The effect of anthropogenic acidification on the hydrofauna of the lakes of the West Tatra Mountains (Slovakia)

Fourteen West Tatra lakes were studied, of which one could be considered to be recently anthropogenically acidified and eight others classified as acidification-endangered. In the anthropogenically acidified lake, the zooplankton assemblage has been substantially altered (three mountain-lake crustacean species have been eliminated). Several littoral macrobenthic species sensitive to acidification have either been eliminated from the acidified and acidification-endangered lakes or occur only sporadically. The effect of acidification has so far not been observed on the benthic fauna of the lakes medial which is probably due to the higher pH below the surface of sediment. In comparison with the High Tatra, acid depositions have had a less pronounced effect on the lakes of the West Tatra.     

Integrated lake monitoring in Europe the macrozoobenthos in the four target lakes in Finland

In four small ( 1 km²) Finnish lakes belonging to the Integrated Monitoring Programme (UN ECE), macrozoobenthos has been studied at different depths since 1989. The lakes are situated between 61°N–70°N latitudes from the southern boreal coniferous region up to the forest tundra ecotone. The macrozoobenthos of the lakes was very different compared to each other, but chironomids were important in all lakes. Acid-sensitive taxa (molluscs, some mayflies) were lacking in one of the lakes because of its low pH. In all lakes the zoobenthos could indicatee.g. the wideness of the littoral region and stagnation conditions or groundwater input through the bottom. In future, both litoral and profundal sampling is needed because of the multi-purpose character of the monitoring (acidification, trophic level).     

Limestone to Mitigate Lake acidification: macrozoobenthos response in treated and reference lakes

The littoral macrozoobenthos (MZB) of two low acid neutralizing capacity (ANC = 50.0 µeq l^–1) northeastern Pennsylvania lakes (treatment and reference) were sampled each ice free season, 1984 through 1988, to evaluate response to limestone addition. Following addition of 100 tons agricultural limestone (CaCO₃) to the treatment lake in February 1985, mean annual ANC rose from 20 µeq l^–1 to 668 µeq l^–1 then decreased. In October 1987, ANC in the treatment lake was decreasing, so 15 additional tons of limestone were added. Pre- limestoning there were few significant (p<0.05) differences between MZB assemblages in the two lakes, but 4 years post treatment the following differences (p<0.05) were detected in the treatment lake: more Chironomidae, Ephemeroptera, Odonata, Hyalella azteca, total MZB numbers and higher Mollusca wet weight than in the reference lake. From 1984 to 1988 in the treatment lake the annual means of the following community characteristics increased (p<0.05): totals of Chironomidae, Ephemeroptera (including Caenis spp.), Odonata, Trichoptera, Sphaeriidae, collectors and MZB numbers; Chironomidae and Ephemeroptera taxa richness and total taxa richness; total and Mollusca wet weight. However, the treatment lake ecosystem is neither self-sustaining nor stable because limestone must be added every 2 to 3 years to maintain ANC above 50 µeq l^–1 In the reference lake annual means of ANC, specific conductance, calcium and magnesium decreased (p<0.05) while Secchi depth increased (p<0.05), suggesting continuing acidification.     

Macrozoobenthos of Lake Peipsi-Pihkva: long-term biomass changes

Macrozoobenthos of the large (3,558 km²) Lake Peipsi-Pihkva was monitored at 22–24 sampling spots yearly in June 1964–1994 as well as 50 shallow-water profiles in mid-summer 1970, 1980, and 1990. No qualitative changes were observed in the bottom fauna, except for the introduction of a Baikalian gammarid species, Gmelinoides fasciatus. The average total biomass in June (without big molluscs) revealed considerable annual fluctuations, with an insignificant general tendency of increase. The increase was significant in the biomass of several Mollusca (including the highly abundant big clam Dreissena polymorpha), Asellus, Gammaridae, and Hirudinea but not in the most abundant animal groups Chironomidae and Oligochaeta. The low biomass of Ephemeroptera and Hydrachnellae decreased significantly. The mid-summer samples taken from the shallow-water zone in three different years revealed the highest biomass in 1980 and the lowest in 1990 (the latter being probably related to the high water level). A gradual decrease in the biomass of the Ephemeroptera and Hydrachnellae as well as the Oligochaeta, Pisidiidae and Bithynia tentaculata occurred in the shallow-water zone, while the Gammaridae increased on the account of the introduced species. No coincidence was found with the neighbouring Lake Võrtsjärv when comparing the annual fluctuations of biomass. A general tendency to a slow increase in total biomass and a decrease in the biomass of the most vulnerable groups Ephemeroptera and Hydrachnellae, probably due to progressing eutrophication, were common for both lakes.     

