zooplankton species associations in quebec lakes: variation with abiotic factors, including natural...

ankton Species Associations in Quebec Lakes Variation with Abiotic Factors uding Natura and Anthropogenic Acidification

Bernadette Pinel-Al loul and Ginette M6thot Bepareernent de Sciences bioisgiques Universite de Montread CP 6128 Montreal (Quebec) M3C 317

and Ghislain Verreault2 and Yvan Vigneault MinistGre des Peches et des Oceans 96 7 Cap Diarnant Quebec (Quebec) C 7 K 717

Pinel-Alloul B G Methot G Verreault and Y Vigneault 1990 Zooplankton species associations in Quebec lakes variation with abiotic factors including natural and anthropogenic acidification Can j Fish Aquat Sci 47 1 10-1 21

Abundances and biomass of 38 zooplankton species and accompanying abiotic data from 54 Quebec lakes were subjected to cluster and correlation analysis to determine (1) characteristic zooplankton associations of cooccurring species (2) relative importance of abiotic variables in Bake typology and (3) relationships between the integrated environmental factors derived From~ lake morphornetry water quality and acidification level and the structure of zooplankton communities The eight groups of species identified in the cluster analysis may be considered separate species associations characterized by distinct patterns of distribution in Quebec lakes Differences in mean pH and sulphate concentrations can be detected between groups of lakes representing the different species associations Factor analysis produced seven factor scores which explain 82 sf the total variance of the morphological physical and chemical variables The distribution pattern of acidity or alkalinity represents the major feature in water chemistry variation but lake morphology also account for the observed environmental variability Each factor represents an integrated environmental property correlated with a set of cosinear abiotic variables These factors are correlated with zooplankton species abundances and biomass The community structure whether expressed in size classes or in trophic groups tends to vary among sets of lakes of different pH

Labcsndance et la biomasse du zooplancton ainsi que les caract6ristiques abiotiques de 54 lacs dtr Quebec ont fait Iobjet doanalyses factorielles et danalyses de correlation visant a determiner 1 ) Bes associations despeces reprksentatives de la variabilite du zooplancton 2 ) limportance relative des variables abiotiques pour la typologie des lacs et 3) les relations entre Bes principaux facteurs envirsnnementaux relies 21 la morphometrie des lacs 2 la physics-chimie des eaux et aux niveaux dacidificatiesn et la structure des commuraaut6s zssplanctoniques Les huit associations despeces deterrninkes par groupement liens csmplets peuvent etre consid6r6es csrnrne des associations distinctes par leur patron de repartition dans les lacs du Quebec Des diff6reraces entre les valeurs moyennes de pH et de sulfates peuvent ampre detectees entre les groupes de lacs reprksentatifs des diffkrentes associations despitces Lanalyse factcsrielle a determine sept facteurs environnernentaux qui expliquent 82 de la variance tstale de la rnorphom6trie et de la physico-chimie des lacs Le patron de distribution de Iacidite ou inversement de 11alcatinit6 represente la rnajeure partie de la variabilite rnais la morphom6trie des lacs influence aussi la variabilite observee dans les conditions abiotiques Chaque facteur represente une caractkris- tique envirsnnementale composite corrkl6e 21 un ensemble de variables abiotiques colineaires Ces facteurs ont 6t6 correles avec Iabowdance et la biomasse des zoesplanctontes La structure de la cornmunaute exprirnke soit en classes de taille ou en grcsupes trophiques est variable selon les grotrpes de lacs de pH different

Received December 14 1 988 Accepted dune 28 7 989 (J9982)

T he spatial analysis sf freshwater zooplankton with reference to acidification has been investigated mainly with respect to crustacean plankton community structure and

lake typology (Spmles 1975 Yan md Stms 1980 Keller a d Pitblado 1984 Pinel-Alod et al 1987) Kelso et al (1986) published a comprehensive study of the relationships between the coarse composition m d diversity of the aquatic biota and the physical and chemical conditions prevailing in eastern

Con$Bibution No 368 Groupe de recherches en Ccslogie des eaux deuces DCpxterneaat de Sciences biologiques Universitk de MontrEal

hesent address LAPEL 6roupe Conseal I400 ave St Jean-Bap- tiste QliCbec (Qutbee) 62E 5B7

Canada lakes but failed to define general trends in occunence md abundance of zooplankton species in relation to pH Similar studies were carried out at a regional level by Pinel-AIlouI mQ MCthot (1985) and Pinel-Allsul et al (1987) in Quebec lakes In acidified regions s f Ontario much research (Spmles 1975 Roff m d Kwiatkowski 1977 Yaw and Stms 1980 Confer et al 1983 Mdley md Chmg 1986) has been conducted to determine species associations in relation to lake pH According to Spmles (1977) patterns of variability in a large group sf species provide more infomation about the habitat than does variation in a single species It was thus decided to use species associations or communities as indicators sf Hake acidity md typology

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Although the part of Quebec lying on the Canadian Shield has often been recognized as am area of high sensitivity to acidification (Hmey et al 198 Lachmce et al 1984) little emphasis has been given to the acidification of Quebec surface waters with respect to its relationship to aquatic biota especially in the case of planktonic organisms Our major objectives in this study were to (1) describe the structure of zooplarnkton communities in Quebec lakes and their chmcteristic associations of cooccurring species (2) determine the relative importance of the abiotic variables (rnorphometry water quality acidification indices) in lake typology a d (3) document the relationships between the critical environmental variables derived from lake morphometry water quality and acidification level and the organization sf the zooplankton c o m u - nity More specifically the definition of the effects of acidification on zooplankton a key component of the food web may aid in the interpretation of field monitoring data

