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AquaDocs is the joint open access repository of the UNESCO/IOC InternationaI Oceanographic Data and Information Exchange (IODE) and the International Association of Aquatic and Marine Science Libraries and Information Centers (IAMSLIC) with support from the FAO Aquatic Sciences and Fisheries Abstracts. It is a thematic repository covering the natural marine, coastal, estuarine /brackish and fresh water environments and includes all aspects of the science, technology, management and conservation of these environments, their organisms and resources, and the economic, sociological and legal aspects. [see About]
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Fatores responsáveis pela variação dos componentes da diversidade beta na assembleia de peixes em riachos de cabeceira.Fish assemblage composition varies across time and space, and beta diversity has been a valuable tool for quantifying this variation and understanding associated mechanisms. Understanding which factors determine the action of these mechanisms is fundamental for headwater stream management and conservation projects. Therefore, was evaluated which component of total beta diversity (species replacement or difference in richness) is most representative for the fish assemblage between streams, identified the scale of effect of land use on this assemblage, and evaluated the relative influence of land use, local environment and distance between collection points on beta diversity components. The study was carried out in 12 headwater streams close to and located in the municipality of Maringá, Paraná, Brazil. The percentage of land use classes was measured at 11 spatial scales, five buffers from the sampled section and six from the water network upstream of the sampled section. The data was analyzed using Redundancy Analysis based on distance and variance partition. The results showed that species replacement was the most important component for total beta diversity, with land use in buffers 100 and 500 meters from the sampled section considered the scale of effect for the variation of the components. Land use and local environmental variables were more representative for total beta diversity and richness differences and the distance between collection points for species replacement. It was concluded that land use and local environmental variables select fish species, reducing richness in urban areas, while the dispersal limit acts on species replacement. Therefore, it is suggested that management and conservation projects should be focused on land use, conserving or restoring riparian forest, which would improve the local quality of streams, mainly urban streams, which are the most altered.
Short-term forecast of the changes in the primary production of organic matter and pollution by priority toxicants in the Azov SeaAquatic Bioresources & EnvironmentModern climate changes and increasing anthropogenic water withdrawal in the Azov Sea river basins have led to a reduction in freshwater runoff and a record increase in the sea salinity. Salinization of the Azov Sea leads to a transformation of the structure of biological communities and a decrease in primary productivity, which inevitably has a negative impact on fish productivity. Another important factor in the stock formation of aquatic biological resources is the quality of their habitat. Aim of this work is to make a short-term forecast of the hydrochemical foundation of biological productivity and toxicological status of the Azov Sea up to 2030. This study was based on the long-term data on the level of primary production, hydrochemical regime and accumulation of priority toxicants in the Azov Sea ecosystem. In the present period, adaptation of the Azov Sea ecosystem to increasing water salinity is manifested in a decrease in the level of primary production. In recent years, during the summer season, an unfavorable physiological state of phytoplankton has been observed due to the high content of pheophytin in the cells. In the Azov Sea, from 1986 (the peak of industrial development and anthropogenic load) up to the present, in the water, bottom sediments and muscles of commercial fish species, has been observed a decrease in the average annual concentration of the majority of monitored toxicants. Under the most likely forecasted scenario for the river flow and water salinity (14.5–16.5 ‰), a further decrease in the level of primary production is expected. It is possible that the ecosystem will adapt to the increase in water salinity; phytoplankton will be characterized by a more favorable physiological state in the summer. No deficiency of biogenic elements is predicted. If the existing anthropogenic load remains unchanged (the most likely scenario), the level of sea pollution by anthropogenic toxicants is predicted to be low, and in certain areas — Taganrog Bay, the waters of the Yeysk and Temryuk Sea Ports — it is expected to be moderate. The quality and safety of aquatic biological resources as a food product will meet regulatory requirements.
