The impact of water-level regulation on littoral macroinvertebrate assemblages in boreal lakes

Regulation of lake water level for power production and flood control is among the major anthropogenic disturbances in boreal aquatic ecosystems. In Finland, over 300 lakes, representing one third of the total inland water area of the country, are artificially regulated. To study the effects of regulation on lake littoral macroinvertebrate communities, samples were taken from upper stony littoral and from lower soft bottom littoral habitats of 11 lakes with different regulation amplitudes (wintertime fall in water level 1.19–6.75 m). Twelve unregulated (wintertime fall in water level 0.11–0.55 m) lakes with otherwise similar characteristics were used as a reference. Non-metric Multidimensional Scaling ordinations showed that the composition of macroinvertebrate assemblages was strongly associated with the amplitude of water level regulation. Taxon richness also decreased with increasing intensity of regulation. Freezing and flushing of sediments in late winter are probably the most important factors leading to the impoverished littoral macroinvertebrate fauna. Invertebrates with long life cycle seem to be particularly vulnerable to unnatural water level fluctuation. Our results show that regulation of water level has a major impact on functionally significant lake littoral macroinvertebrates.     

Spatial scale and ecological relationships between the macroinvertebrate communities of stony habitats of streams and lakes

1. Comparative studies of distinct, but not ecologically isolated, systems such as lakes and streams may improve our understanding of the importance of ecological linkages in aquatic ecosystems. 2. In this study we compared the macroinvertebrate benthos of stony habitats in Swedish lakes and streams. Community composition was used to evaluate zoogeographic patterns and functional feeding guilds were used to identify mechanisms potentially affecting such patterns. 3. Stream communities were generally more diverse and species‐rich and had a higher proportion of grazers, shredders and passive‐filter feeders than lakes. Lake communities had a higher proportion of predators and collector‐gatherers. Of the 10 most common taxa, only Leptophlebia mayflies, clams (Sphaeriidae) and the isopod Asellus aquaticus were recorded in both lakes and streams. 4. Among‐site variance in macroinvertebrate communities accounted for by regional‐scale variables was low (6.4% for lakes and 10.1% for streams), compared with that by local‐scale variables (21% for lakes and 37.6% for streams). For lakes, the among‐site variance in macroinvertebrate communities was best explained by habitat‐scale characteristics followed by ecosystem, riparian, catchment, geographic position and ecoregion. For streams, the variance in macroinvertebrate communities was best explained by ecosystem characteristics followed by habitat, catchment, riparian, ecoregion and geographic position. 5. Conspicuous differences in spatial pattern were revealed between lakes and streams. For lakes, the most unequivocal differences in community composition and function occurred at the transition zone between the mixed forests in the south and the boreal coniferous forests in the north. Surprisingly, streams did not respond as strongly to profound landscape‐level differences in climate and vegetation cover. 6. The spatial differences noted between macroinvertebrate communities of lakes and streams may be because of differences in retention of detrital matter. Our findings imply that detrital inputs are qualitatively similar, but that the retention and processing of coarse particulate organic matter was presumably higher in lake littoral regions than in stream riffle habitats. 7. Although our findings support the conjecture that species distribution is determined fundamentally by conditions prevailing at the local‐scale, regional factors such as land use/type and the role of history were important and seemingly act as strong determinants of large‐scale patterns in biodiversity.     

Multiple scales and the relationship between density and spatial aggregation in littoral zone communities

Understanding the constraints on community composition at multiple spatial scales is an immense challenge to community and ecosystem ecologists. As community composition is basically the composite result of species’ spatial patterning, studying this spatial patterning across scales may yield clues as to which scales of environmental heterogeneity influence communities. The now widely documented positive interspecific relationship between ‘regional’ range and mean ‘local’ abundance has become a generalisation describing the spatial patterning of species at coarse scales. We address some of the shortcomings of this generalisation, as well as examine the cross‐scale spatial patterning (aggregation and density levels) of littoral‐benthic invertebrates in very large lakes. Specifically, we (a) determine whether the positive range‐abundance relationship can be reinterpreted in terms of the actual spatial structure of species distributions, (b) examine the relationship between aggregation and density across different spatial scales, and (c) determine whether the spatial patterning of species (e.g. low density/aggregated distribution) is constant across scales, that is, whether our interpretation of a species spatial pattern is dependent on the scale at which we choose to observe the system. Spatial aggregation of littoral invertebrates was generally a negative function of mean density across all spatial scales and seasons (autumn and spring). This relationship may underlie positive range‐abundance relationships. Species that were uncommon and highly aggregated at coarse spatial scales can be abundant and approach random distributions at finer spatial scales. Also, the change in spatial aggregation of closely related taxa across spatial scales was idiosyncratic. The idiosyncratic cross‐scale spatial patterning of species implies that multiple scales of environmental heterogeneity may influence the assembly of littoral communities. Due to the multi‐scale, species‐specific spatial patterning of invertebrates, littoral zone communities form a complex spatial mosaic, and a ‘spatially explicit’ approach will be required by limnologists in order to link littoral‐benthic community patterns with ecosystem processes in large oligotrophic lakes.     