Matefials md Methods

Study Area

A number of mophometric physical chemical and biotic variables were measured in 54 lakes of first second and third

hydrologic order throughout Quebec (Langlois et al 1983 Pinel-Alloul and Mkthot 1985) Means and ranges are presented in Table 1 The lakes sampled are located on the Canadian Shield north of the St Lawrence River and south of the 52N latitude (Fig I) a region considered highly sensitive to acidification (Bobee and Lachance 1984 Lachance et al 1984 Dupont and Grimmd 19861 mainly because of the composition of its bedrock (gneiss-granitic) and the average pH of rainfall in Quebec (pH = 42 - 50) Most of the chosen lakes were summer stratified easily accessible and not affected by my human or agricultural activity in the immediate watershed Based on principal component m d hierarchical cluster analyses of the 20 physical md chemical variables (Table I ) Pinel-Alloul and MCthot (1198) have already observed a southwest to northeast longitudinal gradient in the hydrogen ion concentration indicating that lakes of the northeastern regions (regions 05 - 07) are generally more acidic than lakes situated in the Maniwaki region (region 04) (Fig 1) Sulphate concentrations follow an inverse gradient and it appears that saalphate levels and anthopogenic acidification are higher in southwestern Quebec lakes (Lachmce et d 1984 Pinel-Alloul et dfl 1987 Dupont 11988) A recent integrated study of spatial variation in physicochemicd quality in our lakes (Department of Fisheries and Oceans 1987) showed that 72 of the lakes

TABLE 1 Mean and range of selected moqhometric physical md chemical characteristics of the 54 study lakes in Quebec

Caacteristic Mean Minimum Maximum

Morphornetric Latitude Longitude Altitude (m) Maximum depth (m) Mean depth (m) Relative depth (9) Lake maximal length (h) Lake maximum width (h) Lake area (ha) Watershed area (ha) Lalee volume (1041nma3) Lalee order Lake volume development Morphoedaphic index

Physical and Chemical Secchi disk (m) Color (U H ) Conductivity (pS-cm- ) Hydrogen (H) (peqLP )

Alkalinity (peqaL- ) Cl (peq-L-I) SO (peqL--I) Ca (peqLW) Mg (peqeL- I) P (paeq-L- ) Na (peq-L- l) Total Al (pager ) Mn (pg-L- ) Fe (kg-L I )

Zn (peqaL- ) Dissolved organic carbn (mg-L-) Total organic carbon (mg -L - ) Nitrate (peq-L- ) Alkalinnitylsulph ratio

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FIG 1 Geographic location of study lakes in Quebec Numbers refer to geographic region

sampled exhibited alkalinity of less than 100 peqeL- and h d described in Pinel-Aloul and MCthot (1984) Counts of zm- alkalinity to sulphate ratios below 1 Both parmeters indicate plankters were expressed as numbers of individuals per eubie an extreme sensitivity to acidification (BobCe et d 1982) metre and were converted to biomass (milligrams per cubic

metre) using the specific dry weights estimated by Pinel-Alloul Field and Laboratory Analysis and Methot (1979) for the same species collected in the James

The field measurements were taken amptween August 1 1 and Bay territory

September 18 1982 Moqhomet~c data were computed for each lake from echo-sounder recordings We derived lake mor- Statistical Analyses

phometry data (area maximum and mean depths length9 width) md watershed data (Table I) h m topographic maps at 1 50 000 scale We calculated the morphoedaphie index (MEI Wyder et al 1984) from the ratio of conductivity to mean depth Water s ap l i ng md preservation were performed following prmedures established by Environment Cmada (1 979) Com- posite unfiltered water samples coUmtd from the epilimisn (0-5 m) were used to determine water quality variables (Table 1) except that total organic carbon was measured in discrete samples taken just below the water surface Ml andyticd deter- minations were made according to methods described by Bobamp et d (1982) Alkalinity was determined by the Grm titration method (ampamer 1980) The alkalinity to sulphate ratis was dso computed to evaluate the importance of the substitution of bicarbonate ions by sulphate ions within sudace waters This ratio indicates the degree of mthopogenic acidification (BsbCe et d 1982)

ooplaampton was sampled between July 9 md August 18 1982 Samples were collected by means of a Wisconsin net (205 cm in diameter 64- pm mesh) which was towed verticdly from depths ranging fmm 2 to 20 m (63 - 628 E of filtered water Pinel-Alloul md Cdn-Blumer 1983) Zsopldtora samples were preserved u p n collecting in 9 fomalin with sucrose (68 gL- hepas 1978) Eabsratsry procdures are

The data consisted of 14 morphomet~c and 20 physicochem- ical variables plus density and biomass sf 38 zooplankton species for each of the 54 study Bakes Statistical analyses were performed at the University of Montreal using the SPSS (Nie et al 1975 Hull and Nie 1981) and R (Legendre and Varador 1984) packages of computer routines

F h t species present in less thm 5 of the sampled sites were eliminated Most of them were littoral or occasional species This reduced the original data matrix to a find subset of 38 taxa The data sets (abundance and biomass respectively) were then transformed (ln (x + 1)) to nomdize the distribution of the variables and to achieve homosceampsticitya The transformed data matrix was then partitioned into groups 0 cow- craning species by mems of a eomplete linkage cluster malysis (Legendre and Legendre 1979) based s n the Gower similarity index The Gower coefficient excludes double zeros (Legendre and Legendre 1979) md the complete clustering characteristi- cally produces clusters of biological data that are functionally distinct from one mother (Earle et al 1987)

Msrphome~c physical md chemical dab were d so transformed (In (x + 1) except pH) so as to nomalize the abiotic data matrix and to give each variable a more equal weight in the analysis Then a factor malysis was pa-formed to simplify the variance structure of these highly correlated and interde-

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pendent variables This process resulted in orthogonally rotated (Vhnmam) factor scores each factor representing m integrated environmental property correlated with a set of colinex abiotic variables

