Search

Microorganisms have been reported to induce settlement in various marine invertebrate larvae but their specificity of inductive capacities for the settlement of coral larvae remains poorly understood. In this study, we isolated 56 microbial strains from the crustose coralline alga (CCA) Hydrolithon reinboldii using five different media either with or without additional antibiotics and/or spiked CCA extract. We tested the isolates for their potential to induce settlement behavior in larvae of the brooding scleractinian coral Leptastrea purpurea. From these 56 CCA-associated microbial strains, we identified six bacterial classes and 18 families. The culturable bacterial community associated with H. reinboldii was dominated by Gammaproteobacteria, Actinobacteria, and Alphaproteobacteria while the Illumina MiSeq analysis showed that the culture-independent bacterial community was dominated by Gammaproteobacteria, Alphaproteobacteria, and Flavobacteria. Furthermore, we found no correlation between inductive settlement capacities and phylogenetic relationships. Instead, settlement behavior of L. purpurea larvae was induced by specific isolated species. Strains #1792 (Pseudovibrio denitrificans), #1678 (Acinetobacter pittii), #1633 (Pseudoalteromonas phenolica), #1772 (Marine bacterium LMG1), #1721 (Microbulbifer variabilis), and #1783 (Pseudoalteromonas rubra) induced settlement behavior in coral larvae at mostly high and significant levels (≥ 40%) but the remaining isolates strongly varied in their activity. Multispecies biofilms consisting of four strains (#1792, #1678, #1633, and #1721) were observed to synergistically increase settlement behavior levels (> 90%); however, the addition of #1772 to the multispecies biofilms negatively affected coral larvae and resulted in a total loss of inducing activity. The findings provide new insights into the role of bacteria in the settlement process of scleractinian corals and may help to identify the true nature of bacteria-derived morphogenic cues. [ABSTRACT FROM AUTHOR]

There is a pressing need to develop simplified sampling protocols that allow invertebrates to be routinely incorporated into terrestrial faunal surveys for informing conservation planning. This study assesses the usefulness of sampling invertebrate by-catch from standard vertebrate bucket pitfall traps for documenting spatial patterns of terrestrial invertebrates. We compare among-site (N = 78) patterns of species richness and composition of ten invertebrate families (comprising ants, beetles and spiders) captured in vertebrate bucket traps with those captured in two different arrays of invertebrate-specific pitfall traps. For three families (Formicidae, Carabidae and Lycosidae) patterns of richness and composition captured in the vertebrate traps were comparable with those captured in the invertebrate-specific trap arrays. Thus, in some cases, vertebrate traps appeared to be as useful in detecting patterns of invertebrate diversity as were invertebrate-specific traps. Our findings show that sampling invertebrate by-catch from vertebrate bucket traps can be a reliable and robust simplified protocol for documenting biodiversity patterns for some key groups of terrestrial invertebrates. This simplified protocol can take terrestrial invertebrates out of the 'too-hard basket' for biodiversity assessment and monitoring, breaking the positive-feedback loop that currently maintains ignorance of invertebrate diversity and distribution and that prevents their inclusion in conservation planning. [ABSTRACT FROM AUTHOR]

There is worldwide growing interest in the occurrence and diversity of metabolites used as chemical mediators in cross-kingdom interactions within aquatic systems. Bacteria produce metabolites to protect and influence the growth and life cycle of their eukaryotic hosts. In turn, the host provides a nutrient-enriched environment for the bacteria. Here, we discuss the role of waterborne chemical mediators that are responsible for such interactions in aquatic multi-partner systems, including algae or invertebrates and their associated bacteria. In particular, this review highlights recent advances in the chemical ecology of aquatic systems that support the overall ecological significance of signaling molecules across the prokaryote-eukaryote boundary (cross-kingdom interactions) for growth, development and morphogenesis of the host. We emphasize the value of establishing well-characterized model systems that provide the basis for the development of ecological principles that represent the natural lifestyle and dynamics of aquatic microbial communities and enable a better understanding of the consequences of environmental change and the most effective means of managing community interactions. [ABSTRACT FROM AUTHOR]

The species-area relationship (SAR) is a well-investigated subject raising questions nonetheless. We hypothesized that SAR can be modified by naturally extreme conditions (high pH, conductivity, and total phosphorus) in a small spatial scale. A bombing range was chosen as a sampling location with a densely scattered cluster of bomb crater ponds, which vary in size and in extremity to study the hypothesis. Macroinvertebrate communities from 25 bomb crater ponds were sampled, along with the macrophyte community, while pH, conductivity, total phosphorus, and area were also registered. A decision tree was used to separate extreme from normal ponds based on their chemical characteristics. SAR was found to be the dominant driving force, increasing species richness in the extreme ponds. However, in the normal ponds, the small island effect was observed. The macroinvertebrate communities and macrophyte community types are congruent in normal ponds. Our findings imply that rules in ecology cannot be handled rigidly and there are dynamics existing between the factors that influence the composition of a macroinvertebrate community that cannot be ignored at habitat restorations. [ABSTRACT FROM AUTHOR]

Africa is faced with an increasing underrepresentation of her research progress in many fields of science including neuroscience. This underrepresentation stems from the very low investments directed towards research by African governments as these are thought to be high-priced. Scientists and researchers within the continent are left to compete highly for the very limited research grants or choose to fund research from their personal purse. Therefore, presenting a need for all possible strategies to make science and research approaches more affordable in Africa. This paper presents one of such strategy, which advocates the use of invertebrate animal models for neuroscience research in place of the commonly used vertebrate models. Invertebrates are cheaper, more available and easy to handle options and their use is on the rise, even in the developed societies of the world. Here, we investigate the current state of invertebrate neuroscience research in Africa looking at countries and institutions conducting neuroscience research with invertebrates and their publication output. We discuss the factors which impede invertebrate neuroscience research in Africa like lack of research infrastructure and adequate expert scientists and conclude by suggesting solutions to these challenges. [ABSTRACT FROM AUTHOR]

Despite a growing understanding of the importance of mesophotic ecosystems, they remain relatively unexplored globally, and particularly in the Indian Ocean. The composition of benthic communities of the Ningaloo Marine Park in deeper water (> 20 m) was determined using autonomous underwater vehicles (AUVs). Environmental variables collected by the AUVs as well as geomorphological variables derived from high-resolution multibeam bathymetry were used to explain the distribution of these communities. Imagery was classified for benthic biota, and non-hierarchical k-means clustering was used to identify community groups. Overall, 12 community groups were identified which fell into three broad categories: (1) coral-dominated, (2) CCA-dominated; and (3) macroalgae- and filter-feeder-dominated. Specific deeper water communities (> 50 m) were characterised by the presence of sponges or other non-photosynthetic filter feeders. Corals were confined to depths < 40 m, and cover was high (29-40%). Generalised additive models identified the importance of substrate (cover of sand, rock, and gravel/pebbles), geomorphological variables (slope and bathymetric position index) and temperature in the distribution of communities. [ABSTRACT FROM AUTHOR]

