Technologies of carp growing and their features

Carp is one of the few fish farms for which a wide range of technologies has been developed: from extensive, with minimal human intervention in the formation of fish productivity of the reservoir, to intensive, with the most controlled production conditions. Carp has many biological features, enhanced by centuries of breeding work, making this fish extremely “technological”, able to more or less fully realize the genetically determined bioproductive properties of different breeding technologies. Technologies for growing commercial carp according to the level of intensification of the production process can be divided into extensive (grazing), semi-intensive, intensive, and continuous, as a distinct type of intensive technology for growing carp in ponds and pools. Extensive technology assumes that the fish will feed exclusively on natural food, zooplankton, and bottom fauna. In this case, the cost of growing carp will be the lowest; the fish will be called “ecological”, but the growth of individuals will be insignificant. Semi-intensive technology assumes that carp feed on natural feeds, and their energy needs are met by providing carbohydrate additives to feed. Intensive technology believes that carp feeding with compound feeds with high protein content is used, which allows achieving productivity of 3–20 tons/ha. This system requires the highest costs, although it gives the highest performance. The pond must provide additional aeration and water flow to prevent contamination of the reservoir and the development of fish diseases. The main disadvantage of popular carp growing technologies is their staging. All operations are carried out strictly one after another in specialized ponds. Moreover, each stage ends with the descent of the tanks, and the fish are transplanted several times from one to another (from spawning to juvenile, from them to nursery). During this, the carp is injured, which negatively affects its productivity and inevitably leads to waste. To remedy this, fish farming is now using continuous rearing technology. The choice of technology for growing carp is a responsible task on which the profitability of fisheries depends.

Discharge of drill cuttings in the Arctic seas and responses of bottom fauna: bivalve Mytilus edulis L.

Drill cuttings are the largest solid waste of drilling operations. Onsite discharge of drill cuttings into the marine environment is relevant and can be permitted under certain conditions and regulations. Environmental impact of the on-site discharge of drill cuttings is poorly understood for the Arctic shelf. A risk assessment of the discharge is required and the related biological effects are estimated in bioassays on various local species. The sublethal screening tests of water-soluble fraction of drill cutting (WSF DC) were performed on a test-organism of the Barents Sea coast, blue mussel, Mytilus edulis. Physiological (oxygen consumption and filtration rates) and behavioral (shell gaping) activity of mussels was affected by the tested WSF DC above the certain threshold concentration. In general, biological effects of WSF DC might be assumed as a toxic stress of low intensity. Behavioral responses are the most sensitive in blue mussels and behavior of this sentinel organism is to be applied as a reliable indicator of environmental stress. Environmental impact from the drill cuttings of water based drilling fluid appears to be less toxic-stressful for M. edulis and many other bottom invertebrates than it might be expected from release of some drilling fluids.

Overview of retrospective and modern data on arrival fodder organisms in lake Balkhash

The article analyzes the acclimatization work carried out, the current state of the food supply and the feasibility of introducing new food items. Lake Balkhash, in the first years of commercial development, was characterized by extreme poverty of the food base, especially the bottom fauna. During the period of planned acclimatization work, 1958–1965, 10 species of valuable food items were introduced into the reservoir. Many species, as expected, settled in the western part of the lake, where they not only expanded the species composition of bentonts, but also increased the feeding capacity of the reservoir — from 1.3 to 20 times. However, with an increase in salinity from west to east, the composition of benthos became poorer and its biomass decreased due to the gradual loss of mysids, corophiids, polychaetes and monodacnae from its composition. At the present stage, the biomass of zoobenthos in the eastern part of Lake Balkhash is 20–40 times lower than the indicators of the western part. To increase feed in Eastern Balkhash in 2012–2014. Experimental work was carried out on the survival in the Balkhash water of euryhaline invertebrates from the Aral Sea — polychaetes and bivalve molluscs. Based on the positive result, a biological justification was developed for the acclimatization of these invertebrates in the lake. Balkhash, but due to lack of funding, the work itself was not carried out. Within the framework of the above program, it is necessary to continue work on the introduction of brackish-water benthic organisms from the Aral Sea, as well as to ensure the feeding needs of juvenile fish throughout the growing season, there is a proposal for the introduction of Calanipeda aquae-dulcis Kritsch into the reservoir. Research on the issues raised in the article is funded by the Ministry of Ecology, Geology and Natural Resources of the Republic of Kazakhstan (Grant No. BR10264205,).

Relics of near-bottom fauna in massive sulfide ores

The additional study of ancient volcanogenic massive sulfide deposits in various regions revealed microtextures, probably of biogenic origin, which could represent varieties of the shells of mineralized fauna. The new finds expand the list of sites containing relics of bioforms associated with hydrothermal vents of "black smokers".

Zoobentos of the Barents sea

Аннотация на английском языке: Based on the analysis of retrospective and recent materials, the species richness of the bottom fauna and the long-term variability of the quantitative characteristics of zoobenthos of the Barents Sea are considered. The role of key taxa in the formation of benthic biomass and its trophic structure is indicated. The negative impact of bottom trawling on benthic fauna is shown and the most vulnerable areas in the basin are identified.