The factor analysis also served to simplify the analysis of relationships between abiotic factors a d zooplamkton species which were investigated though correlation analysis between the factor scores and the abundance md biomass of each species

using Spearman correlations Furthemore the use of Spear- man cornelations of species abundance with water temperature and dissolved oxygen at time of sampling also allowed us to test the effect sf the season on zooplankton species estimates A similar statistical approach was used with success by Earle et al (1986 1987) to analyse the factors influencing the distribution of phytoplankton in Labrador md Newfoundland lakes

No of lakes pH so4

GASTROBUS SP 1 4 5 9 55 SKI STODIAPTOMUS QREGONENSI s 5 7 1 88

SYNCHAETA S P 8 6 1 83

DAPHNHA WOSEA 15 6 1 62

EPI SCWURA LACUSPR I s 2 1 65 64 DAPHN B A LONG I SP INA 1 6 64 72

KEWATELLA HIEMALI s 13 60 6 7 ~ Y C L O P S S C U T I FEW 2 1 59 59 DAP WN I A sc HBDLE w I 2 5 60 73

s NESOCYCLQBS EDAX

~ I A C Y C L O Q S B I C U S P I D A T U S THOMAS1

FIG 2 Results of the complete linkage cluster analysis of zoop8dtow species based on their abundance in 54 lakes The number of lakes md mans of pH a d sulphate concentrations (peq-L- I) s f the lakes in which the taxon occwed are d s o presented

em 9 Fish Aquat Sci VB 47 1990 113

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TABLE 2 Factor analysis of 34 physical chemical and meavhometric variables Correlation coefficients are between the seven derived factors md the 34 original variables Nonsignificant coefficients (ie (0258 p )005) have been omitted

Factor 2 Factor 3 Factor 5 Factor 6 Factor 1 lake depth dystrophy Factor 4 salinity lake volume Factor 7

Variable hwdness-alkalini~ water trmsparency color Lake size sulphate development nitrate

Alkalinity Alkalinitylsulphat ratio Calcium pH Magnesium Hydrogen Conductivity Potassium Zinc

Maximum depth Lake relative depth Lake mean depth Movhsedaphic index Volume Mmgmese Longitude

Dissolved organic cabon Total organic carbon 018r Chlorine Iron Secchi disk Total ahminiurn Lake order

Lake area Maximum length Maximum width Watershed area Sodium Sulphate Latitude Lake volume development Altitude Nitrate

Eigenvalue

Percentage of variance

Species Associzitisns

Fifty-thee zooplmkton tma were identified fmm the 54 lakes examined in this study including the copepodid and the naupliar stages An average of 13 taxa per sample was found ranging from 8 to 19 Many species were present in mare than 66 of the lakes (Fig 2) The most ubiquitous species were Keratella cochlear-is Keampampicottia longispina Bdasmina longirostris md Polyarthra vulgaris The zooplankton density varied between 3720 and 240 423 i n d ~ r n - ~ (Pinel-Alloul and MCthst 1885)

The dendrogram from the complete linkage cluster mdysis (Fig 2) suggests that the zooplankton communities in Quebec lakes can be partitioned into eight different species associations and subgroups (p lt 005) Results from hska lCWdl i s tests (Siege1 1956) showed that mean pH of the lakes from which

they came did not vary significantly from one species group ts another (p gt 005) but sulphate concentrations varied significantly among the species associations (p lt 044) However general trends could be detected from bivaiate Mann-Whitney tests (Siegel 1956) on differences in mean pH or sulphate concentrations between pairs sf species associations Species from groups 1 6 and 7 occurred in the most acidic lakes with a mean pH below 62 Group 5B represented zooplankton species characteristic of the circumneutral lakes Species from groups 4 and 7 seemed to be characteristic of lakes with a low sulphate concentration Species of groups 1 2 3 5A md 5B were found in lakes where the mean sulphate concentration was generally high group 5B associated with the highest level (89-139 peq-L- )

Environmental Factors The factor analysis on the abiotic variables shows that 82

sf the total variance can be explained by the first seven derived

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factors (Table 2) Factor 1 explained 21 of the total variance md was positively correlated with alkalinity alkalinity to sulphate ratio calcium pH magnesium conductivity potassium and the morphmdaphic index md was negatively correlated with hydrogen ion total aluminium and zinc It is considered a hardness-alkalinity factor Factor 2 which explained 17 of the variance was positively correlated with depth and volume morphometric variables and with water transparency It is thus considered a lake depth and water transparency factor It was also negatively related to the rnorphmdaphic index mmgmese longitude and iron Factor 3 responsible for 14 of the variance was positively correlated with dissolved organic caf$sn total organic carbon color chlorine iron total aluminium md lake order It represents a dystrophy factor Factor 4 explained 11 of the variance and was positively correlated with area width length watershed area and volume of lakes which made it a lake size factor High positive loading by sodium and sulphate on factor 5 indicated a salinity-sulphate factor This factor was also associated with low latitude Factor 6 positively associated with lake volume development md negatively correlated with altitude represents the lake shape Fac- tor 7 was correlated with nitrate

Relationships between hplankton Species or Associations and Environmental Factors

Table 3 shows correlations between zooplarakton species abundmces or associations and the derived environmental factors Most species were significantly related to at least one of the factors (p lt 00)

A few species were strongly correlated with factor 1 (alkalinity-hardness) especially Daphnia gsleata rnendotae Meso- cyclops edcuc Diacyclops bicuspidatus thornasi and Diaphan- ssoma sp all group 5A species Species from group 6 showed a negative correlation with factor 1 particularly Keratella tau- aocepampala Bosmim longirostsis and Holopediurn gibberurn

