The effect of pH and calcium on fish and fisheries

The combined effect of Ca and pH on fish and fisheries is considered for both laboratory and field studies. It can be seen that at concentrations less than 100 μeq l^?1, Ca can exert a significant influence on survival times of fish, and similarly in the field, the number of fishless lakes and the number of fish species found in lakes are less dependent on H⁺ concentration at low concentrations of Ca than at high Ca levels. The limited historical field data available suggest that alongside any increase there may have been in surface water acidity, Ca concentrations have also increased, and the latter may have offset to some extent the deleterious biological effects of this increased acidity. Nevertheless, details of seasonal and spatial variations in these important water quality factors will need to be considered before a full understanding of the response to acidity of a fishery can be reached.     

Remote mountain lakes as indicators of diffuse acidic and organic pollution in the Iberian peninsula (AL:PE 2 studies)

In the framework of the AL:PE 2 project, studies on acidification and organic pollution in mountain lakes have been conducted in several ranges in the Iberian peninsula: Pyrenees (Northeastern Spain), Sierra de Gredos (Central Spain), Sierra Nevada (Southern Spain) and Serra da Estrela (Central Portugal). These studies focused on water and sediment chemistry and organisms (benthic diatoms, Zooplankton, aquatic macroinvertebrates, and fish) as indicators of acidification. Organic micropollutants (PAH, PCB, DDE, hexachlorobenzene and others) in lake sediments and fish have been studied as tracers of atmospheric pollution. The Iberian peninsula lakes do not show severe anthropogenic acidification. pH values are in the range of sensitive lakes, but the levels of acidic pollutants are low. The status of the organisms surveyed agreed with this diagnosis. Pyrenean lakes showed the highest fluxes of organic pollutants related to fossil fuel combustion., higher pollutioninduced versus natural acidity ratios, and modeled alkalinity and pH declines.     

Fish species distribution in relation to water chemistry in selected Maine lakes

We examined the possible effects of acidity on the number of fish species in 22 lakes in Maine, ranging in pH from 4.4 to 7.0 (mean values). We caught no fish in three lakes with pH <5.0, but collected 1 to 9 species in the remaining 19 lakes (pH 5.4 to 7.0). Brook trout (Salvelinus fontinalis), golden shiners (Notemigonus crysoleucas), and white suckers (Catostomus commersoni) were ubiquitous, but no common shiners (Notropis cornutus) or creek chubs (Semotilus atromaculatus) were collected from lakes with pH below 6.0 and 5.9, respectively. The fishless lakes differed from the others primarily in water chemistry variables related to acidity, i.e., pH, Al, and concentration of divalent cations. Among lakes that contained fish, the factors related to the number of species collected were lake surface area and maximum depth, which may be related to habitat quantity and diversity. Cluster analysis identified two distinct fish species groups — depauperate and cyprinid-sucker — but multiple comparison analysis failed to relate any measured chemical or physical variable to these two groups, probably because water chemistry was suitable for reproduction by these species.     

Finnish lake survey: the role of organic and anthropogenic acidity

A lake survey consisting of 987 randomly selected lakes was conducted in Finland in autumn 1987. The survey covered the whole country, and the water quality of the lakes can be considered as representative of the approximately 56 000 lakes larger than 0.01 km² in Finland. The median TOC concentration is 12 mg L^-1 and the median pH 6.3. The proportion of lakes with TOC concentrations > 5 mg L^-1 in the whole country is 91 %. Organic anion is the main anion in the full data set (median 89 μeq L^-1). The high organic matter concentrations in Finnish lakes are associated with catchment areas containing large proportions of peatlands and acid organic soils under coniferous forest. The survey demonstrated that organic matter strongly affects the acidity of lakes in Finland. The decreasing effect of organic matter on the pH values was demonstrated by both regression analysis and ion balances. At current deposition levels of ^*SO₄ the pH of humic lakes in Finland is determined to a greater extent by high TOC concentrations than by ^*SO₄ in most areas. In lakes with pH values lower than 5.5 the average organic anion contribution is 56 % and non-marine sulfate contribution 39 %. However, in the southern parts of the country, where the acidic deposition is highest, the minerogenic acidity commonly exceeds the catchment derived organic acidity.     

