Circumneutral Lakes Research Articles

Influence of acidification on metal fluxes in Swedish forest lakes

Five soft water forest lakes in southern Sweden were studied during 1981–1984. The mean pH values were 4.8–6.6 and the total organic carbon (TOC) concentrations were 2–9 mg l −1. Water was sampled for determination of chemical parameters and the concentrations of Al, Fe, Mn, Zn, Cu, Pb and Cd at lake outlets 10–12 times throughout the year. The metals were fractionated by filtration (0.4 μm) and in situ dialysis (0.002 μm). Sediment traps were used to collect particulate material for determination of sedimenting metals. Metal levels were measured by graphite furnace or flame atomic absorption spectroscopy (AAS). Metal concentrations were maximal when water discharge was highest and pH was lowest. Metal outflow was also highest during spring and the output was higher from acidified than from circumneutral lakes. Cadmium occurred mainly in dialysable form, while Pb was mainly in particulate form. The proportion of both Cd and Pb in dialysable form increased at lower pH. Iron, Al, Cu and Pb were largely deposited in the sediments, and pH had a relatively small influence on the sedimentation. In contrast, the distribution of Zn, Cd and Mn was obviously more influenced by pH and their sedimentation was substantially lower in the acidified lakes, about 5–40% of the input, compared with 70–95% in the lakes with higher pH.

Critical Swimming Speeds of Yellow Perch Perca Flavescens: Comparison of Populations from a Naturally Acidic Lake and a Circumneutral Lake in Acid and Neutral Water

ABSTRACT The objectives of this study were to determine if environmental acidity reduces swimming performance in the acid-tolerant yellow perch (Perca flavescens) and to use swimming performance as an indicator of fitness in testing whether fish from naturally acidic environments perform better in acidic water. Perch from a naturally acidic lake (pH 4·4) or a nearby circumneutral lake were swum after either 5–7 months of laboratory acclimation to simulated soft, natural waters or after more than 2 years of acclimation to hard, circumneutral water. The performance test was a critical swimming speed (Ucrit) determination, with 5cms-1 velocity increments at 30 min intervals. Low environmental pH (4·0) produced significant decreases in average swimming performance in each of three experimental series. Acid decreased performance in most but not all fish. The two perch populations had similar mean Ucrit values when swimming in acid water. Pre-acclimation to hard water significantly increased swimming performance. Gravid females acclimated to acid water had very low critical swimming speeds in acid water, whereas Ucrit changed little in acid water when oogenesis occurred in neutral water.

PHOTOSYNTHESIS OF ALGAL CULTURES AND PHYTOPLANKTON FOLLOWING AN ACID pH SHOCK1

ABSTRACTIn acidifying lakes, pH decreases abruptly in response to acid precipitation events. We tested the hypothesis that, in comparison to a circumneutral lake, phytoplankton photosynthesis in an acidifying lake is less sensitive to a rapid decrease in pH (acid pH shock).Phytoplankton in Plastic Lake, which is undergoing acidification, was characterized by a predominance of Pyrrophyta, and phytoplankton photosynthesis decreased to a lesser extent in response to an acid pH shock than the photosynthesis of populations from St. Nora Lake, a circumneutral lake located nearby, in which Pyrrophyta were not abundant. Rates of phytoplankton photosynthesis in acid pH shock experiments were significantly correlated with hydrogen ion but not with dissolved inorganic carbon (DIC) concentrations.Depression of photosynthesis following an acid pH shock occurred in axenic cultures of Chlorella pyrenoidosa Chick but was not observed in axenic cultures of the acidophilic alga Chlorella saccharophila (Krug.) Nadson or in three species isolated from Plastic Lake. However, the three isolates were not acidophilic during growth. We conclude that phytoplankton in acidifying lakes consists predominantly of species which are tolerant to acid pH for short periods (hours) but cannot grow at these pHs.

