remained at similar levels (32 20063 100 ind-m"). Xs w e l

considerable shifts were noted throughout the season in the dominant taxa of the assemblqes,

as chironomids _-du* yîelded to nematodes as the most abundant taxa (6s. 13).

Unfortunately, invenebrate colonization d y r d c s on artiIiciai substrates, and on

buoys, for that matter, rernain relatively unknown and seem to be very condition specific (Le.

habitat, type of submate and time of year), (Rosenberg and Resh 1982, Casey and Kendall

1996). Until such Orne as multi-year data on invextebrate buoy assemblages are available, the

existing evidence leads us to beiieve that the narrow environmental gradients found in the

waters of the St. Lawrence may not be so severe as to upset naturd patterns of succession.

This could also pmly explain why no mong responses were detected in previous benthic

assessments in the St. Lawrence River (Feraris 1994, Cattaneo et al. 1995. Pinell-Alloul et al.

1996, W~llsie and Coaan 1996, 1997). Events which may have influenceci colonization

patterns were the initiai environmental conditions (e.g. the timing of ice breakup, seasonal river

discharge: Vis 1997) and water temperatures (Rosenbere and Resh 1982), which likely were

important determînants of the development of orgmic biofilm. This biofiln which provides

invertebrates with habitat (or structure on smooth surfaces) and tesources (fun@. algae,

bacteria, and detrinis: ;Uan 1995), may ultimately determine invenebrate colonization dynamics

on clean buoys (Rounick and Winterbourn 1983, MacKay 1992, Casey and Kendall 1996).

Not surprisin&. spatial dimibution patterns in September invertebrate composition

and sùe disnibutions were sron& correlateci to periphyton biomass, suspended maner, and

ment velocky. Epiphytic ai- protide texture (heteroeeneous habitat) to the buoys and are

an important food source to -gazer invertebrates (Man 1993, Merrit and Cummins 1996).

Suspended matter in the river water also serves as an important food source for invertebrates

(Anderson and SedeU 1979), Nice it contains fine particdate o w c rnaner (Palmer and

OKeefe 1990) which is consumed direnly by nIter feeders. such as cas& caddifies, or which

accumulata in the periphyton and consumed by collecter-gatherers such as chironornids

(Merrit and Cummins 1996). The sipifkant positive relationship between invertebrate density

(factor 1) and suspended matter and periphyton suggests that invertebrate assemblages found

on buoys are limited by food resources. At the same time, stronger water currents may be

removing periphyton and prwenting certain invertebrates, such as amp hipods. acariaw and

copepods from attaching to buoys (Allan 1995). SwiAer currents may also provide filterers

with a greater nipply of suspended particulate organic matter.

The response in size distribution to organic enrichment (increased density in al1 size

classes), in our study. is different from what Bourassa and Morin (1995) and Morin et al.

(1995) found in temperate Canadian streams. They describeci an increase in the abundance of

large invertebrates only (> 1 pg) with increasing uophy in these srreams. To es~fain their

observations, Bourassa and Morin (1 995) nig~pen that Iarger invertebrates may be better

cornpetitors and can sequester food and/or space in eutrophic tondions, or that large

invertebrates are resource limited. In Our case, it seemed apparent by the increase in density in

aU size cIasses that invertebrates of ail sites were resource limiteci. Merences in sire

distribution responses between midies could also certaidy be due to environmental conditions.

nich as higher current velocities in the river and hi@r TP rance in streams. the t e m e of

substrates (MacKay 1992, Way et ai. 1993), or the distance between the buoys and the river

bottom and littord zones where these invertebrates are found. Since studies on benthic size

distributions are scarce and in their eady developmental nages, unWre pelagic stu&es (Strayer

199 1, Rasmussen 1999, these arguments remain speculative.

Taxonomie rneasures performed ody slightiy berter than did Ne-baseti metrics in their

responses to environmental impacts; DFA classifieci taxonomic composition and size

distnibution into coliform groups at a rate of 56% and 44%, respectively. To Our knowledse,

only one midy has compared size-based with mon-based responses to water quality, and this

for periphytic algae colonking macrophytes in the St. Lawrence River (Cattaneo et al. 1995).

Their r d t s showed that toxkological and ecological variables bener explain the variability in

size distributions (6 1.3% f h m 5 size classes) than the taxonomic composition of dgae (37.3%

from broad tavonomy and 37.1% from the species Ievel). On the other hand, Rodnguez and

Magnan (1993) and Bourassa and Morin (1995) found that N e distributions of invenebrates in

Iakes and streams were surprisingly invariant across submte types compared with the geat

têuonornic changes that occurred. In our study, r e l a ~ g patterns in Ne distributions to

physicochernicai parameters appeared to yield no additional information beyond taxonomic

composition, as both cornmuniq measures were related to the same characteristics of the river

(except for ammonium). However, cornparison of the size distribution of dominant taxa (fig.

1.5) pronded us with a bener understanding of the cornmunity changes taking place dong this

mdient of wastewater discharge. For rnonito~g puposes, size distributions usine whole Ci

comunities are probably not very us& unless used as tools to estimate secondary

production (Morin and Nadon 199 1) or used in models of energ and contaminant trophic

&ers (Griesbach et al. 1982, Vézina 1986).

Conclusion

Irnponant difFerences in water quality were observed at sites around the Island of

Montreal and downstream of emuent ounalls, resulting in a wide concentration range in fecal

coliforms (< 3 to > 20 000 UFUlOO mL) and a narrower concentration range in total

phosphorus (lû-25 p a ) , ammonium (6-1 35 &L), nispended solids (1 - 4 4 . 5 m-elL) and

water clarity (Secchi depth 73-20 m). Invertebrate assemblages underwent strong seasonai

changes and responded weakly to wastewater exponire, since DFA classified 44-6 1% of buoys

in the correct fecal colifom groups for al1 sampling dates, based on taxonomie composition

and size distribution. The best indicaton of urban wastewater exposure were total d e n e of

invenebrates in spring de- of invmebrates in die N e class 8-16 pg in September and

chironornid, nematode and other Diptera den* in September. Chan- in invenebrate

composition and N e distribution in September were both primady related to suspended matter

concentration, periphyton biornass and current velocity. The lack of strong., obiious responses

Born invertebrates colonking navigation buoys in the St. Lawrence River, throughout the

samplino season., Limits their imponance as semitive mdicaton of wastewater to their present

levels of eqonire.

Tables and Figures

Fig. 1.1. The sampling sires in the Beauhamois Canal (upmeam) and the green water m a s of

the St. Lawrence River in Montreal.

Table 1 . I . Mean (SD) p hysico-chernicd characten'stics for five groups of buoys b y water

quality. measured throu&out the sarnpling season. Groups are based on fecd colifom

concentration (UFC/T O0 mL).

Water quaiity group 1 2 3 4 5 (fd mliforrn range. (< 3) (3-200) (2003000) (2000-20000) (> 20000) UFU10Oml~

MUC Location

Light transmission coefficient

12

286 (1 4)

0.77 (O. 14)

0.35 (0.06)

7.3 (3.1)

1.4 (0.6)

455 (75)

233 (30)

6 (4

3.1 (2 -2)

L O

(3

4.9 (5 .O)

0.55 (0.38)

m u r Sept 1993

6

272 (3)

0.92 (O 28)

0.46 (0.03)

4-0 (0.4

2.0 (0.3)

707 (34)

187 (10)

1 O (2)

1.1 (O -3)

13 (2)

7.3 (4.9)

0.54 (O -10)

Seaway and Harbour

24

365 ( 1 7 )

1 .O 1 (0.32)

O .a (O. 18)

2.1 (1)

3.8 (1.5)

53 1 (3 83)

196 (76)

11 (4)

4.8 (2.2)

15 (4

5 7 - -- (4.1)

0.74 (0.50)

Seaway and downstream of MUC efEIucnt

13

247 (28)

0.79 (0.36)

0.53 ( 0 2 6 )

2.0 (0.8)

4 2 (1.5)

1345 (665)

73 1 - (8 1)

6 1 (72)

5-7 (2.5)

20 (4)

3.5 (3 -9)

O -19 (0.36)

cffiuent

7

275 ( 10)

1.22 (O. 18)

0.75 (0.32)

2.3 ( 1 2)

4.5 (1.9)

1155 (5 3 8)

2 13 (78)

135 ( 5 2)

a. 1 (1 -3)

25 (8)

3 -3 (2.5)

0.65 (O -46)

Table 1.2. Pearson correlation coefficients, dong with their p-values, for the correlations

between fecai coliforni concentration and the physico-chernical variables, for each of the

sampiing dates.

