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Nitellopsis obtusa is a large invasive freshwater macroalgae that forms extensive, monotypic beds which have altered habitat and impacted littoral communities in lakes across North America. N. obtusa is native to Eurasia including the UK but is considered to be cryptogenic and likely introduced in Ireland, where it was first recorded in 2016. Recent evidence of its spread prompted this hydroacoustic survey which investigated the distribution and abundance of N. obtusa in two large interconnected lakes, Loughs Ree and Derg, within the Shannon River system. Using a consumer grade depth finder and a simplistic approach, we propose an accessible method of hydroacoustic surveying for macrophytes such as N. obtusa which form dense, often monotypic beds. Nitellopsis obtusa beds quantified within three bays in Lough Ree covered 254.4 hectares with a total biovolume of ~ 2.7 million m3, indicating that it may be one of the most aggressive macrophytes introduced to Ireland. The hydroacoustic survey methodology proved to be cost and time efficient. Measurements of plant height and lake depth gathered from the hydroacoustic survey were comparable to diver gathered measurements which provides confidence in the methodology. The rapid expansion of N. obtusa within Loughs Ree and Derg is a concern for other alkaline waterbodies in Ireland, especially marl lake systems, and warrants monitoring. There is no feasible method to eliminate the extensive populations of N. obtusa in Lough Ree and therefore management interventions should aim to limit the spread of this species to other waterbodies. [ABSTRACT FROM AUTHOR]

In this study, we quantify the differences in gross primary production (GPP), respiration (R), and algal nutrient limitation (nitrogen and phosphorus) in the littoral and pelagic habitats of an oligotrophic Patagonian lake (southern South America). We used submerged high frequency sensors that measure light, temperature, and dissolved oxygen and wind data to calculate GPP and R in both lake habitats. In addition, we carry out nutrient enrichment bioassays with nitrate, ammonium, and phosphate to determine which nutrient(s) limit algal growth in each lake habitat. On average, the productivity rate was 7.2 times higher at the epi-littoral (32.0 to 5.3 mmol O2 m−2 d−1) relative to the epi-pelagic (4.1 to 1.3 mmol O2 m−2 d−1). Algal growth in the littoral habitat was limited by nitrate and ammonium, while the pelagic habitat was co-limited by nitrogen (nitrate or ammonium) and phosphorus. Our work demonstrates that the littoral habitat of a Patagonian oligotrophic lake is more productive than the pelagic habitat and that the nutrients limiting algal growth in both habitats are different. These results underscore habitat variations and their significance in shaping the lake's trophic dynamics for the first time in the southern hemisphere. [ABSTRACT FROM AUTHOR]

For the first time, the size spectra of 28 chironomid genera/species are reported for the most common chironomid taxa in the deep subalpine Lake Maggiore (northwestern Italy). Species-specific length–mass regression models were developed to predict the dry masses of the larval stages of Cladotanytarsus sp., Cryptochironomus sp., Polypedilum bicrenatum, P. nubeculosum, and Stictochironomus pictulus. The predicted dry-mass values differed by less than 20% from the measured values, suggesting that these original equations will be important in chironomid production studies. Regressions at the subfamily level were also developed for case identification at the genus or species level, which is difficult to obtain. The chironomid weights were determined directly and a dry/wet-weight-conversion ratio was estimated. The results were consistent with previously reported results. The relationships between the dry masses and the body lengths were compared with published data for different types of lake all over the world. We found that regression models for other freshwater environments somehow differed from those in Lake Maggiore, albeit slightly. The combination of diversity-based and trait-based approaches improves our knowledge about chironomids and our understanding of the effects of global environmental changes on freshwater biota. This first collection of trait data on summer–autumn chironomid assemblages in a temperate subalpine lake is a valuable contribution to the European trait database. The taxonomic diversity and abundance of chironomids were uploaded for open access on the GBIF platform. [ABSTRACT FROM AUTHOR]

