Feeding of Barbus cyclolepis Heckel, 1837 (Teleostei: Cyprinidae) and its relationship with benthic macroinvertebrate fauna in the Istranca Stream (İstanbul, Turkey)

The aims of the study are to determine what the organisms Barbus cyclolepis consume as food in its feeding environments and to compare prey consumption with prey abundance in the environment. The study was conducted in the Istranca Stream located in Istanbul (Turkey) during the spring and summer of 2012. A total of 142 B. cyclolepis specimens were captured and it is determined that 94 of them had full digestive tracts. Diet analyses of B. cyclolepis showed that its food spectrum consisted of 11 different food types, and the species was found to feed on insects, mainly Diptera (IRI%= 92.26%). The most abundant macroinvertebrate organisms in the environment were Diptera and Gastropoda. The electivity index of B. cyclolepis was positive for Diptera in the spring (E= 0.49), but the value was below the expected value of 0.6 for high selectivity. The electivity values for other macroinvertebrate groups, consumed in low proportions, were negative. In summer, the fish fed on Diptera, Plecoptera, and Trichoptera, but a high electivity index value was found only for Trichoptera (E= 0.87). Results showed that B. cyclolepis mainly consumed Diptera as food and did not consume Gastropoda, although it is the second most abundant macroinvertebrate group in the environment. A relationship was determined between the proportion of food groups consumed in the digestive tracts of fish and the ratios of macroinvertebrates in the environment, and as a result, it was specified that the fish was selective on Diptera.

Environmental Drivers of Macroinvertebrate Assemblages within Peat Pool Habitat-Implication for Bioassessment

Macroinvertebrates are a crucial component of wetland trophic webs. Many taxa are used as bioindicators of ecosystem change. However, relationships between macroinvertebrates and the environmental factors in peat pool habitats are still not well recognized. The present study shows the results of long-term studies during the years 2010–2020, on the responses of macroinvertebrates to the changes of environmental variables in a peat pool habitat formed as a result of peat exploitation on continental raised bog. The RDA analysis significantly explained 87.3% of the variance in macroinvertebrates abundances. Assemblages of most taxa (Anisoptera, Chironomidae, Ceratopogonidae, Coleoptera, Hydrachnidia and Tabanidae) showed a strong relationship with N-NO3 and pH. Moreover, densities of Chaoboridae larvae were explained by chlorophyll-a concentrations. Dominant taxon, Chironomidae, constituted from 48% to 87% of total faunal density. The highest proportions showed larvae of Psectrocladius sp. (gr. sordidellus) and Chironomus sp. Changes in the composition of macroinvertebrate fauna over a period of 10 years reflect the eutrophication process of the peat pool and deterioration of habitat conditions.

Marine invertebrates associated with rhodoliths/maërl beds from northeast Brazil (State of Paraíba)

This study investigates the marine macroinvertebrate fauna of rhodolith beds (non-geniculated red corallinaceaous algae) in northeast Brazilian. A total of 57 species were identified, belonging to six phyla (Platyhelminthes, Annelida, Sipuncula, Mollusca, Arthropoda and Echinodermata), of which 50 are considered here as new records for the Paraíba State. Annelids (Class Polychaeta) were the most representative taxa in Miramar and Seixas Beaches, while molluscs were dominant in Maceió Beach. This is the first study that includes an identification key, diagnostic features and distribution patterns worldwide and local (including new records) of the marine invertebrate fauna associated with rhodolith beds in northeast Brazil (State of Paraíba). Sampling events were performed in 2018, at low tide in the intertidal to shallow subtidal zones (1.5 and 4.0 m depth), in Miramar, Seixas and Maceió Beaches. A total of 17 species were found for the first time on Seixas Beach, as well as all identified species for Miramar and Maceió. This study tries to contribute to the knowledge of marine invertebrates in northeast Brazilian shallow habitats, providing a baseline for future environmental studies.

Crab Diets Differ Between Adjacent Estuaries and Habitats Within a Sheltered Marine Embayment