Ligh t transmisston coeficient

Dissolveci i n o r p i c p hosp horous (pg/L)

Totai phosp horous (W)

9

0.003 ( 1-00)

0.63 (O. 70)

-

-0.92 (0.005)

O .96 (X0.00 1)

O -96 (<O.OO 1)

4 - 9 8 (<O.OO 1)

0.76 (O 2 1)

0.9 1 (0.0 L)

0.37 (0.03)

0.8 1 (O. 10)

0.96 (<O.OO 1)

13

-0.52 (0.3 1)

O -29 ( 1 -00)

0.71 (0.0 t)

4 . 7 8 (0.002)

0.57 (O. 16)

O. 80 (0.00 1)

O. 10 ( 1-00)

0.00 (O. 10)

4.30 (1 -00)

0.80 (0.00 1)

-0.09 (1.00)

4.12 ( 1-00)

0.58 (O. 14)

Fig. 1 -7. Average (=SE) total phosphorous, suspended matter and fecal colifom

concentrations for rhree re@ons of the St. Lawrence River for each sarnpling date. Efnuent

refen to buoys immediately downstream of effluent outfall. Harbour (n=j), etnuent

(n=2) and upstream (n=3).

A Effiuent dume

U pstream r

Effluent plume

1 U pstream 1 a

w 0 : I L l

t

May June August Septem ber

Chironomidae

I

May June August Septem ber

Fig. 1.3. ReIative densit); (%) of dominant tava throu&out the sampling season (n=9 buoys

for May. n= 1 7 for June. n= 1 S for AU-gst and n= 1 8 for September). Note the shifi in

dominance of Chironomidae to Nematoda nom May to September.

Table 1.3. Multiple regression models predicting fecal coliform concentration (iogto

transformecl) from invertebrate taxa densities for each sampling date and fiom size ciasses for

September assemblages.

Regression model parameters prediàing fecal coliforni concentration (logto) t (pvalue) n RMS P adj.^'

May 9.38 4.59 (0.003) 9 1.28 0.01 0.58 + 4.72 l~g~~(Chirnnornidae) 3.47 (0.01)

9.50 + 5.02 logTo(total density)

June

Aug ust

Septem ber

-5.60 4.00 (0.001) 18 0.67 c 0.0001 0.65 + 2.75 l~g:~(density size dass (8 - 16pg)) 5.72 (<0.001)

C hironomidae Ephemeroptera

Amphipoda I

Acafina i I Copepoda !

MUC effluent plume a n

U pstream

P

and

1 -2 1 I

4

-2 -1 O 1 2 3

Factor 1 General abundance

Fie. 1.1. PCA factors 1 and 2 showing the ordination of buoys (n=I8) based on dentity (lo_gio

transformed) of the 9 hvertebrate taxa sampled in Septernber 1995. Factor 1 is an index of

overail invertebrate abundance and factor 2 is a ratio of Chironomidae +- Ephemeroptera /

Amphipoda ..carha - Copepoda (CUAAC). CircIed groups of buoys represent water

q u e goups upmeam. Seaway and harbour and effluent plume. Other points

represent 3 sites M e r downmeam of W C effluent and 3 upmeam harbour sites.

Fie. 1.5. Average size distributions of invertebrates belonging to three çgoups o f buoys by

water quality, sampled in September 1995 (n=5 buoys for upnream, n=j for Seaway and n=2

for effluent plume) (upper panel). Average relative density per sue class (%) o f the three or

four mon dominant taxa of September assemblages. for the three water quality roups (lower

panels).

1 upstream Chironomidae

0.8 Seaway and harbour

i 0.6 1 I

0.4 Ï l

! 0.2 i

!

l 0.0

Chlorophyll a

Current velocity

I

- a \ l

; 1

Suspended matter I I

1 -

I 1

1 Ammonium

Fig 1.6. September 1995 N e distributions predicted by polynomid mode1 (table 1.4) for low

and hi& values of each parameter, while maintainine other parameten at average Ievels. Note

the weak sensiri+ of invertebrate size dimibution to ammonium, in spite of considerable

(15x) increases in concentration.

Table 1 . 1 . Polynomial reqression model, for September 1995, describing invertebrate density

(log10 uansformed) per size ciass (ind.m'2) as a fùnction of dry m a s (M in pg dry mas),

chlorophyll a (Chla, in pg m-'), suspendeci maner (S, in me@), currenr velocity (C, in m set)

and ammonia (Nb in p-fi) (11443, 24.65, RMS4.09). * p c 0.000 1.

Independent variable Coefficient (standard error)

Intercept 1.700 (O. 137)*

( L q i o MY O. 123 (0.020)*

Looro Chla 1.717 (O. 119)*

Logl. Chla x (Loglo M)' 4.156 (0.03 1)*

(Logiu s)' 1.977 (O 186)"

Los10 S x Log10 M 0.366 (0.029)*

L O ~ ~ I O S X (Logio W' -0.255 (0.027)*

(Logio c)' -1.383 (0.302)*

Los10 h'H, 0 - 3 1 (0.047)*

Chapter 2:

Patterns in invertebrate and penphyton size distributions from navigation buoys in the St. Lawrence River

ï he potential use of benthic size distributions for making community structure

comparisons arnong ecosystems (Strayer 199 1, Cattaneo 1993, Poff et al. 1993), predictions

about aquatic processes or components (Borgmann 1987, Boudreau and Dickie 1992) and for

use in environmental assessments (Cananeo et al. 1995, Morin et al. 1993) has ofien been

nated. However, the scarcity of benthic size distributions data and predictive models have

impeded the routine use of benthic size dinniutions as an alternative or complementary

measure to taïonomic descriptions of aquatic orgm.isms. Quantification of seasonal and spatiaI

variability. in relation to environmental characteristic is. therefore. essential to the

undemandi- and practicai use of size dismbutions (Morin et ai. 1993).

There are considerable merences in the amplitudes and shapes of the few existing

benthic sire dismbutions among midies and ecosystems. Unirnodal (Strayer 1956. Morin and

Nadon 199 1, Rodriguez and Magnan 1993, Bourassa and Morin 1995), bimodal (Carraneo

1987, Poff et al. 1993, Rasmussen 1993) and trirnoQl disrniutions (Schwinghamrner 19s 1)

with diffkrent peaks and troughs have been found in lake. stream and marine littoral ecoqgerns

(see Cartaneo 1993). These differences may not only be due to environmental consrraims

(Schwinghammer 198 1 , Warwick and Joint 1987) and/or evolutionary history (Strayer 199 1)

but to rnethodolo@cal differences, nich as or-gm.ism N e ranges examined (Poff a ai. 1993).

trophic goups sampled (Le. zoobenthos ody) and different gaphical representations leadhg to

varyins condusions (Le. non-Iogarithmic scales. Hanson et al. 1989). Some of these

merences were reconaled in temperate North Xmerican streams, when size disaibutions were

conaruaed from organisms spanning a wide range of body sizes, which inciuded protozoans,

algae and macroinvenebrates (Cattaneo 1987, Morin and Nadon 199 1 and Cananeo 1993).

These distributions were found to be very similar to pelaijc distniutions (Sheldon et al. 1972,

Spmfes and Munawar 1986, Ahrens and Peters 199 1) with rou-&Iy even biomass in

loprithmicdly increasing sYe classes and a normalized size distribution (log densis, per size

class) wit h a dope of approlumately - 1.

