Harold H. Harvey

Biogeographic associations in fish assemblages: local vs. regional processes

Six geographic regions along the Laurentian Great Lakes in Ontario, represented by 286 lakes, were examined to identify the existence of regional similarities of fish species composition and their association to geographic location and regional patterns of lake morphology and pH. Lakes differed significantly among regions with respect to surface area, maximum depth, and pH. Species presence/absence data were summarized using correspondence analysis, and the resultant scores were used in multivariate analysis of variance and canonical variates analysis. These results indicated that the fish faunas of the six geographical areas were distinct. Interregional distances based on fish community scores, lake morphology–chemistry data, and geographical distances were contrasted using Mantels test. Regional faunal similarities were correlated significantly with geographical proximity, but not with lake morphology. We propose that post—glacial dispersal and lake thermal regimes are important determinants in structuring regional patterns of fish assemblages, whereas environmental conditions such as lake depth and pH assume greater importance in determining species compositions of individual lakes.

Acidic deposition: effects on aquatic ecosystems

The literature pertaining to the influence of the atmospheric deposition of acidifying substances on aquatic ecosystems is examined in this article. Important chemical species in atmospheric deposition are first identified, and their influence on stream and ultimately on lake water chemistry discussed. Changes that have accompanied acidification among biological communities of decomposers, primary and higher order producers are discussed. Where they exist, hypotheses relating to causes of community changes are examined.

The relative importance of manganese and iron oxides and organic matter in the sorption of trace metals by surficial lake sediments

The sorption of trace metals (Zn, Ni, and Cu) by surficial sediments of four acid (pH < 5.6) and three circumneutral (pH 6.4–6.5) lakes were compared via distribution coefficients (KD). These were calculated from measurements of porewater metal concentrations in the uppermost layer of lake sediments and total sediment-sorped metal, as determined by the sum of the amounts of metal recovered from the easily reducible (ER) (exchangeable and bound to oxides of Mn), reducible (R) (bound to oxides of Fe), alkaline extracted (ORG) (organically bound) fractions of sediment. Porewater Cd concentrations were undetectable in all lakes. A comparison of the relative amounts of metal recovered from the three sediment components was used to illustrate differences in the partitioning of the trace metals among the seven lakes. Calculated KdS for Zn and Ni showed reduced pH dependence with decreasing lake pH (least-squares linear regression, P≤ 0.01). No such pH dependence was noted for Cu. The comparison of the relative amounts of metal recovered from each of the three sediment components revealed that the partitioning of the trace metals Zn, Cd, and Ni differed among the seven lakes. Less metal was recovered in the ER fraction, and more was recovered in the R and ORG fraction of sediments sampled from the four acid vs. the three circumneutral lakes. In circumneutral lakes, more of the metal was recovered in the ER sediment fraction. Based on the three sampling locations in each study lake, we suggest that differences in the concentration of metals in the ER vs. R and ORG sediment component in surficial sediments of recently acidified vs. circumneutral lakes may be the result of two concurrent processes: 1. (1) a pH-dependent decrease in the sedimentation of ER metal, and 2. (2) a concurrent pHinduced precipitation of Fe-humic complexes involving the coprecipitation of trace metals with strongly bound Fe-humic complexes.

RELATIVE ABUNDANCE OF LITTORAL ZONE FISHES: BIOTIC INTERACTIONS, ABIOTIC FACTORS, AND POSTGLACIAL COLONIZATION'

We used multivariate ordination techniques to establish relationships among the abundances of the most frequently occurring littoral zone fishes (fishes that occurred in >60% of the lakes) in 25 central Ontario lakes. Previously, most large-scale comparative studies of freshwater fish communities only measured species presence/absence. Abundance estimates provide an alternative, and perhaps more sensitive, means of assessing the relative importance of biotic processes, geological/chemical factors, and historical determinants of present-day community structure. Seventy percent of the variation in abundances was described by the first two axes from a correspondence analysis. Abundances of white sucker (Catostomus commersoni) and rock bass (Ambloplites rupestris), and abundances of brown bullhead (Ictalurus nebulosus) and smallmouth bass (Micropterus dolomieui) were negatively related. However, abundances of these species pairs were not related where the species occurred in sympatry, suggesting that species presence/absence strongly influenced these patterns of abundance. Most of the variation in species abundance and distribution was attributed to physical factors associated with species colonization processes (i.e., differences in postglacial colo- nization rates may have caused negative associations between white sucker and rock bass). An independent 45-lake data set was used to confirm these zoogeographic patterns. Pre- dation by northern pike (Esox lucius) may be partly responsible for variation in abundance and distribution of white sucker. Where pike and sucker co-exist, sucker abundance is lower than where sucker exist without pike. Habitat differences between lakes provided the best explanation for the variation in abundance of smallmouth bass and brown bullhead. Biogeographic processes, physical environmental factors, and predatory processes have been very influential in shaping abundances and distributions of ubiquitous littoral zone fishes in Ontario.