Even though alderflies, as well as many other aquatic macroinvertebrates, are widely used as indicators of freshwater quality, the knowledge of their distribution, biology and ecology in karst freshwater habitats is still very scarce. Aiming to fill this gap, we investigated alderfly assemblages along an oligotrophic karst hydrosystem. Sampling was carried out on a monthly basis over a one-year period (2007/2008) in different types of freshwater habitats and microhabitats. Our goals were to determine population aspects, habitat and microhabitat preferences of alderflies as well as their relation to environmental factors. Due to the specificity of karst freshwater habitats, alderflies were rather rare in the studied hydrosystem. Yet, their fauna was diverse with four identified species, where Sialis fuliginosa Pictet, 1836 was the most widespread one. Sialis sordida (Klingstedt, 1932) was recorded for the first time in the Balkan Peninsula being the rarest species in our study. Substrate type and water velocity showed as key environmental parameters in determining alderfly assemblages. Alderflies were mostly recorded from a canyon type mountainous stream, and silt with leaf litter, respectively. They were not recorded at sites characterized by predominately solid stones (i.e. cobbles) and mosses, and with intermittent water flow. Our results strongly indicate that alderflies could be used in future conservation and protection management procedures in karst freshwater habitats. [ABSTRACT FROM AUTHOR]

Microinvertebrates play a role as top consumers on glaciers. In this study we tested what kind of cryoconite material the animals inhabit (mud vs granules) on the edge of the Greenland ice sheet (GrIS) in the south-west. We also tested the links between the densities of micro-fauna in cryoconite material and selected biotic (algae, cyanobacteria, bacterial abundances) and abiotic (water depth, pH, ion content, radionuclides) factors. We collected 33 cryoconite samples. Tardigrada and Rotifera were found in 18 and 61% of samples, respectively. Invertebrates in this study were considerably less frequent and less abundant in comparison with High Arctic glaciers. The highest density of tardigrades and rotifers constituted 53 and 118 ind./ml, respectively. Generalized linear models showed no relationship between the densities of fauna and biotic and abiotic factors. The densities of animals were significantly higher in granules than in mud. The difference in the densities of animals between granules and mud reflects a simple mechanistic removal of invertebrates from the sediment during its erosion by flushing which leads to mud formation. These processes may influence a random distribution of micro-fauna without clear ecological interactions with biotic and abiotic variables at the edge of the GrIS. [ABSTRACT FROM AUTHOR]

Instream large wood (LW) constitutes an indispensable element of natural river ecosystems. It affects local hydraulics, morphology, nutrient budget, overall habitat complexity, and dynamics. Despite numerous studies about LW as a habitat for benthic communities, information on the varying importance along the longitudinal gradient of a river is lacking. The focus of this study is therefore to investigate general differences between lithal and xylal colonizers and to further investigate trends along the river course. We analyzed lithal and xylal communities at ten sites along the medium-sized Lafnitz River in Southeast Austria. Our results significantly show (1) a general differentiation between lithal and xylal communities, (2) an increasing distinction of the lithal and xylal fauna along the longitudinal gradient of the river, and (3) a distinct correlation between the distance from source and the number of exclusive xylal and nowadays predominantly rare taxa. The presence of LW is therefore directly linked to higher aquatic biodiversity compared to rocky substrates and presents a unique element for river restoration, especially in lower river sections. [ABSTRACT FROM AUTHOR]

We investigated the influence and relative importance of insecticides and other agricultural stressors in determining variability in invertebrate communities in small streams in intensive soy-production regions of Brazil and Paraguay. In Paraguay we sampled 17 sites on tributaries of the Pirapó River in the state of Itapúa and in Brazil we sampled 18 sites on tributaries of the San Francisco River in the state of Paraná. The riparian buffer zones generally contained native Atlantic forest remnants and/or introduced tree species at various stages of growth. In Brazil the stream buffer width was negatively correlated with sediment insecticide concentrations and buffer width was found to have moderate importance in mitigating effects on some sensitive taxa such as mayflies. However, in both regions insecticides had low relative importance in explaining variability in invertebrate communities, while various habitat parameters were more important. In Brazil, the percent coverage of soft depositional sediment in streams was the most important agriculture-related explanatory variable, and the overall stream-habitat score was the most important variable in Paraguay streams. Paraguay and Brazil both have laws requiring forested riparian buffers. The ample forested riparian buffer zones typical of streams in these regions are likely to have mitigated the effects of pesticides on stream invertebrate communities. This study provides evidence that riparian buffer regulations in the Atlantic Forest region are protecting stream ecosystems from pesticides and other agricultural stressors. Further studies are needed to determine the minimum buffer widths necessary to achieve optimal protection. [ABSTRACT FROM AUTHOR]

Numerous marine and terrestrial species have shifted their ranges poleward in response to warming from global climate change. However, few studies have examined range shifts of subtidal benthic communities in estuarine and nearshore waters. This study examined 20 years (1990-2010) of occurrence and abundance data of soft-bottom, benthic invertebrates along the Atlantic coast of the USA. Data from two biogeographic provinces (Carolinian and Virginian), which spanned 15° of latitude from mid-Florida to Cape Cod, were extracted from a national coastal assessment program. Mean water temperatures increased significantly during the study period, bottom water by 1.6 °C and surface water by 1.7 °C. Of 25 species with significant changes in centers of abundance (out of the 30 most prevalent), 18 (60%) shifted northward and 7 (23%) shifted southward. Species that shifted north moved an average distance of 181 km, in contrast with 65 km for species that shifted south. The southern limits of 22 species showed significant northward shifts; because there was little change in northern limits, this resulted in an average 25% range contraction. Community composition changed during the study period, most notably in southern latitudes. Five Carolinian species surmounted their northerly biogeographic boundary. Consequences of these range shifts include changes in benthic community structure and function, which have strong implications for ecosystem functioning and services including changes in fisheries dependent upon benthic prey. [ABSTRACT FROM AUTHOR]

Species inhabiting intermittent streams must survive flow cessation and drying in situ (resistance) or recolonize temporary habitats when flow returns (resilience). Some studies have found that species are resistant to seasonal drying and can persist in small remnant pools after flow ceases, while others observed rapid declines in species richness when flow ceases. However, relatively few studies have demonstrated both resistance across dry seasons and resilience across multiple wet and dry cycles. Here, we quantify seasonal and interannual changes in aquatic invertebrate community structure from 2009 to 2012 in a coastal California intermittent stream. We predicted that temporary pools and riffles would have lower richness and distinct assemblages when compared to perennial pools, and that richness would decline across the dry season. Temporary riffles exhibited lower richness values than pools, but we found no richness differences, and small compositional differences, between perennial and temporary pools. Furthermore, invertebrate richness, density, and composition changed significantly in temporary pools only immediately before drying, when depths declined >80%. These results suggest that invertebrate communities at John West Fork were not only resilient (exhibiting recovery in <6 months) to flow cessation, but also were resistant to declining water levels across the dry season. [ABSTRACT FROM AUTHOR]

The distributions of two ubiquitous fouling cheilostome bryozoans, Cryptosula pallasiana (Moll, 1803) and Watersipora sp., on a ship moored for almost six years in Qingdao Bay show differences with respect to illumination, Cryptosula being dominant on the side of the ship which was exposed to the sun and Watersipora dominating on the other side which was in shadow for most of the time. Competitive interactions for substrate space were nearly always won by Watersipora, which succeeded in overgrowing the edges of Cryptosula colonies regardless of the side of the ship. Reasons for the superiority of Watersipora in spatial competition with Cryptosula could include faster growth rate and the stronger feeding currents created by the larger lophophores of Watersipora. [ABSTRACT FROM AUTHOR]