.Althou& size distributions for pelagic assemblages compnsing aleae. protozoa and

invertebrates appear similar arnong sites and across ecosystems, there is a subnantial amount

of variability from the smooth linear trend. It is this variability. according to Sprules and

Mtnawar ( 1956). t hat may contain information about anthropogenic impacts. It is therefore

important to examine the effm of season and environmental factors. not only on the senerd

nqative trend berneen nomalïzed biomass and orgmïsm body mass, but dso on the

synematic dwiations fiom diis senerd trend.

In this paper. the seasonal and temporal patterns in invenebrate and aleai N e

dimiutions From navkptional buoys sampled over a trophic -nadient in the Montreal area of

the St. Lawrence River are investisated. Sire spectra observed on buoys are then compared to

previously descnied N e distributions. L a d y , their usef5hess as descripton of aquatic

comrnunities for entironmentd assessrnena is discussed.

Methods

Sm+ mea and sampling

Detailed descriptions of the study area sampling design and protocol are found in the

previous chapter and in V i s ( 1997). Invertebare and algai N e meanirements were taken from

4 buoys on May 7&. 5 buoys on June 7&, 6 buoys on .2ugun ln and 6 buoys on September

26'h, 1993. These buoys were chosen to represent the widest trophic gradient possible in the

Montreal area of the Sr. Lawrence River (a 5 - 28 us$-' range in total phosphorous).

I'enebrate md algae collection and procem-ng

Invenebrate processine and meaninne, dons wkh physicd and chemicai water

measurements were conducted in the same manner as in the previous chapter. Due ro time

required for slide preparation and deal identifications. the 3 subsamples of material collected

kom buoys intended for algai meanirements were combined, hornogenized and subsampled

(Vis 1997). Therefore. al@ meanirements are based on 1 replicate per buoy per date,

whereas invertebrate estimates have 3 replicates.

.Usal ceUs were counted at 640X and 160X in randorn fields usine a Zeiss inverteci

microscope. kvi th 0.4 - 5 mi subsamples depending on alpl de* (Vis 1997 and persond

communication). Fiamentous dgae (e.g Cladophora) were coumed under a dissecthe scope

at 6.6X using whoIe samples (- 600d). The [en-mh and width of individuai ceUs were

meanireci using an base anaiysis *-stem connecred to the microscopes. .Al@ volumes were

dculated by approximation to known p m e t r i c shapes us iq mean species la+& and width

(Vis 1997). Each dgd filament (e.g. Clodophora) was treated as an individual, as it was done

by Cattaneo (1 987) and VIS (1997). Therefore, estimates of al@ volume represent whole

colonies and not individual cells within filaments. However, some measurement error in

lengths of individuals are undoubtedly due to fiapentation fiom bnishing and sonication

during sampling. In order to reduce this error, the lengh of each individuai was considered to

be equal to the average filament Iengh of each sample (Catraneo 1987).

Ce11 volumes were convened to wet m a s by mulr iplyin~ volume (p?) wirh 1 9epm''

(specific density of aquatic ooanisms. Schwin$armner 198 1 and Cattaneo 1993) and to dry

mass by dividine wet mass by 1 (Cummins and Wuycheck 197 1). Density and biomass of

orgnisrns was detemined by dividing the number of or~anisms and total dry mas of

orgmisms by surface area of sarnpler (45cm2).

Invenebrates and algae were gouped into 1 1 Iogarithmic size classes which correspond

to an 8-fold increase in individuai dry mass or a doubling of "equiialent sphericai diameter'

(ESD) (Cattaneo 1993) and ran_ee in size fiom 1 0 ~ to 10' p,e DM (fi-me 1). Larger size

intervals were used to quanti@ size dianbutions in this chapter in order to reduce noise due to

meanirement error (Ahrens and Peters 199 1) when cdculatiq ai@ densiry per N e class

based on average species N e and not individual N e .

SfafisticaI mulyses

.As in chapter 1, the effects of environmental characteristics on the amplitude and shape

of the N e distniutions of the invenebrates and algae were assessed by fi- their

distributions to polynomiai regession rnodels (Bourassa and Morin 1995). These models

included rems such as TP and suspended matter to test for physico-chernical effects on

density, regardless of size class. as wzll as interaction terms between logtoDM and

environmental factors which tes for size dependent chanses in density.

Monte Carlo simulations were mn to estimate Our ability to detea changes in size

distributions in response to TE? To senerate simulated data sets. we used the regession model

to first predict the logio density in each size class for each buoy. We then added a normaily

distributed error term with a mean of O and a variance equal to the RiMS of the regression

model. To this randomized predicted density, we tindly added hypothetical trophic effens in

various scenario. In one of these xenario, for example. we increased density in al1 size classes

y 50041. over the observed 5 - ZS pz TP -pdient. For each analysis, we snerated 500

simdated dara sets and counted the percentage of rimes TP was sipificant in the regession

modeis.

Results and Discussion

Ngae and invertebrates measured to describe size spectra, ranged in N e from 1 o4 to

1 O' pg dry mass (fie. 2.1). Diatoms (Bacillariophyceae) and blue green algae (Cyanophyceae)

occupied the smdlest size classes ( 10" to 10'' pj), whereas green aigae (Chlorophyceae)

spanned 6 orders of mapitude in size From 10" to 10 pg. The filamentous aigae, CIadophora,

was found in the laqest classes (10 to IO' pg). Invenebrates occupied the 10" to 10' pz s i x

classes.

Biomass was not evenly distributed among size classes but average values in moa

intervals were generally within an order of ma-intude of the geometric mean biomass for each

sarnpling date (fis 2.3. Biomass in three size classes were consistently lower than the

reometric mean biornass. corresponding to organisms < IO" and between 0.004 and 0.160 pg C-

DM for each sampline date. This trou- beween large non-filamentous aleae and small

invertebrates rnay correspond to ciliates. which can be hi-dy abundant in areams (Bon and

Kaplan 1989 and Cananeo 1993) and ranged in N e fkom lo4 to 0.26 pg DM in Laurentian

Sneams (Cattaneo 1993). Rasellates may also have overiapped in N e with the mailest algae

(< 104 pe DM) (Bon and Kaplan 1989). Udortunately. ciliates and flaeellates were not

quantified in this m d y but their presence on buoys were obsewed when dgae samples were

counted (C. Vis personal communication); it is unlcnown whether inclusion of protozoans

would have produced more even biomass distributions.

Seasonal changes in the biomass occurred between spring and fall of 1995. Some of

the successional events which can be reIated to these changes include slower invertebrate

colonization relative ro unicellular algae (in May), potential zazing of algae by invenebrares

(June) and the development of filamentous algae, predominantly CZadophoa, in August and

September (fig. 2.2). In May. overall biomass was hi& (60 1 2 2 3 mg m") and mainly

composed of non-filamentous algae (585914 mg rn*'). In June, aigai biomass was much lower

( 11 1 = 1 O 4 mg rnS2). whereas. invertebrate biomass was considerable higher (Z?= 117 me m")

than in May (see larse size classes. fig. 2.2). In August and September, filamentous aigae

(mainly Cladophoru) had developed resulting in an increase of biomass in the large size classes

(> 16 pg DM). Overall biomass Ievels in . \ugst and September (61 El77 and 685f95 mg

-9 m '. respectively) were comparable to those found in May.

Density distributions (or nomalized biomass spectra) of buoy assernbla~es. for each of

the sampling dates. were best described by fourth and fifth order polynornids (fig 2.3). These

dimiutions had similar shapes throughout the sampling penod aithou& variability in density

per size class increased in the mid to large size classes (> IO*' pg) nith the . The difficuities in

edat in_e the density of algai filaments and assi-dg them to their proper N e classes

undoubtedly contribureci significantiy to this vm-ability. The founh and fifth order curves that

were fined to these data are probably not representative of the curves that would nomalIy be

observeci if ail orgmisrns (including protozoans) witftin the ske ranges sampled had been

quantified. Cananeo ( 1993) fitted linear regessions to her benthic disuibutions. as in many

peIagic studies (e.g Sheldon et al. 1972, Spruies and Munawar 1986 and Ahrens and Peters

199 1), with slopes rangng from 4 - 9 7 to 4.81. However. regession residuals were probably

highly correlated due to the presence of peaks and trou& in her distributions (Rasmussen

1993 and Morin et ai. 1995). therefore, higher order polynomial regressions may have provided

better fit in some cases.