Macrozoobenthos of Lake Verevi

An overview on studies of macrozoobenthos in the small, hard-water, stratified and hypertrophic Lake Verevi (South-Eastern Estonia) is given. The list of macroinvertebrates comprises at least 105 taxa. In the open water habitats, the biomass and abundance of macrozoobenthos (except the phantom midge Chaoborus flavicans) was rather constant beginning from the epilimnion up to the upper hypolimnion (depth 2–4 m), but very low in the lower hypolimnion (depth 6 m), which was inhabited mainly by Chaoborus. Comparison with long-term reference data from other Estonian lakes, belonging to similar limnological types, indicated that the total biomass and abundance (without Chaoborus) in the profundal of Verevi were very low.     

Decoupled trophic responses to long‐term recovery from acidification and associated browning in lakes

Increases in the concentration of dissolved organic matter (DOM) have been documented in many inland waters in recent decades, a process known as “browning”. Previous studies have often used space‐for‐time substitution to examine the direct consequences of increased DOM on lake ecosystems. However, browning often occurs concomitant with other ecologically important water chemistry changes that may interact with or overwhelm any potential ecological response to browning itself. Here we examine a long‐term (~20 year) dataset of 28 lakes in the Adirondack Park, New York, USA, that have undergone strong browning in response to recovery from acidification. With these data, we explored how primary producer and zooplankton consumer populations changed during this time and what physical and chemical changes best predicted these long‐term ecosystem changes. Our results indicate that changes in primary producers are likely driven by reduced water clarity due to browning, independent of changes in nutrients, counter to previously hypothesized primary producer response to browning. In contrast, declines in calcium concomitant with browning play an important role in driving long‐term declines in zooplankton biomass. Our results indicate that responses to browning at different trophic levels are decoupled from one another. Concomitant chemical changes have important implications for our understanding of the response of aquatic ecosystems to browning.     

Population responses of perch (Perca fluviatilis) and roach (Rutilus rutilus) to recovery from acidification in small Finnish lakes

Decreasing trends in atmospheric emissions and acidic deposition during the 1990s have resulted in chemical recovery from acidification in the sensitive surface water systems of southern Finland. Responses of perch and roach populations to the improved water quality were studied in 30 small lakes with the aid of water chemistry monitoring data gathered in 1987–2002 and the data collected from two consecutive periods of gillnet test fishing, 1985–1988 and 2001–2002. In the most acidified lakes, alkalinity and ANC have increased and sulphate and labile aluminium concentrations decreasæed markedly. The response of perch populations to the improved water quality is seen in improved reproduction success, indicated by a higher CPUE in numbers and a lower mean weight. The growth rate of perch has declined as the population density has increased. Roach populations have not recovered in the same way as perch, there being no major changes in NPUE or mean weight. Lower growth rates were, however, observed in the roach populations of all study lakes. The increased perch population density as an obstacle to the recovery of roach populations is discussed. Despite the chemical and biological recovery of the study lakes, the buffer capacity of many headwater lakes is low and the lakes will be sensitive to any increases in acidic deposition in the future.     

The effects of acidification on metal budgets of lakes and catchments

Metal (Cu, Ni, Zn, Fe, Mn and Al) budgets were measured for 5 lakes and their catchments near Sudbury, Ontario, an area severely affected by the emission and deposition of strong acids (H₂SO₄/SO₂) and metals. Three of the lakes were circum-neutral (pH 6.3–7.1) during the study period, while one lake had a pH of 4.8 and a fifth had very low pH ( 4.4).The lakes' catchments were all sources of Al, Mn and Ni, but were sinks for Cu and Zn. The Fe results were inconsistent; two lakes' catchments were sources while three were sinks.The acidic lakes were conservative (i.e. net retention of zero) with respect to Cu and Ni, while the circum-neutral lakes were effective sinks for these 2 metals. All of the lakes were sinks for Zn and Al, but the acidic lakes were less effective. All lakes were also Fe sinks. While there was no pattern relative to the lakes' pH's, there was a trend towards increasing Fe retention with increasing water replenishment time. The most acidic lake was actually a source of Mn, while the others were sinks.     