Microbes and benthic macro-invertebrates interact in sediments to play a major role in the biogeochemical cycling of organic matter, but the extent to which their contributions are modified following natural and anthropogenic changes has received little attention. Here, we investigate how nitrogen transformations, ascertained from changes in archaeal and bacterial N-cycling microbes and water macronutrient concentrations ([NH-N], [NO-N], [NO-N]), in sand and sandy mud sediments differ when macrofaunal communities that have previously experienced contrasting levels of chronic fishing disturbance are exposed to organic matter enrichment. We find that differences in macrofaunal community structure related to differences in fishing activity affect the capacity of the macrofauna to mediate microbial nitrogen cycling in sand, but not in sandy mud environments. Whilst we found no evidence for a change in ammonia oxidiser community structure, we did find an increase in archaeal and bacterial denitrifier (A nirKa, nirS) and anammox ( hzo) transcripts in macrofaunal communities characterized by higher ratios of suspension to deposit feeders, and a lower density but higher biomass of sediment-reworking fauna. Our findings suggest that nitrogen transformation in shelf sandy sediments is dependent on the stimulation of specific nitrogen cycling pathways that are associated with differences in the composition and context-dependent expression of the functional traits that belong to the resident bioturbating macrofauna community. [ABSTRACT FROM AUTHOR]

The colossal squid Mesonychoteuthis hamiltoni (Robson 1925) is the largest (heaviest) living invertebrate and although it is preyed upon by many top predators, its basic biology and ecology remain one of the ocean's great mysteries. The present study aims to review the current biological knowledge on this squid. It is considered to be endemic in the Southern Ocean (SO) with a circumpolar distribution spreading from the Antarctic continent up to the Sub-Antarctic Front. Small juveniles (<40 mm mantle length) are mainly found from the surface to 500 m, and the late juvenile stages are assumed to undergo ontogenetic descent to depths reaching 2000 m. Thus, this giant spends most of its life in the meso- and bathypelagic realms, where it can reach a total length of 6 m. The maximum weight recorded so far was 495 kg. M. hamiltoni is presently reported from the diets of 17 different predator species, comprising penguins and other seabirds, fishes and marine mammals, and may feed on various prey types, including myctophids, Patagonian toothfish, sleeper sharks and other squid. Stable isotopic analysis places the colossal squid as one of the top predators in the SO. It is assumed that this squid is not capable of high-speed predator-prey interactions, but it is rather an ambush predator. Its eyes, the largest on the planet, seem to have evolved to detect very large predators (e.g., sperm whales) rather than to detect prey at long distances. The study of this unique invertebrate giant constitutes a valuable source of insight into the biophysical principles behind body-size evolution. [ABSTRACT FROM AUTHOR]

Research on the ecology of water mites in flowing water has focused mainly on analysis of factors directly affecting these organisms in the aquatic environment. The hypothesis of this study was that apart from factors acting within the aquatic environment, the formation of Hydrachnidia communities in lotic ecosystems may also be affected by factors acting in the terrestrial environment. The analysis was made at three different levels of organization of the environment: (1) landscape level (sub-catchments, terrestrial environment), (2) macrohabitat level (sampling sites, aquatic environment) and (3) mesohabitat level (sampling sub-sites, aquatic environment). Some correlation was noted between certain species and some sub-catchment parameters. This may indicate a link between some landscape features (terrestrial environment) and the formation of water mite assemblages in the river. The low percentage for physicochemical parameters together in explaining the variance in occurrence of species, very low correlations between species and physicochemical parameters and the discrepancy in the grouping of sites in the case of faunal data and data on the physicochemical indicates that physicochemical factors had little influence on water mites. Taking into account all three levels of organization of the environment analyzed, we can say that at the landscape level we can find only indirect relationships between environmental factors and the fauna inhabiting the aquatic environment; at the macrohabitat level the description of Hydrachnidia is more precise but still of a general nature. Only analysis at the mesohabitat level fully explains the specific character of Hydrachnidia assemblages. [ABSTRACT FROM AUTHOR]

The process of macroinvertebrate drift in streams is characterized by dislodgement, drift distance and subsequent return to the bottom. While dislodgement is well studied, the fate of drifting organisms is poorly understood, especially concerning Trichoptera. Therefore, the aim of the present study was to determine the ability of six case-building Trichoptera species to return to the stream bottom under different flow velocity conditions in a laboratory flume. The selected species occur in North-West European sandy lowland streams along a gradient from lentic to lotic environments. We determined species specific probability curves for both living and dead (control) specimens to return to the bottom from drift at different flow velocities and established species specific return rates. Species on the lotic end of the gradient had highest return rates at high flow velocity and used active behaviour most efficiently to return to the bottom from drift. The observed gradient of flow velocity tolerance and species specific abilities to settle from drift indicate that, in addition to dislodgement, the process of returning to the bottom is of equal importance in determining flow velocity tolerance of Trichoptera species. [ABSTRACT FROM AUTHOR]

Temporal and spatial variability in macroinvertebrate community structure in relation to environmental variables in Gbako River, Niger State, Nigeria was evaluated monthly for a period of six months using modified kick sampling techniques. Four study stations were selected along the river course (upper reaches of less human impacts through mid-reaches with relative high human impacts to lower reaches of less human impacts), designated as stations 1, 2, 3, and 4. High concentrations of dissolved oxygen, lower nutrient and BOD levels were recorded in stations 1 and 4 while lower concentrations of dissolved oxygen, higher nutrient, conductivity levels, and BOD levels were recorded in stations 2 and 3. There was an abundance of the pollution sensitive taxa such as Ephemeroptera (mayflies), Coleopteran (Gyrinus spp., Dytiscus spp.) and Anisoptera (Gomphus sp., Lestinogomphus, Cordulex spp.) in all the stations, especially the upper and lower reaches, whereas on the other hand, some pollution tolerant species like the Crustaceas, Dipterans, Mollusca (Neritina rubricate, Potadoma sp.) were merely restricted to the middle reaches (stations 2 and 3). Of the total number of individual benthic invertebrates recorded during the entire study, 53% was recorded in the dry season while the remaining 47% was recorded in the wet season. However, this difference was not statistically significant (P > 0.05) when the student t-test (tstat/cal = 0.388), tcrit = 2.447) for the densities and abundances of macroinvertebrates recorded during the two sampling seasons was applied. Canonical Correspondence Analysis (CCA) separated the less impacted from the more impacted sites and also showed that the invertebrate fauna was significantly (P < 0.05) associated with environmental factors of Gbako River. The CCA identified conductivity, depth, flow velocity, dissolved oxygen, biological oxygen demand, and phosphates as important variables structuring the macroinvertebrate assemblages. The higher number of benthic invertebrates recorded in the dry season could be attributed to the unstable nature of the substrates through inputs and influx of storm water during the rainy season months. [ABSTRACT FROM AUTHOR]