Benthic communities of exposed littoral sand-flats in eighteen Dutch lakes

Benthic communities of the exposed sandy littoral zone in eighteen Dutch lakes were sampled using a small, hand-held core (surface area 0.8 cm²). A community dominated by chironomid larvae, chydorid cladocerans, nematodes and copepods was found to be characteristic for this habitat, especially in large and/or deep lakes. Bray-Curtis similarities between sites were generally high (>70%). A hierarchical cluster analysis distinguished two clusters at a 75% similarity level only, varying in copepod and chydorid densities. The chironomidsCladotanytarsus andStictochironomus reached high densities in many lakes, whileRhynchotalona falcata, Monospilus dispar, Disparalona rostrata, Alona spp. andChydorus spp. (mainlyChydorus piger) were the most abundant chydorid taxa.     

Epilithic algal communities and their relationship to environmental variables in lakes of the English Lake District

1. The relationship between epilithic algal communities and 17 environmental variables from 17 oligo- to eutrophic lakes in the English Lake District was explored using canonical correspondence analysis (CCA). Total phosphorus (TP) and calcium (Ca) concentration were the most important variables accounting for species distribution.
2. Weighted-averaging regression and calibration models with tolerance downweighting and classical deshrinking were developed to infer TP, Ca, dissolved inorganic carbon (DIC) and conductivity from the relative abundance of 138 epilithic algal taxa.
3. The ranges of the environmental variables covered by the models are 0.8-49.2 μg L−1 for TP, 2.2–13.0 mg L−1 for Ca, 0.5–8.6 mg L−1 for DIC and 38–124 μS cm−1 for conductivity. Within these limits the models can be used to infer chemical properties of lakes from epilithic communities in the English Lake District.
4. The major advantages of using transfer functions based on epilithic communities are the low logistic requirements and the integrative character of algal samples compared to direct point measurements of chemical parameters of the lakes.     

Untangling the assembly of littoral macroinvertebrate communities through measures of functional and phylogenetic alpha diversity

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Habitat connectivity and dispersal ability drive the assembly mechanisms of macroinvertebrate communities in river networks

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Structure and dynamics of zooplankton communities in the littoral zone of some North Carolina lakes

Species composition and seasonal, dynamics of zooplankton in the littoral zone were studied in three piedmont North Carolina lakes for one year. Nygaard's compound index indicated oligotrophic conditions in Belews Lake and eutrophic conditions in Salem Lake and Lake 150. A total of 32 species of zooplankton were found in the samples. Significantly fewer species of truely littoral zooplankton were present in the oligotrophic lake regardless of season (P < 0.05). Eutrophication appears to favor increased diversity in zooplankton of the littoral zone. Habitat heterogeneity, provided by a well developed littoral zone containing aquatic macrophytes, may be the major factor contributing to the maintenance of more taxa of zooplankton in eutrophic systems.Distinct taxa of Cladocera and Copepoda are present in the littoral zone, exhibiting seasonal dynamics that are largely different from the limnetic fauna. Such dynamics may result from predation by characteristically limnetic species of cyclopoid copepods which seek prey in the littoral zone. The numerical and seasonal abundance of predators and prey are inversely related and the true littoral taxa, represented in the present study by the genera Alona, Chydorus, Pleuroxus, Sida, Simocephalus, and Eucyclops, contained no predaceous species. The seasonal dynamics of these genera are very similar even in widely separated geographical regions, indicating that the factor(s) responsible operate independently of climatic and chemical variables. Intrazooplankton predation appears to be a more plausable explanation than segregation along depth which, although consistent with data from studies of limnetic waters, cannot be related to populations of zooplankton in shallow littoral areas.     