Analysis of multiple depth profiles in sediment cores: an application to pollen and diatom data from lakes sensitive to acidification

The methods of clustering and ordination were compared with polynomial and segmented regression methods by application to the pollen and diatom profiles from two sediment cores obtained from lakes susceptible to acid precipitation. Clustering and ordination methods have previously been used to determine zones in sediment profiles, but regression methods which summarize the changes with depth in terms of one or more smooth curves, explicitly use the depth information. Plots of running means were also used to characterize profile shapes. The latter two methods provided a clearer understanding of the changes in diatom and pollen levels in the cores. For low diatom concentrations, non-parametric methods were used to test for a change in concentration with depth. Changes in dry weight of sediment, different bases for concentration and depth, and the effect of poor represententation of an extreme group on the pH spectrum were also considered. The regression procedures were shown to provide summaries useful for comparison of different species or of the same species in different cores. Finally, a summary is given of the similarity of the patterns in the depth profiles of eight pollen types and the non-rare diatom species in one core from each of Kejimkujik and Beaverskin Lakes, respectively.     

Life history characteristics of brown trout in lakes at different stages of acidification

In 66 Norwegian lakes with allopatric populations of brown trout Salmo trutta that ranged from highly acidified to non-acid (pH 4·7–6·6) there was a significant inverse correlation between mean age and relative abundance (CPUE). As mean annual survival rates were not significantly related to CPUE, this population response may indicate that recruitment was lower in low-density lakes. Age-specific masses were significantly higher in populations that had declined in abundance than in unaffected populations. Mean body mass at sexual maturity in both males and females was inversely correlated with CPUE. Between populations, high age at maturity was associated with high survival rates in both sexes. Age at maturity correlated positively with specific growth rate between the ages of 1 and 2 years in females only.     

Recovery from acidification in boreal lakes inferred from macroinvertebrates and subfossil chironomids

Acidification of waters and soils caused by emissions and the long-range transport of air pollutants has been a serious worldwide problem during the last decades. The extent of the acidification problem in Finnish acid-sensitive forest lakes was examined in the Acidification Research Project (HAPRO) in the mid-1980s. The recent decline in the emissions of air pollutants has resulted in the chemical recovery of watersheds in many regions, and the present work on the recovery processes in acidified Finnish headwater lakes (REPRO) was launched to examine whether the chemical recovery has already been accompanied by biological recovery. The patterns of recovery were studied by re-sampling littoral macrozoobenthos in a subset of the previously sampled HAPRO lakes. Paleolimnological samples were taken in order to assess the possible dependence of lacustrine chironomid communities on the changing degree of acidification. Acid sensitive and moderately acid sensitive benthic species revealed slight recovery in the formerly most acidic (pH 5.5) but recently recovered lakes. The most significant factors affecting the response of benthic communities were increased mean lake pH and decreased labile aluminium concentration. Paleolimnological chironomid analysis revealed a slight response along the pH gradient, but also significant structural similarity between the present and pristine chironomid assemblages. This implies that no major changes in chironomid communities of these acidic lakes have occurred during the past centuries. The alternative future trends and threats to biological recovery in small headwater lakes are discussed.     

Limnological research on northern Apennine lakes (Italy) in relation to eutrophication and acidification risk

Substantial variability was found in the water chemistry of 22 northern Apennine lakes. In a group of lakes there is evidence of disturbance linked to eutrophication processes. Other lakes showed weak ion concentrations and alkalinity below the acidification risk threshold. However no acidified lakes were found. The lack of waterbodies with severely altered hydrochemistry may explain why no clear relationship between plankton community structure and water chemistry was observed.     

Macrozoobenthos of Lake Peipsi-Pihkva: taxonomical composition, abundance, biomass, and their relations to some ecological parameters

The large but shallow (3,558 km², up to 15.3 m deep) lake is eutrophic, with Chironomus plumosus and Potamothrix hammoniensis as dominating macroinvertebrates in the profundal. The extensive well-aerated sublittoral with sandy bottom sediments has a mesotrophic appearance and supports a diverse fauna with several oxyphilous species, including a very abundant population of Dreissena polymorpha. The phytophilous fauna is limited to small sheltered areas only. The average abundance of the small animals of macrozoobenthos (without big molluscs) was 2,617 ind. m^–2, their biomass 12.34 g m^–2 (corresponding to 52.2 kJ m^–2) in 1964–1994. The same figures for big molluscs (mostly Dreissena) were 304 ind. m^–2 and 238 g m^–2 in 1964–1994, and even 864 ind. m^–2 and 687 g m^–2 in 1985–1988, at the time of their special mapping. The sublittoral zone revealed the lowest biomass of small animals but the highest biomass of big molluscs. The southern, shallower lake regions, more enriched with nutrients and better protected from wind, revealed a significantly higher biomass of small macrozoobenthos in the near-shore zone than the cleaner and open northern part, while no positive effect of enrichment was observed neither in the biomass of profundal zoobenthos nor in that of big molluscs. The production of the small macrozoobenthos was calculated as 111 and 53 kJ m^–2 during two annual cycles in Lake Peipsi s. s., the most productive period being the autumn overturn. Lake Peipsi-Pihkva has the highest abundance and biomass of macrozoobenthos among the large lakes of North Europe.     