Ponds are common and abundant landscape features in temperate environments, particularly on floodplains where lateral connectivity with riverine systems persists. Despite their widespread occurrence and importance to regional diversity, research on the ecology and hydrology of temperate ephemeral and perennial floodplain ponds lags behind that of other shallow waterbodies. This study examines the aquatic macroinvertebrate diversity of 34 ponds (20 perennial and 14 ephemeral) on two unregulated riverine floodplain meadows in Leicestershire, UK. Perennial ponds supported nearly twice the diversity of ephemeral ponds. Despite frequent inundation of floodwater and connectivity with other floodplain waterbodies, ephemeral ponds supported distinct invertebrate communities when compared to perennial ponds. When the relative importance of physical, chemical, biological and spatial characteristics was examined, physical and chemical characteristics were found to account for more variation in community composition than biological or spatial variables. The results suggest that niche characteristics rather than neutral colonisation processes dominate the structure of invertebrate communities of floodplain ponds. The maintenance of pond networks with varying hydroperiod lengths and environmental characteristics should be encouraged as part of conservation management strategies to provide heterogeneous environmental conditions to support and enhance aquatic biodiversity at a landscape scale. [ABSTRACT FROM AUTHOR]

Springs are spatially restricted and insular ecotones. In the Alps, topography enhances this isolation. Springs are to a certain extent inhabited by organisms which are adapted to the relatively constant environmental conditions in springs. We examined thirty-six springs in eight different areas in the Swiss National Park (SNP) to understand if the macroinvertebrate assemblages of high-elevation springs are isolated or interconnected communities. We quantitatively and qualitatively sampled the macroinvertebrate assemblages of the springs and monitored environmental parameters. The similarity of the macroinvertebrate assemblages of the springs within and the dissimilarities between the different areas were relatively high; a clear spatial isolation was not evident. The differences of macroinvertebrate assemblages in different areas were explained by substrate parameters: springs in areas at lower altitudes were characterized by organic substrates and many water mite species. High-elevation springs were characterized by coarse inorganic substrates and Trichoptera of the genus Drusus. For spring conservation, it is important to decide on an individual basis if the loss of a single spring will have severe consequences for spring biodiversity. [ABSTRACT FROM AUTHOR]

Genus Veigaia Oudemans, 1905 of the Veigaiidae family (Acari: Mesostigmata: Veigaiidae) is one of the most ubiquitous genera from Holarctic Region. In Romania 10 species were recorded as being distributed across the entire country. In the frame of this study we present the distribution data of all recorded Romanian Veigaia species: Veigaia cerva (Kramer, 1876); Veigaia exigua (Berlese, 1917); Veigaia kochi (Trägårdh, 1901); Veigaia nemorensis (C.L. Koch, 1839); Veigaia paradoxa Willmann, 1951; Veigaia planicola Berlese, 1892; Veigaia propinqua Willmann, 1936; Veigaia transisalae (Oudemans, 1902), Veigaia transylvanica Kontschán & Ujvári, 2008 and Veigaia uncata Farrier, 1957. At the same time, new characteristic ecological requirements for the Veigaia species were described (type of ecosystem, habitat, altitude and soil). [ABSTRACT FROM AUTHOR]

Foundation species are crucial to understanding the mechanisms underlying faunal community structure. The present study aimed to clarify the habitat function of empty shells from dead oysters Saccostrea kegaki for the benthic faunal community of an intertidal rocky shore. We evaluated whether macroinvertebrates used the shells as a habitat. Results demonstrated that limpets (the dominant macroinvertebrates at the study site) did so more frequently than they inhabited live oysters, other sessile organisms, or rock surfaces. The dead oyster shells successfully functioned as a refuge from predation and as a nursery for limpets, because of their structural complexity (the presence of a depression on the inner side of the shell). Therefore, our study demonstrates the importance of dead S. kegaki, a shell-forming foundation species, and illustrates that the structural complexity of such species might result in habitat functions upon their death. [ABSTRACT FROM AUTHOR]

Wetlands of Lake Tana Watershed provide various ecological and socioeconomic functions. However, they are losing their vigor at alarming rate due to unwise management. Hence, there is an urgent need to monitor and assess these resources so as to identify the major drivers of its degradation and to provide information for management decisions. In this context, we aimed to assess the effects of human activities on macroinvertebrate assemblages of wetlands in Lake Tana Watershed. Biotic and abiotic data were collected from 46 sampling sites located in eight wetlands. A total of 2568 macroinvertebrates belonging to 46 families were recorded. Macroinvertebrate metrics such as Biological Monitoring Working Party score, Shannon diversity index, Ephemeroptera and odonata family richness, and total family richness portrayed a clear pattern of decreasing with increasing in human disturbances, whereas Family biotic index score, which is an indicator of organic pollution, increased with increasing in human disturbances. The regression analysis also revealed that livestock grazing, leather tanning, and eucalyptus plantation were important predictors of macroinvertebrate metrics ( p < 0.05). In conclusion, human activities in and around the wetlands such as farming, leather tanning, solid waste dumping, and effluent discharges were contributed to the degradation of water quality and decreasing in the macroinvertebrate richness and diversity. These alterations could also reduce the availability of wetland products (sedges, craft materials, etc.) and the related ecosystem services. This in turn has an adverse effect on food security and poverty alleviation with considerable impact on communities who heavily depend on wetland products for their livelihood. Therefore, it is essential to formulate wetland policy for achieving wise use goals and necessary legal and institutional backup for sustainable wetland management in Ethiopia. [ABSTRACT FROM AUTHOR]

The biogeography of the Southern Ocean and its subdivisions has attracted the interest of the scientific community for many years, especially for those border regions with great sub-Antarctic influence. The Scotia Arc, located between the Antarctic Peninsula and the Magellan region, has been considered as a biogeographic bridge and hence widely discussed, but there are still gaps in the knowledge of some zoological groups and its inclusion in truly Antarctic waters still constitutes an unresolved topic. The faunistic affinities between the benthic hydroids from the Scotia Arc and those from nearby regions (i.e., High Antarctica, Patagonian region and Bouvet Island) were evaluated with different similarity index and hierarchical analyses in order to put into evidence the biogeographic connectivity among those regions. The results show that the Scotia Arc archipelagos have greater affinity with continental Antarctica than with the Patagonian region, with an increasing similarity while approaching to High Antarctica, highlighting their importance as a biogeographic bridge and the effectiveness of the Polar Front as a major oceanographic barrier. Evidences from the present study on benthic hydroids supports the placement of the whole Scotia Arc within of the Antarctic region. Present data were compared with those from other benthic invertebrates groups to contribute to a better understanding of the biogeography of the Scotia Arc as a whole. [ABSTRACT FROM AUTHOR]

Structural characteristics of benthic macroinvertebrate communities in mountain watercourses of different sizes have been studied in the Upper Ob basin. It has been found that species richness, diversity of zoobenthos, and most biotic indices in the background areas increase in the series from the smallest watercourses to large rivers. On the contrary, the values of the above parameters in areas polluted with mercury has proved to decrease, thereby indicating a significant transformation of the benthic communities. Approaches are proposed to select reference indices for assessing the ecological state of watercourses in the basin with regard to the size of the river, the structure of benthic communities, and variability of biotic indices along the background cross sections. [ABSTRACT FROM AUTHOR]