Only a small number of species all from groups 4 and 5B were positively correlated with factor 2 (lake depth and water transparency) especially Cyclops scutijer Keratella hiemalis Daphnia schodleri and Keaatella quadrata Ow the other hand dl other species associations had representatives that were negatively associated with factor 2 Trichocerca cylindsica Polyarthra vulgaris and Leptodiaptomus minutus having the highest degree of negative comlation

Only a few species were correlated with factor 3 (dystrophy) some positively Ceriodaphnia reticulata from group 2 md Daphnka rosea and Epischum lacustais from group 4

Factor 4 (lake size) also showed few significant correlations with my species Positive correlations were noted with Lep- todiaptomus a s h h d i from group 2 and Conochilus sp from group 7 A negative correlation was obsemed with ipiopocy- clops prasinw in group 5B

Many zooplmkters were positively associated with factor 5 (salinity-sulphate) included are Sida crystaklim Diaphano- soma sp Asplanchna priodonta Leptodiaptsrnus sicilis Mesocyclops edm Filinia longiseta Polyarthscs vulgaris and the cyclopoid copepodids These taxa belonged to groups 12 5 (A and B) 6 and 7 Negative correlations with factor 5 were noted for Gastropus sp Cyclops scutifer Leptodiaptomus minutus and Conochilus sp

The majority of the species positively associated with factor 6 (lake volume development) belonged to groups 6 and 7 Bos- mim longisostris Leptodiaptomus minutus and Keratella

cochlearis showing the strongest correlations Species that were negatively related to this factor were from group 4 including Dqhnia rosea D longiremis and D schsdkeri Asglanchncs priodonta Trichocerca multicrenis and Keraella quwdrata in groups 1 2 md 5B also showed preferences for lakes with greater lake volume development index

A few species were positively related to factor 7 (nitrate) notably Asplanchna priodonta Trichocerca multicrenis and Biuphu~eosoma sp Negative correlations with this factor were noted for Epischurs lacustris Eeptodiaptornus minutus and Conochilus sp

To evaluate seasonality effects ow zooplankter abundawces we calculated the correlations between species abundances water temperature md dissolved oxygen at the time of sampling (Table 3) Some species presented a significant correlation with one of the seasonality factors Among the wmwater species were Diaphanosoma sp Sida crystallina Fikinia 1on- gkseta Mesocyclops edax Kercstella quadrata and Trieho- cerca multicrenis Coldwater species consisted of Conochilus sp Leptodiaptomus minutus Cyclops scutfer and Epischura laeustris Few relations were obtained with dissolved oxygen Conochilus sp and keptodisptomus minutus were associated with well-oxygenated waters Inverse relations were noted for Ceriodaphnia retieuiata Daphnia rosea and Biaphanosoms SP

Correlations between the species groups considered as a whole and the derived environmental factors were also calculated (Table 3) Group B was negatively correlated with the lake depth md water transparency factor the dystrophy factor and the lake size factor Group 2 was positively correlated with the salinity-sulphate factor and group 3 showed the inverse pattern Group 4 was positively correlated with the dystrophy factor and negatively correlated with the 1ampe volume development factor Group 4 also contained the coldwater species association Group 5A was positively correlated with the dkalinity- hardness and salinity-sulphate factors it was negatively associated with the lake depth and water transparency factor Inversely group 5B was positively correlated with the lake depth and water t-ranspmncy factor Group 6 was negatively correlated with the alkalinity-hardness factor and the lake depth and water transparency factor It was positively associated with the lake volume development factor Group 7 was negatively correlated with the lake depth and water transparency factor and positively related to the lake volume development factor

The comlation analysis between zooplankton species estimates expressed as biomass and the derived environmental factors gave similar results to those obtained for species abundances However except for group 5A the species associations were not quite the m e in biomass and in abundance Asso- ciations based on biomass gathered together species of the same weight rather than species with identical numerical importance

Zooplankton Size and Trophic Structures in ReBation to pH

The community structure whether expressed in size classes (Fig 3A) or in trophic groups (Fig 3B) tended to v q among sets of lakes of different pH Assignment of species to size classes was based on specific mean length and followed Roff et a1 ( I 98 1) categories In more acidic lakes most of the community was represented by small organisms (lt099 mm rotifers small crustaceans) In neutral lakes all size classes were represented and there was an increase of large plankters En more alkaline lakes small planktern were again dominant

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TABLE 3 S p e m a n correlation coefficients between the seven derived factors and the ablrndances of selected mopladton species Species taxa are grouped according to the results of the clustering analysis Significant comelsations p S 005 005 ( p S 001 801 ( p a 0001

Factor 2 Factor 6 a 1 1ampe depth Factor 3 Factor 4 Factor 5 lake hardness water dystrophy l salinity volume Factor 7

Species To DO alkalinity transparency color size sulphate development nitrate

Group 1 Trichseerca cyampidica - - - -05 - - - - - Asplanchn~ pf- i~dont~ - - - 02 - - - 03

- - Q3 03

Rstifer ind - 03 - - - 03 - - Daphnes dubia - - - - - - 02 - - Leptkodom kidtii - - - - - - - - -

Group - - -

Group 2 Darphpeia ssp - - - Lsptodiaptomus sicklis 02 - - Sida c8ysfalbinkz 04 - - Cerisdqhnia rerticulata - - 03 - Trichocerca rnulticrenis 03 - - 03 Leptdiiegtomus ashhszdi - 02 -

Group - - -

Group 3 Gasrtropus sp Skisampodiaptornus - - - oregomnsks 02 - 02 Synchaeta sp - - -

Group - - -

Group 4 Daphnia gosea - - 03 - Epischura hcustris - 83 - - Daphnis kkongirernis - 02 - Keraklla hiemkis - - - Cyclops scutifer -04 - - Daphazka scbdieri - - -

