This series includes un~HoIj*~,~~ preliminary reportsand data records not intendea ~o; g~~~ra •cTlS~ bo.They should not be ref~~·~ fnATP\iblico1ions with­out clemance from the i~i.l)g~(..~...wl'lWJ)1pndwithout clear indication of their manuscript status.

FISBEBIE~ BESEAB£B BOABDOF £ANADA

MANUSCRIPT REPORT SERIES

No. 1114

An Oceanographer's View

of Eutrophication

byMichael Waldichuk

Fisheries Research Board Headquarters

Oltawa • Canada

July 1970

This series Includes unpublished preliminary reportsand data records not intended for general distrlbullon.They should not be referred to In publications with·out clearance from the issuing Board establishment andwithout clear Indlcalion 01 their manuscript status.

FISHERIES RESEARCH BOARDOF CANADA

MANUSCRIPT REPORT SERIES

No. 1114

An Oceanographer's View

of Eutrophication

byMichael Waldichuk

Fisheries Research 80ard Heudqunrlers

OUawa - Canada

July 1970

AN OCEANOGRAPHER'S VI EW OF EUTROPHICATION'

by Michael Wa1dichuk

Fisheries Research Board of Canada

Ottawa, Ontario

INTROOUCTION

There has been a great deal said about eutrophicationrecently, following reco""",ndations for control to the Inter­national Joint Conmission (International Lake Erie WaterPollution Board and the International Lake Ontario - St. LawrenceRiver Water Pollution Board, 1969). Part of this has resultedfrom reaction to the recoOlllendations, particularly from thedetergent industry which has been especially sin91ed out forcontrollin9 input of phosphates. There has been some scientificsupport for the detergent industry, suggesting that phosphate isnot the villain, or at least the major villain responsible foreutrophication. A report to this effect was published in theMarch/April issue of Canadian Research and Development (Anon.,1970), followed quickly with a rebuttal in the May/June issueof the same magazine by Vallentyne (1970).

* Prepared for presentation in a Seminar at the CanadaCentre for Inland Watel'8~ BUl"lingtonJ Ontario,2S June Z970.

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After the smoke of heated debate has cleared away, thereare a few items of new knowledge which errerge and certain bits ofold knowledge become more clearly crystallized. It is proposedhere to review the old and new information objectively and drawsorre conclusions in the light of the existing condition in theGreat Lakes. Then I hope to translate the concept of eutrophica­tion to the marine environment and review some work which we havedone in a highly-enriched inlet on the south coast of VancouverIsland.

PHOSPHORUS IN PLANT NUTRITION

Justus von Liebig was perhaps the first agriculturalchemist. He showed that of the principal elerrents found inplants, i.e., carbon, hydrogen, oxygen, potassium, phosphorusand nitrogen, only the last two elerrents can be controlled by man.Liebig'. l&! of the Minimum was enunciated in 1840 and it statedthat growth is limited by the factor present in minimal quantity.Carbon and hydrogen are extracted by the plants from theenvironrrent, and with the energy from the sun, they produce thecarbohydrates. However, they require the building blocks inaddition to carbon and hydrogen, which in this case are thenutrients, to produce the essential plant material. In fresh­water environments, there are certain plants, such as the blue­green algae, which can actually extract nitrogen from theatmosphere. Potassium is always available in non-limitingquanti ti es. Therefore, in freshwater envi ronments phosphorusbecomes the limiting nutrient. On land, as in the sea, the sizeof the crop is proportional to the amount of nutrient in leastsupply. Because the facility of plants to extract nitrogen fromthe atmosphere is not present to the same extent in the sea asin fresh water, the nutrient which is generally present inlimiting quantities in the marine environment is nitrate.Phosphorus is seldom found to be limiting to plant growth in thesea. Because of its rapid apparent rate of turnover, phosphoruscan be re-used a nunber of times. The input of nutrients intonatural waters is illustrated diagramatically in Fig. 1.