We describe an approach to assessing biological health in a heavily utilized, large lowland river setting, using the example of the lower Yellow River, China. In this study, the river was divided into four reaches, and a field survey of fish, benthic macroinvertebrates, and riparian plants was undertaken. Data from historical records were used for reference. The scoring system used weighting to adjust for differences in the importance of the chosen indicators and the relative efficiency of the sampling effort. The results indicated that the biological health of the lower Yellow River is distant from historical reference conditions, with its condition generally declining in the downstream direction. This result is consistent with the river's history of impairment of hydrology, water quality, wetland area and character, and physical form. We conclude that the reference river state based on historical conditions is unlikely to equate to the best attainable river health because certain changes have occurred in the river that may prohibit a return to the previous state of ecological health. On the basis of the results of this assessment as well as a review of the literature, we propose field data collection methodologies and indicators that can be applied in future assessments. [ABSTRACT FROM AUTHOR]

The Santa Cruz River is the last free-flowing river in Argentinean Patagonia. Two dams are projected, and no comprehensive pre-impoundment study has been undertaken. The present study investigated macroinvertebrate communities along three different hydrological periods and at three river sections located upstream and downstream of future dams. Fifty-three macroinvertebrate taxa were identified, with the most abundant orders being Ephemeroptera, Plecoptera, Coleoptera, and Crustacea (particularly amphipods). Ordination methods (CCA) and generalized linear models (GLM) were applied. According to the CCA, the main environmental variables related to macroinvertebrate density were temperature, suspended solids, depth, and substrate size. For the GLM, the main factors associated with macroinvertebrate abundance were location and hydrological period, and variables with the highest influences were temperature, substrate size, current speed, and depth. We anticipate that dam construction will modify in-stream habitat conditions, leading to changes in (i) macroinvertebrate community structure and (ii) local fish abundance due to loss of key prey taxa. [ABSTRACT FROM AUTHOR]

Macroinvertebrate colonization of restored rivers is a function of dispersal into the restored reach and its suitability for population establishment. To maximize potential for colonization success, spatial considerations such as distance to colonizer source pools and dispersal pathways must be included in restoration planning. Unfortunately, the dispersal abilities of macroinvertebrates and ecological importance of different dispersal modes for colonization are still poorly understood. We used a field experiment that controlled colonization by passive drift and allowed distinction between active upstream aquatic and active/passive aerial dispersal, thus testing their differential importance during colonization of experimentally restored stream reaches. Two agricultural streams emanating below culverts were longitudinally separated along the first 30 m and one stream side each was covered with a fine-mesh net to limit aerial dispersal. Colonization of manually disturbed background and experimentally introduced cobble substrate was investigated over 6 months. We found that upstream in-stream dispersal, especially in these agricultural streams, can be rapid (days) and play an important role in the short-term colonization of restored streams. We conclude that a landscape perspective, in addition to in-stream measures, must be considered when attempting to restore streams dominated by agricultural and urban land use that constrains available species pools and limits dispersal pathways. [ABSTRACT FROM AUTHOR]

While anthropogenic biodiversity loss in fresh waters is among the most rapid of all ecosystems, impacts on the conservation of associated riparian zones are less well documented. Riverine ecotones are particularly vulnerable to the combined 'squeeze' between land-use encroachment, discharge regulation and climate change. Over a 3-year period of persistent low discharge in a regulated, temperate river system (River Usk, Wales, UK; 2009-2011), specialist carabid beetles on exposed riverine sediments (ERS) were used as model organisms to test the hypotheses that catchment-scale flow modification affects riparian zone invertebrates more than local habitat character, and that this modification is accompanied by associated succession among the Carabidae. Annual summer discharge during the study period was among the lowest of the preceding 12 years, affecting carabid assemblages. The richness of specialist ERS carabids declined, while generalist carabid species' populations either increased in abundance or remained stable. Community composition also changed, as three ( Bembidion prasinum, B. decorum and B. punctulatum) of the four dominant carabids typical of ERS increased in abundance while B. atrocaeruleum decreased. Despite significant inter-annual variation in habitat quality and the encroachment of ground vegetation, beetle assemblages more closely tracked reach-scale variations between sites or catchment-scale variations through time. These data from multiple sites and years illustrate how ERS Carabidae respond to broad-scale discharge variations more than local habitat character. This implies that the maintenance of naturally variable flow regimes is at least as important to the conservation of ERS and their dependent assemblages as are site-scale measures. [ABSTRACT FROM AUTHOR]

Climate changes, geomorphologic modifications and the rise in water demand for human uses contribute to 'aperiodic summer drought' (ASD) events in Mediterranean-type rivers. ASD results in a reach that flows in one summer, dries in next or more summers, and then flowing again. The ecological structure and function of streams affected by ASD are understudied, especially with respect to permanent and regular intermittent streams. We tested the drying memory in a reach of Aterno River (Italy) disturbed by ASD. Leaf litter breakdown of Phragmites australis and macroinvertebrate assemblages were studied. Discharge was monitored since 2006. The experiment was performed during summer 2010 using the litterbag technique, and was replicated four times. The disturbed site was affected by drought in the three previous summers while the control was always flowing. Taxonomic diversity indices, abundance and structure of macroinvertebrate assemblages varied significantly between sites. Instead, leaf litter breakdown wasn't influenced by ASD. Therefore ASD events seem to affect the structure of macroinvertebrate assemblages, confirming the role of drying memory of the systems. The resilience of leaf litter breakdown in reach affected by ASD seems to be high, probably depending on the activity of selected microbial communities and macroinvertebrate features like metabolism and biomass. [ABSTRACT FROM AUTHOR]

Macroinvertebrates are widely used as indicators to detect and assess anthropogenic impacts on freshwater ecosystems. However, despite being considered useful in indicating effects of environmental change in alpine catchments, little is known about species preferences for local conditions in such environments. In exploring the occurrence of 59 taxa within the dipteran family Chironomidae in relation to key-environmental variables in alpine and sub-alpine streams, we showed that sediment load, water temperature, periphyton density, and fine particulate organic matter mostly explain assemblage structures. Two-way-cluster analyses identified stream-type specific assemblages, indicator value analysis defined indicator species for glacial and non-glacial streams, and weighted averaging regression models confined preferences for local environmental conditions by summing their optima and tolerance widths regarding environmental key factors. The definition of habitat requirements identified stenoecious taxa with preferences for high and low values of respective variables thus identified most suitable indicators for future studies. Our work reveals manifold preferences within the dominant benthic invertebrate family, underlines their enormous potential for monitoring purposes, and is a step forward in better understanding ecosystem properties and biodiversity. Fundamental requirements for these kinds of indicative traits, essential to understand cause-effect relationships in environmental change issues, are a robust taxonomy and a comprehensive set of physical and chemical data. [ABSTRACT FROM AUTHOR]