Group - 03 - -

Group 5A $Piqmanosom sp 05 -02 03 Mwcyclops edax 03 - 05 Diayclops bicaspidatus fhomasi - - 03 Daphnia gakeat~ mendotararc - - 06

Group - - 05

Group 5B Keratella q ~ d r a t a 03 - - KPiinea longiseta 04 - 03 Tropmylcops prssinraw - - -

Group 03 - -

Group 6 Bosminkz longnrostris - - - 04 Leptodiaptomus minutus - 04 03 - Kegatella taurocepmaia - - - 08 Holopediakrn gibberurn - - - 02 Pokyarfhra vuampgaris - -

Group - - - 05

Group 7 $Piaptomid copepod - - - Nauplii - - - Kelbicottia longispnna - - -

Keratelh cochlssris - - - Qckopoid copepodid - - 04 Conochikus sg -06 04 -

116 Can 3 Fish Aqua Sei V01 47 1990

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I

lt 80

Size classes

microf iltar feeders-aedime~ers

macsof ilter feeders- raptors predator inefficient micrefilter feeders

[ efficient micsoQiBter feeders macref ilter feeders

FIG 3 Average () contribution of (A) size classes and (B) traphic groups of zooplankters to total zooplankton abundance md biomass Assignment of species to size classes is based on specific mean length and followed Roff et al (1981) Assignment of species to trophic classes followed Karabin ( 8 985)

When expressed in tems of biomass there was a shift upwards terers from acidic to neutral lakes and a general increase of in dominance of the size class greater than 67 mm efficient microfilterers (Daphnia)

W e n organisms were classified on the basis of their trophic preferences following Karabin (1 985) it appeared in this study mscussion that microfilter feeders-sedimentors (Keratella Kellicottiea) - macrofilter feeders-raptors ( ~ o l ~ a r t h r a Trichocerca) and Comparisons with Lakes of Other Regions in Canada inefficient microfilter feeders (Bosrnim) were more abundant in acidic lakes while macrofilterers (Leptodiaptornus Holo- Our survey of 54 lakes throughout Quebec shows that water gediurn Sib) and efficient microfilters (Daphnia) dominated chemistry is variable among lakes (Table I) Comparisons with in neutral lakes In more alkaline lakes 50 of the zooplankton other surveys done in Quebec lakes by Kelso et al (1986) and consisted of small microfilters-sedimentom and macrofilters- Lachance et al (1984) using the same sets of variables (Table raptors (Fig 33) The results expressed in tems of contribution 4) indicate that our lake sample can be considered representative to total biomass showed a decline of microfilter feeders-sedi- of the variability of Quebec lakes for most of the morphometric mentors macrofilter feeders-raptors md inefficient microfil- characteristics with a bias toward lager lake size Ranges of

Can J Fish Aquat Sci Vil 47 I990 117

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TABLE 4 C o m p ~ s o n of m o ~ h o m e h c physical and chemical characteristics of sampled lakes in Quebec Mean (range) N = number of lakes in each data set

Lachance et al (1984) sent study Kelso et al (1986) Canadian Shield Canadian Shield

Mophome$9ie Lake area (ha) Maximum depth (m) Watershed area (ha) Elevation (m)

Physical md Chemical pH Alkalinity (peq-L- I) Conductivity (pScrn

pH alkalinity conductivity organic carbon and ions from our data we similar to those of the larger sample of Quebec lakes mdysed by Kelso et al (1986) despite the absence of lakes with pH lower than 5 in our sample C o m p ~ s o n s between our sample and that of Lachmce et al (1984) consisting sf 199

adian Shield lakes indicate a bias toward higher alkalinities higher pH and lower levels of organic carbon and sulphate in our lake sample (Table 4)

Lakes Characteristics and Acidification

Five environmental composite factors (Table 2) account for the most discriminant abiotic characteristics of our lakes The distribution pattern of acidity or alkalinity represents the major feature in water chemistry but lake morphomegry also accounts for the observed environmental variability

Natural acidity as expressed by the hydrogen ion and levels of metal contamination (zinc aluminum md manganese) has a significant negative loading on the first factor (alkalinity- hardness) and is related to Bakes at higher altitude in the northeastern regions of Quebec Higher pH is associated with the akalinity-hardness factor dong with calcium magnesium conductivity and levels of sulphate and is related to lakes that are situated in southwestern Quebec To estimate antkopogenic acidification of lakes in uebec we have to consider sulphate and metal concentrations High loading sf reveals the importance s f the process The shows that in our lake sample the atmospheric deposition of sulphates has not yet resulted in a substantial reduction of since the majority of Iakes affected are well buffered by high

obCe md Lachmce (1984) and Pinel-Alloul et al (1987) Quebec lakes can be classified in relation to acidification processes Vulnerability or sensitivity to acidification depends on the water mineralisation indicated by calcium magnesium md conductivity values Anthropogenic acidification is related to the sulphate content of lakes and natural acidity

buffered capability with high vulnera- S to Lawrence River

and in the Parc des Laurentides the least vulnerable zones were situated in midwestern Quebec (La Tuque and Lac St-Jean regions) and lakes with low vulnerability were located in regions affected by acid precipitation with high sulphate values and high mineralisation levels (Maniwaki region) Although this last region was considered by J Dupont (pen comm) as enriched in sulphate by the high levels of pyrite in the soil the

trations (mean of 764 peq-L- ) (Ta d to anthropogenic acid ce et al 1984) Lakes with

are considered to be impacted en when their alkalinity and mineralis-

ation are high (Harvey et al 198 1) As indicated by the factors 2 and 4 mophornetkc features

also play an important role in lake typology (Table 2) Deeper lakes of large volume are situated in the eastern regions at low altitude they show tmnsparent waters as suggested by the load- ings of the Secchi disk on factor 2 Factor 3 shows evidence of dystrophic influence in lakes of greater hydrologic order

sponses to Environmental Factors

Our study showed that many factors in addition to acidification served to determine the zooplanampon communities of Quebec Iakes Furthemore although not evaluated in the present study the distribution of zooplankton species might depend dso on biological factors such as trophy (Pinel-Alloul et al 1987) and predation and competition (Kerfost 1987 Kerfoot and Sih 1987)

