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.     

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.     

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.     

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.     

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.     

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.     

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.     

Physiological responses of rainbow trout Salmo gairdneri exposed to plastic lake inlet and outlet stream waters

In Plastic Lake, Ontario, stocked rainbow trout (Salmo gairdneri) have failed to survive, one endemic fish species has become extinct and annual fish kills included up to five species, but especially pumpkinseeds (Lepomis gibbosus). The potential toxicity of Plastic Lake water was assessed by holding (hatchery) rainbow trout in the major inlet stream, the outlet, and in a portion of the outlet stream acidified to the pH of inlet No. 1. Stress on rainbow trout was assessed by measuring plasma and muscle concentrations of Na ⁺ Cl^?, and K⁺, plus gill A1 concentration. Trout held in Plastic Lake inlet No. 1 showed a rapid loss of plasma Na⁺ from 138 to 85 meq.L^?1and Cl^? from 120 to 75 meq.L^?1 within 24 hr. Gill A1 concentration increased from 20 to 105 μg.g^?1 dry weight. Trout held in the outlet steam showed only slight loss of plasma Na⁺ and Cl^? and no accumulation of Al on the gills. Trout held in the acidified outlet showed a significant loss of ions with plasma Na⁺ depressed from 140 to 115 meq.L^?1 and plasma Cl^? from 125 to 95 meq.L^?1over 24 hr. Gill Al concentration increased from 18 to 30 μg.g^?1 dry weight. The differences in stress response of rainbow trout held in the inlet and acidified outlet are likely due primarily to the difference in Al species concentrations in the two waters.     

Aluminum speciation in running waters on the Canadian pre-Cambrian Shield: Kinetic aspects

To evaluate the extent to which chemical disequilibrium may exist in stream waters following naturally occurring short-term pH changes, surface water samples were collected from two streams in the Lake Laflamme watershed north of Quebec City, placed in large polyethylene containers and stirred continuously at the in situ temperature; changes in Al speciation were followed with time for up to 24 hr. The original samples were collected during the spring snow-melt period and during summer low flows. In this latter case, a pH depression was induced by artificial acidification (H₂SO₄; pH 4) and changes in Al speciation with time were followed in both the acidified and the unacidified samples. Aluminum speciation as operationally defined did respond to artificial acidification (pH lowered; non-exchangeable and non-extractable Al decreased), and these pH-induced changes occurred rapidly (< 4 hr). During storage of natural water samples at in situ T for up to 24 hr, little change in Al speciation was noted, even in the case of samples collected during spring snow-melt; no clear cases of chemical disequilibrium existed among the studied samples. The distribution of Al among its various physico-chemical forms thus appears to be established within the stream itself; at a given stream sampling point the speciation of A1 will not necessarily reflect its geochemical origins, but rather the prevailing in situ conditions (e.g. pH, ligand concentrations).     

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.     

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.     

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.     

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.     

Simulation of nutrition of forests under stress using forgyte-11

Forest ecosystems are being subjected to an increasing variety of stresses for which we do not yet have rotation-length experience. Where we lack such experience, we cannot make experience-based predictions of the long-term effects of these stresses. While we are accumulating such experience, computer models can be used to make interim knowledge-based predictions. Most scientific knowledge has been produced by reductionist; disciplinary, process-based research. Such knowledge is a vital component of any explanation of natural or human-induced landscape phenomena, but cannot, in its reductionist, disciplinary form, provide an adequate basis on its own for long-term predictions about these phenomena. Such predictions require the development of computer models of ecosystem form and function based on the integration of knowledge from eco-physiology, autecology, community ecology, soil science, and climatology into ecosystem-level models that accurately describe the function and temporal dynamics of forest ecosystems.The ability of the ecosystem-level forest management simulation model FORCYTE-11 (FORest nutrient Cycling and Yield Trend Evaluator) to simulate forest stresses is described briefly. The question of how to model other stresses, such as air pollution, acid rain, climate change, soil compaction and erosion, and moisture competition is discussed, and the outline of a new model (FORECAST: FORestry and Environmental Change ASsessmenT) is presented.     

Simulation of nutrition of forests under stress using FORCYTE-11

Forest ecosystems are being subjected to an increasing variety of stresses for which we do not yet have rotation-length experience. Where we lack such experience, we cannot make experience-based predictions of the long-term effects of these stresses. While we are accumulating such experience, computer models can be used to make interim knowledge-based predictions. Most scientific knowledge has been produced by reductionist, disciplinary, process-based research. Such knowledge is a vital component of any explanation of natural or human-induced landscape phenomena, but cannot, in its reductionist, disciplinary form, provide an adequate basis on its own for long-term predictions about these phenomena. Such predictions require the development of computer models of ecosystem form and function based on the integration of knowledge from eco-physiology, autecology, community ecology, soil science, and climatology into ecosystem-level models that accurately describe the function and temporal dynamics of forest ecosystems. The ability of the ecosystem-level forest management simulation model FORCYTE-11 (FORest nutrientCycling andYieldTrendEvaluator) to simulate forest stresses is described briefly. The question of how to model other stresses, such as air pollution, acid rain, climate change, soil compaction and erosion, and moisture competition is discussed, and the outline of a new model (FORECAST:FORestry andEnvironmentalChangeASsessmenT) is presented.     

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.     

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.     

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.     

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.