Fish responses to acidity in Québec lakes: A review

To establish the impact of acidity on fish populations,studies were conducted in 37 Québec lakes located in four regions; the réserve des Laurentides and Portneuf and the Charlevoix and Témiscamingue regions. Density (catch per unit effort) of brook chary (Salvelinus fontinalis) decreases with increasing acidity. Moreover, in the Charlevoix region, this species has disappeared from three acid lakes (4.6 ?pH?5.l) with low Ca levels. Unlike growth, condition demonstrates a close relationship to acidity in brook charr populations. The total Al concentration in gills decreases with increasing size and pH. Lake acidity and sensitivity to acidification introduces problems in gamefish management. A survey of 17 lakes of the Témiscamingue region reveals that species diversity and total fish biomass are much lower in acid lakes than non acid lakes. In addition, two acid lakes are devoid of fish. Cyprinidae and Johnny darters (Etheostoma nigrum) are abundant in lakes with a pH level of 5.9 to 7.0 but are absent in lakes with a pH lower than 5.2. The yellow perch (Perca flavescens) is the only fish that appears to be tolerant to a wide pH range. This species, however, is in poor condition in acid lakes as compared with non acid lakes.     

Influence of Physical and Chemical Characteristics on Mercury in Aquatic Sediments

Given the variation observed in mercury in fish from natural lakes, it is difficult to determine what represents a background mercury level. Mercury in aquatic sediments is a potential source of this trace metal to biota, notably fish. Site specific factors, such as acidity and dissolved organic carbon have been shown to affect the mobilization of mercury and methylation of mercury. Methyl mercury is the most toxic form of this metal and the form most readily accumulated by biota. Thirty-four headwater lakes, selected for a range in pH, were sampled for sediment mercury levels as part of an investigation of the impacts of acid rain on insular Newfoundland lakes. Selected physical and chemical data were also collected on all of the study sites. Acidity was not found to be significantly related to sediment mercury concentrations despite the wide range in pH. Pearson correlation analysis indicated that sediment mercury level was positively correlated with WA:LA (watershed to lake area ratio). WA:LA was also correlated with Secchi depth and colour. Linear regression was used to estimate the parameters of a model relating sediment mercury to WA:LA. Watershed area to lake area ratio was more important than site specific factors in governing the concentration of sediment mercury in lakes without industrial input.     

Metal concentration in the gill,gastrointestinal tract,and carcass of white suckers (Catostomus commersoni) in relation to lake acidity

Adult white suckers were collected from four lakes in Maine that ranged in pH from 7.0 to 5.4. The gastrointestinal tract and remainder of the carcass of fishes of similar age and size from each lake, and gills from additional fishes of similar size, were analyzed for Al, Cd, Pb, and Zn. Carcasses were also analyzed for Hg. Concentrations of Al, Cd, and Pb were highest in the gastrointestinal tract and lowest in the carcass; Zn concentration was highest in the gill. For carcass, all metals except Al differed significantly among lakes, for gill tissue Cd and Pb differed, and for gastrointestinal tract, only Cd differed among lakes. Where differences were significant, patterns among lakes were similar in each tissue analyzed. Concentrations of Cd, Hg, and Pb were negatively correlated with lake water pH, acid neutralizing capacity (ANC), Ca, and lake:watershed area, and positively correlated with lake water SO₄, indicating that concentrations were higher in fish from more acidic lakes. Zinc concentrations in gills were unrelated to lake acidity, and carcass concentrations were higher in the less acidic lakes, which is the opposite of the pattern for the other metals studied. Zinc in gastrointestinal tract did not differ among lakes. Although the lakes we studied were located in undisturbed watersheds and did not receive any point source discharges, fish metal concentrations were comparable to or higher than those reported from waters receiving industrial discharges.     

Effects of acidity on fish communities in southwestern Québec (Canada)

Surveys of fish populations were conducted on 74 lakes of the Outaouais hydrographic region during the summers of 1985 and 1986 to assess the potential impact of acidity on ichtyologic fauna. Results show that species diversity declined with the increasing acidity. The color of water does not seem to mitigate the adverse effects of acidity. On the contrary, the number of species decreased similarly in both brown lakess (>30 Hazen) and clear lakes (≤30 Hazen) with the increase of acidity. The species tolerance threshold levels to acidity show that 72% of fish species are no longer captured when pH reaches 5.0, compared to 32% at pH ≤5.5. The pH range 5.0 to 5.5 can possibly be regarded as the break point for the occurrence of most fish species in this area. Analysis of the size frequency distributions show that recruitment failures have occurred in acidic waters for walleye and lake trout. We have estimated that anthropogenic acidification is responsible for the loss of more than 10000 fish populations in the Outaouais area.     