Selective feeding by larval dytiscids (Coleoptera:Dytiscidae) and effects of fish predation on upper littoral zone macroinvertebrate communities of arctic lakes

Carbon and nitrogen stable isotopic data from the primary producers in mangrove ecosystems are needed to investigate trophic links and biogeochemical cycling. Compared with other mangrove species (e.g. Rhizophora mangle) very few measurements have been conducted on the white mangrove, Laguncularia racemosa. The carbon and nitrogen stable isotopic and elemental compositions of L. racemosa were analyzed and compared from Florida and Belize. ¹³C values of L. racemosa from Florida (mean = –26.4) were slightly higher than those from Twin Cays, Belize (mean = -27.4), which may be due to higher salinity in some parts of the Florida site. There was no difference between the ¹⁵N values from L. racemosa from these two sites (Florida mean = 0.6; Belize mean = 0.3), which are indicative of nitrogen derived from nitrogen fixation in a planktonic marine system. However, higher ¹⁵N values from L. racemosa at Man of War Cay in Belize (11.4 and 12.3), which is fertilized by roosting marine birds (14.0), illustrate that L. racemosa can sensitively reflect alternative nitrogen sources. Although the isotopic data could not distinguish between Avicennia germinans, R. mangle and L. racemosa in Belize the L. racemosa had considerably higher C/N ratios (46.5 – 116.1) compared with the Florida samples (42.2 – 76.0) or the other mangrove species. Unlike some previous findings from R. mangle, substrate characteristics (e.g. salinity, NH₄ ⁺, and H₂S) were not related to the isotopic or elemental composition of L. racemosa. ¹³C, ¹⁵N and C/N were analyzed for ecosystem components from L. racemosa habitats at Twin Cays, including other plants (e.g. R. mangle, A. germinans and seagrass), detritus, microbial mats and sediments. Results from mass-balance calculations show that mangrove detritus composes very little of the sediment, which is principally composed of microbial biomass (80 – 90%). Detritus at some sites is also influenced by sources other than that from L. racemosa, including seagrass leaves.     

Ordination of some littoral benthic communities in Bear Lake,Utah-Idaho

Summary Bottom invertebrate communities were compared along the western shoreline of a large oligotrophic lake (Bear Lake, Utah-Idaho). A technique of community ordination was used for the comparisons. Ordination indicated that differences among stations were associated with local differences in bottom type. The bottom type was apparently influenced by isolation from lake currents, nutrient additions, and increased amounts of fine sediments and organic matter. The amount of silt+clay was the most important sediment factor affecting the invertebrate communities. Most communities were dominated by a small species of larval chironomid, Tanytarsus.     

Effects of water-depth and water-level fluctuations on the macroinvertebrate community structure in the littoral zone of Lake Constance

This article presents an evaluation of two sampling methods for assessing the biodiversity of heavily vegetated wetlands. The aim was to establish an effective sampling regime to maximise total taxon richness and minimise sampling effort. Three Integrated Constructed Wetland (ICW) systems in Annetown Valley, Co. Waterford, SE of the Republic of Ireland, were sampled during spring and summer 2005. The two methods that were evaluated were pond netting and two types of horizontal activity traps, namely “horizontal activity traps” (HATs) and modified “horizontal activity traps” (modified HATs). The activity traps provided a one-way funnel system and were constructed from 2 l plastic bottles, allowing for the passive collection of taxa. HATs were designed to capture macroinvertebrates in open water and modified HATs, which were designed specifically for this study, were used to sample within stands of dense emergent vegetation. Results show that a combination of pond netting and activity traps will yield a more complete estimate of taxon richness. The performance of Modified HATs was not significantly different from that of the HATs in dense vegetation. Tests on the sampling effort required for each method are also discussed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: R. Céréghino, J. Biggs, B. Oertli and S. Declerck The ecology of European ponds: defining the characteristics of a neglected freshwater habitat     

The relationship between fish yield and primary production in large European freshwater lakes

The data published on fish yield (Yf) and primary production (PP) in three large European freshwater lakes (Ladoga, Ilmen and Pskovsko-Chudskoe) were analyzed on a long-term basis. The ratios between Yf and PP were found to vary from 0.02% to 0.46%. It was shown that there was an optimal level of PP, above which the efficiency of energy transfer in the pelagic food chain began to decrease. An individual optimum of PP was characteristic of each of the lakes studied. This level was primarily determined by the original trophic status of a given lake as well as by its morphometry and hydrochemistry. The results warn practical ecologists against erroneously predicting commercial harvests from PP.     