Portunid crabs contribute to significant commercial and recreational fisheries globally and are commonly fished in estuaries and/or marine embayments, which are amongst the most degraded of all aquatic ecosystems. Portunus armatus were collected seasonally between April and February from five locations across three systems in temperate south-western Australia. The dietary composition of crabs was quantified and compared between two estuaries (Peel-Harvey and Swan-Canning) and a sheltered marine embayment (Cockburn Sound) containing three distinct habitats: shallow seagrass, shallow sand and deep sand. Overall, crabs ingested large volumes of bivalves (both live organisms and dead shell), polychaetes, crustaceans (e.g., amphipods, small decapods), and smaller volumes of teleosts, echinoderms and plant material (seagrass, algae). Analysis of Similarities showed that dietary composition varied significantly among the five locations (two estuaries and three habitats within Cockburn Sound) and seasons, with greater location than seasonal differences in the two estuaries. Diets were most distinct in the Cockburn Sound seagrass due to greater volumes of decapods and teleosts and smaller volumes of bivalve shell consumed in this habitat. Crabs from both estuaries consumed greater quantities of bivalves than those from Cockburn Sound. Seasonal differences in both estuaries were greatest between summer and winter, with a more diverse range of prey and large quantities of bivalves ingested in summer, whereas small bivalves and bivalve shell in the Peel-Harvey and polychaetes and other crustaceans in the Swan-Canning, were consumed in greater quantities in winter. The summer diet in the Peel-Harvey Estuary in the current study was compared to that 20 years previous and with documented change in the benthic macroinvertebrate fauna. Currently, crabs consume smaller volumes of high-calorie prey, i.e., polychaetes, small bivalves and teleosts, and instead ingest greater proportions of calcareous material than previously. This marked shift in dietary composition parallels changes in benthic macroinvertebrates in the Peel-Harvey Estuary. Overall, prey availability appears to be the major factor influencing the spatial and temporal differences in P. armatus diets in these three coastal systems.

Revealing the influence of hyporheic water exchange on the composition and abundance of bottom-dwelling macroinvertebrates in a temperate lowland river

We studied distributions and abundances of macroinvertebrates in relation to hyporheic water exchange (HWE) patterns of the upper Biebrza − a small, lowland, low dynamic European river located in Northeast Poland. On a 6-km stretch of the river; we determined the variability of water exchange in the hyporheic zone by using direct field measurements of the pressure gradient to determine groundwater–surface water interactions. We identified locations with upwelling and downwelling fluxes of HWE as well as ambiguous hydraulic contact between groundwater and surface water along the river. In these locations, we sampled bottom-dwelling macroinvertebrates. In total, 627 individuals of benthic macroinvertebrates of 34 taxa were identified. We revealed that bottom-dwelling macroinvertebrate fauna is more abundant and diverse in river stretches where water from the river infiltrates the hyporheic zone. Results also show higher taxonomic richness and abundances of benthic macroinvertebrates in stretches with diagnosed infiltrating conditions (downwelling flux in a hyporheic zone) compared to in stretches where the river drained groundwater (upwelling flux in a hyporheic zone), but the recorded differences were not statistically significant.

The diversity of marine invertebrate macrofauna in selected rocky intertidal zones of Matara, Sri Lanka

The present study was conducted in intertidal rocky shores at Wellamadama and Kamburugamuwa of Matara district from June to November 2018. A line transect method was employed perpendicular to the shore and randomly placed quadrats were used to identify and quantify the species. Collectively 34 species of intertidal macroinvertebrate fauna were identified. Shanon-Weiner index, Menhinick’s index, and Pielou’s index for Wellamadama were 1.8271, 0.5612, and 0.7620 respectively, while those in Kamburugamuwa were 1.9281, 0.4307, and 0.7517. Higher species diversity was recorded at the rocky shores of Kamburugamuwa, while higher species richness and evenness at Wellamadama rocky shores. The Jaccard similarity index indicates a low similarity (<50%) between two study rocky shores. Clypidina notata, Cellana rota, and Patelloida striata were the dominant species in the low tide zone. Highly abundant species in mid tidal zone at Wellamadama was Nodilittorina quadricincta, while that of in mid-tide zone at Kamburugamuwa was Chiton sp. Periwinkle snails were dominating the high tide zone of both study rocky shores of which Nodilittorina trochoides dominated at Wellamadama and Littoraria undulata dominated at Kamburugamuwa. The study indicates that community assemblages in intertidal rocky shores vary spatially and comprehensive studies are essential to investigate the controlling factors.

FACTORS GOVERNING DISTRIBUTION OF BENTHIC MACROINVERTEBRATE FAUNA IN THE SPRINGFED HEADWATERS OF DOON VALLEY, INDIA

The benthic macroinvertebrate communities are compared to know their distribution pattern in the headwaters of Asan, Suswa and Tawa streams in Doon valley and to determine environmental variables operational at regional level. Samples were collected during monsoon, winter and summer between July 2011 to June 2012. Total density of the benthic macroinvertebrate community was high in the winter season in Asan and Suswa compared to monsoon in Tawa. Total density was significantly different among the headwaters. The mayfly prevails over caddisfly during winter and summer in the Asan and during summer and monsoon in the Tawa. The share of Planorbidae and Chironomidae were also present noticeably in the Asan during summer, especially the former that attains notable abundance only in the Asan. Chironomidae was most abundant taxa in the Suswa during winter and summer while Caenidae prevails over it during monsoon. CCA revealed that differences in assemblages were driven by water temperature in both Suswa and Tawa streams, while conductivity in the Asan stream, though streams belong to same eco-region.