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.     

Fish species distribution in relation to lake acidity in Ontario

Survey data from approximately 2,900 Ontario lakes were used to examine the distribution of 12 fish species with respect to lake pH. Yellow perch (Perca flavescens), white sucker (Catostomus commersoni), brook trout (Salvelinus fontinalis), pumpkinseed (Lepomis gibbosus), fathead minnow (Pimephales promelas) and redbelly dace (Phoxinus eos) proved to be tolerant of low pH (pH <6.4). Lake trout (Salvelinus namaycush), common shiner (Notropis cornutus), blacknose shiner (Notropis heterolepis), lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum vitreum) and northern pike (Esox lucius) showed limited distribution in low pH lakes (pH <6.4). The limited distribution of lake whitefish and northern pike likely relates to zoogeographic factors rather than their intolerance to low pH. Lake trout and common shiner occur in lakes susceptible to, and receiving high loadings of acidic deposition. However, without historical data, we cannot determine if their decreased distribution in low pH systems is due to intolerance to low pH.     

Patterns of plankton species,pH and associated water chemistry in Nova Scotia lakes

In order to assess the patterns of distribution of plankton species in relation to acidity, water chemistry, and physical characteristics, twenty lakes in Nova Scotia were selected for examination, with pH ranging from 3.5 to 7.6. Correlation and multiple regression analyses revealed associations between plankton and chemical variables. Patterns of plankton abundance and diversity were noted with respect to both pH and nutrient status, with occasionally conflicting effects of these two factors. Phytoplankton abundance was most closely associated with nutrient status, while zooplankton abundance was related to measures of primary production. pH tended to affect plankton diversity more than abundance or standing crop. Several lakes were outliers from overall patterns, with several possible explanations. Cluster and factor analyses were used to identify associations of plankton species, and to relate these associations to lake characteristics. Certain species were noted with relatively wide distribution, but which never occurred at low pH (<4.6). These were Chroococcus limneticus, Asterionella formosa, Cyclotella meneghiniana, Pinnularia braunii, and Surirella robusta for phytoplankton, and Polyphemus pediculus, Diaptomus oregonensis, and Tropocyclops prasinus for zooplankton.     

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.     

Increase in the abundance of cladocera at pH 5.1 in experimentally-acidified lake 223, Experimental Lakes Area,Ontario

Lake 223 in the Experimental Lakes Area, northwestern Ontario was experimentally-acidified with H₂SO₄ from 1976 to the present. Cladocerans increased in absolute and relative abundance and in total biomass when the pH of Lake 223 was lowered from 6.7 to 5.1. Comparing the cladoceran community at pH 6.7 (1974) with that at pH 5.1 (1981 to 1983), Daphnia galeata mendotae disappeared, Diaphanosoma birgei became rare, Holopedium gibberum increased in abundance and Daphnia catawba, recorded for the first time in 1980, became abundant. Bosmina longirostris became more abundant. Except for the decline in D. birgei, the changes in cladoceran species composition with acidification are consistent with known responses of these species to low pH. The increase in importance of cladocerans in 1981 to 1983 was at the expense of copepods. It was hypothesized to be caused by the decline in predation by small fish during 1981 to 1983 as acidification reduced minnow populations and inhibited reproduction in trout and sucker. The loss of the population of the invertebrate predator, the opposum shrimp, Mysis relicta, in 1979 had little effect on cladoceran biomass.     

Population dynamics of yellow perch (Perca flavescens) and pumpkinseed (Lepomis gibbosus) in two acid-stressed lakes

Fish population parameters: abundance, age-class composition, and size-at-age, which respond to environmental stresses, were investigated in two lakes showing chemical and biological evidence of acidification. Plastic Lake, Muskoka District of Ontario, shows spring pH depression and A1 toxicity in surface waters, with an associated annual fish kill. In Crosson Lake, pH 5.2 to 5.3, there has been a dramatic decline in abundance of the white sucker (Catostomus commersoni). In Platic Lake the abundance of pumpkinseed (Lepomis gibbosus) has declined and that of rock bass (Ambloplites rupestris) has increased. In Crosson Lake size-at-age has increased in yellow perch (Perca flavescens), pumpkinseed abundance has increased but with no change in growth rate.     