Relationship between littoral grazers and metaphytic algae in five softwater lakes

The zoobenthos communities within the littoral zones of five low alkalinity, Ontario lakes were examined during summer 1987. Detached algal clouds or metaphyton, dominated by algae from the family Zygnemataceae, accumulated over the summer in three of these lakes. Previous researchers have hypothesized that diminished grazing pressure due to extirpation of acid sensitive herbivores might enhance the development of metaphytic algae at pHs less than 6. No overt consistent differences existed among the abundances of small (cladocerans, cyclopoids, ostracods, oligochaetes, dipterans) or medium (amphipods, gastropods, emphemeropterans, trichopterans) grazers in study lakes with or without metaphyton. Notable differences did exist, however, with respect to what we term large grazers. Crayfish, algivorous fish (mostly cyprinids), and to a lesser extent tadpoles, were absent or rare in the three lakes with metaphytic algae but abundant in those without. If a reduction in grazing pressure can be implicated as a factor in enhanced metaphyton development, our correlative results suggest that it is the large grazers, particularly crayfish, that are the most likely candidates.     

Response of macroinvertebrate communities to land use and water quality in Wudalianchi Lake

Macroinvertebrate assemblages are structured by a number of abiotic and biotic factors interacting simultaneously. We investigated macroinvertebrate assemblages along gradients of human disturbance and morphometric characteristics in five lakes connected by the same stream. We aimed to assess the relative effects of environmental gradients on macroinvertebrate assemblages and to investigate whether water quality effects on the assemblages were correlated with buffer land use. There were significant differences in macroinvertebrate community compositions among lakes, and our results indicated that oligochaetes (mainly Limnodrilus) and insects (mainly Chironomus) contributed highly to the differences. We used redundancy analysis with variation partitioning to quantify the independent and combined anthropogenic effects of water quality and land use gradients on the macroinvertebrate community. The independent effect of water quality was responsible for 17% of the total variance in macroinvertebrate community composition, the independent effect of buffer land use accounted for 6% of variation, and the combined variation between land use change and water quality accounted for 12%. Our study indicated that both the independent effects of land use and within‐lake water quality can explain the influence in macroinvertebrate assemblages, with significant interactions between the two. This is rather important to notice that changes in buffer land use generally may alter nutrient inputs and thus severely affect abiotic conditions encountered by macroinvertebrate. Our study demonstrates that considering buffer zone effects explicitly may be significant in the selection and application of conservation and management strategies.     

东湖沿岸带底栖藻类群落的时空变化

武汉东湖是一个浅水富营养湖泊,其沿岸带底栖藻类群落的季节分布特征明显,夏季的优势种群是一些体积很小的硅藻类曲壳藻(Achnanthes spp.),其他大部分季节是绿藻门的团集刚毛藻(Cladophora glomerata)和硅藻门的变异直链藻(Melosira varians)。不同样点间的底栖藻类现存量差异不显著,但优势种类不同,以团集刚毛藻为优势的绿藻在处于中富营养区域的磨山样点比例最高,以变异直链藻为优势种的硅藻在严重富营养化的水果湖样点中比例最高。底栖藻类月平均现存量(以叶绿素a计)的时间变化格局为夏季最低(41.5μg/cm2),逐渐增加到秋、冬季节的最高峰值(55.3μg/cm2)。造成东湖夏季底栖藻类现存量低的原因是雨季水体环境的不稳定性和水位升高造成的低光照。不同样点间的chlb、chlc及chlb/a、chlc/a值具有显著差异,分析这种差异显示:在东湖的富营养化条件下,过渡的富营养化能增加底栖藻类群落中硅藻的比例,却降低了绿藻的比例;不同环境条件下的底栖藻类群落结构具有特异性,分析底栖藻类群落结构可以用来评价水环境健康状况。东湖底栖藻类现存量的季节变化规律与浮游藻类不同,它和水温成显著的负相关,但温度和浮游藻类并不是影响东湖沿岸带底栖藻类生物量变化的直接因子。团集刚毛藻等底栖丝状藻类给各种底栖动物提供了食物和栖息环境,在东湖生态系统中具有重要的作用和功能。     