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Phosphorus has contributed to the world water pollutionproblems in that it has modi fied the ecosystem. It started12,000 years ago after the last Ice Age, when 100,000 sizeablelakes were left. The large-scale use of inorganic fertilizers,the utilization of detergents, the large increase in sewage fromcities, and the large-scale development of irrigation havecontributed to an increasing input of phosphates into our naturalwaters. Because phosphates are needed for the production ofplant organisms in the aquatic environment, they become rapidlyutilized, if other factors are favourable for algal growth. Thissets up a phosphate cycle in that large quantities of algae areproduced, which later decompose and contribute to the sedimentsof natural bodies of water. Some of the phosphate may be fixed inthe sediments as a refractory-type of material, but most of it isregenerated and released back into the water for further algaeproduction. The curious situation arises that, as bottom watersbecome anaerobic with the decomposition of organic materials, thephosphate is released from the sediments. As the oxidation­reduction potential is decreased and a reducing envi ronmentprevails, the phosphate cOll"l'Ounds which were insoluble in thepresence of oxygen become sol ub1e in the presence of hydrogensulphide.

With an increase in the phosphate in the water, bothfrom the sediment release and from new input with wastes, thealgae production increases in succeeding years. The action ofbacteria on the dead algae requires dissolved oxygen, and as aresult, the water's oxygen supply may become depleted. It isnot yet known how the cycle can be broken of deposition oforganic material, depletion of dissolved oxygen from bottom waterby decomposition of the organic material and then release ofphosphates. Oredging has been suggested as a solution, and thereis even a study underway at the University of Waterloo, under Or.H.B.N. Hynes' direction, to study the effect of lining thebottom of lakes with polyethylene or other plastic sheets.

The new carbonaceous materi a1 fi xed in the sediments,of course, accelerates the shoaling process which occursnaturally in all our lakes and inshore coastal waters. In short,the input of phosphate into our natural waters accelerates

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eutrophioation (Greek, eu we11, trophein to nouri sh). Thi sis anaging process that occurs naturally in all lakes, faster in somethan in others. Man's contribution to the envi ronment generallyaccelerates it. This speed-up of aging and final death of lakesthrough the activity of man has been compared to the aging ofliving organisms, including man, which can be accelerated bycertain excesses.

It has been suggested that other constituents presentin water may be responsible for the stimulation of algal growth,aside from phosphate and the other major nutrients. Micro­constituents such as molybdenum, cobalt and manganese may, infact, have a fairly profound effect on the production of algae.It is well known that the presence of vitamins can also beeffective in stimulating algal growths {Provaso1i, 1969}. It hasbeen seen that some 1akes are naturally more prone towardseutrophication with input of sewage effluents than others. Forexample, in the Okana9an Valley it appears that clear, oligotro­phic Lake Ka1ama1ka does not support much algal 9rowth even withsome sewage input. It exhibits less tendency than Okanagan Laketoward eutrophication and certainly much less than Skaha Lake.A small lake draining into Ka1ama1ka Lake, on the other hand,seems to have undergone a tremendous algal growth even with asmall input of sewage. The water in the small lake evidentlycontains a certain arrount of brown humic substances of naturalorigin which render it more productive than Ka,jamalka Lake.

Ferguson {196B} suggests the need for more research todetermine the effect of various forms of organic matter on excessivealgal growth. More knowledge is needed also about the conditions1eadi ng to such growth and about the source of algal growthmaterials. He cites the fact that algae occur in some waterscontaining 0.001 ppm soluble phosphorus, but do not occur in somewaters where the concentration is 15 or even 50 times greater.There is definitely an urgency for more research in algal nutritionand in algal physiology. Studies such as performed in the fieldwith injections of single doses of nutrients into estuarinewaters {Abbott, 1967} can elucidate certain processes.

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Wollenweider (1968) reviewed the scientific fundamentalsof lakes and flowing waters, with particular reference to nitrogenand phosphorus as factors in eutrophication. He clearlyderoonstrated tha\ in fresh water, phosphorus is the limiting elementfor algae production.