Neutralization of acidic raindrops on leaves of agricultural crop and boreal forest species

The abilities of foliage of selected agricultural crop and native boreal forest species to neutralize acidic raindrops were compared. The species differed widely in their responses. Neutralization was influenced to a large extent by leaf wettability and was poorly related with species' susceptibility to foliar injury from acid rain sprayings. Little neutralization of pH 3.0 droplets occurred on very waxy leaves, e.g. cabbage (Brassica oleracea L.), due to the small contact area between the leaf surface and raindrops. In contrast, on sunflower (Helianthus annuus L.) and radish (Raphanus sativus L.) leaves, which are pubescent and easily wettable, neutralization was considerable. For all agricultural crop species examined, the pH of droplets drying on cotyledons was consistently higher than on the leaves. The pH values of raindrops were also higher when the foliage was injured by the acid rain, probably due to leakage of cellular contents. Among boreal forest species examined, bunchberry (Cornus canadensis L.) was particularly good at neutralizing natural acid rain, increasing the pH from 3.9 to 6.6 after 9 hr of foliar contact, while the response of other boreal species ranged from a final pH of 4.8 to 5.7 under the same conditions. Simulated raindrops on wild sarsaparilla (Aralia nudicaulis L.) were never neutralized but increased in acidity as they evaporated. Chemical analyses of droplets collected from foliage showed calcium (Ca) and potassium (K) to he the major cations entering the neutralized droplets. Neutralization of acidic raindrops appears to occur through two processes: solubilization of alkaline dusts and exudates on the leaf surface, and ion exchange removal of H⁺ by the foliage.     

Biological indicators of lake acidification

Indicator taxa are identified, based on both synoptic surveys and whole lake acidification experiments, for lake acidification in the pH 6.0 to 5.0 range. Acidobiontic diatoms (e.g Asterionella ralfsii, Fragillaria acidobiontica, etc.), periphyton (Mougeotia and related species), macroinvertebrates (e.g. Hyalella azteca, Orconectes sp., etc.), leeches, and cyprinid fishes (e.g. Pimephales promelas, Notropis cornutus, etc.) are identified as target organisms during early phases of lake acidification.     

Distribution,abundance and biomass of benthic macroinvertebrates relative to pH and nutrients in eight lakes of Nova Scotia,Canada

The lakes investigated ranged widely in pH (3.6–6.3), total phosphorus (3.3–33.1 μg.L^-1) and calcium (0.352-6.30 mq.L^-1). Several macroinvertebrate groups especially Pelecypoda, Hirudinea and Gastropoda do not occur in lakes of low pH (<5.0). The bivalve Pisidium sp. occurred in one acidic lake (pH 5.2). Apparently, this is the lowest pH occurrence for Pisidium sp. at such low calcium levels (0.35 mg.L^-1). Macroinvertebrate richness was reduced with increased levels of acidity but nutrient availability apparently controlled macroinvertebrate abundance and biomass in the lakes.     

Fertilizer application in aid of plantation establishment in the savanna areas of Nigeria

Fertilizer trials were conducted to stimulate tree establishment and growth in the savanna region of Nigeria. The main nutrients investigated were N, P, K and B while the tree species included Azadirachta indica (Neem), Acacia auriculiformis, Eucalyptus spp., and Pinus spp. Borate application reduced the incidence of die-back of eucalypts and it also increased height growth. There was positive response to phosphate application by all species; phosphate reduced mortality considerably in pines on some sites. Response to N fertilizer by the species varied and related to type of N fertilizer. Urea was often found injurious to pines. There was strong interaction between N and P and usually response to N was not obtained on P-deficient sites. In all the cases where it was applied, there was no response to K. On more arid sites with poorly buffered soils, mineral fertilizers alone were insufficient to produce satisfactory tree growth. Application of animal manure on such sites increased survival and growth of Azadirachta indica, E. camaldulensis and A. auriculiformis.     

The impact of acidification on aquatic biota in North America: A comparison of field and laboratory results

Acidification of lakes and streams can lead to adverse effects on aquatic biota, and the recognition of widespread atmospheric deposition of strong acids in eastern North America has led to considerable concern over its existing and potential impact on th flora and fauna of sensitive (i.e. low alkalinity) systems. While most of the concern has been directed toward the impact on the fisheries resource, it is well documented that all levels of biota are affected (Almer et al., 1974; Likens et al., 1983; Dillon et al., 1984), and full appreciation of the impact of acidification requires examination of all living components of the aquatic ecosystem. Although extensive work has already been conducted in tho Scandinavian countries, there are numerous differences in species between those countries and North America, and a sound appraisal of the threat to North American biota requires comparable work for this continent. Large scale surveys and monitoring programs are under development or are in the early phases of execution by various institutions, but much has already been learned from laboratory and field acidification experiments, and from comparisons of acidic and non-acidic lakes and streams. The purpose of this paper is to compare the results of these studies for several dominant species from several major groups of organisms. We hope to focus attention on the nature and quality of information about the sensitivity of organisms with known or apparent significant ecological roles, identify gaps or weaknesses, and provide insight into the merits and limitations of the various methods of study.     