胶州湾西北部潮滩湿地大型底栖动物功能群

2009年2、5、8和11月进行了7个断面35个站位的大型底栖动物调查,选取高潮区(A)、中潮区(B、C、D)和低潮区(E)研究了胶州湾西北部潮滩湿地大型底栖动物功能群组成及其时空变化.调查共发现大型底栖动物71种,主要种类为软体动物(31种)、环节动物(20种)和节肢动物(14种).潮区A、B、C、D、E物种数分别为26、33、35、38、31.依据食性将主要底栖动物划分为肉食者、浮游生物食者、碎屑食者和杂食者4个功能群.各功能群物种数占总物种数的百分比由高到低依次是肉食者、浮游生物食者、碎屑食者和杂食者.各功能群中肉食者的多样性指数最高,杂食者最低.各功能群的丰度、均匀度指数、多样性指数一般都是中潮区较高,高潮区和低潮区较低.大型底栖动物功能群的分布随潮区环境的改变而变化,是对生境状况的综合反映.     

Contrasting physiological responses to future ocean acidification among Arctic copepod populations

Widespread ocean acidification (OA) is modifying the chemistry of the global ocean, and the Arctic is recognized as the region where the changes will progress at the fastest rate. Moreover, Arctic species show lower capacity for cellular homeostasis and acid‐base regulation rendering them particularly vulnerable to OA. In the present study, we found physiological differences in OA response across geographically separated populations of the keystone Arctic copepod Calanus glacialis. In copepodites stage CIV, measured reaction norms of ingestion rate and metabolic rate showed severe reductions in ingestion and increased metabolic expenses in two populations from Svalbard (Kongsfjord and Billefjord) whereas no effects were observed in a population from the Disko Bay, West Greenland. At pH_T 7.87, which has been predicted for the Svalbard west coast by year 2100, these changes resulted in reductions in scope for growth of 19% in the Kongsfjord and a staggering 50% in the Billefjord. Interestingly, these effects were not observed in stage CV copepodites from any of the three locations. It seems that CVs may be more tolerant to OA perhaps due to a general physiological reorganization to meet low intracellular pH during hibernation. Needless to say, the observed changes in the CIV stage will have serious implications for the C. glacialis population health status and growth around Svalbard. However, OA tolerant populations such as the one in the Disko Bay could help to alleviate severe effects in C. glacialis as a species.     

Ocean acidification alters sperm responses to egg-derived chemicals in a broadcast spawning mussel

The continued emissions of anthropogenic carbon dioxide are causing progressive ocean acidification (OA). While deleterious effects of OA on biological systems are well documented in the growth of calcifying organisms, lesser studied impacts of OA include potential effects on gamete interactions that determine fertilization, which are likely to influence the many marine species that spawn gametes externally. Here, we explore the effects of OA on the signalling mechanisms that enable sperm to track egg-derived chemicals (sperm chemotaxis). We focus on the mussel Mytilus galloprovincialis, where sperm chemotaxis enables eggs to bias fertilization in favour of genetically compatible males. Using an experimental design based on the North Carolina II factorial breeding design, we test whether the experimental manipulation of seawater pH (comparing ambient conditions to predicted end-of-century scenarios) alters patterns of differential sperm chemotaxis. While we find no evidence that male–female gametic compatibility is impacted by OA, we do find that individual males exhibit consistent variation in how their sperm perform in lowered pH levels. This finding of individual variability in the capacity of ejaculates to respond to chemoattractants under acidified conditions suggests that climate change will exert considerable pressure on male genotypes that can withstand an increasingly hostile fertilization environment.     

Effects of recent acidification on Cladocera in small clear-water lakes studied by means of sedimentary remains

Cladoceran populations, as revealed by sedimentary remains, were studied in six lakes which by diatom evidence have become strongly acidified during the past 30 years. The accumulation rates of cladoceran remains and in two of the most strongly acidified lakes both relative and absolute numbers ofBosmina greatly increased during this period. Species numbers were not reduced, but there were shifts in relative abundances of cladoceran species.Bosmina longispina dominated all the lakes. Low pH (4.7) seemed not to be straight-forwardly harmful toDaphnia longispina, but the relative abundances of this taxon were reduced because ofBosmina.