Changes in Al,Mn and Fe from sediments and aquatic plants after lake drawdown

Lake drawdown is often practiced during the winter season, causing freezing and/or drying of the sediments in order to retard subsequent rooted aquatic plant growth. In both lake and jar experiments, Zn and Mn levels in tissues of Elodea canadensis and seeded aquatic plants were elevated when grown on softwater sediments (pH 6.4) exposed to winter drawdown conditions, compared to plants grown on unexposed sediment. Dry weight production was likewise reduced by half. Sediment exchangeable acidity, and extractable Al, Zn and Mn were higher after exposure, and sediment Zn and Mn levels were highly correlated to growth (negatively) and tissue content (positively) of rooted aquatic plants. There were no consistent changes in metal concentrations of the overlying water after reflooding. It is proposed that plant growth inhibition upon reflooding is chemically mediated by increased root-available metal concentrations, found after sediment exposure and the associated oxidation of organic materials, metals, and reduced S, with release of H⁺ and a temporary drop in pH.     

The influence of organic acidity on the acid-base chemistry of surface waters in Maine,USA

Results from surveys of low-ANC lakes (high elevation, and seepage lakes), and of surface waters in dystrophic, acidic bogs, indicate that acidic precipitation and organic acidity are each generally necessary, but not solely sufficient, for chronically acidic status in Maine lakes. Acidic, low DOC (ANC < 0; DOC < 5 mg L^-1) lakes of all hydrologic types are acidic due largely to acidic deposition; high DOC (DOC > 30 mg L^-1) acidic seepage lakes are acidic due largely to organic acidity, and high DOC drainage lakes are acidic due to a combination of both factors. No low DOC drainage lakes are known with pH less than about 5.0, suggesting that organic acidity is necessary to depress lake pH values to below 5 in Maine at current deposition loadings,The dominant anion of low DOC, acidic waters is sulfate. Acidic waters with intermediate concentrations of DOC (5 to 30 mg L^-1), may be dominated by S04 and/or organic acidity. Seepage-input lakes were the only group to include both organically-dominated (37% of the acidic lakes) and S0₄-dominated members (63% of the acidic lakes). High DOC systems are typically low pH bogs, and are all organic acid-dominated.     

Water acidification by air pollutants in the Federal Republic of Germany

In the Federal Republic of Germany (FRG), airborne pollutants are leading to an increased rate of acidification of aquatic systems. In particular, the upper reaches of rivers and obligotrophic lakes in low-carbonate areas are affected. These areas are a minority of the total number of waterways, but are of great importance for environmental protection. Water acidification cannot be viewed as an isolated issue. In forested areas, it is associated with damage to the entire ecosystem. In lakes and streams, one of the most significant effects of water acidification is fish mortality; several bodies of water in which fish were once plentiful are now devoid of fish. With increasing acidification of the ground water, drinking-water supply problems may also be expected, All measures which can be taken to prevent the entry of pollutants into aquatic systems are preferred to those which merely treat the symptoms of acidified aquatic systems (e.g. addition of lime). The Federal Environmental Agency therefore considers the reduction of air pollutants to be the most effective solution to the problem of acidified of aquatic systems.     

Aluminum toxicity to fish in acidic waters

An important consequence of acidification is the mobilization of Al from the edaphic to the aquatic environment. Elevated Al levels in acidic waters may be toxic to fish. Eggs, larvae, and postlarvae of white suckers (Catostomus commersoni) and brook trout (Salvelinus fontinalis) were exposed in laboratory bioassays to pH levels 4.2 to 5.6 and inorganic Al concentrations of 0 to 0.5 mg l^?1. Aluminum toxicity varied with both pH and life history stage. At low pH levels (4.2 to 4.8), the presence of Al (up 0.2 mg l^?1 for white suckers; 0.5 mg l^?1 for brook trout) was beneficial to egg survival through the eyed stage. In contrast, Al concentrations of 0.1 mg l^?1 (for white suckers) or 0.2 mg l^?1 (for brook trout) and greater resulted in measurable reductions in survival and growth of larvae and postlarvae at all pH levels (4.2 to 5.6). Aluminum was most toxic in over-saturated solutions at pH levels 5.2 to 5.4. The simultaneous increase in Al concentration with elevated acidity must be considered to accurately assess the potential effect of acidification of surface waters on survival of fish populations.     