Comparison of the macrophyte communities of a clearwater and a brownwater oligotrophic lake in Kejimkujik National Park,Nova Scotia

Beaverskin and Pebbleloggitch Lakes are small, proximate, acidic, oligotrophic, headwater lakes located in southwestern Nova Scotia. Beaverskin Lake has clear water, its euphotic zone is deep, and it has extensive beds of macrophytic vegetation that cover most of its bottom to a depth of 6.5 m. In contrast, the water of Pebbleloggitch Lake is highly colored by dissolved humic substances, and macrophytes are restricted to a narrow littoral fringe in depths of less than about 1.8 m. The most widespread macrophyte community in Beaverskin Lake occurs at depths of 2.0–6.5 m and is dominated by Sphagnum macrophyllum and Utricularia vulgaris, while the second most prominent community is littoral and is dominated by Eriocaulon septangulare, Lobelia dortmanna, and Eleocharis acicularis. The most prominent community in Pebbleloggitch Lake is dominated by the floating-leaved Nuphar variegatum rooted as deep as 1.8 m, while communities dominated by E. septangulare and Sphagnum spp. occur in water less than about 0.7 m deep.     

Response of lake trout (Salvelinus namaycush) and brook trout (S. fontinalis) to surface water acidification in Ontario

Netting surveys of lakes varying in pH (4.4–7.1) showed that lake trout (Salvelinus namaycush) populations fail to recruit at pH <5.5 and are lost from lakes with pH<5.2. Brook trout (S. fontinalis) were extirpated in lakes with pH <5.0. In regional chemical surveys of Ontario lakes, it was found that 2% of sampled brook trout lakes and 2.5% of lake trout lakes were acidified (alkalinity <0 uEq L^?1). Threshold pH levels determined from fisheries assessments were used to estimate that 1% of lake trout and brook trout populations have been lost due to acidification.     

Effects of liming on crayfish and fish in Sweden

The effects of lime treatment on crayfish (Astacus astacus and Pacifastacus leniusculus) populations in 17 lakes and fish populations in 47 lakes and 7 rivers within the trial period 1976–82 have been evaluated. An increase in the catch of crayfish per unit effort was observed in 7 lakes, although significantly in one lake only. The varying results in the other lakes indicate that factors other than pH may be of greater importance for the development of crayfish populations after liming. Recruitment of fish improved in waters where liming resulted in pH >5.5. In lakes with pH <5.5 before and pH >5.5 after treatment, there was a significant increase in the number of fish caught, from 12 to 34 per unit effort. Due to improved recruitment the individual average weight was smaller and hence the catch in weight per unit effort was about the same as before liming. After lime treatment in streams which resulted in a stable pH of >5.5, the abundance of juvenile salmonids increased to numbers found in non-acidified streams. In other streams acid spates reduced the positive influence of liming on the abundance of juvenile salmonids.     

Foliar sensitivity of eight eastern hardwood tree species to ozone

As part of a larger 3-yr study, container-grown seedlings of black cherry (Prunus serotina) red maple (Acer rubrum), red oak (Ouercus rubra), sweetgum (Liquidambar styraciflua), white ash (Fraxinus americana), white oak (Ouercus alba), yellow-poplar (Liriodendron tulipifera), and yellow birch (Betula allegheniensis) were exposed to 0,0.075, or 0.15 μL L-¹ O₃ in laboratory controlled-environment chambers for 6 hr d^?1 on 2 consecutive days for 12 weeks. On the third consecutive day of each week, plants were treated for 45 min with precipitation at pH 3.0 or 4.2. The only significant foliar symptoms were induced by the O₃ treatments, and the severity of symptoms was not influenced by precipitation pH. The most common symptom was a dark, adaxial stipple which was most severe on the oldest leaves. Equations were developed to express the influence of leaf position on percent leaf injury following 4, 8, and 12 weeks of treatment. Based on percent leaf tissue showing stipple and defoliation following exposure to 0.15 μL L^?1 O₃, the most sensitive species to O₃ was black cherry, followed by sweetgum, yellow-poplar, white ash, red maple and yellow birch. Red oak and white oak foliage did not exhibit stipple.     