The aim of the study was to estimate the impact of oxygen depletion on macroinvertebrate community structure in benthic space. Macroinvertebrate assemblages and potential of dissolved oxygen (DO) consumption were investigated simultaneously in the plain rivers of the Ziya River Basin. The degree of DO depletion was represented by sediment oxygen demand (SOD) and DO, chemical oxygen demand (COD), and ammonia nitrogen (NH-N) in the overlying water. The results showed an all-around hypoxia environment formed, and the values of DO, SOD, COD, and NH-N were separately 0.11-4.03 mg L, 0.41-2.60 g m day, 27.50-410.00 mg L, and 1.79-101.41 mg L. There was an abnormal macroinvertebrate assemblage, and only 3 classes, Insecta, Gastropoda, and Oligochaeta, were found, which included 9 orders, 30 families, and 54 genera. The biodiversity was at a low level, and Shannon-Wiener index was 0.00-1.72. SOD, and NH-N had major impact on the macroinvertebrate community, and the former had negative effect on most taxa, for instance, Nais, Branchiura, Paraleptophlebia, etc., which were sensitive or had a moderate-high tolerance to pollution. NH-N had both positive and negative impacts on benthic animals, for instance, Dicrotendipes, Gomphus, Cricotopus, etc., for the former, and Procladius, Limnodrilus, Hippeutis, etc., for the latter. They all had a moderate-high tolerance to pollution. It is significant to improve DO condition and macroinvertebrate diversity in river harnessing and management. [ABSTRACT FROM AUTHOR]

The mechanisms underlying responses of stream invertebrates to low flows are poorly understood. To clarify the strategies used to tolerate and survive low flow periods, we tested associations between patch-scale invertebrate densities and velocity within riffle habitats during moderate and low flows. We focused on filter-feeding and respiration traits because they have a mechanistic link to invertebrate low flow responses. 228 samples were collected from 3 riffles at 2 low and 2 moderate flow periods. Maximum densities of filter-feeders were positively associated with the highest velocities during low flows, but not moderate flows, partly consistent with our prediction that they would be structured along velocity gradients to meet nutritional requirements. Gill-respiring invertebrate densities were inversely related to velocity during both flows, probably attributable to organic matter accumulated in low velocity areas. O requirements during low flows did not constrain tegument-respirers to higher velocity patches, inconsistent with perceived views of their response to low flows. We found high velocity areas could act as refuges for some invertebrates during low flows, while low velocity patches, which are vulnerable to rapid flow recession, are important habitats for other invertebrates. Environmental flow management should focus on strategies that preserve these habitats during low flows. [ABSTRACT FROM AUTHOR]

The study evaluated the response of macroinvertebrate assemblages to changes in water quality in different land-use settings in Manyame catchment, Zimbabwe. Four land-use categories were identified: forested commercial farming, communal farming, Great Dyke mining (GDM) and urban areas. Macroinvertebrate community structure and physicochemical variables data were collected in two seasons from 41 sites following standard methods. Although not environmentally threatening, urban and GDM areas were characterised by higher conductivity, total dissolved solids, salinity, magnesium and hardness. Chlorides, total phosphates, total nitrogen, calcium, potassium and sodium were significantly highest in urban sites whilst dissolved oxygen (DO) was significantly higher in the forested commercial faming and GDM sites. Macroinvertebrate communities followed the observed changes in water quality. Macroinvertebrates in urban sites indicated severe pollution (e.g. Chironomidae) whilst those in forested commercial farming sites and GDM sites indicated relatively clean water (e.g. Notonemouridae). Forested watersheds together with good farm management practices are important in mitigating impacts of urbanisation and agriculture. Strategies that reduce oxygen-depleting substances must be devised to protect the health of Zimbabwean streams. The study affirms the wider applicability of the South African Scoring System in different land uses. [ABSTRACT FROM AUTHOR]

An ecological engineering project with confined growth of 1.5 km of Eichhornia crassipes was implemented to remove pollutants in Lake Dianchi. To assess the ecological effects of this project on benthic macroinvertebrate assemblages, a 1-year investigation at the areas inside and outside E. crassipes mats was conducted from May 2013 to May 2014. All the 10 sampling sites in the areas were grouped into two statistically significant clusters mainly corresponding to inside and outside E. crassipes mat areas (EMAs), by clustering analysis. E. crassipes reduced the densities of pollution indicator taxa (e.g., Oligochaeta and Chironomidae larvae); thus, the total densities of benthic macroinvertebrates at the area inside EMAs (mean 328.2 ind./m) were slightly lower than that at the area outside EMAs (mean 505.6 ind./m). Four functional feeding groups including 38 species of benthic macroinvertebrates were collected at the area inside EMAs, while only three functional feeding groups containing 17 species were collected at the area outside EMAs. The biodiversity indices (Shannon-Weiner, Margalef, Simpson, and Peilou indices) and K-dominance curves also showed higher diversity of benthic macroinvertebrates at the area inside EMAs than at the area outside EMAs. These results suggested that a certain scale of engineering application of E. crassipes was beneficial to benthic macroinvertebrate communities in the ultra-eutrophic Lake Dianchi and it could be used as a pioneer species in ultra-eutrophic lake for pollutant removal. [ABSTRACT FROM AUTHOR]

Unlike lower latitude coastlines, the estuarine nearshore zones of the Alaskan Beaufort Sea are icebound and frozen up to 9 months annually. This annual freezing event represents a dramatic physical disturbance to fauna living within intertidal sediments. The main objectives of this study were to describe the benthic communities of Beaufort Sea deltas, including temporal changes and trophic structure. Understanding benthic invertebrate communities provided a baseline for concurrent research on shorebird foraging ecology at these sites. We found that despite continuous year-to-year episodes of annual freezing, these estuarine deltas are populated by a range of invertebrates that represent both marine and freshwater assemblages. Freshwater organisms like Diptera and Oligochaeta not only survive this extreme event, but a marine invasion of infaunal organisms such as Amphipoda and Polychaeta rapidly recolonizes the delta mudflats following ice ablation. These delta sediments of sand, silt, and clay are fine in structure compared to sediments of other Beaufort Sea coastal intertidal habitats. The relatively depauperate invertebrate community that ultimately develops is composed of marine and freshwater benthic invertebrates. The composition of the infauna also reflects two strategies that make life on Beaufort Sea deltas possible: a migration of marine organisms from deeper lagoons to the intertidal and freshwater biota that survive the 9-month ice-covered period in frozen sediments. Stable isotopic analyses reveal that both infaunal assemblages assimilate marine and terrestrial sources of organic carbon. These results provide some of the first quantitative information on the infaunal food resources of shallow arctic estuarine systems and the long-term persistence of these invertebrate assemblages. Our data help explain the presence of large numbers of shorebirds in these habitats during the brief summer open-water period and their trophic importance to migrating waterfowl and nearshore populations of estuarine fishes that are the basis of subsistence lifestyles by native inhabitants of the Beaufort Sea coast. [ABSTRACT FROM AUTHOR]