Alleviation of soil acidity improves the performance of oil palm progenies planted on an acid Ultisol

Abstract

Soil acidity is one of the main factors that limit profitable and sustained agricultural production. Oil palm (Elaeis guineensis Jacq.) is mainly planted in acidic soils. In the last years, there has been a stagnated yield and increases in disease incidence and severity worldwide that could be attributed in some extent to soil acidity. This study was conducted to determine the effects of soil acidity alleviation on oil palm seedlings. The effects of ground magnesium limestone or dolomite and magnesium carbonate (0, 1.1, 2.2, 3.3 and 4.4 t ha^?1) applied to an Ultisol dominated by kaolinite (pH in water 4.4) were evaluated on selected morphological, physiological and nutritional characteristics of hybrid (Deli dura × AVROS pisifera) and clonal (clone 366) oil palm progenies under nursery conditions for 8 months. Increasing rates of ground magnesium limestone and magnesium carbonate showed a significant effect on improving soil pH and lowering exchangeable aluminium. The hybrid oil palm showed significant either linear or quadratic trends for most of the parameters evaluated, indicating that the best responses for morphological and physiological traits were achieved from 2.5 to 4.23 t ha^?1 with ground magnesium limestone and 2.87 to 3.45 t ha^?1 with magnesium carbonate. Positive effects of increasing rates of ground magnesium limestone and magnesium carbonate were observed on nitrogen and magnesium uptake. Aluminium concentration in the third frond decreased significantly with increasing ground magnesium limestone rate. A significant reduction of manganese uptake was also observed with increasing rates of both ameliorants. The clonal oil palm progeny exhibited a better performance on un-amended treatment. This may be explained by the significant higher root growth of this progeny. Soil acidity alleviation improved the oil palm seedling growth. These results are important for the oil palm industry and could be applied in the nursery stage as well as extended to the immature stage.     

Water quality improvements in the Sudbury,Ontario, Canada area related to reduced smelter emissions

Data from water quality studies conducted in the Sudbury, Ontario, Canada area indicate that substantial decreases in the acidity of surface waters have accompanied reductions in SO₂ emissions from the Sudbury smelting industry since 1977. On average, acidic lakes in the Sudbury area showed a decrease in H⁺ of ～ 50% between 1974–76 and 1981–83, and the severity of springtime pH depressions in streams decreased. Although many Sudbury area surface waters remain highly acidic, general decreases in acidity appear to be continuing. The results demonstrate that reductions in emissions of acids and acid precursors result in concomitant improvements in water quality.     

Natural acidification of lakes and rivers in Japan: The ecosystem of Lake Usoriko (ph 3.4–3.8)

Most of the acid lakes and rivers in Japan have been influenced by acid waters of volcanic origin. Acidophilic and acidotolerant organisms are observed in these natural acid lakes and rivers, each of which has its own ecosystem and history. Lake Usoriko (pH 3.4–3.8) is a lake which.has been acidified by strongly acid water containing sulfuric acid and hydrochloric acid. The ecosystem of Lake Usoriko consists of aquatic vascular plants, aquatic bryophytes (Drepanocladus fluitans, etc.), algae, fish (Tribolodon hakonensis), insects, Zooplankton, fungi and bacteria. The paleosediment distributed along Lake Usoriko's northern shore is partly silicified and it contains fossils of a moss (Drepanocladus fluitans) and diatoms such as Pinnularia braunii var. amphicephala which are also distributed in the present lake. ¹⁴C dating of the specimens in the paleosediment, shoots of D. fluitans and the wood and cones of Picea glehnii gave values in the range 11500–34000y B.P. This record shows how long Lake Usoriko has been an acid lake.     

Association of wetland acidity with reproductive parameters and insect prey of the Eastern Kingbird (Tyrannus tyrannus) near Sudbury,Ontario

A three year study (1981 to 1983) was conducted to determine possible influences of wetland acidification on the reproduction and growth of the Eastern Kingbird (Tyrannus tyrannus). This species uses emergent aquatic insect prey to feed its nestlings. Egg characteristics and nestling growth were monitored for birds nesting in 26 lakes in the Killarney region near Sudbury, Ontario (pH range 4.27 to 6.26). The major percentage of variation in kingbird reproductive factors including clutch initiation, egg weight loss and torso-metatarsus bone growth was explained by differences between siblings and among nests on a single lake. A smaller percentage of the variance in reproductive parameters was explained by the variation in water chemistry among lakes. Canonical correlation showed that sulfate, nitrate/nitrite, alkalinity, pH, and several metals (Fe, Mn, Al) accounted for a minor but significant variance in growth characteristics. These water chemistry parameters are influenced by lake acidification. The relationship observed between lake acidity and kingbird reproduction is therefore measurable but minor compared to the influence of genetic and inter-nest variables. The study showed no food limitation for the kingbird attributed to lake acidity.     