Reproductive Success of Amnicola limosa (Gastropoda) in Low Alkalinity Lakes in South-Central Ontario

The reproductive success of the gastropod Amnicola limosa was examined in six lakes ranging in pH from 4.62 to 7.42 to determine which stages in the life cycle were most sensitive to acidification. Although fecundity was significantly greater (p < 0.01) for adults reared at pH 7.42 than at pH 5.89–6.64, a failure to oviposit was documented only at pH 4.62. Hatching success was uniformly high (88–97%) at pH 5.59 to 7.42, while embryos incubated at pH 4.62 suffered complete mortality. The most critical stage in the life cycle is the newly hatched stage. Survival during the 20 d post hatch ranged from 23% at pH 5.59 to 69% at pH 7.42. There was an order of magnitude difference in the cumulative percent survival of recruits in lakes ranging in pH from 5.59 (5.1%) to 7.42 (44.0%). Juveniles raised at low pH (5.59–5.70) were on average 0.20 mm (20%) smaller than those in circumneutral lakes (pH 6.64–7.42). The present low densities of Amnicola limosa in Heney Lake (pH 5.59) can be explained by low recruitment since 1980. Evidence presented suggests that the disappearance of this species from clear low pH lakes (pH < 5.8) is due to reductions in fecundity and hatchling survival.

Production and Growth Efficiency of Brook Trout (Salvelinus fontinalis) in Two Adirondack Mountain (New York) Lakes Following Liming

Yearling and spring fingerling brook trout (Salvelinus fontinalis) stocked in two Adirondack lakes after liming in the spring of 1985 produced 10–14 kg∙ha−1yr−1 at average standing crops of 8–10 kg∙ha−1 during the first year after stocking. These values were similar to levels observed in other limed and circumneutral Adirondack lakes, which collectively support a limited range of biomass (10–20 kg∙ha−1) and production (7–16 kg∙ha−1) compared with more fertile waters in other regions. The estimated level of food consumption required to maintain initial production rates observed in the two limed lakes was 80–100 kg∙ha−1. This level of predation was sufficient to significantly alter the size structure and composition of the invertebrate prey community within a few months after stocking. However, mean production efficiency in these populations remained at levels of 20–25% and the development of adverse water quality conditions in the first year after liming appeared to be of greater significance than food limitation in regulating production and biomass of these stocked brook trout populations. Reacidification of one lake 5 mo after liming resulted in rapid declines in biomass and production as a result of both increased mortality and reduced growth.

Metal contents in liver tissues of non-fledged Goldeneye,Bucephala clangula, ducklings: A comparison between samples from acidic, circumneutral, and limed lakes in South Sweden

The risk of increased exposure to metals for a vertebrate predator foraging on aquatic insects in acidified lakes was investigated through analyses of the content of Al, As, Ca, Cd, Cu, Fe, Hg, Mn, Pb, Ru, Se, and Zn in the liver tissue of 42 non-fledged Goldeneye, Bucephala clangula, ducklings from acidic, circumneutral, and limed lakes in South Sweden. No indications of significantly different concentrations in samples from acidic lakes in comparison with circumneutral lakes were detected for any metal, but among individual birds from acidic lakes there were high contents of Hg. Liming probably affects the exposure to some metals; lower contents of Hg were recorded from limed lakes in comparison with acidic lakes, while the reverse trend was recorded for Cd and Mn.

Blood Oxygen Capacity Differences in Yellow Perch (Perca flavescens) from Northern Wisconsin Lakes Differing in pH

Whether chronic exposure to environmental acidity reduces oxygen loading in fish is still uncertain. We evaluated this question by looking for evidence of adaptations to hypoxia in a population of yellow perch (Perca flavescens) isolated in a well-oxygenated, naturally acidic lake. Perch were sampled directly from this naturally acidic lake (pH 4.5) and two circumneutral lakes, one of which experiences low oxygen. Fish were bled rapidly via cardiac puncture. Hemoglobin, hematocrit, and erythrocyte number were determined by standard methods. Hemoglobin concentrations were highest in perch from the acid lake (6.4 g/dL) intermediate in the neutral lake with anoxic zones (5.7 g/dL) and lowest in the well-oxygenated neutral lake (4.8 g/dL). Increased hemoglobin per red cell accounted for this trend. Slightly larger hematocrits in acid lake perch (41.2 versus 36.2) were achieved through small increases in red cell number and volume. Evidence suggests that these results are part of an adaptational response different from the hematological responses of fish to acute acid exposure.