Coastal lagoons are ubiquitous along coastlines worldwide. Here, we compare the abundance of epifauna, seagrass-associated macroinvertebrates, and small fish across a gradient of seagrass cover in shallow coastal lagoons of the northern Gulf of Mexico. Two of the lagoons had little or no seagrass cover (0-18.8 %), and four had high cover (83.8-97.5 %). All of the lagoons were partially covered with fringing marsh. We hypothesized that, due to habitat redundancy between seagrass beds and fringing marshes, seagrass-associated fish and macroinvertebrates would not be largely reduced despite the large differences in seagrass cover among the lagoons. Our results support this hypothesis. For most sampling dates, we did not find significant differences in fish and macroinvertebrate abundance among the lagoons and, when we did, several highly vegetated lagoons did not have larger abundances than sparsely vegetated lagoons. The extreme shallowness of the lagoons studied (<1 m) may also provide further protection from large predatory fishes in the absence of seagrasses. Our results also suggest that marsh detritus, by providing habitat for epifauna and helping maintain prey availability, may further temper reductions in seagrass-associated fishes and macroinvertebrates following seagrass decline. The results highlight the importance of marsh-bordered, shallow lagoons as habitat for small fish and macroinvertebrates regardless of seagrass cover. This study contributes to the characterization of habitat redundancy in coastal ecosystems and pinpoints the importance of considering all habitats in concert for the proper understanding and management of coastal ecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding landscape influences on stream ecosystems is a challenging task due to the spatial complexity and connectedness of stream networks. Here, we control for longitudinal connectivity to provide a robust test of the relative importance of reach- and catchment-scale factors in determining macroinvertebrate community structure in southwestern Pennsylvania streams. We determined that sites separated by ≤510 m along the stream network had significantly correlated macroinvertebrate community scores. After controlling for this spatial autocorrelation, a partial least squares regression identified two factors that together accounted for 32% of the variation in community scores. In this model, two reach-scale factors-habitat assessment score and stream pH-were the most important factors for predicting a stream's macroinvertebrate community score. However, landscape diversity was also important. Landscape diversity is a catchment-scale factor that was highly correlated with percent pasture/hay and measures of habitat fragmentation. Our results provide support for the idea that stream communities in undisturbed areas are heavily influenced by reach-scale characteristics. Furthermore, our results indicate that Pennsylvania natural resource managers should consider habitat score and stream pH after accounting for spatial autocorrelation when identifying restoration targets for impacted streams. [ABSTRACT FROM AUTHOR]

Headwater stream macroinvertebrates play an important role in processing allochthonous leaf litter, which suggests that bottom-up forces control macroinvertebrates. However, because larvae of stream-breeding salamanders are predators of macroinvertebrates and are abundant consumers in these ecosystems, macroinvertebrates in fishless headwater streams might also be controlled by top-down forces through predation by salamander larvae. The aim of this study was to test if and to what degree taxa richness, abundance, and biomass of macroinvertebrates are affected by bottom-up and top-down forces. We selected headwater streams with high abundances of fire salamander larvae (1.2-2.6 individuals per 1 m of shore length) and manipulated bottom-up and top-down forces on macroinvertebrates by leaf litter addition and by the exclusion of salamander larvae. The amphipod Gammarus fossarum Koch, 1836 was the dominant taxon and responded positively to litter addition. Linear models showed that neither predator exclusion nor leaf litter addition affected richness. However, variation in biomass and density were both explained by the individual and joint effects of bottom-up and top-down forces. These findings suggest that macroinvertebrates in these streams are strongly dependent on the organic matter input and salamander larvae, and headwater streams interact strongly with their adjacent terrestrial areas. [ABSTRACT FROM AUTHOR]

To better understand the impacts of water temperature variation on stream invertebrates, we sampled benthic assemblages and measured water temperature monthly in headwater streams located in northeast Japan during 2011 and 2012. The sites in headwater streams had similar hydraulic and topographical settings, were free of man-made structures, and ranged in elevation from 100 to 850 m above sea level. The results of month-by-month analysis on the relationship between temperature and Plecoptera density revealed that the abundance declined with highly elevated temperatures in mid-summer (July, August). The strongest relationship between variation in Plecoptera abundance (June to October in 2012), however, and water temperature occurred during early summer (June). Thus, early summer temperatures contribute to greater seasonal increase in abundance, suggesting that snapshot data may be unreliable for detecting consistent relationships between the abundance and temperature. The degree of similarity in benthic fauna between sites was significantly negatively correlated with differences in water temperature but not correlated with geographical distance. These results suggest that faunal composition varies along the water temperature gradient rather than habitat connectivity in temperate headwater streams. [ABSTRACT FROM AUTHOR]

Since the twentieth century, freshwater ecosystems have been extensively drained. Despite the magnitude of artificial drainage, its impact on freshwater biodiversity, especially on small forest waterbodies, is still poorly known. We examined macroinvertebrate taxon richness and assemblages in forest landscapes, comparing natural temporary waterbodies situated in drained and undrained areas, ditches, and wheel rut pools. We aimed to determine macroinvertebrates that are characteristic to these waterbodies, the impact of forest drainage on them, and the functioning of ditches as an alternative habitat for aquatic macroinvertebrates. Altogether 181 waterbodies within six landscape regions were surveyed, identifying 171 macroinvertebrate taxa. Taxa accumulation curves pooling all the regions indicated that natural waterbodies situated in drained areas harbored less invertebrate taxa than other waterbody types. Thus drainage has effect at supraregional scale. At the waterbody scale, however, we did not detect substantial forest drainage effect on taxon richness or assemblages. Ordering of the waterbody types by richness differed between landscape regions, suggesting that macroinvertebrates are largely dependent on landscape characteristics. Since neither total and mean richness nor assemblages did not differ significantly between natural temporary waterbodies and drainage ditches, the latter could be considered as an alternative habitat for invertebrates at least in semi-naturally managed forests. [ABSTRACT FROM AUTHOR]

Riparian deforestation in rural areas has led to changes in bankside vegetation communities that may have unexpected effects on stream ecosystems. In particular, plants such as grasses can colonize the streambed from adjacent terrestrial habitats, thus altering the physical structure of the streambed and potential influencing macroinvertebrate communities. Here we evaluated if the presence of patches of grasses ( Urochloa sp.) on the streambed influenced the structure and composition of macroinvertebrate communities in deforested rural streams. We sampled patches with and without grasses in three low-order streams, in the wet and dry seasons. We recorded higher abundances of macroinvertebrates in patches with grasses in the wet season when compared with bare patches. We also found significant differences in taxonomic and functional feeding group composition between patch types, due to higher overall abundances in patches with grasses, probably due to more food and shelter there. These influences were stronger in the wet season, when in-stream grasses may have provided greater refugia from flood disturbance that occur with increased frequency and intensity. Therefore, although deforestation of rural streams can simplify streambed habitats, in-stream grasses such as Urochloa sp. provide resources that contribute for the maintenance of macroinvertebrate communities. [ABSTRACT FROM AUTHOR]

While parasites are increasingly recognized as important components of ecosystems, we currently know little about how they alter ecosystem nutrient availability via host-mediated nutrient cycling. We examined whether infection alters the flow of nutrients through hosts and whether such effects depend upon host diet quality. To do so, we compared the mass specific nutrient (i.e., nitrogen and phosphorus) release rates, ingestion rates, and elemental composition of uninfected Daphnia to those infected with a bacterial parasite, P. ramosa. N and P release rates were increased by infection when Daphnia were fed P-poor diets, but we found no effect of infection on the nutrient release of individuals fed P-rich diets. Calculations based on the first law of thermodynamics indicated that infection should increase the nutrient release rates of Daphnia by decreasing nutrient accumulation rates in host tissues. Although we found reduced nutrient accumulation rates in infected Daphnia fed all diets, this reduction did not increase the nutrient release rates of Daphnia fed the P-rich diet because infected Daphnia fed this diet ingested nutrients more slowly than uninfected hosts. Our results thus indicate that parasites can significantly alter the nutrient use of animal consumers, which could affect the availability of nutrients in heavily parasitized environments. [ABSTRACT FROM AUTHOR]