Environmentai conditions apparently were not important in derermining size

distributions since none of t he p hy sico-chernical parameters significantly improved the fit of

polynomial models descnbing size distributions (table 2.1). Monte Carlo simulations revealed

that our ability to detect changes in size distribution related to TP was low. Density in al1 size

classes would have to increase by Xoid over the observed TP range for 5006 chance of

detection, and by 5-fold increases if only the 5 Iarger size classes were affected. When

applying the mode1 developed by Bourassa and Morin (1995) for Eastern Canadian streams

over our observed 5 - 28 ~JL-' range of total phosphorous, only a 1.1 - 1 -8 fold increase in

density. in response to this increase in TP, would be expected. Therefore. given the residuai

varÎation of our polynornial models. the chance of detectine trophic effécts on size

distributions. if they e'cist, were low.

Size distributions of algae and invertebrates colonizing buoys were visually compared

with the mon complete published benthic distributions, which containeci protozoans.

macroinvenebrates and epiphyton found in lakes (Cattaneo 1987), streams (Cattaneo 1993)

and marine littoral areas (Schwin&arnrner 198 1) (fie 2.4). Our size dismiution had similar

abundance in most size classes. except for the obvious trou&s in the nailest class and the

midde size classes, which probably correspond to missine fl agellates and ciliates, respectively.

These mong nmilarities despite ciearly different species assemblages. across eco-stems and

subsuates, suggest nrong size based constraints on comrnunity organization and resource

allocation (Petm 1983). Environmental conditions, therefore, seem to be of lesser importance

in determining benthic size distribution. especiaüy when quanti.ng a broad size range of

orsanisms.

The difficulties in detecting syaematic deviations related to Montreal area trophic

mdients (or wasrewater discharse). along with the apparent similarity of size spectra across C

ecosystems imply that they are not v e q useh1 or practical community meanires to assess

ecological chanses in the St. Lawrence River. In order to obtain higher measurement precision

ro increase the chances of detecting trophic effécts, if indeed they exist. more data or more

precise data (e-g. reducing measurement error of CIadophora filaments) would be required for

natinical anaiysis. The only way to achieve this level of precision would be to conduct more

field sarnpling and organism measurements. even in studies such as this one where nandardized

habitats were used to d u c e sarnpling noise (Rosenberg and Resh 1981). However. these

effon may be much more labour intensive than rneasunng other potentially more sensitive

components of the benthic assemblases, partinilady in situations of low levels of pollution

which elicit subtle responses. For example, size dimibutions ofparticulat trophic ~ o u p s (eg .

epiphyton or invenebrates) May be more responsive to environmental conditions (see chapter

1. Bourassa and Morin 1995. Cananeo et ai. 1995) because these organisrn share similar

ecolo@cal limitations (e.g. particulate orsanic matter for invenebrates) or are physiologically

susceptible to pam-cular messors ( e . ~ . herbicides). Akematively, the use of size distributions

of partïcular taxa (e.g. Baetidae t d y of Epherneroptera) which are evpected ro be

particularly tolerant or sensitive to changes in water quality would probably be more sensitive

and Iess labour intensive (S. McKee personal communication). Future research in integrating

size distributions with environmentai assessments should probably focus on the 1 s t approach

to maximize our ability to detect ecosynem pemrbations.

Tables and Figures

Table 2.1 . Polynomial regession mode1 parmeters descnbing invextebrate and algae

looiodensity per size class (ind. mm') as a funaion of dry Mass (34, pg ) (adj. ~'=0.83.

k M S = 1 . 23 , n= 198). Note that TP and the interaction TP*M were not significant parameters

in the model.

Independent variable Coefficient P (standard error)

lntercept 5.22 (0.25) <O. O00 1

Lo~to M -0.52 (O. I l ) <o. O00 1

( L o ~ i u M' 0.38 (0.04) <O. O00 1

(Lo_oio My -0.02 (0.01) <o.ooo I

Cyanop hyceae

Chlorophyceae

Nernatoda

Chironomidae

Copepoda

Oiigochaeta

Amphipoda

Cladophora

Fie. 2.1. Size ranses for dominam groups of or-ginimis found colonizino navigation buoys.

The ChIorophyceae g o u p does not include Cladophora.

Fig. 1.7. Average dry biomass (SE) of orgmisms per size class (lefi panel) and average

biomass of invertebrates (empty bars) and aige (filled bars) per size class (right panel) ( n 4 in

May. n=4 in June. n=5 in Aupst and n=j in September). The reference line represents the

eeometric mean biomass for sach date. -

1 June -

600 August n

Septem ber -1

May June 12 12

Y =3.20 -1.01X ' Y = 3.92 + 0.13 X* i

Septernber 12

- -

U) t August C; 12 -

O Y = 3.24 + 0.56X2

F i 2 Density ofinvertebrates and dgae per N e class colonizing buoys for each sampling

date in 1993 (n=4 in May, n=4 in June, n=5 in .4uCIeust and n=5 in September). The h e

represents founh and fifth order hear regressions. The symbols 0 O A A . are in order of

ïncreasine trophy.

+ Laurentian strearns 1 -P Lake Memphremagog 1

1 / + NOM Scutia littoral 1 1 + 3. Laurence buoys i

Fie. 3.4. Size dimibutions of invertebrates and d ~ a e from St. Lawrence River buoys and

protozoans, dgae and macrokvertebrates 60m lakes (Cattaneo 1987), marine littoral zones

(Schwin-ghmmer 1951) and temperate meams (Cattaneo 1993).

Generai Conclusions

General Conclusions:

In the first chapter, which dealt specifically with developing bioindicators of Montreal

area wastewater discharge, it is concluded that invertebrates colonking navigational buoy s are

of lirnited use under the current Ievels of exponire. Even though f e d coiifom concentration

associated to wastewater discharge increased by 5 orders of magnitude, environmental

parameters nich as nutnents (TP, m) and water dari- (Secchi depth, suspended rnarter and

light extinction coeficienr) varied only 2-10 fold. These narrow environmental gradients

coupled with the possible selecrive colonkation of buoys by more tolerant assemblages. could

be responnble for the small responses of invenebrates to wanewater discharge.

In the second chapter, the potential use of size specrra of aleae and invertebates

colonin'n_g buo. as community measures for wemblage response dong a rrophic -=dient was

examined. Size distributions were found to be of limired use for this purpose since physico-

chemicai parameters of the river water were not si-gificantly related to changes in N e

distniutions. Monte Car10 simulations su~,eest that density would have had to increase 3-5

fold over the observed TI? _-dient (ninosate meanire for trop hy) for the analyses to l ie-

detect significant ef fms. Intereslln@y. size spectra from buoys. which unfominatelp Iacked

protozoans, had s t r i k i ~ similarities with other comp Iete size distributions (containi- algae,

protozoans and invenebrates) fkom areams (Cananeo 1993), lakes (Cattaneo 1987) and

marine littoral zones (SchwÎn@mnrner 198 1). Size distnbutiow of whole assemblases may be

too robun to entironmental conditions for diagnosis in cases where Iow to rnid-Ievels of

pollution persist and do not threaten to impair ecosystems at a Functional level (Odum 1985),

or when sample size is small.

In conclusion. ooanisms inhabiting navigational buoys in the St. Lawrence River fiom

May to September of 1995 ~enerally exhibited weak comrnunity level effects from exposure to

wastewaters originatine forrn n o m sewer overflows and wanewater treatment facilities in the

Montreal area ( s e Vis 1997). when these effects could be detected (see Chapter 2). Fecal

colifoms, which were hamless to biota (Gddreich 1978). provided usefbl tracers of exposure

to wastewaten both spatially and temporally, by reflecting the physico-chernical chanses

associated to wastewater discharge. Furthemore, the weak responses observed in the

bioindicators, referenced by upstream conditions, suggest that natural nvenne communities

may not be senously irnpaired by Montreal wastewater discharge, at least within short time

periods (Le. fiom ice break to ice formation) and amal exposure levels. Efforts to improve

physico-chemkai treatment of wastewaters in Montreal may have been efficient in reducine

ecologcal impact to the Sr. Lawrence River, however, the data presented in this thesis cannot

be used to address this possibility. Future studies should focus on quantifjing the long-term

idluence of urban wastewater pollution on econornically and ecolo~caliy important ooanisms

and to validate the use of biologîcai indicaton in protectino ecolo@cal inte-@y.