Fish are known to pose strong effects on invertebrate abundance, species richness and assemblage structure. Littoral vegetation may play a crucial role as a refuge for invertebrates vulnerable to fish predation. We studied relative densities and taxonomic composition of water mites, aquatic beetles and bugs in large lake-like ponds with different fish status (fish-free and containing fish) and mesohabitats (emergent littoral vegetation and open water zone). The macroinvertebrate taxa differed in their responses to the fish presence and in mesohabitat preferences. The density and species richness of water mites were greater in fish-containing ponds, while no differences were found between littoral and open-water habitats. In contrast, beetles were far more numerous and species-rich in fish-free ponds and in littoral vegetation. Total densities of aquatic bugs were non-significantly higher in fish-containing ponds, and they preferred littoral areas, but species richness was independent of fish presence and mesohabitat. No statistical interactions between fish presence and the densities of individual macroinvertebrate groups in the littoral habitat were detected, indicating that their use of emergent littoral vegetation was not an antipredator response to fish. The assemblages of the three macroinvertebrate taxa exhibited nested structures of a different order, consistent with their species richness patterns. Our research stresses the importance of littoral vegetation for the distribution and abundance of aquatic insects; however, high fish presence may not affect or may even benefit ecologically important macroinvertebrate groups, such as water mites or bugs. [ABSTRACT FROM AUTHOR]

The maritime trap-jaw ant Odontomachus malignus Smith, 1859 is thought to be widespread throughout islands in the Indo-Pacific and parts of the Oriental realm. Because of its unique nesting preference for harsh littoral habitat and distinct morphology, O. malignus has usually been assumed to consist of only one species. We, however, describe a new species similar to O. malignus found in the mangroves of Singapore, Southeast Asia - Odontomachus litoralis sp. nov. We find strong evidence of both species existing in (near) sympatry, and also distinct morphological differences between O. malignus and the new species. Additional complementary DNA evidence in the form of COI barcodes (313 bp) supporting putative species identification and delimitation is provided. Defining morphological characteristics for the O. malignus species group (nested within the larger O. infandus clade) are given in detail for the first time. The worker and queen castes of the new species are described; a redescription of the worker caste of O. malignus, based on specimens from Singapore and the Philippines in addition to the holotype, is also given. The males of both species are also described for the first time, including male genitalia. A preliminary key to most known species of the O. infandus group based on the worker caste is provided. [ABSTRACT FROM AUTHOR]

Reed is one of the most widespread and productive wetland plant species worldwide, but few studies have addressed carbon utilization of this plant in natural environments. By collecting reed samples from lakes and ponds in the middle and lower reaches of the Yangtze River, weexamine the association between the carbon isotopic ratio (δ13C) of reed stem and root, and dissolved inorganic carbon concentration (DIC) and δ13CDIC, respectively. Our results suggest that 1) although atmospheric carbon is the dominant pathway, the pathway that uptake DIC through root system also plays an important role in determining the carbon stable isotope signal of reed, and 2) juvenile reedbed incorporates more carbon resources from DIC pool than the matured ones. Our study demonstrated that δ13C of emergent macrophytes could also be influenced by underwater carbon, especially at their early life stages. [ABSTRACT FROM AUTHOR]

Central Mexico, home to a unique and imperilled freshwater fish fauna, high in endemism, is also a very densely populated region with considerable human activity.Aquatic systems in the region have been heavily disturbed by human activity in the form of species introductions, pollution, and habitat modification, which has resulted in the extirpation of native fishes and the alteration of the native fish fauna.An analysis of the roles of these factors in the decline of the fish fauna and an overview of its conservation status are presented. Both current and historic fish assemblages were characterized and water physicochemical parameters recorded at 62 localities within the region. Water quality, hydrological modification, and the presence of introduced species were used as variables in a linear model to explore their respective influence on the integrity of local fish assemblages.Analyses suggest that both water quality and the presence of introduced species have had adverse impacts of similar magnitude on the conservation status of native species, whereas hydrological modification has had no statistically significant effect.This survey revealed the profound alteration of the fish fauna. Only 40% of the expected native populations were found, and only 30% of the sampled assemblages were free of introduced species. As little as 17% of the sampled assemblages were taxonomically intact. The mean species richness per locality was only half of that indicated by historical records. The conservation value of springs, where many threatened microendemics can still be found, is highlighted, and we argue that their small size and isolation make them key targets for conservation efforts. [ABSTRACT FROM AUTHOR]