Distribution of scaled chrysophytes in 17 Adirondack (New York) lakes with special reference to pH

Thirty-four scaled chrysophyte taxa are described from 17 Adirondack lakes located in either Hamilton or Franklin counties. Ten taxa, Synura sphagnicola, Syn. echinulata, Syn. petersenii, Mallomonas acaroides var. muskokana, M. hamata, M. caudata, M. crassisquama, M. galeiformis, Spiniferomonas trioralis, and Chrysosphaerella longispina, were found in more than 40% of the study lakes. Mallomonas acaroides var. muskokana, M. hamata, Syn. sphagnicola, Syn. echinulata, and Spiniferomonas coronacircumspina were common and important components of the phytoplankton floras in lakes with a pH < 5.4; however, M. hamata and Sp. coronacircumspina were noticeably absent from bog lakes. Synura sphagnicola and Syn. echinulata were as common in samples with a pH between 5.4 and 7 as they were below pH 5.4. Mallomonas crassisquama, M. caudata, M. pseudocoronata, and Synura spinosa were found in a significantly greater percentage of samples from circumneutral lakes and were lacking from waters with a pH < 5.4. Differences in species distributions between Hamilton County (higher mean pH) and Franklin County lakes further supported the observed pH ranges of the common taxa. Similarities and differences are made with a study of Smol et al. (Can. J. Bot. 62: 911–923), who described the distribution of scaled chrysophytes from the surface sediments of Adirondack lakes.

Planktonic Indicators of Lake Acidification in the Adirondack Mountain Region of New York State

ABSTRACT Recent studies of plankton community structure in Adirondack lakes are summarized in relation to lake acidity status. Species richness of phytoplankton, planktonic rotifers, and crustacean zooplankton declines with decreasing pH. Highly acidic waters (pH < 5.0) average fewer than 20 phytoplankton and fewer than 12 zooplankton species in midsummer collections. More circumneutral lakes (pH > 6.0) average more than 33 phytoplankton and 20 zooplankton species. This decline in species number represents a simplification of plankton community structure rather than the invasion of new species. Very few Adirondack plankton species can be considered alkalibiontic or acidobiontic. The dominant species of acidic lakes are also generally important in non-acidic lakes of the region. Thus, presence or absence is generally not a very good indicator of lake acidity. However, shifts in the relative abundance/biomass of some species or species groups appear to be consistent with changes in pH. The relative biomass of acidobiontic diatoms and mallomonads is reported to provide a good index of acidity status. The relative biomass of the rotifer, Keratella taurocephala provides a consistent indicator of acidity. Among the crustacean zooplankton it appears that the combined relative biomass of Diaptomus minutus and Bosmina longirostris may be a useful indicator of water quality changes associated with acidification.

Abundance, Distribution and Life Cycles of Midges (Chironomidae: Diptera) in an Acid Strip-Mine Lake in Southern Illinois

The chironomid population of an acid (pH 3) strip-mine lake was studied by taking pairs of Ekman dredge samples from five stations along one transect at fortnightly to monthly intervals for 1 year; only two species were found. For Chironomus near maturus the range (and annual mean) of larval numbers in the transect were 3055 to 14,137 (X =3,936) m2, and maximum station density was 49,972 m2. Range (and annual mean) of larval biomass in the transect were 4.15 to 19.78 g m2 (X = 4.23) and maximum station biomass was 44.46 g m2 preserved wet weight. In 1977 at the deepest (8 m) station, C. nr. maturus was usually abundant, but in 1978 it was scarce or absent. Chironomus nr. maturus was univoltine, but with part of the population emerging in the autumn and part in the spring and summer. The respective numbers for Tanytarsus dendyi Sublette were 0-17,352 (2,360) and 50,105 m2; and respective weights were 0-1.20 (0.16) and 2.99 g m2. Tanytarsus dendyi was almost always scarce or absent at the deepest station. It was trivoltine; each summer generation lasted ca. 2 months. It overwintered in the egg stage or as first instar larvae. Abundance of both species was higher than for species in the same genera in most other acid and circumneutral lakes. The sparser populations in deep water in 1978 may be related to a strong stratification in which oxygen supersaturation persisted for several weeks at intermediate depths.

Microcrustacean community structure and biomass in marsh and lake habitats of the Okefenokee Swamp: seasonal dynamics and responses to resource manipulations