Refe tences

Ahrens, M.A. and R.H. Peters. 199 1 . Patterns and limitations in Iimnoplankton size s p m .

Can. J. Fish. Aquat. Sci. 18: 1967-1978.

?illm, D. 1995. Stream Ecoloey: Structure and funaion of running waters. Chapman & Hall.

London.

Anderson, NH. and I.R. SedeIl. 1979. Detritus processing by rnacroinvenebrates in nream

ecosynems. .Annu. Rev. Entomol. 3435 1-377.

.APKA - Amencan Public Heaith Association. I995. Standard methods for the examination of

water and wastewater. .herican hblic Health Association. Washington D. C., G. S. -4.

. h t a g e , P.D., D. Moss. J.F. Wight and MT. Furse. 19S3. The performance of a ne*&

bioIo@cd water quality score -stem based on macroinvertebrates over a wide range of

unpolluted runninpater sites. Wat. Res. 17:333-XT

Barbour. MT.. J. Gerritsen GE. Griffith R Frydenborg E. MeCaron J.S. White and ML.

Bastian. 1996. X hmework for biolo@cal critena for R o d a nreams usine benthic

macroinvertebrates. J. S. Am. BenthoI. Soc 1 j(?): 185-2 1 1.

Ber-pan, M. and R.H. Peters. 1980. A simple reflectance method for the meanirement of

particdate pigment in lake water and its application to phosphorous-chlorophyl1-seston

relationships. Can. J. of Fish. Aquat. SQ. 37: 1 1 1-1 11.

Borgmann, L!. 1987. Models on the siope of, and biornass flow up. the biornass size spectrum.

Can. I. Fish. Aquat. Sci. 34: 136-130.

Boa. T.L. and LA. Kaplan. 1989. Densities of benthic protozoa and nematodes in a

Piedmont Stream. J. X. .Am. Benthol. Soc. 5: 187-196.

Boudreau. P.R. and L.M. Dickie. 1997. Biomass spectra of aquatic ecosytems in reiation to

fishenes yield. Can. J. Fish. Aquat. Sci. 19: 1525-1558.

Bourassa. Y. and .A. Morin. 1995. Relationships benveen size structure of invertebrate

assemblages and trophy and substrate composition in nreams. J. Y. Am. Benrhol. Soc.

13(3):39%O3.

Cairns. I.. Jr.. P.V. McCormick and B.R Nederlehner. 1993. .A proposed Framework for

developing indicators of ecosystern health. HydrobioL 263: 114 .

Casey. RJ. and S A Kendall. 1996. Cornparisons among colonitation of artiftciai substratum

Npes and natural subsvatum by benrhic rnacroinvenebrates. Hydrobiol. 34 1 : 57-64.

Cananeo, A. 1987. Size distribution in periphyton. Can. .J. Fish. Aquat. Sci. 4420252028.

Cattaneo, A. 1993. Size spectra of benthic communities in Laurentian streams. Can. I. Fish.

Aquat. Sa. 502659-2666.

Cananeo, A. and B. Mousseau. 1995. Empirical analysis of the removal rare of periphyton by

m e r s . Oecologia 103 ( 2 ) : î G M X C

Cattaneo. A., G. Méthot. B. Pinel-.Mou1 and T. Niyonseng 1995. Epiphyte size and

taxonomy as biolo@cal indicators of ecolo~cal and to'cicological factors in Lake Saint-

François (Québec). Environ. Pollut. 8 7 3 57-3 73.

CERS. 1996. Monthly nimmary repon for 19911995. Aquacers. Sotiété de gestion du

CERS (Centre d'Épuration de la Rive Sud) Inc. Lonpeîl. Quebec. Canada.

Chambers. PA., M. rU1ard. S.L. Walker. J. Marsdek. I. L a ~ ~ e n c r . M. Sevos. J. Busnarda

K. S. Mu-r. K. Adare. C. Jefferson R A Kent and M.P. Wong 1 997.

wastewater effluents on Canadian waters: .A retiew. tt'ater Qual. Res. J.

713.

Impacts of municipal

Canada 3 z(3): 659-

Cook S.E. 1976. Quest for an index of community structure sensitive to water pollution.

Environ. poUut. 1 1 :268-287.

Counemanch, D.L. 1994. Bridgng the old and new science of biological monitoring. J. N.

Am. Benthol. Soc. iS(1): 117-131.

Culver, D. A.. iM.M. Boucherie, D. J. Bean and J. W. Fletcher. 1985. Biomass of

freshwater crustacean zooplankton From [ength weight r e p s i o n s . Can. J. Fish. Aquat. Sci.

43: 1380-1390.

Cummins. K. W. and J C. Wuycheck. 197 1. Caloric equivaients for investi-ions in rcological

energetics. [nt. Ver. Theor. Anpw. Limnol. Mt. IS: 1-1 58.

Deschamps, G., C. Iuteau and P. Cejka. 1997. Bilan Sommaire des activités du réseau de

suivi écologque de 1990 à 1995. Communauté Lrrbaine de Montréal, Montreal. Quebec.

Canada.

Entironment Canada. 1993. Manuel des méthodes d'analyses (.Anexes B). Regional

Laboratory-Quebec Region. Ecoto>Qcolog and Environmental Chemistry section St.

Lawence Centre, Eniironment Canada Montreal Quebec. Canada.

Environment Canada. 1996. Daîly ffow values for the St. Lawrence. Hydrolog Section

Amosp heric Environment Senice. Quebec Region Montreal, Quebec, Canada-

Ferraris. J. 1984. Maiacroinvertébrés V (Benthos et Invertébrés Phytophiles): Synthèse de

la Variabilité Spatio-temporelle des Macroinvertébrés Benthiques et Phytophiles Récoltés du 7

Avril 1987 au 17 Juillet 1982. Élaboration de la Clé de Potentiel et Description des

Communautés aux Habitats-Types. Ministère du Loisir. de la Chasse et de la Pèche. Rapport

Technique, 368 p.

Fisheries and Oceans. 1992. Marine Fisheries in Quebec - .Annual Statistical Review 1992-

1991. Econornics, Statistics and Informatics Branch. Statistics and Informatics Division.

Québec.

Geldreich E.E. 1975. Bactend populations and indicator concepts in faeces. sewaee.

aormwater and solid wastes. In: G. Berg (Ed.) Indicators of vimses in water and food. .Am

-4rbor Science Publishers Inc.. Ann Ahor. pp.5 1-97

Griesbach. S.. R.H. Peters and S. Youakim. 1952. An allometric mode1 for pesticide

accumulation. Cm. I. Fish. Aquat. Sci. 3 9:727-73 5.

Gurtz. M.E. 1994. Design of bioiogcai components of the National Water-Quaiity

.Assessrnent (NAWQA) Pro-gram. In: S.L. Loeb and .A- Spacie (eds.). Bioiogical monitoring

of aquaric -stems. Lewis Pubiishen. Boca Raton Horida.

Hanson. J.M.. E.E. Prepas and W.C. WacKay. 1989. Size distribution of the

rnacroinvenebrate community in a freshwater Iake. Can. J. Fish. Aquat. Sci. 16: 1 5 10- l5 19

Hart. D.D. 1994. Building a nronger ppamiership between ecological research and biolo@cal

monitoring. J. N. Am. Benthol. Soc. I3(l): 1 10- 1 16.

I ïFM - International Task Force on .Monitoring Water Quality. 1993. Ambient water-quality

monitoring in the United States: Fim year review, evaluation, and recommendations. Repon

to Ofice of Management and Budget. Washingon, D.C.