THE CARBON THEORY

A nunter of suggestions have been advanced on the role ofcarbon in eutrophication and how it can limit algal production.Tied in with the carbon hypothesis is the activity of bacteria inconversion of dissolved organic carbon into carbon dioxide. Thereare about three significant recent publications and reports notingthe role that carbon compounds play in 1imiting algal production(Lange, 1967; Kuentze1, 1969; and Kerr et aZ, MS, 1970).Lirmo10gica1 studies even at the tum of the century (Birge andJuday, 1911), however, recognized the importance of camonate,bicarbonate and bacterial oxidation of organic material as asource of carbon dioxide for aquatic plant growth.

The work of Kerr et aZ (MS. 1970) appears to be quitedefinitive with respect to the nutritional needs of the blue-greenalga, AnaCY8n8 nidu/.ans. They showed that C02 produced bybacteria stimulated the growth of axenic cultures of A. niduZansand that C02 is important in regulating the size of populations ofaxenic cultures and natural crops of the alga. They alsoderoonstrated that the reroova1 of phosphorus from solution byA. niduZan8 is dependent on the cell ular concentration of P andthat the luxury cellular concentration of P is 10 times as highas the limiting concentration of P for that alga. Diurnalobservations on the concentrations of A. niduZans and on nutrientsin a culture and in an enriched creek showed that inorganiccarbon reached very high levels during the night but was a1roostdepleted during the day. while phosphorus levels stayed a1roostconstant. The maximum increase in bacterial populations occurredbetween 7:00 p.m. and 7:00 a.m. and was correlated with the peak

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rerroval of ol\Ygen from the water. The dissolved carbon dioxideand bicarbonate content of the water also decreased during thisperiod.

Although Vallentyne (1970) has maintained thatphosphorus is the only limiting nutrient which can be contronedwith present technology, his work has shown the importance ofcarbon compounds in plant nutrition, particularly in soft waters(Fisheries Research Board Annual Report for 1969, 1970;Canadi an Committee on Oceanography Annual Report for 1969, 1970).In the FRB Experimental Lakes of Northwestern Ontario, thederrons trati on that inorgani c carbon is growth-l imiti ng sugges tsthat the addition of carbon from sewage may be an importantfactor in lakes having igneous rock watersheds. This could betrue, regardless of whether the carbon is in organic ori norgan; c form.

An important consideration that must be given all workconducted on algal nutrition is the species with which theinvestigators worked. Certain desirable algal species, such asdiatoms, have very different nutritional requirements than manyof the "weed" species, such as blue-green algae. Because ofthe nitrogen-fixing capability of blue-green algae, fertiliza­tion of lakes can lead to growth of these nuisance organismsonce the supply of introduced nitrogen compounds is exhausted(Provasoli, 1969). Much of the work on carbon requirements ofaquatic plant organisms has been done on blue-green algae(Lange, 1967; Kerr et a~. MS, 1970).

SOME CONCLUSIONS FROM RECENT WORK ON ALGALNUTRITION AND EUTROPHICATION OF-FRESH WATERS

(1) Phosphate can limit growth of algae but the limitingconcentration may be considerably lower than 0.1 mg/loriginally proposed by Sawyer (1966).

(2) Algal cells have the unique capacity of storing phosphate,when it;s present in excess, to use it later when presentin only a small arrount (Levin, 1963).

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(3)

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The limiting and luxury cellular concentrations of P for theblue-green alga Anacysns nidutans are 0.3xlO-8 and 3.0x10-8

)1g/cell, respectively, spanning a range of a factor of 10(Kerr et at, MS, 1970).

(4) Work by Vallentyne et at (FRB Annual Report for 1969, 1970) hasalready demonstrated that carbon can be a limiting factorin soft water.

(5) Phosphate is the only nutrient which is Umiting and can beccntrotted wi th present technology.

(6) In general, nitrate is the limiting factor in the sea.

(l) In fresh water, nitrogen can be fixed from the atmosphereby specialized plant organisms like blue-green algae.

(8) In certain lakes, which are not too deep but stratified insummer, phosphate is fixed in the sediments by settlingdead plankton. When oxygen at the water-sediment interface; s rerooved by ox; dati on processes, and sul phide forms)phosphorus is released to add nutrient to the water andsti-..1ate further algal growth.

(g) Different algal species have different nutritional require­ments (Provaso1i, 1969). Some oligotrophic species cantrap P from very low concentrations and some tend to beinhibited in P concentrations above 10-12 )'gl1.