Optimal life-history strategies are currently considered to be a major driving force for the maintenance of animal personalities. In this experimental study we tested whether naturally occurring predation causes personality-dependent mortality of a marine isopod (Idotea balthica), which could maintain personality variation in nature. Moreover, as isopods are known to have sex-differences in behaviour, we were interested in whether personality-dependent predation was sex-specific. We also hypothesised that predation pressure among personality types could vary according to habitat type, as it has been shown in correlative studies that habitat may influence personality variation. We used natural predator (European perch Perca fluviatilis) of I. balthica and studied relative mortality of males and females with a different personality types in laboratory settings with two different habitats. We found that survival in males was lower than in females for high active individuals. Moreover, survival under predation was linked to body size differently in females and males. This, however, depended on personality class as larger size was advantageous for low-active males and middle- and high-active females. Conversely, smaller size was advantageous for low-active females and middle-active males. Size did not affect survival in high-active males. Our results suggest that predation can encourage life-history differences between sexes leading to different optimal life-history strategies and also maintains consistent activity for both sexes. [ABSTRACT FROM AUTHOR]

Purpose. Environmental - faunal studies of juvenile fish in the littoral zone of the reservoir, study of changes in species composition and behavior of juvenile fish depending on various environmental factors. Methodology. An integrated monitoring studies of spatial - temporal distribution of juvenile fish were performed within 14 research stations of the Kiev reservoir, according to the methodological developments of V. Trohimtsya. The material was collected with a juvenile fish beach seine of 4 m long and 1 m high and "ACT" traps. Species were identified using a fish guide specially developed for the analysis of Dnieper River species composition. Material processing was performed in the field and in laboratory conditions according to generally accepted methods. The similarity of the species lists of various stations was determined by Jaccard’s indexes. Findings. Dominant and rare representatives of the littoral fish fauna of the Kanev reservoir have been determined. The effect of vegetation density degree and depth on the spatial - temporal distribution of juvenile fish in the different periods of the year has been found. The relationship between the depth of the "AST" traps and fish fry catch has been found. It is shown that in the morning fry moved to the shore in search of food (53.8 %), and at night it actively moved away from the shore (44,4 %) that was associated with a decrease of water temperature in the littoral zone. Originality. The relationship between the spatial and temporal distribution and species composition of the juvenile fish of the littoral zone of the Kanev Reservoir has been investigated taking into account the effect of dominating species on habitats, in the dynamics during three years. Practical value. The conducted studies give an idea about peculiarities of species composition and spatial - temporal distribution of juvenile fish in the littoral zone of the Kanev reservoir. The results allow predicting further changes in fish abundance and future catches.

Global warming is expected to influence lake gross primary production (GPP) and ecosystem respiration (R) by increasing water temperature and terrestrial export of organic material and inorganic nutrients from the catchment. We experimentally tested the effects of warming (3 °C) and natural humic river runoff, separately and in combination, on habitat-specific and whole ecosystem net ecosystem production (NEP = GPP − R) in replicated large scale (136 m) experimental pond ecosystems over one open water season. Pelagic NEP was reduced by warming and increased with humic river water addition. Littoral NEP (benthos, macrophytes, periphyton) showed an opposite pattern with increasing NEP following warming and decreasing NEP following humic river water addition. These changes were a result of changes in GPP with warming (negative in pelagic, positive in littoral) and with humic water addition (positive in pelagic, negative in littoral), while no effects were observed on pelagic respiration. As a result of the counteracting effects on NEP in pelagic and littoral habitats, whole ecosystem NEP was not affected by the treatments. The study suggests that climate mediated changes in temperature and river runoff have relatively small effects on the overall metabolic balance of shallow aquatic ecosystems but there may be large habitat-specific effects. [ABSTRACT FROM AUTHOR]

