Species Composition Of Macrozoobenthos Research Articles

Macrozoobenthos in mid-mountain lakes of river Multa basin (Republic of Altai)

In August 2020, taxonomic composition and quantitative characteristics of zoobenthos from 4 lakes located in the upper reaches of the R. Multa basin (the R. Ob basin) were studied. Because of the basin inaccessibility the hydrobiological information about these lakes was previously fragmentary or absent at all. The data on macrozoobenthos composition and its structure were not available. In these lakes, 49 species of benthic invertebrates from 7 classes were identified, i.e. Demospongiae (1), Turbellaria (1), Oligochaeta (3), Gastropoda (4), Euchelicerata (1), Crustacea (1) and Insecta (38). Among insects, Diptera were the most diverse (22 chironomids out of 23 species). Beetles, mayflies and caddisflies were also found. In terms of species number, abundance and biomassб chironomids were the dominant taxonomic group in the studied lakes. The species composition of macrozoobenthos consisted of species widely spread in the Palearctic and Holarctic. The investigated lakes differed in species composition of zoobenthos. When comparing the species lists of benthic animals, lakes Sredneye Multinskoye and Poperechnoye were similar at most, whereas the fauna of Lake Nizhneye Multinskoye was the most original. The studied water bodies were distinguished by poor macroinvertebrate development and thereby corresponded to ultra-oligotrophic and oligotrophic reservoir types. The oligochaete index by Goodnight and Whitley corresponded to quality class I–II, i.e. “conditionally clean” and “slightly polluted waters”. We defined the trophic structure of macrozoobenthos of lakes and identified five main trophic groups of hydrobionts (Deposit feeders, Сollectors-detritus feeders and facultative filter feeders, Collectors-obligate filter feeders, Shredders, Predators), among which Collectors-detritus feeders and facultative filter feeders dominated.

Оцінка процесів евтрофікації водних об’єктів річки Стрижень

According to the results of hydrological, hydrochemical and hydrobiological studies (May-October 2017) the estimation of eutrophication processes in water bodies of the Stryzhen River within the city of Chernihiv is presented. The seasonal dynamics of abiotic and biotic factors which form the water quality and trophic level of water bodies has been analyzed. It was found that the features of the hydrological regime of the Stryzhen River in 2016–2017 were low water content, the offset of the passage and a decrease in the duration of the spring flood. The volume of spring runoff was very low and reached 65% of the total annual runoff. Due to the moderate and heavy rains the water level rose slightly to 5-10 cm. It was established that at this time the movement of water in the channel sections of the reservoirs was absent. The important hydrodynamic characteristics of the ponds from an environmental point of view are mixing and wind-generated waves which cause horizontal and vertical migration of substances and enhance the self-purification capacity of water in the ponds. In the spring and summer, when forming a direct temperature stratification, the thickness of the surface layer of water which took part in the mixing processes in the first, second and third ponds was 0.5, 1-2 and 1 m, respectively. The thermocline divided the water column vertically into two parts, which differed from each other in temperature values, as well as in dissolved oxygen content and saturation, pH values, concentrations of ammonium nitrogen, nitrate ions and inorganic phosphorus. The surface layer of water was characterized by enough concentration of dissolved oxygen, whereas in the water column below the thermocline its deficiency was observed. In spring and summer there was alkalinization of the water in the surface layer of the ponds, which was caused by displacement of the hydrocarbon-calcium balance as a result of photosynthetic activity of algae. Under anaerobic conditions the concentration of ammonium nitrogen and inorganic phosphorus in the bottom water layer increased to 1.29–9.99 mgN/dm 3 and to 0.39–4.76 mgP/dm 3 respectively, the maximum values of which were observed in the first pond. During studies of the ponds of the Stryzhen River, it was found that phytoplankton was characterized by a rather rich species diversity of algae and high quantitative development rates that reached the level of water “blooming” due to the massive development of blue-green algae in July and October 2017. The species composition of macrozoobenthos in the studied ponds of the Stryzhen River was very poor, in total 35 species were found. The most favorable conditions for the development of benthic organisms were found in the river section above the third pond and below the first pond before the Stryzhen River flows into the Desna River. Bioindication analysis showed that the zoobenthos in the studied ponds was in a depressed state (TBI = 1-2), but in flowing river sites it was in the best conditions (TBI = 8). According to most of the studied indicators, water quality corresponded to categories 2-5, but content of dissolved oxygen and an inorganic phosphorus belonged to category 6-7 environmental water quality classification. According to the trophic index the studied ponds belonged to mesotrophic, but during “blooming” of water - to hypertrophic.