(10) Observations in Israel on monthly fertilized fish pondsshowed that in the first 15 days, the beneficial bluealgae grew. Then the bl ue-greens took over. It wassuggested that blue-greens took over when the N-nutrientswere depleted and the N-fixing blue-greens survived. Morefrequent fertilization (once weekly) was suggested(Provaso1i, 1969).

(11) Bacteria obviously playa vital role in making availablecarbon dioxide by oxidation of dissolved organic material.in release of nutrients through decomposition of deadalgae and other organic solids, in utilization themselvesof certain nutrients such as P, and in release of certaingrowth-stimulating substances such as Vitamin 812'

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EUTROPHICATION IN COASTAL WATERS

We normally associate eutrophication only with lakes.Perhaps this is so because the problem has been IOOst acute infresh water and limnologists have brought our attention to itIOOre strongly. The process of eutrophication, however, is notrestricted to fresh water. In many of our shallow coastalembayments and inlets, where input of nutrients by tributarystreams has led to heavy enrichment, there is a definite transi­tion from the normal coastal environment to algae-infestedwaters, not unlike eutrophic lakes. This is particularly truein those waters which are shallow and partly enclosed. Theformation of salt marshes (Chapman, 1942; Tansley, 1942) is oneof the last stages in the eutrophication of such coastal waters.

An early study of the effect of sewage input into ashallow, narrow fjord in Schleswig-Hol~tein on the 8alticseacoas t of Germany, was reported by Kandl er (1953). Theenrichment by phosphate and amlOOnia compounds was recognized inthis work. More recent investigations have been carried out onthe pollution of Inner Oslo Fjord (8aalsrud, 1964). This studyhas taken into consideration primari ly the effects of thesewage disposal into Inner Oslo Fjord by the city of Oslo. 8yits very nature, this fjord is not well flushed, having a shallowthreshold sill, which restricts circulation. Man-made effects ofsewage input have accentuated a natural pollutional problem inthe deeper, poorly-ventilated waters. Six papers on the studiesof pollution in Oslo Fjord were presented in an InternationalSymposium on Bio~ogica~ and hydrographica.~ prob~ems of waterpoLLution in the North Sea and adjacent watere, hel d duringSeptember 1967 in Helgoland. These have been publ ished in full,and F~yn (1968) describes the nutrient picture of Oslo Fjord inone of the presentations.

While phosphate is certainly one of the nutrientsinvolved in enrichment of coastal waters. it does not appear tobe the limiting factor. This is so not wi thstanding the fact

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that F~yn (1968) suggests that phosphate is the limiting factorin productivity of Oslo Fjord. Most of the studies reported sofar indicate that nitrate is the limiting nutrient in the sea.Generally speaking, marine phytoplankton do not possess thecapacity of fi xing nitrogen from the ai r, as do the blue-greenalgae of fresh waters. Hence, once nitrogen compounds areexhausted from the water, there is no other source of nitrogen,and algal growth has to cease.

The study of Portage Inlet, at the head of the Gorgeand Victoria Harbour, carried out by our team at Nanaimo from1965 to 1969 has been described in a preliminary paperpresented to the 34th Annual Meeting of the Pacific NorthwestPollution Control Association in Yakima, Wash., in October1967 and later in publication (Waldichuk, 1969). PortageInlet is another typical shallow inlet which has been affectedby urbanization. By virtue of its geometry, the inlet does notget flushed rapidly and, in fact, durin9 the sUlll11er period mayactually concentrate by evaporation wastes which it receives.Durin9 the late summer, Portage Inlet becomes a ne9ativeestuary with its salinity actually higher than that in thewaters of Victoria Harbour. Consequently, there must be a netinflow from Juan de Fuca Strai t to maintain the water and saltbalance.