Near-shore physical habitat is crucial for supporting biota and ecological processes in lakes. We used data from a statistical sample of 1101 lakes and reservoirs from the 2007 US Environmental Protection Agency National Lakes Assessment (NLA) to develop 4 indices of physical habitat condition: (1) Lakeshore Anthropogenic Disturbance, (2) Riparian Vegetation Cover Complexity, (3) Littoral Cover Complexity, and (4) Littoral–Riparian Habitat Complexity. We compared lake index values with distributions from least-disturbed lakes. Our results form the first US national assessment of lake physical habitat, inferring the condition (with known confidence) of the 49,500 lakes and reservoirs in the conterminous United States with surface areas >4 ha and depths >1 m. Among the physical and chemical characteristics examined by the NLA, near-shore physical habitat was the most extensively altered relative to least-disturbed condition. Riparian Vegetation Cover Complexity was good in 46% (±3%), fair in 18% (±2%), and poor in 36% (±2%) of lakes. Littoral–Riparian Habitat Complexity was good in 47% (±3%), fair in 20% (±2%), and poor in 32% (±2%) of lakes. In every ecoregion, habitat condition was negatively related to anthropogenic pressures. Gradients of increased anthropogenic disturbance were accompanied by progressive simplification of littoral and riparian physical habitat. Nationwide, the proportion of lakes with degraded near-shore physical habitat was equal to or greater than that for excess nutrients and much greater than that for acidic conditions. In addition to better management of lake basins, we suggest an increased focus on protecting littoral and riparian physical habitat through better management of near-shore anthropogenic disturbance. [ABSTRACT FROM AUTHOR]

This study describes the inshore fishery on the littoral cichlids in Lake Tanganyika, to evaluate the potential impact of fishing gear on the cichlid fishes and their diversity. The fishing activity at the northwestern end of Lake Tanganyika in Uvira was examined from March to July 2010. In total, the catch examined was composed of 3,555 cichlid fish: 47 species and 30 genera identified representing 10 of the 16 tribes of Lake Tanganyika cichlids. Fishermen in Uvira, exploiting littoral cichlids, used three main fishing gears including beach seine, frame gillnet and mosquito net, varying according to the substrates of the littoral habitat at different study sites. They generally captured immature fishes (63%) and small-sized fish due to their small mesh size and unsuitable fishing techniques. The beach seine caught more species on the sandy substrate while the frame gillnets caught more individuals. The cichlid speciesAulonocranus dewindtiwas the most abundant in the catches. [ABSTRACT FROM AUTHOR]

This study assessed the spawning activity of the threatened Australian lungfish Neoceratodus forsteri by measuring egg densities within the artificial habitat of a large impoundment (Lake Wivenhoe, Australia). Eggs were sampled (August to November 2009) from multiple locations across the impoundment, but occurred at highest densities in water shallower than 40 cm along shorelines with a dense cover of submerged terrestrial vegetation. The numbers of eggs declined over the study period and all samples were dominated by early developmental stages and high proportions of unviable eggs. The quality of the littoral spawning habitats declined over the study as flooded terrestrial grasses decomposed and filamentous algae coverage increased. Water temperatures at the spawning site exhibited extreme variations, ranging over 20·4° C in water shallower than 5 cm. Dissolved oxygen concentrations regularly declined to <1 mg l−1 at 40 and 80 cm water depth. Spawning habitats utilised by N. forsteri within impoundments expose embryos to increased risk of desiccation or excessive submergence through water-level variations, and extremes in temperature and dissolved oxygen concentration that present numerous challenges for successful spawning and recruitment of N. forsteri in large impoundment environments. [ABSTRACT FROM AUTHOR]