Microcrustacean community and biomass dynamics were studied for two years in a Nymphaea‐Eriocaulon macrophyte marsh and a nearby shallow lake which lacked macrophytes in the Okefenokee Swamp. In this blackwater, acidic wetland, microcrustacean diversity and biomass were similar to other circumneutral lakes and littoral areas, contributing to a productive fish assemblage. In the lake, the annual biomass pattern (15–1627 μg 1−1) was unimodal and was dominated by the crustaceans Diaptomus sinuatus and Eubosmina tubicen. Rotifers were occasionally important, constituting up to 55% of total biomass. Over the long term, mean annual biomass in this post‐drought study are higher than in pre‐drought years. In the marsh, biomass (11–777 μg 1−1) fluctuated biomodally with late winter depressions corresponding to low temperatures and midsummer declines indicative of increasing fish predation. Summer dominance shifted between years from Macrothricidae in 1982 to Sididae in 1983. Variation in biomass correlated most strongly with algal chlorophyll in the marsh and with bacterial density in the lake.In field enclosure experiments in which primary production was reduced by shading, microcrustacean responses varied between lake and marsh habitats and with season. Lake zooplankton were consistently suppressed by reduced algal resources in winter, spring and summer experiments, with greatest responses to shading in the summer. Marsh microcrustacea were most affected in the winter experiment and became less sensitive to manipulated resource levels in spring and summer. Decoupling of these consumers from autotrophic resources in the marsh, but not in the lake, coincides with times of high macrophyte turnover and warming temperatures which promote the conversion of detritus into heterotrophic resources such as bacteria. The conflict between interactions implied by the experimental approach vs statistical criteria emphasizes a need to interpret resource dependence from seasonal dynamics of field populations with caution.

Effects of Acid pH Shock on Phosphate Concentrations and Microbial Phosphate Uptake in an Acidifying and a Circumneutral Lake

Water samples from Plastic Lake and St. Nora Lake, Dorset, Ontario, were subjected to a rapid decrease in pH (acid pH shock). In both lakes, phosphate concentrations changed following pH shock. Minimal phosphate concentrations were observed in the pH 5.2–5.8 range. Maximal concentrations in both lakes occurred at pH 4.0: in Plastic Lake the mean increase at pH 4 was 3.0 times ambient and in St. Nora Lake was 2.5 times ambient. Particles &gt; 0.45 μm were the major source of the phosphate released on acid pH shock. Rate constants of 32PO4 uptake by microorganisms decreased in response to acid pH shock, and bacteria were affected more than algae; the decrease in rate constants was more severe in Plastic than in St. Nora Lake but we could not distinguish the relative contributions of H+ toxicity and isotope dilution (by the extra phosphate released) to the observed decline.

Modelling the effect of acidity on mercury uptake by walleye in acidic and circumneutral lakes

An association between acidification of lakes and high mercury concentrations in fishes has been reported. In northern Wisconsin (USA), for example, walleye ( Stizostedion vitreum) in naturally acidic lakes have higher mercury concentrations than walleye in circumneutral lakes (Weiner, 1983). In this study a bioenergetic based model for mercury uptake is applied to identify potential causes of higher mercury concentrations in fishes living in acidic lakes. Application of the model to walleye populations in northern Wisconsin indicates that higher mercury concentrations in acidic lakes are most likely a result of both increased concentrations in the water and increased efficiencies of uptake from water. Higher concentrations in the water would result in higher concentrations in the food.

Size- and age-specific patterns of trace metal concentrations in freshwater clams from an acid-sensitive and a circumneutral lake

We collected freshwater clams (Elliptio complanata) from an acid-sensitive and a circumneutral lake in south central Ontario and compared tissue metal concentrations. Clams from the acid-sensitive lake had higher concentrations of Cu and Cd and lower concentrations of Zn and Mn than clams from the circumneutral lake. Tissue concentrations did not reflect metal levels in the water. Competition may be occurring between metals for binding substrate in clam tissue. Clam size and (or) age successfully predicted tissue metal concentrations, but in a metal-specific and tissue-specific manner. Clam biomonitoring studies should therefore control for size and age variability. Lake buffering capability was not very important in influencing size- and age-specific patterns of tissue metal concentrations. However, this conclusion is based solely on data from two lakes.

Survival and Growth of Stocked Lake Trout in Relation to Body Size, Stocking Season, Lake Acidity, and Biomass of Competitors

Abstract Juvenile, hatchery-reared lake trout Salvelinus namaycush, 25–36 months old, were stocked (about 24 fish/hectare) in six small oligotrophic lakes to test the effects of fish size, stocking season, and lake water acidity on survival and growth of introduced fish. The test lakes had few, if any, native lake trout. Little or no survival of stocked lake trout occurred in lakes with pH 5.0 or less. High survival and growth occurred in intermediately acidic (pH 5.6–6.1) and circumneutral (pH 6.9–7.3) lakes. Survival of stocked lake trout increased with size at the time of stocking. Size differences of the three size-classes introduced in each lake were maintained throughout the 2-year study. Competition with other resident fish species appeared to influence stocking success strongly. There was an inverse relationship between the biomass of stocked lake trout subsequently recaptured and biomass of all hypolimnefic species present in the lake. Intraspecific competition with previously stocked lake trout ...