The majority of species belonging to group 5A (Fig 2) were d to the hadness-alkalinity factor These species were

likely to occur most prominently in lakes of the western region aniwaki La Tuque and Chapais (Binel-Alloul 85) Bssminw Iongirostris Leptodiaptomus min-

Cars J fish Aquat Sci V01 47 1990

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utus Keratelampa taurocephaampa and Polyarthra vulgaris and Hobopedium gibberurn represented the acid-tolerant species (group 6 Fig 2) the first two were found in eastern and western parts of the sampling area and the rotifers were dominant mainly in the western regions (Pinel-Alloul and MCthot 1985)

The examination of trends in the occurrence and abundance of zooplankton species in relation to the acidity-alkalinity con- tinuum yielded ambiguous results Many authors reported different species associations for acidic or nonacidic lakes but most of the dominant species in eastern Canadian lakes have an ubiquitous nature Messcyclops edax Leptodiaptomus rnin- utus Hobopediurn gibberurn Diacyclgss bicuspidatus thomasi and Diaphanosoma leuchtenbergianum are listed as species occurring over a Iarge range of pH (Carter et al 1980 Confer et ale 1983) Bosmina bongirostris generally documented as a c o m o n inhabitant of acidic lakes (Spmles 1975 Woff and Kwiatkowski 1977 Malley and Change 1986 Pinel-Alloul et al 1987) also occurs as a dominant species over a large range of pH (Yan and Stms 1980 Keller and Pitblado 1984) How- ever North American lakes with low pH are often numerically dominated by Bosmina longirostris and Leptodiaptornus minutus (Yan and Stms 1 980) On the contrary Diaphassnsma sp and Daphnia galeata mendotae are reported to be intolerant to acidity (Woff md Kwiatkowski 1977 Malley and Chang 1986 Pinel-Alloul et al 1987 Bmns and Wiersma 1988) Cluster analyses of zooplankton communities in Quebec lakes support these generalities on species distribution in relation to pH (Table 3) witb few exceptions Hence H~spedium gibberurn considered in our study as an acid-tolerant species is reported over a wide range of pH (Confer et ds 1983) md in calcium-deficient water of the temperate Holmtic (Hutchinson 1967) But it is also categorized as tolerant to acidification (Spmles 1975 Woff and Kwiatkowski 1977 Pope et d 1985 Havas and Likens 1985 Bruns and Wiersam 1988 present study) Within the acid- tolerant rotifers Kerateblu taurocephaampa is a sporadic species in the Great Lakes but commonly occurs in acid bogs or lakes of Iow conductivity and Poyartha vulgaris is a dominant SF- cies in the Great Ekes (Stemkrger 1979)

The mechanisms responsible for the size structure of zooplankton communities in acidic lakes remain unclear even though the general trends towards the increasing importance of smaller tma and Bower abundance are apparent in many studies (Confer et al 1983 Keller and Pitblado 1984 Kelso et al 1986 Pinel-Alloul et al 1987 present study) Community changes in size structure may imply direct toxicity by acid and metal contamination (Malley md Chang 1986) indirect cascading effects of changes in phytoplankton or fish cornunities (Kerfoot 1987) and reduced competition by large cladscerans (DeMott and Kerfoot 1982 Goulden et ala 1982) Tropkic structure of z o o p l ~ t o n communities is also related to the acidification process Keller and Pitblado (1984) observed a reduction of daphnids concomitant with an increase in the abundmce of small grazers (Leptodiaptomus minutus) and a decrease in abundance of predators in more acidic lakes Our results were similar to theirs when expressed in terns of biomass because these authors considered only cmstacems in their study and rotifers represented tm important fraction of the totd zooplankon density but not biomass Compared with daphnids Bosmim lon- glrostris is an inefficient microfilter-feeder (Karabin 1985) its optimum food particle size is below 2-5 prn and its diet is therefore dominated by PBmicroplmkton bacteria and detritus (Gliwicz 1977) The increased importance of cladocem grazers such as Bssmim longirosie8i~ and Holopedium gibberurn

in acidic lakes suggests a reduction in competition from daphnids which are less tolerant to acidification

The morphomegmdc and light penetration features of lakes also influence the distribution of zooplankton species or groups (Table 3) Most species were negatively related to the second factor (lake depth and water transparency) Deep lakes situated in eastern Quebec harboured few species (Pinel-$8110~1 et al 1987) and most species seemed to prefer shallow lakes except some representatives from groups 4 and 5B Daphnia rmea D Iongiremis Keratella hiemalis Cycampops scutifer and Daphnia schodleri were found in deep and clea lakes odand lakes with convex slopes and showed positive correlations with factor 2 (lake depth and water transparency) andor negative correlations with factor 6 (lake volume development) These specics occurred mainly in eastern Quebec Havre St-Pierre Sept-Hles and Mmicouagan (Pinel-AlHoul and MChot 1985) Some of these species (Daphreia longiremis and Cyclops scu- lifer) were coldwater organisms (Table 3) Similar themd preferences were noted by Brooks (1957) and Cater et al (1980) The rotifer Keratella hiemalis was dso categorised as a coldwater fom (Hutchinson 1967) Such a preference for deep lakes was rather unexpected for Daphnia schodkri which occurred in a wide spectrum of habitats and was principally a lake dweller confined to small lakes (Brandlova et aB 1972) This discrep- ancy might be related to the taxonomic difficulties encountered in the discrimination between Daphnia rosea and D schodieri