Using volunteers to monitor the effects of acid precipitation on Common Loon (Gavia immer) reproduction in Canada: The Canadian Lakes Loon Survey

The Common Loon (Gavia immer) is a conspicuous and popular aquatic bird that inhabits large lakes (generally >10 ha) on Precambrian Shield across Canada. Because it relies on fish, it is a key bioindicator species linking acid precipitation to higher trophic levels in aquatic food chains. The Canadian Lakes Loon Survey (CLLS), a monitoring program involving volunteers, was initiated in 1981 to collect information on loon reproductive success, such as the number of loons nesting and the number of young they produce which survive to fledging, to help researchers determine whether loons were adversely affected by acid rain or human disturbance. Between 1987 and 1993, 4236 records for loons nesting on 1529 lakes in Ontario (historically the principal region of study) were received from volunteers. We used logistic regression to examine relationships between loon productivity (number of large young produced per pair for 721 lakes), lake area, and pH (from provincial and federal databases). After controlling for lake size, we determined that loons were less likely to nest on acid lakes (pH<5.5), and when they did attempt to breed, their reproductive success was lower, in part due to the reduced survival of two-chick broods, presumably linked to reduced fish biomass. However, we found no conclusive evidence that breeding success exhibited any temporal trends in relation to pH over this time period. Continued monitoring by volunteers of loon reproduction on CLLS lakes will provide a reliable, costeffective method of assessing the long-term health of large, acid-sensitive lakes across Canada.     

Effect of simulated acid rain on the growth of soybean

Soybean seedlings (Glycine max) grown in a glasshouse were exposed to simulated acid rain using a solution of deionized water containing sulfate, nitrate and chloride in concentrations and proportions equivalent to those in ambient rain water. Plants were subjected to acid rain treatment twice a week during the growing season, for a 1 hr period at a rate of 5 mm hr^?1. When the acid rain was below pH 3.0, visible symptoms developed in the young trifoliate leaves. However, at a pH above 3.0 there was no evidence of visible leaf injury; also tissue dry weights and leaf areas were not affected even after 7 weeks of exposure. The number of root nodules in plants exposed to acid rain at pH 4.0 tended to be higher than those of control plants maintained at pH 5.6, but decreased subsequently with decreasing pH. Based on our results current ambient levels of rain acidity in Japan should not have an adverse impact on seedling growth in soybean.     

Trace element accumulation in the tissues of fish from lakes with different pH values

Two species of fish, omnivorous Catostomus commersoni (white suckers) and carnivorous Perca flavescens (yellow perch) were collected from three natural lakes with different pH ranges (circumneutral, pH 6.5 to 6.8; variable, pH 5.8 to 6.7; and acidic, pH 4.9 to 5.4). The lakes are located in the North Branch of the Big Moose River drainage system in the New York State Adirondack Park Preserve. Concentrations of potentially toxic elements (Al, Cd, Cu, Ph, and Se) were measured by electrothermal atomic absorption spectrophotometry in water, sediment and fish (bone, gill, kidney, liver and muscle) from each lake. The results showed that concentrations of Pb and Cd were significantly higher (P < 0.05) in some of the tissues of the fish collected from the acidic lake. Also, the yellow perch from the acidic take had significantly higher (P<0.05) Se concentrations in their muscle and livers than fish from the other lakes. The concentrations of Al were elevated in the gill tissues of both fish species from the acidic lake relative to fish from the other lakes. Possible mechanisms contributing to these differences in tissue concentration are discussed.     

Influence of acidity and competition with fish on the development of ducklings in Quebec

In Quebec, in 1984 and 1985, a number of American Black Duck (Anas rubripes) and Common Goldeneye (Bucephala clangula) ducklings were reared on two acid lakes (pH 4.8 to 5.0) and one circumneutral lake (pH 6.0) in which the brook trout (Salvelinus fontinalis) populations had been manipulated. This allowed us to determine how acidity and competition with fish affected duckling feeding and growth. Strong acidity and the presence of fish were both required before the birds' development was restricted, the Black Duck being particularly affected. This result supports hypotheses on competition between fish and some waterfowl species.