Metal concentrations in chironomids in relation to the geochemical characteristics of surficial sediments

Concentrations of Fe, Mn, Al, Zn, Cu, and Cd were determined in Chironomidae (Diptera) sampled from three locations in six lakes ranging in pH from 5.0 to 6.5. Results of a two-way ANOVA with sample location and lake as the two co-factors showed that, in general, chironomid larvae metal concentrations were lake and sample site dependent (P<0.05). To determine if differences in chironomid larval metal concentrations among the six lakes could be related to the geochemistry of the sediments, specifically concentrations of: organic matter, reducible Fe (Fe oxides), easily reducible Mn (Mn oxides) and metal (Fe, Mn, Al, Zn, Cu and Cd) associated with either the easily reducible, reducible and alkaline extract (organic) components of the sediment, a partial correlation analysis was employed. Chironomid Mn, Al, and Fe concentrations correlated positively with total sediment Mn, Al, and Fe concentrations, respectively, and negatively with organic matter; chironomid Zn and Cu concentrations correlated positively with an easily reducible measure of sediment Zn and Cu concentrations and negatively with sediment concentrations of reducible Fe. No combination of sediment geochemical variables significantly correlated with chironomid Cd concentrations. These results support the hypothesized action of reducible Fe (Fe oxides) modifying Zn and Cu accumulation by chironomids. In contrast, sediment organic matter rather than reducible Fe modifies Mn, Al, and Fe accumulation in chironomids.

Composition of the Benthos in Relation to pH in the LaCloche Lakes

In the LaCloche Mountains of Ontario, 11 lakes spanning the pH range 4.8 to 6.7 were sampled for benthic organisms. Sixty sediment cores were collected from each lake, organisms >0.5 mm were separated and 25 taxa were identified. The number of taxa present was correlated negatively with [H+]: Y=23.2−4.27 × 105 ×, r2=0.61, p<0.005. The density of all organisms was not correlated with lake pH. Six taxa: gastropods, pelecypods, daphnids, ephemeropterans, amphipods and ceratopogonids, either were reduced in abundance or absent from the more acid lakes. Bosminids and acari were more abundant in lakes of pH 5.0 to 5.5. The densities of the remaining taxa, notably chironomids and oligochaetes, appeared to be independent of pH over the range 4.4 to 6.7. These results are discussed in relation to the hypotheses which have been advanced to explain the differences observed in benthos distribution between lakes in Europe and in North America.

Growth responses of yellow perch,Perca flavescens (Mitchill), to lake acidification in the La Cloche Mountain Lakes of Ontario

SynopsisAcidification of the lakes of the La Cloche Mountains, Ontario, has reduced population densities of the yellow perch. Yellow perch of age groups 1 to 3 responded with increased rates of growth. Yellow perch of age groups 4 to 9 responded with reduced rates of growth. On the basis of these findings it is suggested that the growth rate of yellow perch may serve as a valuable indicator of environmental stress.

Uptake and tissue distribution of manganese in the white sucker (Catostomus commersoni) under conditions of low pH

Concentrations of manganese were determined in the liver, kidney, muscle and bone of white suckers (Catostomus commersoni) from five acid (pH < 5.8), and two circumneutral lakes in south-central Ontario. Manganese tissue concentrations were greater in fish captured from the most acidified lakes with the greatest concentrations of dissolved manganese. These fish had increased concentrations of manganese in the liver, as indicated by a comparison of liver:kidney manganese concentration ratios among the seven fish populations. Tissue concentrations of manganese from all populations either were negatively correlated (P < 0.05) or remained constant with fish size indicating homeostatic regulation of this metal. Manganese concentrations of the benthic fauna were positively correlated to sediment concentrations (R=0.30). Lake sediment manganese concentrations were significantly correlated to maximum lake depth (R=0.80, P < 0.03), with the concentrations in the top 0–1 cm dependent on the redox conditions in the seven lakes. Based on the seven lakes studied, manganese concentrations in the benthic-feeding white sucker correlated better with dissolved manganese, than with either the concentrations in food or surficial sediments.

Growth, Abundance, and Food Supply of White Sucker

Abstract Twenty-three populations of white suckers Catostomus commersoni from Ontario lakes were investigated to determine if growth was density-dependent and if the abundance of chironomid larvae in the lake littoral zone was an important factor influencing growth. White sucker population sizes were estimated with either the Petersen mark–recapture or the catch-per-unit-effort method. White sucker fork length at age was back-calculated from the first pectoral fin ray. Each lake was divided into three thermal zones based on the position of the thermocline, and the benthos was quantified from 60 core samples prorated over the three zones. Canonical correlation and redundancy analyses indicated that the abundance of benthos, especially chironomids in the littoral zone, was a good predictor of white sucker growth. Growth was not so important in explaining benthos abundance. Regression and correlation analyses indicated white suckers from lakes with more abundant chironomid larvae in littoral zones and low wh...

Concentrations and distribution of Fe, Zn and Cu in tissues of the white sucker (Catostomus commersoni) in relation to elevated levels of metals and low pH

This study examines whether the process of lake acidification influences the accumulation of Fe, Zn and Cu in the tissues of the white sucker (Catostomus commersoni). Concentrations of Fe, Zn and Cu were measured in the liver, kidney and muscle of white sucker sampled from 4 acidic (pH range 4.8–5.3), 1 slightly acidic (pH = 5.8) and 3 circumneutral (pH = 6.3, 6.4) lakes located in south-central Ontario, Canada. Pearson product-moment correlation coefficients were used to determine relationships between average elemental concentrations in the 3 tissues and both sediment and water metal concentrations plus lake pH, DOC and alkalinity. Despite the 1000-fold difference in H+ concentration among the 8 study lakes, tissue concentrations of Fe, Zn and Cu did not correlate with lake pH. Average Fe, Zn and Cu tissue concentrations did not correlate with metal concentrations in lake water. Only Zn concentrations in the liver and muscle were correlated with Zn concentrations in the sediment (r = 0.83 and r = 0.88, P < 0.05). Iron and Cu were regulated by the white sucker over a wide range of lake pH and metal concentrations in both the water and sediment. In contrast, Zn tissue concentrations were correlated with sediment Zn concentrations, the latter are thought to result from Zn inputs of anthropogenic origin.