Inland Waters Directorate. 1990. Water - Here. there and everywhere. Fact sheet No. 2.

Environment Canada. Conservation and Protection. Ottawa.

Johnson, B.L., W.B. Richardson and T. J. Naimo. 1995. Past. Present. and Future Concepts in

Large River Ecolog. Bioscience 45(3): 134- 14 1.

Karr, J.R. 1993. Defining and assessine ecological integity: Beyond water quaiity. Environ.

Toxicoi. Chem. 12: 152 1 - 153 1.

Kerans. B.L. and J.R. Karr. 1994. A benthic index of biotic inte*? (B-[BI) for rivers of the

Tennessee Valley. Ecologcd .App[ications 4: 768-785.

Ladle. M. and G.I. Bird. 1981. The biolog of Psem0n;cn'des bbmbnis (Grube) in

English challc streams. Hydrobiol. 1 15: 10% 1 12.

Lafont. M. 1957. Production of Tubificidae in the littoral zone of Lake Léman near

68

Thono-les-Bains: A methodological approach. Hydrobiol. 155: 179- 187.

Legendre, P. 1993. Spatial autocorrelation: Trouble or new paradi-m?. Ecoiogy

74(6): 1659- 1673

Lindepard, C.. K. Hamburger and P.C. Dall. 1994. Population dynamics and energv

budget of Mizrionzna soltrhemi (Cemositov) (Enchytraeidae, Oli-chaeta) in the linoral of

Lake Esrom Denmark. Kydrobiol. Y 8 : 29 1-5 0 1.

MacKay. R.I. 1992. Colonization by louc macroinvenebrates: .A reciew of processes and

patterns. Cm. J. Fish. Aquat. SQ. W 6 17-628.

Manly. B.F. J. 1986. Muitivariate Statisticd Methods. A Primer. Chapman and Hall. London.

Marchant. R et H.B.N. Hynes. 1981. field estimates of féeding rate for Gammarus

pseudolmmeus (Cwtacea: ..bp hipoda) in the C redit River. Ontario. Freshwater Biol. 1 1 27-

36.

McKee. S. Onaw-a-carieton Lnstimte of B i o i o ~ . Universin; of Onawa P.O. Box 150. Stn. .i

Ottawa Canada, K 1 Y' 6N5.

MEQ - hhistere de i*Enviromement du Québec. 1990. Critères de quaiité de l'eau.

SeMce d'ewduation des rejets toxiques et Direction de la qualité des cours d'eau, Ministère de

l'Environnement du Québec, Québec. Canada. 323 p.

M e ~ t . R. W. and K. W. Cummins. 1996. .An introduction to the aquatic insens of Nonh

America. Kendall/Hunt Publishins Company, Iowa.

Meyer. E. 1989. The relationship beween body len-gh parameters and dry mass in

ninni- water invenebrates. .*ch. Kydrobiol. 1 17(7): 19 1-39;.

Morin. .A- and D. Nadon. 199 1. Size distribution of epilithic Iotic invertebrates and

implications for community rnetaboiism. I. N. .Am. Benthol. Soc. 10(3):300-208.

Morin. A.. M. Rodri-ez and D. Nadon. 1993. Temporal and environmental variation in the

biomass spectrum of benthic invenebrares in streams: an application of thin-plate splines and

relative warp analysis. Can. J. Fish. Aquat. Sci. 51: 1 SS 1- 1891.

W C . 1996. MontMy nimmary reports for 1994-1995- Montreal LTrban Communîty,

Environment Semices, MontreaI. Quebec, Canada.

Xaiman R J., J.J. Maguson DM. >kKni& J. A S t d o r d and J.R Karr. 1 995. Freshwater

ecosyaems and their manasement: A national initiative. Science 270:581586.

Odum E.P. 198% Trends expected in messed ecosysrems. Bioscience 3 511 1 9 4 2 .

Palmer, R. and J. O'Keefe. 1990. Transponed material in a smd1 river with multiple

impoundments. Freshwater Biol. 24: 563-575.

Peters. R.H. 1983. The ecological implications of body size. Cambridee Universi- Press,

Cambridge, Engand . 3 29p.

Pham. T.-T. and S. Proulx. 1996. Caractérisation des biphényles polychlores et des

hydrocarbures aromatiques polycycliques dans les eaux de la nation d'épuration de la

Communauté Urbaine de Montréai er dans le panache de son effluent dans le Saint-Laurent.

Rapport scientifique et technique ST.43. Environnement Canada - Régon du Québec.

Conservation de l'environnement, Centre Saint-Laurent. Montréal.

Pinell-Ailoul. B., G. Mithot L. Lapierre and A. WtIlsie. 19%. Wacroinvenebrate community

as a biolo&al indicator of ecological and tolricolojical factors in Lake Saint-François

(Québec). Environ. PolIut. 9 1( 1):65-57.

POE X.L.. M A Palmer. P.L. Angemeier, RL. Vadas Ir.. C.C. Hakenkamp. .A- Bely, P

.knsburger. and A.P. .Mmin. 1993. Size strucnire of the metazoan community in a

Piedmont Stream Oecolo@a. 9 5 : 202-209.

Ports Canada 199 1. Tour d'horizon et répertoire. Canada Ports Corporation SeMces.

Ottawa

Purenne, P. 1996. Analyse de la qualité des au^ brutes et de I'eau traitée à la nation

d'épuration et évaluation du rendement des installations. Communauté Urbaine de Montréal.

S e ~ c e de I'Environnement. Montreai, Quebec, Canada.

Rasmussen, J.B. 1 993. Patterns in the size stmcture of linord zone macroinvertebrate

communities. Cm. J. Fish. Xquat. Sci. 502192-2307.

Resh. V.H. 1995. Freshwater benthic macroinvenebrates and rapid assessment procedures for

water quality monitorinr in developping and newly industrialized countries. In: Biolopical

assessrneni and crkria: Tools for resource planning ami decisio~t makzng (eds. W. S. Davis

and T. Simon) Lewis Publishers. Chelsea MI, USA

Reynoidsoa T.B. and I.L. Metcalfe-Smith. 1992. .An oveerview of the assessment of aquatic

ecoqaem health using benthic invertebrates. I. Aquat. Ecosys. Health 1:795-308.

Rodnquez M..- and P. Magnan. 1993. Comrnunity structure of lacustrine macrobenthos: Do

taon-based and size-based approaches yield similar insi@ts? Cm. J. Fish. Aquat. Sa. 5O:SOO-

815.

Rosenbers D.M. and V.H. Resh. 1982. The w o f d c i d substrates in the midy of

kshwater bemhic macroinvertebrates. p. 1 75-23 5. In: J. Cairns (ed. ) . . f i c i a i substrat es.

.km Arbor Science Publishers, -AM .k-bor, &II:.

Rosenberg, D.M. and V.H. Resh (eds. ). 1993. Freshwater biomoniroring and benthic

macroinvenebrates. Chapman and Hall. New York 188 p.

Rounick, J. S. and M. J. W~nterboum. 1983. The formation. stmcture and utilkition of srone

surface organic layers in two New Zeaiand streams. Freshwater Bioi. 1357-77.

Schindler, D.W. 1987. Detecting ecosystem responses to anthropo_genic stress. Can. J. Fish.

Aquat. Sei- 44(SuppI. 1): 6-25.

Schwinghammer, P. 198 1. Characterisic size distributions of inte@ benthic communities.

Can. f . Fish. Aquat. Sci. 33: 135-1263.

Sheldon. R.W.. A Prakash and W.H. SutcISe Jr. 1977. The size distribution of pmicles in

the ocean. Limnol. Oceanog 17:327-310.

SLC - St. Latt~ence Centre. 1996. State of the Environment Report on the St. Lawrence

River. Volume 1: The St. Lawence Ecosystem. Environment Canada - Quebec Region

Eniironmental Consenaion and Les Éditions h1uItiMondes. Montreai. Sr. L m ~ e n c e

LT?D.ATE senes.