The physical and chemical features will be only brieflysummarized here. In Fi9. 2 is shown the general configurationof the coastline of the system. Seasonal salinity and temperaturevariations are shown in Fig. 3 and 4, respectively. The annualnitrate cycle, shown in Fig. 5, has a seasonal trend as might beexpected I wi th hi gh concentrati on duri n9 the wi nter months,diminishing to zero in spring and continuing at very low levelsduring the summer through to the early autumn. Inorganicphosphate, shown in Fig. 6, on the other hand, is very different.High concentrations appear during the winter mnths I but evenhigher concentrations during the summer. It is this nitrate­phosphate imbalance in SUlll11er which is very puzzling. Quiteobviously, nitrate is the limiting nutrient for plant production.Phosphate is not only in abundant supply but seems to be verymuch in excess during the sunmer IOOnths.

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We have explored all sources of phosphates that mightlead to the high summer concentration. but we are sti 11 in aquandary as to its origin. Either there is a very high input ofphosphate during the summer IIllnths, from some source unknown tous, or else there is a great deal of phosphate being regeneratedby the sediments. U1fortunately, we sti 11 do not have a set ofdata on the phosphate in the plant life and in the sedimentarymaterials.

The seasonal chlorophyll variation, as obtained frompigment analysis of millipore-filtered samples. showed thetypical high peak in spring at IIllst stations and a secondarypeak in late summer (Fig. 7). The concentrations of chlorophyllare nKlch in excess of those normally found in inshore waters.Because rooted aquatics (eel grass. Zosterol enter into thenutrient cycle. it is difficult to establish a good phosphatebudget. taking into account all factors that might be involvedin the cycle. without having data on the rooted plants. Thephosphate-nitrate ratio in the plankton has not been determined,but it would not be surprising if it happens to have a dis­proportionately high phosphorus, compared to normal P:N ratiosobtained for phytoplankton of other pollution-free areas. It isknown that plants can adjust the intake of certain nutrients.when there is an excess of one over the other. but the algalphysiology of such adjustments is not too well understood. Inany case. it is believed that plants can survive on a lownitrate diet if phosphate is present, but the cells of suchplants may have certain abnormal characteristics.

SUr+1ARY AND GENERAL CONCLUSIONS

To sUlTIT1ar; ze, one can say that eutrophication of ournatural waters has become a serious pollution problem. It notonly interferes with beneficial water uses in a utilitarian way,but also poses an impediment to our enjoyment of the environment

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in which we live. Phosphorus appears to be a major contributor tothe eutrophication problem in the freshwater environment. How­ever, nitrogen-containing compounds, particularly nitrate, limitproduction in the marine environment; phosphate seldom appears tobe a limiting factor in the sea. The role of carbon, particularlyin the dissolved organic form and as carbon dioxide, is emergingas an important factor in eutrophication of certain types of water.

The nutrient enrichment of Portage Inlet on VancouverIsland has led to extraordinary production of algae and rootedaquatics. The water is almost always turbid with a yellowishcolouration. Nitrate is virtually eliminated in spring andremains at near-zero concentration all 5unmer. Phosphate, on theother hand, increases from rroderately high concentrations inwinter to extremely high concentrations in surrmer. The cause ofthis large phosphate-nitrate imbalance in summer has not beenrevealed, but may be associated with regeneration from rootedand floating aquatic plants and with processes at the sediment­water interface.

In conclusion, it can be stated that a better under­standing of the phosphate problem can only be gained by attackingit on an ecosystem approach. This involves the whole environment,the organisms contained therein and the input of materials into andout of the system. Phosphate has to be looked at on a budget basiswhere every bit that is added through the cycle can be accountedfor, as well as that which is removed.

A better understanding of the algal physiology must begained through laboratory experiments, where algae can be culturedunder varying conditions. It is obvious that certain micro­constituents, inorganic and organic, are important in thereproduction, growth and survival of algae. What are the mostvital elements involved? Different species of algae behave indifferent ways. What are the essential requirements of some ofthe useful forage organisms, and what are the needs for largeblooms of bl ue-green algae? These questions must all be answeredbefore we can proceed with suitable remedial measures. In themeantime, of course, it behooves us to cease putting into ournatural waters the nutrients which are the obvious causes forlarge productions of algae and undesirable effects on waterqual ity.

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REFERENCES

Arrott, W. 1967. Microcosmwaters. II. The effectsand phosphate. J. Water22(1): 113-122.

sturlies on estuarinp.of single noses of nitratePoll. Control. Fed.,

Anon. 1970. The Lange-Kuentzel-Kerr Theses. CanadianRes. & Dev., 1: 20-27.