In this paper, we describe the new genus Pauropygus gen. n. which includes three minute species, blind and unpigmented, living in interstitial littoral habitats in tropical or subtropical countries. Two of these species are new to science (type species P. projectus sp. n. from New Caledonia and P. pacificus sp. n. from China); the third one, originally described in the genus Cryptopygus (C. caussaneli Thibaud, 1996), has a larger pantropical distribution. We synonymize here Cryptopygus riebi Barra, 1997 from South Africa with Pauropygus caussaneli. Two paratypes of the Mexican species Cryptopygus axayacatl Palacios & Thibaud, 2001 turned also to be P. caussaneli, while the holotype and remaining paratypes of this species support its placement in Proisotomodes. Among the Cryptopygus complex, Pauropygus gen. n. is easily recognized by characters of mouthparts (presence of two large projections on pleural fold, basolateral field with 6 chaetae, modified mouthparts) and reduced sensillar chaetotaxy (tergal sensilla 2-3,0-1/0-1,0-1,1- 2,1-2,1-3, microsensilla reduced in number: 00/0-100, with sensilla situated in p-row on the abdomen). Small size, absence of eyes and pigment are also shared by all its species. The three species belonging to the genus differ by sensillar chaetotaxy. [ABSTRACT FROM AUTHOR]

Biomass and growth of Pumpkinseed fLepomis gibbosus/ Yellow Perch (Perca flavescensj and cohabiting species varied among different bays of Prince Edward County in eastern Lake Ontario. Biomass (B) and a calculated fish production (P) index of fishes, estimated as the product of average seasonal biomass and P/B, was about 6x higher at the electrofishing transects with medium to high macrophyte cover and low fetch than at sites where macrophytes were absent or sparse and fetch was high. The production index -aquatic plant relationship was species-dependent. The biomass component offish production was related to macrophyte cover but the growth component and P/B (determined by allometry with body size) was not. Biomass and inferred production could be predicted from fetch, macrophyte abundance and water temperature, but with low precision. Results were consistent with index trawling in showing that changes in aquatic vegetation following Dreissena colonization in the Bay ofQuinte and vicinity have affected the abundance of phytophilic fishes in this region of eastern Lake Ontario. [ABSTRACT FROM AUTHOR]

Developing quantitative ecosystem-scale expectations of habitat restoration projects and examining trade-offs associated with alternative approaches has been a challenge for restoration ecology. Many of the largest freshwater lake restoration projects have occurred in Florida to remediate degradation to vegetated littoral habitats resulting from stabilized water levels, but effects across lake food-webs have not been assessed. We developed an ecosystem model using Ecopath with Ecosim and Ecospace for a generalized large, eutrophic Florida Lake to explore how simulated restoration activities could influence fish communities with emphasis on sport fish abundance. We modeled three habitat restoration scenarios: (1) 'no control,' (2) a '10-year control' that restored littoral habitat every 10 years, and (3) a 'combined control' scenario that restored littoral habitat every 10 years with maintenance controls between 10-year periods. Our 'combined control' scenario provided the largest long-term habitat restoration benefits for sport fish abundance and the fisheries they support. In Ecospace, we simulated a littoral habitat restoration project that reduced lake-wide tussock coverage from 30 to 15%. Ecospace predicted positive benefits to sport fish and fisheries following the restoration simulation and highlighted the importance of habitat edge effects, spatial design of habitat restoration projects, and sampling designs for evaluating restoration projects. [ABSTRACT FROM AUTHOR]

This article discusses a study which examined oribatid mites from marine littoral and freshwater habitats in India. The study used four mite species in marine coastal and semi-aquatic, freshwater habitats during a flood. It proposed a revised diagnosis of the genus. It found species living in marine littora zones in the tropics and subtropics and identified a new species found in marine coastal areas. In addition, the study described several species found among weeds and sediments of the Karamana during a flood.