Smock. L A 1980. Relanonships bemeen body Ne and biomass of aquatic insects.

Freshwater Biol, IO:>E-3 53.

Spniles, W.G. and M. Munawar. 1986. Plankton size spectra in relation to ecosystem

productivity, site and perturbation. Cm. I. Esh. Aquat. Sa. 13 : 1789- 1794.

St. Lawrence Action Team. 1992. Bilan provisoire de [a réduction des rejets des 50 industries

du Plan d'action Saint-Laurent. Environment Canada and Ministère de IrEnvironnement du

Québec. 21p.

Strayer. D. 1986. The size structure of a lacunrine zoobenthic communiry. Oecologia

69:jl3-5 16.

Strayer. D. 199 1. Perspectives on the size distributions of lacustrine zoobenthos. its causes.

and its consequences J. North Am. Benthol. Soc. 1 O:? 10-22 1.

Suter, G.W.. II. 1993. .A cririque o f ecoqaem health concepts and indexes. Environ.

To'acol. and Chem. 12:15334539.

Sweeting, RA 1994. River PoUuuon. In: P. Caiow and G.E. Petis (eds.). The rives

handbook U: Hydrological and ecoiogkal principles. Blachwell Stientific Publications.

Mord. U.K.

US EP.. - LÏ. S. Environmental Pro teaion Asen-. 1 990. Environmentai monitoring and

assesment pro-gram oveniew . EP A /600 19-90 /O0 1.

Vénna, A. 1986. Body size and mass flow in eeshwater planbon: models and tests. J.

Plankton Res. 8:939-956.

Vis, C. 1997. L'influence de la qualité physico-chimique des eaux du Saint-Laurent sur le

périphyton. Thèse de Maîtrise. Dépanement de Sciences Bioiogiques. Université de Montréal.

Ks. C. St. Lawrence Centre. Environment Canada 105 McGill St.. 7" floor. Montreal,

Quebec. Canada, H2Y 2E7.

Warwick. R.M. and T.R. Joint. 1987. The size distribution of organisms in the CeItic Sea:

fiom bacteria to metazoa. OecoIogÎa 73 : 155- 19 1.

Washingon. H.G. 1981. Diversity. biotic and simÎlarity indices: a review with specid

relevance to aquatic ecosysterns. Wat. Res. 18: 653-694.

Way C.-M.. rlJ. Burhy. C R Bin-am and .K. Miller. 1995. Subnrate roughness. \reIotity

refkes. - and macroinvenebrate abundance on ar t i f id substrates in the lower Mssissipp~

River. J. North Am. Benthol. Soc. l3(3):5 10-5 15

Wetzel. RG. and G.E. Likens. 195 1. Lirnnologïcal analyses. Second Edition. Spnnger-

Verlag, Xew York. 39 1 pp.

Wilkinson, L., G. Blank and C. Gmber. 1996. Desktop data analysis with SYSTAT.

Prentice-Hall. New-Jersey. 795 p.

Willsie, A. and G. Costan. 1996. halyse des communaurés benthiques comme indicateur de

santé des écosynèmes du Saint-Laurent. S t . Lawrence Centre, Environmental Conservation,

Environment Canada - Quebec Region.

Density of invertebrate tava (ind-cm-') of each replicate collected on each navigation buoy for May. June, Augus and September sampling dates.

June 7, 1995

Buoy Rcplicat Ncrnatoda Chironomidac Amphipoda Diptcn Ephemeroptera Trichoptcra .\carina Copcpoda Oligochacta

Buoy Rcplicat Ncmatoda Chironornidae .4mp hipoda Diptera Ep hemcroptcra Tnchoptcn Acarina Co pepoda Oligochacta e

Buoy Rcplicat Nematada Chironomidae Amphipoda Diptera Ephemcroptera Trichoptera Xcarina Copepoda Oii~ochaeta e -

,WB A 9.96 0.53 0.06 0.18 O 0 O 0x3 0.41 hW58 B 5.55 0.54 O 0.03 0.03 O. 11 O 1-49 0.09 iW58 C 2.63 0.27 O 0 O 0.09 O 0.30 O. l t

September 26, 1995

Buoy Replicat Nernatoda Ciuronomidae Amphipoda Diptera Ephcrneroptera Trichoptera Acarina Copepoda Oligochaeta e ..__________._-*-..-*--. ~I.f.f---.-.-.---------..-..~-------------.~*...-----l----.~-------.*.-.-.--.-.-.-.........----.~

C U A O O. 12 0.06 O O 0.03 O 0 O C U B O O 0.03 O 0 0.07 O O O C U C O O. 12 0 O O O O O O C A O 0.06 O O 0 O 0 O O C46 B O 0.06 O O O O O 0 O CJ6 C 0.75 0.36 0.07 O 0 0.11 O O 0.29 C4S A 0.06 O O. 17 O O 0.03 0 O 0.03 C48 B O 0.08 0.05 O O O O O O C4S C 0 O . 16 0.07 O O 0.03 O O O

.CI104 A 0.03 0.56 0.06 0.09 0.06 O. 19 O 0.03 O iMlO-8 B 3.64 0.36 0.03 0.1 1 0.1 l 0.3 1 O 0 0.25 Ml04 C 10.54 1.33 O 0.14 0.08 0. I l 0.03 0.08 0.60 .LI122 -4 0.03 0.33 O O 0.07 0.03 O 0 O hl122 8 0. 10 0.73 O O o. 10 O 07 [ 1 O O Ml22 C O 0.39 O O 0.04 O. I 1 O 0 O MI24 .A O 0.37 O 0 O. 10 t1.24 O 0 O Ml24 B O O. 15 O 0 O 0.07 O 0 O 51124 C 0 O. 1 t 0 O O (1 O O O Xi130 A O 0.42 O O O. 10 1) O O O Ml30 B 0.03 0.34 O O 0.03 11 11 O O XI130 C O 0.69 0.03 0 O. 13 O. 13 0 O O hl132 .A 0.2 1 2.30 O 0.03 0 0.0; 0 O O hi132 B 0.09 2.02 0 0.06 '3 0 . 0 3 n O o. 06 3,1132 C O 1.13 0.03 0.06 0.03 0.06 O O O, 12 XI138 A 0.56 2.64 0.12 0.12 0.09 0.03 O O 0.75 31135 B O. 75 3 .;O 0 0 0.03 O. 1: O O 2.30 MISS C 0.2 1 3.32 O 0.15 0.03 0.09 O O 0.4s >II40 A 0.06 1.21 0.06 O 0.2 1 0.06 O O O Ml40 B 1.57 0.S 1 0.03 O 0 I I O O O. 16 Icfl-FO C 1-40 1.85 0.03 O. IZ 0.03 0.06 O 0.03 3.68 ?JIU X 0.25 0.69 O O 0.03 0.09 O O O M I U B O. 12 0.24 O O O 0.09 O O O Ml44 C 0.25 0.7s O O 0 .O6 0 .O6 0 O O >il52 A O.IL 0.95 O O 0.03 0 - 0 3 O 0 0.10 ML52 B 5-03 0.77 0 0.09 0.24 0.09 0 O 0.06 Ml52 C 0.99 1.39 O 0 O 0.03 O O O .MI66 A O 0.09 O O 0.03 (1 O O O hl166 B O. 10 0.36 0 O 0 0 O O O 31166 C r) 0.03 O 0 0.03 o O 0 O 343-4 A 0.43 1.55 0.03 O 0.03 O. 15 O O 0.36 MSS B 0.S: 1.63 0.13 0.03 O.OS 0.2 1 O 0.05 0.03 .MW C 37.04 4 13 O 0.t5 0.21 0.33 0.06 0.6 1 0.64 ,CL414 A 1.02 0.54 0.22 0.06 0 O .O6 0 O. 10 O. 10 -MA14 B 0.09 0.29 0.03 0.03 O (1 O O O hiAl4 C 0.03 0.32 0.09 0 O 0.05 0.03 0.03 O W " 3 S A 26-58 0.25 0.06 0.3 1 O 0.48 0.13 2-8s 1.63 .W-S B 6.7 1 0.53 O 0.30 O 0.06 0.1s 0.89 0.47 ,Lfi2S C 2 1-80 0.44 0.13 0.56 O 0.50 0.63 1.25 0.94 -54 A 5-89 0.46 0.03 0.03 0.03 0-06 O O. 12 O ,MW4 B 1-92 0.Z; i3 0.11 0.03 O O O O hW54 C O O O 0 O O O O 0.03

/conrinued frorn prevr ous rab le)

Physicochemical measurements made at each naLigation buoy for May' June. .Aupst and September sarnpline dates.