Global climate change has become an important issue, particularly for organisms living in the Antarctic region, as the predicted temperature increase can affect their life history traits. The reproductive mode and life history traits of one of the most widespread species of tardigrades in Antarctica were analyzed. Specimens of the eutardigrade Acutuncus antarcticus from a temporary freshwater pond at Victoria Land (Antarctica) were individually cultured. This species reproduced continuously by thelytokous meiotic parthenogenesis. Its life cycle was short (60-90 days) and the reproductive output was low, with a short generation time (25-26 days). The maternal effect can be responsible of the phenotypic plasticity observed in life history traits of the three analyzed generations that may be seen as a bet-hedging strategy, as also observed in other animals inhabiting stochastic environments. These traits, along with the cryptobiotic capability of A. antarcticus, are advantageous for exploiting the conditions suitable for growth and reproduction during the short Antarctic summer, and can explain its wide distribution on the Antarctic continent. These results open new avenues of research for determining the role of bet-hedging strategy in organisms living in unpredictable environments. [ABSTRACT FROM AUTHOR]

Tardigrades are found in most terrestrial and freshwater Antarctic ecosystems and are one of the most diverse and important groups of invertebrates in Antarctica. We developed a new laboratory system for rearing the Antarctic tardigrade Acutuncus antarcticus (Richters 1904), one of the most widespread and common Antarctic tardigrade species. To provide a description of the life history of this tardigrade, survival and reproduction of 68 individuals were observed and recorded daily at a constant temperature of 15 °C. The life-history data obtained are consistent with previous studies of other tardigrades. The exceptionally high hatching success obtained is suggested to be an important life-history characteristic of this species contributing to it often being a common and dominant species in the Antarctic habitats in which it occurs. Furthermore, high hatching success combined with very low variation in development time, under the protocol used in the current study, indicates that A. antarcticus may be a good model species for studies in developmental biology. Integrating data from this and previous studies, the importance of temperature on reproduction and growth in A. antarcticus was inferred. With terrestrial and freshwater ecosystems in some parts of Antarctica experiencing sometimes drastic contemporary climatic and environmental changes, studies of the effect of temperature on generation time and reproductive success in Antarctic tardigrades are urgently required, as these animals are important elements of community structure and function in polar ecosystems. [ABSTRACT FROM AUTHOR]

Nototanais is the most commonly found peracarid crustacean genus in Antarctic waters. The only two species in the genus, Nototanais dimorphus and Nototanais antarcticus, have been found to have overlapping circumpolar distributions in depths from 7 m to 585 m around Antarctica. However, only one species, N. dimorphus, has been recorded during yearly sampling from 2000 to 2010 at nine shallow (12-36 m) benthic pollution monitoring sites in Winter Quarters Bay and waters adjoining McMurdo Station, McMurdo Sound, Antarctica. These stations varied by depth, anchor ice formation and anthropogenic contamination. In 2011 and 2012, 1071 specimens of Nototanais spp. were collected and separated by species, gender and life stage . N. antarcticus was confirmed to co-occur with N. dimorphus at four of nine long-term monitoring sites. One station had no occurrences of either species. N. antarcticus was found in very low abundances in relation to N. dimorphus, indicating that individual species distributions may be modified by pollution and anchor ice, among other biological factors. [ABSTRACT FROM AUTHOR]

The survival and reproduction of individual or small groups of modules affords colonial organisms a great regenerative capacity. Consequently, modular loss due to fragmentation or senescence may not necessarily lead to colony mortality. This study (1) examines in situ partial mortality for colonies of the invasive bryozoan Membranipora membranacea in Nova Scotia by quantifying the location, magnitude, and timing of partial mortality for colonies growing on kelp ( Saccharina latissima) in the field, and (2) estimates the effects of temperature (5-20 °C), and location and magnitude of modular loss on the recovery capacity of experimentally damaged colonies in the laboratory. In situ zooid mortality was substantial, with 50-100 % of colonies experiencing some level of partial mortality by the end of the growing season. Colonies with damage to older centrally located zooids maintained their capacity for growth and recovery, while colonies where younger peripheral zooids were removed showed no sign of recovery, and often experienced further loss of zooids. The effect of temperature depended on the location of colony damage, with increasing temperature resulting in increased loss of zooids for peripherally damaged colonies, but having no effect on the recovery of colonies with damage to central zooids. Variation in colony recovery may be related to the age distribution and reproductive maturity of zooids within a colony. Alteration of resource allocation between sexual and asexual reproduction may be adaptive in that it maximizes lifetime fitness in response to localized partial mortality. [ABSTRACT FROM AUTHOR]

The harsh climate and patchy distribution of habitable terrestrial ecosystems constrain soil invertebrate communities in continental Antarctica. The Windmill Islands in East Antarctica have a relatively gentle climate by Antarctic standards, and the region supports some of the most well-developed moss beds on the continent. These moss beds and soils are known to sustain invertebrate communities dominated by nematodes, rotifers and tardigrades, but our knowledge of the diversity and composition of these communities remains limited. We extracted soil fauna from 74 soil samples representing a wide range of microhabitats, and 24 moss samples, collected at Clark Peninsula, Bailey Peninsula and Robinson Ridge in the Windmill Islands during the 2012-2013 austral summer. Invertebrates were present in all samples, but densities varied considerably both within and between sites with limited correlation with edaphic variables or cover type. Taxa found included two species of nematodes ( Plectus murrayi; Plectus frigophilus), one mite ( Nanorchestes antarcticus) as well as tardigrades and rotifers (enumerated only). No springtails were found in this study, but individuals of the genus Cryptopygus were later recovered from moss collected near Casey Station. The Windmill Islands soils and moss beds support dense populations of soil fauna. However, despite the relatively mild climate conditions and favorable soil properties, species diversity is low. The diversity is possibly limited by recent deglaciation and limited dispersal opportunities to the region. Given favorable local conditions, it is likely that colonizing species will perform well, whether these arrive by natural means or are accidentally introduced by humans. [ABSTRACT FROM AUTHOR]

Global transformations extend beyond local habitats; therefore, larger-scale approaches are needed to assess community-level responses and resilience to unfolding environmental changes. Using long-term data (1996-2011), we evaluated spatial patterns and functional redundancies in the littoral invertebrate communities of 85 Swedish lakes, with the objective of assessing their potential resilience to environmental change at regional scales (that is, spatial resilience). Multivariate spatial modeling was used to differentiate groups of invertebrate species exhibiting spatial patterns in composition and abundance (that is, deterministic species) from those lacking spatial patterns (that is, stochastic species). We then determined the functional feeding attributes of the deterministic and stochastic invertebrate species, to infer resilience. Between one and three distinct spatial patterns in invertebrate composition and abundance were identified in approximately one-third of the species; the remainder were stochastic. We observed substantial differences in metrics between deterministic and stochastic species. Functional richness and diversity decreased over time in the deterministic group, suggesting a loss of resilience in regional invertebrate communities. However, taxon richness and redundancy increased monotonically in the stochastic group, indicating the capacity of regional invertebrate communities to adapt to change. Our results suggest that a refined picture of spatial resilience emerges if patterns of both the deterministic and stochastic species are accounted for. Spatially extensive monitoring may help increase our mechanistic understanding of community-level responses and resilience to regional environmental change, insights that are critical for developing management and conservation agendas in this current period of rapid environmental transformation. [ABSTRACT FROM AUTHOR]