The European catfish (Silurus glanis) was introduced in Italy during the last century for aquaculture purposes, and now it is well-established. S. glanis is an invasive species and a top predator that can deplete prey supply in the surrounding habitat, leading to changes in the aquatic food web. Consequently, its presence is considered a threat to native fish populations. Its presence in the Lake Maggiore (Northern Italy) is recent and there is a lack of knowledge about its ability to completely exploit this new ecosystem throughout the year. This study corroborated the ability of European catfish to exploit both pelagic and littoral habitats, promoting trophic interactions in both habitats. Over 2019, multiple sampling approaches have been applied by collecting S. glanis and analysing its stomach contents with the aim of inferring interactions with the freshwater community. Its diet was mainly based on crayfish (Orconectes limosus), followed by six prey fish and the genus Corbicula; two fish species (Padogobius bonelli and Salaria fluviatilis) were added to the list of known prey fish. Notably and alarmingly for the early potential top-down pressure towards all trophic levels, young individuals were proved to also feed on fish and crayfish. S. glanis showed the ability to hunt at deep depths (>60 m) and a high growth rate, despite Lake Maggiore being oligotrophic. [ABSTRACT FROM AUTHOR]

While the impacts of high exploitation on fish populations and aquatic ecosystems are well-documented for commercial fishing, particularly in the marine environment, the potential biological impacts of angling received less attention.This paper discusses angling patterns within a framework of basic ecological and evolutionary literature and examines potential biological impacts of angling by focusing on study results associated with high exploitation rates and pronounced selective exploitation. The impacts range from impacts occurring directly on the exploited species (truncation of the natural age and size structure, depensatory mechanisms, loss of genetic variability, evolutionary changes), to those that occur on the aquatic ecosystem (changes in trophic cascades, trait-mediated effects). As a third category, impacts related to the angling activity per se are distinguished (habitat modifications, wildlife disturbance, nutrient inputs, loss of fishing gear).Although the main threats to fish often are localized outside recreational fisheries, there is growing evidence that angling and angling associated activities can lead to a decline of fish populations and affect aquatic ecosystems in various ways provided that the degree of the fishing mortality is high and the selective exploitation is intensive. In conclusion, management implications for sustainable recreational fisheries and areas for future research are outlined. [ABSTRACT FROM AUTHOR]

1 Residential development is often concentrated near aquatic ecosystems and understanding riparian–littoral zone interactions is therefore critical for assessing its ecological effects. 2 Introduction of wood from riparian forests into the littoral zone, where it becomes habitat for aquatic organisms, is an important, but poorly understood, process. We related the density of littoral coarse wood both among and within 45 lakes in Vilas County, Wisconsin, USA, to forest structure, abiotic drivers and land use. 3 Among all lakes and among a subset of low-development lakes, the best predictor of the density of littoral coarse wood was the density of riparian coarse wood. At the within-lake (site) level, two alternative models explain variability in coarse wood abundance: as a function of exposure to wind and amount of riparian coarse wood or as a function of exposure to wind and land-use intensity. 4 Both among and within lakes, areas more modified by humans had a lower density of littoral coarse wood. Conversely, areas with little (current) human impact were tremendously variable; some sites and lakes had abundant wood and others had virtually none. 5 Contrary to previous studies, there was no relationship between living trees and coarse wood density, suggesting that riparian and littoral coarse wood densities may be strongly influenced by past disturbance, both human and natural. 6 This study highlights the importance of cross boundary subsidies in understanding the impact of development on ecosystems. The concentration of residential development at the boundary between terrestrial and aquatic ecosystems appears to reduce the flow of coarse wood from forests to lakes. Loss of this resource may have negative consequences for lake biota and the aquatic food web. [ABSTRACT FROM AUTHOR]