Only a few species (Daphnia roses and Epischura lacustris from group 4 and Ceriodqhnia reticukata from group 2) dem- onstrated positive correlations with the dystrophy factor (factor 3) These species occurred in lakes situated in midwestern Que- bec (Pinel-Alloul and MCthot 1985) These preferences seemed peculiar since either Epischesra lacustris or Daphnia sp was not usudly found below a pH of 5 (Confer et al 1983) HQW- every Epischura Iacustris was tolerant to dB extreme conditions of lake morphometry water temperature or water chemistry (Cuter et al 1980) Ceriodaphnia usually found in weedy lie- toral regions of lakes or weedy p o l s (Brmdlova et al 19721 was better adapted to humic lakes According to G m o n and Stemberger (1978) no crustacean p l d t e r s a e strictly confined to dystrophic lakes a d can be used as indicators

Few species were related to lake size (factor 4) The large cdanoid Leptodiaptornus ashlandi and the rotifer Conochilus sp seemed to prefer large lakes while Tropocyclops garasinus occurred in small lakes According to Patalas (1 972) the former was found associated with Leptodisgatornus siciampis in large oli- gotrophic Lake Suprior Conochilus sp has been one of the most frequently encountered rotifers following the impoundment of northern Quebec reservoirs (Pinel-AlBoul et aB 1989) This species was classified as a detritus bacterial feeder (Kar- abin 1985) Although it was found in large lakes its presence c a be better associated with the trophic status of the lake than with its size

The majority of zoopldcters were positively correlated with factor 5 (salinity-sealphate) particularly species belonging to groups 1 2 and 5A As discussed previously the latter group of species was idso related to the hardness-alkalinity factor Sida crystalbina and Leptsdiaptomus sicilis occurred in hard- water lakes (Carter et al 1980) ~eptodiaptomus sicilis md Daphnia dubia had been found in larger less productive HA- iburton lakes (Spmles 1977) Species from group B included the rotifer Pkspampanchm priodonta previously reported by Fuller et al (1977) from mesotrophic Douglas Lake The majority of these species were found in lakes located in western Quebec

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Sennetene Mmiwaki and La Tuque regions (Pinel-Alloul md MCthot 1985) Chlorine did not have any loading on factor 5 md d l these lakes were f a from the influence of sea spray Hence high sodium loading on factor 5 was difficult to inter- pret Gastropu~ s ~ and Cyclops scutifer were negatively related to the salinity-sulphate factor The cyclopoid was already h o w to be absent from hadwater lakes (Cater et al 1980)

Most of the species correlated with nitrates (factor 7) were positively so except for some species from groups 4 6 and 7 However the very smdl fraction of the variance explained by this factor (475) md the low vdue of the comelation coefficients did not allow us to infer zmplmkton relationships with h i s variable

Significant correlations between species abundances and the seasonality parameters9 especially water temperature might suggest that the distribution of zooplankton species in Quebec lakes was dso related to their thermal preferences or their seasonal development Leptodiaptomu ashlandidk L minutus Epischura lacu~tris Daphnia lo~agirerni~ Cyclops seeetijer md Csnochilus sp were coldwater foms (Table 3) not found in southern US lakes or found only in deep lakes (Carter et al 1980) Most of the species positively related to temperature were

stenothem Filinia ongisrampta eurythem Keratea quadraga md Trichscerca multicrenis or midsummer species Biapknosoma sp Sida cristaamplina md Mesocycampq~ edax (Hutchinson 1967 Stemberger 1979 Cater et al 1980) In our study seasonal development effects could be considered neg- ligible because zooplankton sampling was performed in 1 mo Hence conelations between zoop1adton species md water temperature should be interpreted in terns of geographic distribution brought a b u t by temperature preferences

Ecological Significance of Species Associations

The eight goups of species identified in the cluster analysis may be considered separate species assmiations9 characterized by distinct patterns of distribution The species composing each sf these associations cooccur because they have similar reactions to the environment Correlations between species abundances and the seven derived environmental factors define the nature of individual zooplanktonic responses to abiotic conditions

Our results show that groups of species demonstrate strong homogenous correlations with one sf the seven derived environmental factors For example group 1 is an associadon of species which probably prefer smdl shallow dystrophic 1akes rich in sdts or sulphates Gmup 2 represents species associated with shallow lakes with high levels of sulphate Group 3 represents species found in lakes with low sulphate concentrations Group 4 are coldwater species found in deep dystrophic lakes Gmup 5A is an association of hadwater species found in shallow lakes Group 5B represents w -water species found in deep lakes Group 6 is the acid-tolerant association found in shallow lakes with high volume development Gmup 7 are species found in more neutral shallow lakes

Our study suggests that acidification patterns in Quebec lakes fail to account fully for the observed zooplankton species dis- tributions Additional factors related to morphometric features of lakes are also responsible for the observed spatial heterogeneity The weakness of the relationships between zooplankton species md the abiotic environmental factors probably means that biotic factors might also generate heterogeneity in zmpladcton cornunity structure Indeed cascading indirect

effects of acidification within the aquatic food web related to changes in competition predation or grazing patterns are not considered at all in this study It is noteworthy that this para- digm is just becoming the base of the most recent studies on generative processes of zooplankton community structure (Ker- foot 1987 Kesfoot and Sih 1987)

Acknowledgements

A Leduc assisted us in the statistical analysis of the data m d C Blanchad helped us in the preparation of the figures and the manu- script Funds were provided by a contract from the Department of Fisheries and Oceans and fmm both an NSERC operating grant to B PA and a FCAR team grant to the Groupse de recherches en 6co1- ogie des eaux deuces of the UniversieC de Montreal from the Quebec Ministry of Education The authors gratefully acknolewdge the contribution of F D e l o m e - H q w for her careful revision of the English text