Baalsrud, K.III(II):

1964. Oslofjordens forurensninF,. Tek. Ukerl.,255-264.

Birge, E.A., and C. Juday. 1911. The Inland Lakes ofWisconsin. The dissolv€0 gases of the water anntheir biological significance. Wisconsin Geologicaland Natural History Survey, Bull. No. XXII.

Canadian Committee on Oceanography. 1970. Annual Reportfor 1969. Ottawa, Canada. (In Press).

Chapman, V.J. 1942. Studies in salt-marsh ecology.Section VIII. J. Ecol., 12: 69-81.

Ferguson, F.A. 1968. A nonmyopic approach to the problemof excess algal growths. Environ. Sci. Tech., ~(3): 18$-193.

Fisheries Research Board of Canada. 1970. Annual Reportfor 1969. Ottawa, Canada. (In Press).

F~yn, Ernst. 196$. Biochemical and dynamic circulationof nutrients in the Oslofjord. HelgolMnrler wiss.Meeresunters., 11: 489-495.

International Lake Erie Water Pollution Boar0, ann theInternational Lake Ontario - St. Lawrence fliverWater Pollution Board. 1969. Pollution of LakeErie, Lake Ontario anrl the International Sectionof the St. Lawrence River. Report to the InternationalJoint Commission, Vol. I, Summary, 150 p.

.1}

K~n~ler, R. 1953. Hynrographische Untersuchun~enzum ner OstseekUste Schleswig-Holstp.in::;. KielerMeeresforsch., 2(2): 176-200.

Kerr, P.C., D.F. Paris ann D.L. Brockway. MS, 1970.The interrelation of car~on and phosphorus inregulating heterotrophic and autotrophic populationsin an aquatic ecosystem. Manuscript, U.S. Dept.Interior, Federal Water Quality Administration,Southeast Water Laboratory, National PollutantsFate Research Program, Athens, Georgia.

Kuentzel, L.F. 1969. Bacteria, carbon rlioxine, andalgal "looms. J. Water Poll. Control Fed., ~(10):1737-1747.

Lange, Willy. 1967. Effect of carbohydrate on thesymbiotic growth of plankton,c blue-green algaewith bacteria. Nature, ~(5107): 1277-1278.

Levin, G.V. 1963. Reducing secondary effluentphosphorus concentration. First Progress Report,Dept. San. Eng. & Water Resources, The Johns HopkinsUniversity, Baltimore, Md.

Provasoli, LUigi. 1969. Algal nutrition anneutrophication. p. 574-593 f!l: Eutrophication:causes, conseguences, correctives. Proceedin~s

~ymposium, 11-15 June 1967, University of Wisconsin,Madison, Wis., National Academy of Sciences,Washington, D.C., 661 p.

Sawyer, C.N. 1966. Basic concepts of eutroph,cat,on.J. Water Poll. Control Fed., ~(5). 737-744.

Tansley, A.G. 1942. Note on the status of salt-marshvegetation and the concept of "formation". J. Ecol.,2Q: 212-214.

Vallentyne, J.R. 1970. Phosphorus ann the control ofeutrophication. Canadian Hes. & Dev., 1: 36-43, 49.

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Waldichuk, M. 1969. Eutrophication studies in ashallow inlet on Vancouver Island. J. Water Poll.Control Fed., il(5): 745-764.

Wollenweider, R.A. 1968. Scientific fundamentalsof the eutrophication of lakes and flowing waters,with particular reference to nitrogen and phosphorusas factors in eutrophication. Organization forEconomic Cooperation and Development. Directoratefor Scientific Affairs. Report DAS!CSI/68. ~,159 p.+ 34 Figs.

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Fig. 3 Seasonal variation 1n salinity at selected stations 1n VlctorbHarbour, the Gorge and Portage Inlet, during 196~-1966.

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.21

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Fig_ 4 5"50nal nrl&tion 1n temperature at selected stations 1n Victoria Harbour,the Gorge and Portage Inlet, during 196~1966.

.23

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.25

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