1. Research has often focused on the pelagic areas of lakes; the littoral zone has received less attention. The few studies concerning fish distribution in littoral habitats have concentrated on stands of submersed macrophytes, whereas other littoral habitat types have seldom been investigated. 2. This study aimed to predict the occurrence of juvenile fish in several littoral habitats of a shallow lake as a function of food availability, complexity of habitat structure, water depth and substrate. Habitats comprising reed, woody structures, and two open water areas differing in depth were sampled for fish and invertebrate biomasses on two shores, over 6 months and during both daylight and at night. 3. The juvenile fish community consisted almost exclusively of 0+ and 1+ roach and perch. There was a strong diel component in habitat use, with a predominant occurrence of fish in complex habitats (mainly woody structures) during the day, and a partial migration towards the open habitats at night, more strongly expressed in roach than in perch. 4. The diet of all fish groups was relatively constant over the seasonal cycle, and was independent of habitat. There was a higher degree of planktivory in roach than in perch, but both species fed on benthic macroinvertebrates to a substantial extent. 5. According to a logistic regression model, the biomass of potential food organisms in the different habitats had little predictive effect on the spatial distribution of the fish, whereas the structural complexity of the habitats combined with the diel cycle explained about 28% of the occurrence patterns in 0+ and 1+ perch and 1+ roach. [ABSTRACT FROM AUTHOR]

A GIS model of the littoral bathymetry and substrate composition of Lake Taupo was created using ArcInfo. Littoral substrates were mapped by aerial photography and confirmed by ground-truthing. Water depths were determined by echosounding linked to a differential GPS. These data were imported into ArcInfo where a 3D GIS model was used to calculate the total area of smelt, Retropinna retropinna Richardson, spawning habitat (i.e. clean sand between depths of 0.5–2.5 m) at each of five lake levels. There was little change in area over the first 50 cm below the natural maximum lake level, but spawning habitat decreased rapidly over the next 1.4 m such that a 30% reduction occurred at the natural minimum level. Anecdotal information on inter-annual variations in lake level and smelt abundance supported the notion that high lake levels in spring result in high recruitment of smelt. The GIS model also predicted effects of lake level change on areas of macrophyte cover and on other littoral substrates, and could be used to assess effects of lake level changes on the habitats of other biota. [ABSTRACT FROM AUTHOR]

Residential development of lakeshores is expected to change a variety of key lake features that include increased nutrient loading, increased invasion rate of nonnative species, increased exploitation rates of fishes by anglers, and alteration of littoral habitats. All of these factors may alter the capacity of lakes to support productive native fish populations. Fourteen north temperate lakes were surveyed to examine how growth rates of two common fish species (bluegill sunfish, Lepomis macrochirus; largemouth bass, Micropterus salmoides) varied along a residential development gradient. Size-specific growth rates for both species were negatively correlated with the degree of lakeshore residential development, although this trend was not statistically significant for largemouth bass. On average, annual growth rates for bluegill sunfish were 2.6 times lower in heavily developed lakes than in undeveloped lakes. This effect of lakeshore development on fish growth was not size specific for bluegills between 60 and 140 mm in total length. An index of population production rate that accounted for both the size-specific growth rate and the size distribution of fishes showed that bluegill populations were approximately 2.3 times less productive in highly developed lakes than in undeveloped lakes. Our results suggest that extensive residential development of lakeshores may reduce the fish production capacity of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The ecological features of invasive alien species are crucial for their effective management. However, they are often lacking in newly invaded ecosystems. This is the case of the European catfish Silurus glanis L. in Lake Maggiore, where the species is present since 1990, but no scientific information is available on its ecology. To start filling this knowledge gap, 236 catfish (67 cm to 150 cm of total length) were collected, measured, and dissected for stomach content analyses from three localities and in two habitats (littoral vs. pelagic) in late autumn/early winter. The NPUE and BPUE (individuals (N) and biomass (B, in grams) per unit effort (m2), respectively) of catfish were generally higher in littoral (NPUE > 0.01; BPUE > 96) than in pelagic habitats (NPUE < 0.009; BPUE < 114), but the catfish had, on average, larger sizes in pelagic habitats. Overall, 581 individual prey items were recorded, belonging to 12 taxa. Pelagic catfish specialized their diet exclusively on three prey fish (coregonids, shad, and roach), whilst the diet of littoral catfish was more variable and dominated by crayfish, perch, and roach. These results highlighted for the first time the interaction of larger catfish with the lake's pelagic food web, and thus possible consequences are discussed, including the potential contrasting role S. glanis may have for the lake's fishery. [ABSTRACT FROM AUTHOR]