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Although the part of Quebec lying on the Canadian Shield has often been recognized as am area of high sensitivity to acidification (Hmey et al 198 Lachmce et al 1984) little emphasis has been given to the acidification of Quebec surface waters with respect to its relationship to aquatic biota especially in the case of planktonic organisms Our major objectives in this study were to (1) describe the structure of zooplarnkton communities in Quebec lakes and their chmcteristic associations of cooccurring species (2) determine the relative importance of the abiotic variables (rnorphometry water quality acidification indices) in lake typology a d (3) document the relationships between the critical environmental variables derived from lake morphometry water quality and acidification level and the organization sf the zooplankton c o m u - nity More specifically the definition of the effects of acidification on zooplankton a key component of the food web may aid in the interpretation of field monitoring data

Matefials md Methods

Study Area

A number of mophometric physical chemical and biotic variables were measured in 54 lakes of first second and third

hydrologic order throughout Quebec (Langlois et al 1983 Pinel-Alloul and Mkthot 1985) Means and ranges are presented in Table 1 The lakes sampled are located on the Canadian Shield north of the St Lawrence River and south of the 52N latitude (Fig I) a region considered highly sensitive to acidification (Bobee and Lachance 1984 Lachance et al 1984 Dupont and Grimmd 19861 mainly because of the composition of its bedrock (gneiss-granitic) and the average pH of rainfall in Quebec (pH = 42 - 50) Most of the chosen lakes were summer stratified easily accessible and not affected by my human or agricultural activity in the immediate watershed Based on principal component m d hierarchical cluster analyses of the 20 physical md chemical variables (Table I ) Pinel-Alloul and MCthot (1198) have already observed a southwest to northeast longitudinal gradient in the hydrogen ion concentration indicating that lakes of the northeastern regions (regions 05 - 07) are generally more acidic than lakes situated in the Maniwaki region (region 04) (Fig 1) Sulphate concentrations follow an inverse gradient and it appears that saalphate levels and anthopogenic acidification are higher in southwestern Quebec lakes (Lachmce et d 1984 Pinel-Alloul et dfl 1987 Dupont 11988) A recent integrated study of spatial variation in physicochemicd quality in our lakes (Department of Fisheries and Oceans 1987) showed that 72 of the lakes

TABLE 1 Mean and range of selected moqhometric physical md chemical characteristics of the 54 study lakes in Quebec

Caacteristic Mean Minimum Maximum

Morphornetric Latitude Longitude Altitude (m) Maximum depth (m) Mean depth (m) Relative depth (9) Lake maximal length (h) Lake maximum width (h) Lake area (ha) Watershed area (ha) Lalee volume (1041nma3) Lalee order Lake volume development Morphoedaphic index

Physical and Chemical Secchi disk (m) Color (U H ) Conductivity (pS-cm- ) Hydrogen (H) (peqLP )

Alkalinity (peqaL- ) Cl (peq-L-I) SO (peqL--I) Ca (peqLW) Mg (peqeL- I) P (paeq-L- ) Na (peq-L- l) Total Al (pager ) Mn (pg-L- ) Fe (kg-L I )

Zn (peqaL- ) Dissolved organic carbn (mg-L-) Total organic carbon (mg -L - ) Nitrate (peq-L- ) Alkalinnitylsulph ratio

Can J Fish Aqua Sei Vol 47 1990

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of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly











Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly




No of lakes pH so4






s NESOCYCLQBS EDAX




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly








Eigenvalue









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly


















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly





- - Q3 03


Group - - -


Group - - -


Group - - -


Group - 03 - -


Group - - 05


Group 03 - -


Group - - - 05




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly











Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly




No of lakes pH so4






s NESOCYCLQBS EDAX




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly








Eigenvalue









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly


















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly





- - Q3 03


Group - - -


Group - - -


Group - - -


Group - 03 - -


Group - - 05


Group 03 - -


Group - - - 05




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly




No of lakes pH so4






s NESOCYCLQBS EDAX




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly








Eigenvalue









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly


















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly





- - Q3 03


Group - - -


Group - - -


Group - - -


Group - 03 - -


Group - - 05


Group 03 - -


Group - - - 05




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly








Eigenvalue









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly


















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly





- - Q3 03


Group - - -


Group - - -


Group - - -


Group - 03 - -


Group - - 05


Group 03 - -


Group - - - 05




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly


















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly





- - Q3 03


Group - - -


Group - - -


Group - - -


Group - 03 - -


Group - - 05


Group 03 - -


Group - - - 05




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly





- - Q3 03


Group - - -


Group - - -


Group - - -


Group - 03 - -


Group - - 05


Group 03 - -


Group - - - 05




Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly

I

lt 80

Size classes








Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly
















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly






















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly









Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly










Acknowledgements


References




















Can

J F

ish

Aqu

at S

ci D

ownl

oade

d fr

om w

ww

nrc

rese

arch

pres

sco

m b

y U

nive

rsity

of

PE

I o

n 02

21

13Fo

r pe

rson

al u

se o

nly



































Can

J F

ish

Aqu

at S

ci D

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ww

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arch

pres

sco

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rsity

of

PE

I o

n 02

21

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r pe

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nly
















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ish

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of

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I o

n 02

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Can

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Acknowledgements


References




















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nive

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of

PE

I o

n 02

21

13Fo

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nly










Acknowledgements


References




















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J F

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Aqu

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Can

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zooplankton species associations in quebec lakes: variation with abiotic factors, including natural...

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