Mercury in plants,soil and atmosphere near a chlor-alkali complex

Data of atmospheric Hg concentrations measured near the chlor-alkali complex of Rosignano Solvay (Livorno, Italy) show that the impact of the industry on the terrestrial environment is restricted to a close area around; background values (3 to 5 ng m^?3) are reached within a radius of 4 to 5 km. Hg levels in plants (Poa sp. Pinus nigra and Solidago sp.) and in soil show the highest values in the sampling stations near the electrolytic cells.     

Biology and chemistry of three Pennsylvania lakes: Responses to acid precipitation

The biology and chemistry of three northeastern Pennsylvania lakes was studied from summer 1981 through summer 1983 to evaluate lakes with different sensitivities to acidification. At the acidified lake (total alkalinity ≤ 0.0 μeq L^?1) there were fewer phytoplankton and zooplankton species than at the moderately sensitive lakes. The most numerous plankton species in all three lakes are reportedly acid tolerant. Among the benthic macro- invertebrates (BMI) there were more acid tolerant Chironomidae at the acidified lake, but more acid intolerant Ephemeroptera and Mollusca and a higher wet weight at the least sensitive lake. There were no differences among the lakes' BMI mean total numbers or mean number of taxa. The fish community at the acidified lake was dominated by stunted Lepomis gibbosus, but L. machrochirous were most abundant in the other lakes. Principal component analysis suggested a shift in all three lakes over the sampling period toward combined lower pH, alkalinity, specific conductance, Ca and Mg and higher Al and Mn. Such chemical changes have been associated with acidification. The rate and extent of acidification appeared to be controlled by geological and hydrological characteristics of the drainage basins.     

Natural changes in the planktonic rotifera of a small acid lake near Sudbury,Ontario following water quality improvements

Swan Lake is a small, acidic, metal-contaminated lake located near Sudbury, Ontario. During the past 8 yr, the lake has experienced a substantial increase in pH, together with significant reductions in the concentrations of heavy metals and base cations. These changes were observed only after acid and metal emissions from Sudbury area smelters were reduced. The composition of the planktonic Rotifera in the lake has changed concurrent with improvements in water chemistry. Dominance of the rotifer community by the acidophile Keratella taurocephala has been sharply reduced in recent years, while significant increases in the densities of Polyarthra spp., Chromogaster ovalis, Conochiloides natans and Trichocerca similis have been observed.     

Fertilizer application in aid of plantation establishment in the savanna areas of Nigeria

Fertilizer trials were conducted to stimulate tree establishment and growth in the savanna region of Nigeria. The main nutrients investigated were N, P, K and B while the tree species includedAzadirachta indica (Neem),Acacia auriculiformis, Eucalyptus spp., andPinus spp. Borate application reduced the incidence of die-back of eucalypts and it also increased height growth. There was positive response to phosphate application by all species; phosphate reduced mortality considerably in pines on some sites. Response to N fertilizer by the species varied and related to type of N fertilizer. Urea was often found injurious to pines. There was strong interaction between N and P and usually response to N was not obtained on P-deficient sites. In all the cases where it was applied, there was no response to K. On more arid sites with poorly buffered soils, mineral fertilizers alone were insufficient to produce satisfactory tree growth. Application of animal manure on such sites increased survival and growth ofAzadirachta indica, E. camaldulensis andA. auriculiformis.     

The effect of simulated acid rain on feather mosses and lichens of the boreal forest

Permanent field plots containing a dominant ground cover of feather moss (Pleurozium schreberi) and the forage lichen, (Cladina), were established in mature, boreal forest jack pine stands to monitor the effects of simulated acid precipitation. For a five-year period commencing in 1981, bimonthly sprays (pH range 2.5 to 5.6) were given throughout the growing season. The feather moss wefts were extremely sensitive to simulated rains of pH 2.5 and 3.0; but loss of cover and frond blackening were also observed at pH 3.5. The pH 2.5 treatment killed almost all of thePleurozium, while the cover remaining in the pH 3.0 treatment after 5 years was reduced by 44%. In laboratory studies designed to compare the effects of H₂S0₄, HN03 and a 2:1 mixture of both, microcosms sprayed with H₂S0₄ alone (pH 3.0) were more significantly affected than fronds treated with HN0₃ alone or pH 5.6 sprays of any ratio. Although less sensitive thanPleurozium, field-sprayed lichens were also visibly damaged. At pHs less than 3.5,C. stellaris andC. rangiferina had reduced podetial height and dry weight; whileC. mitis was affected by a combination of the acid rain treatment and other associated factors. While ambient rains of pH 4.2 may not in themselves be harmful to the boreal ground flora, it is apparent that the feather mosses and lichens, lacking a cuticle and true roots, are very sensitive to occasional, extremely acidic rain events.