Evolutionary trends in Late Permian Darwinulocopina are summarised with reference to extensive collections from eastern European Russia, from the White Sea in the North to the Cis-Caspian in the South. Theyinhabited large, shallow lakes in which the variety of habitats was favourable for high ostracod diversity. Three superfamilies are represented: the Darwinuloidea preferred lakes with terrigenous sedimentation and insignificant bicarbonate, the Suchonelloidea inhabited lakeswith increased bicarbonate and could also live in low-sulphate waters, and the Darwinuloidoidea inhabited high-bicarbonate water bodies and could also survive in low-magnesium waters. Different evolutionarytrends account for the different ages of the crucial stages of development of each superfamily: the beginning of the mid-Tatarian for theDarwinuloidea, the late Tatarian for the Suchonelloidea and Darwinuloidoidea. [ABSTRACT FROM AUTHOR]

I present the findings of two detailed studies on Steinheim lake ostracods carried out over the last eight years. The 178 samples studiedcover a combined section about 30 m thick, comprising the whole sequence of seven planorbid beds. Of the 53 species found, 44 occur in the basic sediment layers, the kleini beds. In contrast, all of the subsequent beds contain 16 species, and only seven species withstood theextinction at the kleini-steinheimensis boundary.This may be mainly due to the loss of littoral habitats brought about by a constantly increasing lake level, as the majority of the species in the kleini beds were shallow water dwellers. Long-term lake level fluctuations are considered the most important external factor of the post- kleini period. Density fluctuations of the ostracods Pseudocandona steinheimensis and Potamocypris gracilis broadly reflect these water level fluctuations. At the beginning of the sulcatus period, when the lake level was very high, some species show morphological changes in their carapaces. During this time Leucocythere immigrata split into the daughterspecies L. sieberi and L. esphigmena. In the following trochiformis period, when the water level was lowest, the most curious carapace sculptures appear. The morphological changes detected, however, cannot simply be interpreted as ecophenotypic. The speciation event in Leucocythere, the non-recolonization with ubiquitous species during the low water level stage (trochiformis period), as well as the types of morphological changes indicate mainly evolutionary processes, as also the planorbid molluscs prove. Moreover, ostracods and planorbids show convergent evolutionary patterns. Compared with data on ostracod speciation in ancient lakes, the ostracod assemblage of Lake Steinheim seems to be a good palaeontological example of intralacustrine evolution at an early stage. [ABSTRACT FROM AUTHOR]

Extensive growths of filamentous green algae (metaphyton) developed at pH 4.5 in the littoral zone of Lake 302S and dense populations of microcrustacean grazers occupied this new habitat. Microcrustacean community composition in this metaphyton consisted predominantly of cladocerans (e.g. Chydorus piger, Acantholeberis curvirostris, Alona intermedia, A. rustica, Acroperus cf. harpae and Simocephalus serrulatus), as well as substantially fewer copepods, including Macrocyclops albidus and Eucyclops agilis. Despite the development of this new littoral habitat, the metaphyton-associated microcrustacea were relativelyhomogeneous throughout the littoral zone in terms of composition, species richness and diversity, which varied little among any of the benthic habitats (macrophytes, sediments, boulders, metaphyton). Cladoceran and copepod density varied seasonally and synchronously in all habitats with highest densities occurring in June-July and September. Densities were much higher in metaphyton than in other littoral habitats. [ABSTRACT FROM AUTHOR]

This paper describes a previously unknown ctenopod crustacean of thefamily Sididae, collected in Brazil and Venezuela which, along with the forms known as Diaphanosoma volzi, displays distinctive characteristics that are here recognized as being of generic magnitude. Phenetic analysis of the species within the family Sididae, supports the hypothesis that Neodiaphanosoma constitutes a well defined group, differentiated enough from Diaphanosoma to be accepted as a different genus. The new genus seems to be a group of specialized species, close toDiaphanosoma with advanced features. Some features shared with Sarsilatona, Latonopsis and Pseudosida probably reflect convergence related to littoral habitat more than ancestry. [ABSTRACT FROM AUTHOR]