Appendix C

..ometric relationships for the conversion of invenebrate lenghs (mm) to dry mass (pg). conversion factors for weight measurements and biornasddensity calculations.

Taxon Lengh-Mass relationship Reference

Acarina 1 L' Morin and Nadon 1 99 1 .Amphipoda 1.86~' .Marchant and Hynes i 98 1 Chironornidae 5.1 L"' Smock 1980 Copepoda 7 . 0 7 ~ " ~ Culver et al. 1985 Diptera 2 . 3 8 ~ ~ ~ ~ Meyer 1989 Ephemeroptera 6 . 5 6 ~ ~ " Smock 1980 Nematoda 1 L~ Monn and 'ladon 199 1 Oligochaeta 1 L' Ladle and Bird 1983

Lafont 1987 Lindegaard et al. 1993

T richoptera 5 . 0 6 ~ ~ " Mever 1989

Measurement Conversion Reference

dry weight wet wei~ht Cattaneo 1993 ratio a11 taxa etcept Schwinghamrner 135 1 Oligochaeta

dry weight wet weight O. 13 Linde-aard et al. 1994 ratio Oligochaeta

dry weight ah Free dry 1.18 Cattaneo and Mouseau 1995 weight ratio

biomass number of individuals/sarnpling surface (45. 6cm2)

density total dry mass of indi\iduds(m-)/sampIing surface (45.6m2)

Invenebrate density (ind.m-') per size class (loglo upper lirnit) for each taxa of each replicate iiom September. 1995.

A ~ ~ ~ p h i p t ) t I i ~ ---i-- ----Cm- .-- site -1.8 -1,5 -1.2 -0.9 -0.6 -0.3 O 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3

O O O 81C O O O O O O O O O O O O O O O O LE9 O O POE O O O

O O LE9 6Pb6Z 8620 1 O O +OC 98EP ÇÇCP

8 Ç l C 1 O O O O O O O O LC9 OPEE L9Z O O O

BAW QAW

8ÇAW 0ÇAW 8ÇAW PÇAW PÇAW PSA W 8ZAW QZAW 8ZAW 8tAW 81AW 8 LAW VlAW blAW PIAN tlVN t lVW b 1 V W

DI8W PBW b8YU

991w Q9lW

1 O O O O O O O O O O O O O O O O O O ODlW ........................................................................................................................................................................................................................................................... .............................. 4....a~~,....~..............~...........d..m....~..~..........,......................*....

ï C C C 6 L a t P'Z I'Z 8'1 9 '1 2'1 0'0 9'0 C'O O E'O- 9'0- 6'0- 2'1- 9'1- 8'1- @Ils

O O O O O O O O O LZ9 O O O O O O O O O O O troc m ç LOO O O O

O O O O O O O O O O O O O O 81C O O O LZ9 O O O O Wll O O O O O 9P8 O O O O O bOC CGZL CÇZC LZ9 LZ9 b6Ç O PLSZ O 129 EÇZ1 EÇEI O O O O O O O O bOC O O O ÇEE O O O O O bLZ O O O61 O O O O O O O O 981 O O O O LE9 O POC O 116 O O O L9Z O toc O O O O O O O O O O O

8AW SAW

Q9AW 8ÇAW QÇAW DIÇAVV t9AW DIÇAW QZAW QZAVU 8ZAN 8 IAN 8 LAW 8 LAW PlAW blAVV P1AW DICVW DI lVW eivw

PB& P8W 018W

991W 091W

O - - O O O O O 981W 1'6 E'C E L'Z P'Z 1'2 8'1 Ç ' 5 2'1 6'0 9'0 C'O O , , , , O 9'0- 0'0- ' 1 9'1- 8'1- QlP

-- --- site -1.8 -1.5 -1.2 -0.9 -0.6 -0,3 O 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.( C44 O O O O O O O O O O O O O O O O O O I C44 O O O O O O O O O O O O O O O O O O

-. CII- -CIL-

site -1.8 -1.5 -1.2 -0.0 -0.6 -0.3 O 0.3 0.6 0.8 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.6 C44 O O O O O O O O O O O O O O O O O O O

'l'ricliopt ci-a

- - sile -1.8 -1.5 -1,2 -0.9 -0.6 -0.3 O 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.1

i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

~ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

i000000000000000000000000000

I O O O O O O O O O O O O O O O O O O O O O O O O O O O

~i00000000000000000000000000C . . 1 i

... site -1.8 -1.5 -1.2 -0.9 -0.6 -0.3 O 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.f --..........-....-.,........-.....*........,-.....-..-.-..... c44 O O O O O O O O O O O O O O O O O O (

Appendix E

Invenebrate and algal density (ind.m-5 pper size class (logo upper lirnit) for rach tava of each replicate from May. lune. Augus and September. 1995.

Size -5,l -4.2 -3,3 -2.4

).."............."...",m.... i... ri--.ri.."..., ...... m m m m m m m r . . . . . ........ r..+.",i....r..r.--.--.-.--.mm..~ ...,. -i-rrii-ri- . - . i . m . m . m " . . . r r r . r . " r n i r . - r i r . r ~ . . m m m m . m m m m m . m m . m . . ~ . " " ~ ~ ~ . .I-..-.."i.-..--.I

Sim -5.1 -4.2 -3.3 -2.4 -1.5 -0.6 O. 3 1.2 2.1 3.0 3.9 ...............,...........*..............................,......+................................,....................................~-...~.........~...........................~............. *.........................-.........~*.,.......*~..............................,...--..-.........--...........--..-.-...----~.-.-...-*..-..-.....-.--..--..--..--..-.---..---

Alg ae c46 ml40 ml52 11-184 inal4 inv18

Appendix F

Classificarion and jackknifed classification matrices for the buoys sampled in May. June. A u p a and September based on f d coliform goups usine density of 3 taxa (logl,, transfomd) and

densio; from 3 size classes (logln transformed) from September.

May - (Nematoda. Chironomidae and Amphipoda) Classification matcix

Coliform Grnup 1 3 4 5 O/D cnrrcct

Total

Jackknifcd ciauuific;itian matrix

Colifnrm Gmup I 3 4 5 'Yi correct

June - (Chironomidae. Dipten and Oligochaeta)

Coliform Group 1 3 4 5 '% corrcft

Jackknifcd ciassificatian matrix

Coiiform Gmup 1 3 4 1' O h correct

1 - 4 Total - 1 4 59

August - (Diptera, Ephemeroptera and Acarina) Classification matnx

total 5 1 O 7 1 7s

Jackknifed classification matrix

Coliform Gmup 1 3 4 5 O h correct

September - (Chironomidae, Amphipoda and Triehopien) Classification matnx

Coliform Group 1 2 3 4 5 % correct

Total 3 4 6 1 4 75

Jackknifcd classification matrix

Coliform Group 1 2 3 4 5 % corrcct

September - size classa (0.031-0.062,0.062-0.125 and 125-250 pg). Classification matrix

Coliform Group 1 2 3 4 5 '% corrcct

Jackknifed classification matrix

Colifcmn Gmup 1 1. 3 1 5 '% correct

Total 3 J S - 1 U 7

Component Ioadings of the first rwo eigenvecton from the principal component analysis of the density of all tava (logio transformed). collened in Seprember 1995.

Eigenvector

Chironomidae 0.62 0.69

Diptera 0.86 0.03

Ep hemeroptera

Tnchoptera

Copepoda O. S9 -0.3 1

Oliochaeta 0.86 O. 10

compcnents Percent of total variance 5S.S 19.5 e'cplained