Micro-benthic crustacean communities in tundra lakes of North-East European Russia

We studied micro-benthic copepods and cladocerans in the bottom substrates of 12 lakes in the Bol’shezemel’skaya tundra in North-East European Russia during the summer. About 30 species of Cladocera and 28 species and subspecies of Copepoda were found. The majority of the micro-crustaceans are palaearctic or northern palaearctic. But the harpacticoid fauna of the western part of the studied region had specific European features, and three species of the harpacticoid fauna in the eastern part of the region were Siberian. It is therefore a boundary territory for two zoogeographical regions, the arctic and subarctic zones. Acidophilic (Arcticocamptus arcticus (Lilljeborg 1902)) and halophilic (Microsetella norvegica (Boeck 1864)) harpacticoid species were found in the lakes of the eastern part of Bol’shezemel’skaya tundra. On basis of their way of locomotion we distinguished five ecological groups and on basis of their feeding habits four ecological groups of micro-crustaceans. Groups with a similar way of locomotion were likely distributed over the studied water bodies. Habitat (inshore versus offshore), substrate particle size and substrate hardness were of paramount importance for the species distribution.     

Phytoplankton communities in the littoral zone of lakes: Observations on structure and dynamics in oligotrophic and eutrophic systems

Summary The structure and seasonal dynamics of phytoplankton communities in the littoral zone were compared between oligotrophic and eutrophic lakes in the southeastern United States. Differences in diversity and species composition between lakes could be ascribed to long-term variation in nutrients corresponding to trophic status. However, significant within-lake variation could not be accounted for by microstratification of nutrients or other abiotic variables. Local biotic factors, perhaps dominated by the spawning activities of centrarchid fishes, resuspend periphyton and generate tychoplankton which becomes a persistent and integral part of the phytoplankton community in eutrophic systems. The patchy distribution of these biotic factors and resultant tychoplankton may lead to the observed variation. Grazing by herbivorous zooplankton was considered to be the major factor affecting the relative abundance of phytoplankton in the littoral zone, completely overriding the effects of nutrient concentration and biotic interactions between phytoplankton species during spring and summer.The relative importance of tychoplankton and grazing as regulatory factors operates independently of the trophic status or geographical location of a lake, making comparisons of different studies difficult and perhaps meaningless if traditional analyses based only on nutrients and interactions between species of phytoplankton are used. Limnetic as well as littoral components must be considered in future studies of phytoplankton communities in the littoral zone.     

Lake browning impacts community structure and essential fatty acid content of littoral invertebrates in boreal lakes

Hydrobiologia - Many lakes in the northern hemisphere are browning due to increasing concentrations of terrestrial dissolved organic carbon (DOC). The consequences of lake browning to littoral...     

The invasive crayfish Faxonius immunis causes the collapse of macroinvertebrate communities in Central European ponds

Aquatic Ecology - The invasive crayfish Faxonius immunis is regarded as a threat to amphibians and macroinvertebrates in the Upper Rhine Valley, Germany, eradicating macrophytes and establishing...     

Classification and ordination of profundal macroinvertebrate communities in nutrient poor, oligo-mesohumic lakes in relation to environmental data

SUMMARY. 1. Profundal macroinvertebrates and water chemistry of sixty-eight nutrient poor, poorly buffered lakes were sampled in 1983 or 1986. Assemblages of profundal zoobenthos were classified using two-way indicator species analysis (TWINSPAN), ordinated by canonical correspondence analysis (CCA), and related to physico-chemical factors using CCA. discriminant analysis, and regression.
2. 90% of zoobenthos (TWINSPAN) groups were classified correctly using discriminant analysis. Depth (Function 1), soluble reactive Si(OH)₄ and HCO₃, -(2), and phytoplankton biovolume and pH (3) were the strongest correlates with the three discriminant functions.
3. Regression analysis showed that depth, KmnO₄, consumption, and phytoplankton biovolume were the best estimators of zoobenthos biomass in the profundal.
4. Multivariate analyses showed species assemblages amongst the profundal zoobenthos to be good indicators of lake type, particularly depth, pH, and phytoplankton biovolume.