ON THE INVASION OF THE GENUS MARENZELLERIA (POLYCHAETA, SPIONIDAE) REPRESENTATIVES INTO THE CASPIAN SEA BASIN

In 2018, in the bottom fauna of the Caspian Sea, single specimens of a previously unknown species of polyhaetes were discovered. Since 2019, pelagic larvae of this species have been recorded in zooplankton samples. These worms are also found in the nutrition of migratory and semi-migratory fish species. According to morphological features, this polychaete species is identified as Marenzelleria arctia , an Arctic species dominating in the Gulf of Finland and probably invaded the Caspian along the Volga-Caspian invasion corridor.

RETROSPECTIVE ANALYSIS OF RESTRUCTURING IN COMPOSITION OF MACROZOOBENTHOS UNDER CASPIAN SEA TRANSGRESSION

The article highlights the processes of lowering and raising the Caspian Sea level and its influence on the quantitative and qualitative characteristics of the aquatic bioresources, including zoobenthos. The development of macrozoobenthos in the Caspian Sea including the Northern Caspian is associated with various processes: chemical, physical and biological. The presence of macrozoobenthos determines the fish productivity in the sea, it is an integral part of the ecosystem of the northern part of the Caspian Sea. In this regard, the assessment of the composition and quantitative characteristics of bottom communities becomes important. One of the urgent tasks of modern hydrobiology is detecting the basic regularities in the biotic processes that affect the qualitative and quantitative changes in the aquatic organisms. This research is of a retrospective nature. On the basis of a long-term analysis of the dynamics of the species structure of bottom zoocenoses there have been revealed the changes in the macrozoobenthos of the western part of the Northern Caspian in the first and second periods of the sea level rise (1978–1988 and 1989–1995). Decreasing water salinity, increasing desalinated zones and areas with oxygen deficiency in the bottom horizon (in the extremely high-water years of 1990 and 1991) contributed to the significant changes in the quantitative and qualitative composition of the bottom fauna. From the first stage to the second there was recorded a decrease in the number and biomass of crustaceans and molluscs. The species Stenogammarus macrurus (G. O. Sars) and Stenogammarus similis (G. O. Sars), which are tolerant to the significant salinity fluctuations, as well as abra, which is resistant to oxygen deficiency were most abundant in the water complex with light salinity. Also, there has been considered the water content of the rivers of the Caspian basin and the type of soil as factors influencing changes in the concentration of macrozoobenthos.

MACROPHYTE-ASSOCIATED MACROINVERTEBRATES OF HETEROGENEOUS WATER BODIES OF THE VOLOGDA REGION, RUSSIA

In august 2018, fauna of aquatic macroinvertabrates from Persicaria amphibia (L.) Delarbre, Butomus umbellatus L. and Potamogeton perfoliatus L. was studied in Kubenskoe Lake as well as in Vozhe Lake and Mologa River in order to compare the phytophilic and bottom fauna of heterogeneous water bodies. Macrophyte-associated invertebrates and samples of zoobenthos in thickens (in total 37 samples were analyzed) were collected. 68 species of aquatic invertebrates were recorded, including 49 species from Kubenskoe Lake, 41 from Mologa River, and 31 from Vozhe Lake. In the thickets of three macrophyte species, less than a third of all macroinvertebrate richness from the investigated water bodies is recorded. The most abundant species were Endochironomus albipennis Meig., Glyptotendipes gripekoveni Kief., Cricotopus gr. sylvestris. By using cluster analysis, the fauna of all biotopes was divided into macrophyte-associated and bottom-associated. The abundance and biomass of invertebrates in zoophytos in most cases is 3–15 times higher than in zoobenthos. In lakes, species diversity in zoophytos is 1.5–5 times lower than in soil. In the Mologa River the species diversity of zoophytos, on the contrary, is slightly higher. In lakes in the trophic structure, filter-collectors predominate. In the Vozhe Lake a high proportion of predators in the biomass is also recorded. In the Mologa River the trophic structure is more various: along with the collector-filterers, scrapers, shredders and predators are represented. In comparison with research of the 1970s, community structure of macrophyte-associated invertebrates in Vozhe Lake has not practically changed. The dominance of E. albipennis was detected in the Kubenskoe Lake and that was not previously indicated for this reservoir. The species composition and abundance of aquatic macroinvertebrates is determined by the type of substrate (soil or plant), while the structure of communities depends primarily on a type of reservoir, and not on a type of thicket.

Taxonomic structure of the zoobenthos of the Lukoml GRES cooling reservoir

The species composition of zoobenthos in the heated and non-heated zones of the cooling lake Lukoml State District Power Station was studied. 80 taxa of bottom animals have been registered, and two new species of chironomid larvae have been identified. The bottom fauna includes a protected relict species of Pallaseopsis qudrispinosa, which is preserved in the conditions of warming.it is listed in the Red book of Belarus and the alien species – freshwater shrimp Macrobrachium nipponense. The high taxonomic diversity indicates that the Lukoml State District Power Station operation has little impact on the bottom community throughout the lake’s water area. However, species richness is reduced locally by half in the zone of influence of heated water discharge, especially in summer. Under the influence of heating, the taxonomic structure and spatial distribution at different depths change.

Absolute Population Estimates by Sampling a Unit of Aquatic Habitat

Methods for quantitative sampling of open marine and freshwaters are described, including fishing nets, plankton nets, pump samplers, the Patalas–Schindler volume sampler, and specialized methods for freshwater insects. Specialist methods for sampling freshwater floating, emergent, and submerged vegetation are described. Methods for quantitatively sampling the bottom fauna in the various substrates found in streams, rivers, lakes, and the sea bed are reviewed. The use of various poisons and anaesthetics for sampling fish are described.