Life Stage and Population Variation in Resistance and Tolerance ofHyalella azteca(Amphipoda) to Low pH

Lethality experiments revealed that resistance of Hyalella azteca (Amphipoda) to low pH was directly related to size and developmental stage. Exposure of adults to water below pH 5.0 during pulses of acid snowmelt, or of juveniles to below pH 5.5 through gradual lake acidification, could result in population decline. Hyalella azteca from moderately acidic Ontario lakes (pH 5.6–5.7) survived longer at lethal pH than did amphipods from circumneutral lakes (pH 6.4–7.2) where spring pH depressions do not occur. Resistance and tolerance to low pH was neither readily lost by tolerant amphipods exposed to neutral water for 10 d nor readily gained by nontolerant amphipods exposed to sublethal low pH for a similar duration. This absence of physiological plasticity of individual H. azteca suggests that population differences in acid tolerance may result from processes of selective mortality with or without a genetic basis.

Reproductive Responses of Five White Sucker (Catostomus commersoni) Populations in Relation to Lake Acidity

White sucker (Catostomus commersoni) in three acid lakes (pH 4.90, 5.56, and 5.58) frequently matured at older ages and larger sizes and had shorter reproductive life spans than white sucker in two circumneutral lakes (pH 6.30 and 6.35). Reproductive life span was positively correlated in females (r = 0.97) and males (r = 0.85) with lake pH. In the acid lakes, elevated mortality rates coincided with the onset of sexual maturity whereas in circumneutral lakes, mortality rates did not change at maturity. Ovarian weight and ovarian somatic index values were not significantly different between females from two acid and two circumneutral lakes. Values of fecundity, ova dry weight, testicular weight, and testicular somatic index of fish in acid lakes were either significantly greater than or equal to values in white sucker from circumneutral lakes. Results are discussed within the context of life history theory.

Measurements of Specific Rates of Net Methyl Mercury Production in the Water Column and Surface Sediments of Acidified and Circumneutral Lakes

Specific rates of mercury methylation and demethylation were determined for water and surficial sediment samples taken from several lakes located in the Experimental Lakes Area, northwestern Ontario. Specific rates of mercury methylation were found to increase with decreasing pH in epilimnetic water samples in which pH was adjusted prior to incubation and in epilimnetic water samples taken from lakes of different pH. Reduction of pH also increased methyl mercury production at the sediment surface. Both increases and decreases in pH reduced specific rates of mercury demethylation. However, these changes were smaller than for methylation. Proportionally, specific rates of methylation increased faster than increasing concentrations of Hg2+, while specific rates of mercury demethylation increased linearly with increasing concentrations of methyl mercury. Overall, this study predicts that the net rate of methyl mercury production in the water column and at the sediment–water surface will increase as a result of lake acidification, and this may at least partially explain why the mercury concentration of fish appears to increase during lake acidification.

Abundance, growth, and food supply of white suckers (Catostomus commersoni) in relation to lake morphometry and pH

Associations between the abundance, body growth, and food supply (chironomid and ephemeropteran larvae) of white suckers, and lake morphometry and water chemistry were determined for eight Ontario lakes. White sucker abundance was low in three deep–acid lakes, intermediate in two deep–circumneutral lakes, and high in three shallow–acid lakes. Abundance was negatively correlated with both maximum lake depth (r = −0.71) and mean lake depth (r = −0.67) and positively correlated with the morphoedaphic index (r = 0.67). Generally, 4-year-old white suckers were largest in deep–acid lakes, intermediate in size in deep–circumneutral lakes, and smallest in shallow–acid lakes. Fork length and somatic weight at age 4 were negatively correlated with white sucker abundance (r = −0.76 and −0.80, respectively), positively correlated with density of chironomid larvae (r = 0.62 and 0.68, respectively), and negatively correlated with pH (r = −0.67 and −0.70, respectively). The von Bertalanffy estimates of maximum attainable fork length (Lx) for both sexes were substantially larger in both deep–acid and deep–circumneutral than in shallow–acid lakes. Correlations indicated that oligotrophic lakes contain white suckers with a large Lx, the strongest correlation being with maximum lake depth (female Lx, r = 0.84; male Lx, r = 0.89).

Bone concentration of manganese in white sucker (Catostomus commersoni) from acid, circumneutral and metal-stressed lakes

Bone concentration of manganese in white sucker (Catostomus commersoni) from acid, circumneutral and metal-stressed lakes