ASSESSMENT OF THE CURRENT STATE OF BENTHIC FAUNA AND WATER QUALITY OF CHANNELS OF THE VOLGA DELTA

Aim. We present the findings of studies of the current state of benthic fauna of the Volga delta channels by the structure of benthic communities. The study has been carried out in the framework of researches by FSBSI "Caspian Fisheries Research Institute" conducted in the period from 2010 to 2014. The main goal was to assess the current state of benthic fauna of output channels of the Volga delta areas against the backdrop of changing water availability of the Volga river. Methods. We have conducted sample processing of zoobenthos within investigated watercourses of the Volga River according to conventional methods of Zhadin V.I. (1960), Winberg G.G. (1984) and Abakumov V.A. (1992). Results. The results of the work on the study of the modern state of the benthic fauna of the Volga delta channels show that the species composition of macrozoobenthos in these sections of the river in dry years was characterized by mass development of oligochaetes. With the increase of water content (between the years 2012 and 2013) in all studied water streams there is a change of the dominant group. With the decrease in the annual runoff (in 2014) the qualitative characteristics of zoobenthos have changed. In the average long-term aspect, the distribution pattern of quantitative indicators of benthic invertebrates in the delta of Volga river was uneven, and their greatest density has been marked in the wet year. Main conclusions. Thus, the research found that increase of the water content of the Volga River positively influences the hydrobiological picture in the output channels of the delta of the Volga River.

Species composition of macrozoobenthos in lagoons of Sakhalin Island

Species composition of macrozoobenthos in lagoons of Sakhalin Island (in total, 637 species) is described on the base of cited data and results of author’s surveys. Its species composition is formed under influence of wide spectrum of environmental factors, as size of lagoon, water salinity, periodicity of connection with the sea and type of the water exchange, river discharge regime, climatic and geographical isolation, etc. Generally, 6 types of lagoons are determined on the coast of Sakhalin differed by composition of benthic fauna: 1) large semiclosed salty lagoon (Lake Busse in southern Sakhalin); 2) small semiclosed salty lagoons with water stratification and periodic connection with the sea (Lake Izmenchivoe and Lake Ptichye in southern Sakhalin); 3) large shallow semiclosed lagoons (in northern Sakhalin); 4) small isolated brackish lagoon (Kuegda Bay in northern Sakhalin); 5) closed oligosaline lagoons (Lake Tunaicha and Lake Aynskoe in southern Sakhalin); 5) isolated freshwater lagoons (Vavaysko-Chibisanskaya lake system in southern Sakhalin). Salty and freshwater lagoons are distinguished by the highest species diversity.

Relationships between macrozoobenthos and habitat characteristics in an intensively used area of the Dutch coastal zone

Abstract Distribution patterns and species composition of macrozoobenthos were studied in the Dutch coastal zone in front of the Port of Rotterdam. Relationships between macrozoobenthic assemblages and environmental variables were determined using non-metric dimensional scaling (nMDS) based on 470 boxcore, bottom sledge, and sediment samples collected in spring 2006 and 2008 in a 2500-km2 research area. We investigated two types of benthic assemblages, infaunal assemblages sampled with a boxcorer and epifaunal assemblages sampled with a bottom sledge. Five main in- and epifaunal assemblages were distinguished using clustering techniques and nMDS ordinations. Macrozoobenthic species composition correlated with combinations of measured sediment variables and modelled hydrodynamic variables. Macrozoobenthic species richness and biomass were highest at 20 m deep areas with a grain size of 200 µm, elevated mud and sediment organic matter, and low mean bed shear stress. Considerable interannual differences in macrozoobenthic assemblage distribution were observed which resulted from more Echinoids, Phoronids, and jackknife clams. A distinct, highly productive and species-rich macrozoobenthic white furrow shell Abra alba assemblage coincided in a 8-m deepened shipping lane and near a disposal site for dredged fine sediment. This may be an indication that the benthic system can be changed by these human activities. Modelled bed shear stress is an important variable in addition to sediment variables in explaining distribution patterns in macrozoobenthos.

Faunenverarmung in einem Schlickgebiet in der Nähe Helgolands

Variations in abundance and species composition of macro-zoobenthos were studied at a sublittoral muddy-bottom station in the inner part of the German Bight from 1969 to 1976. The fauna of this area can be included in the classicalAbra alba community. A total of 98 species were found in 62 samples. Of these, only 4 species occurred in all samples:Nucula nitidosa, Diastylic rathkei, Ophiura texturata andNephtys hombergii. Species richness has declined since 1969. Populations of several species disappeared in the investigated area and its surroundings. Other populations are shown to exhibit remarkable fluctuations in abundance with sometimes heavy spatfalls or sudden breakdowns in population density, mainly during late summer. The long-term trend of impoverishment of the fauna is attributed to the development of anaerobic conditions in the muddy sediment. Such conditions are favoured by stable, thermohaline strafications of the water during summer, resulting in low oxygen levels and, probably, enrichment of hydrogen sulfide even in near-bottom water. Moreover, both continuou influx into the area of Elbe water, rich in suspended matter and nutrients and dumping of sewage sludge about 8 km east of the investigated area are considered to have increased the strees on the bottom fauna.