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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