Possible scenarios for the formation of the continental runoff and the salinity of the Azov Sea, taking into account the current and future trends in climate changeAquatic Bioresources & EnvironmentThe ongoing climate changes have a significant impact on the formation of the habitat conditions for the aquatic biological resources of the Azov Sea. Salinity of the Azov Sea waters and continental runoff, which role in maintaining the ecological well-being of the habitat of aquatic biological resources is paramount, has underwent particularly noticeable transformations. Relevance. Assessment of the degree of influence of ongoing and expected climate changes on the formation of abiotic parameters of the marine ecosystem is a prerequisite for planning the successful development of the fisheries industry of the Azov Sea Basin. The aim of this work is to assess the current and expected changes in the hydrometeorological parameters of the Azov Sea ecosystem, as well as to identify the most probable scenarios of changes in the Azov Sea salinity depending on the annual volume of continental runoff. Methods. The study is based on the data from AzNIIRKH database for the time range 1960–2020 collected over the course of the expedition surveys examining the Azov Sea hydrological regime and the data of the reference observation network of the Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet). Methods of mathematical statistics, graphoanalytical construction, mapping and analogy have been used for the data analysis. Results. This paper assesses the changes in the hydrological regime of the Azov Sea based on the annual monitoring of the habitat of aquatic biological resources. Preliminary calculations have been performed, and new data on the changes in the parameters of the sea water balance equation not covered by monitoring over the past forty-five years have been presented. The most probable formation scenarios for the continental runoff and the Azov Sea water salinity for the future up to 2030 are considered, with the observed trend of climate warming taken into account. Conclusions. Both the climatic and anthropogenic factors have contributed to considerable changes in the current hydrometeorological regime of the Azov Sea. These changes have mainly been manifested in an increase in air and water temperatures, a decrease in wind activity, and in a reduced continental runoff, in the formation of which, since 2006, a prolonged low water content cycle has been observed. The shortage of river runoff and increased water evaporation rate, along with other factors, have induced an unprecedented increase in the Azov Sea salinity, the average annual value of which in 2021 reached a record high (14.97 %). In the most probable scenario (60 %) with the continuation of the low water content period and the continental runoff into the Azov Sea of about 22 km3 in volume, the average annual salinity of the Azov Sea, including Taganrog Bay, can reach 15±0.40 ‰ with a variation range from 14.5 to 16.5 ‰ in the sea itself (excluding Taganrog Bay). 2021 can serve as an analogous year in terms of salinity formation and its spatial distribution.
Aquatic Bioresources & Environment. Vol. 6, issue 4Possible scenarios are given for the formation of the continental runoff and the salinity of the Azov Sea, taking into account the current and future trends in climate change. Short-term forecast are suggested for the changes in the primary production of organic matter and pollution by priority toxicants in the Azov Sea. Specific features of photometric determination of organic carbon in bottom sediments are presented. Exploitable resources of commercial invertebrates in the Azov Sea and the dynamics of their exploitation in 2000–2022 are considered. The Azov Sea populations of sturgeon fish species as a part of monitoring the catches by stationary fishing gears along the Kuban coast are investigated. Morphological characteristics and biological features of Smith's barb Puntioplites proctozystron (Bleeker, 1865) in the Mekong River Delta are studied. Artificial reproduction of semi-anadromous fish species under different development scenarios of hydrological situation in the Azov Sea is analysed. Release of juvenile sturgeons in the Azov–Kuban region by sturgeon hatcheries of the Federal Agency for Fishery in 2016–2022 is reported.
Exploitable resources of commercial invertebrates in the Azov Sea and the dynamics of their exploitation in 2000–2022Aquatic Bioresources & EnvironmentIn the context of a low water conent in the Azov Sea along with an increase in its salinity and the background temperature, a decrease in the stocks of stenohaline species of bioresources and an expansion of the species composition of halotolerant species are observed; out of the latter ones, the populations of commercial invertebrates are presently characterized by a drastic increase in their stock abundance and biomass. Upon the development of an increased salinity regime of the Azov Sea, it becomes relevant to monitor the undergoing fundamental changes in the exploitable resources of commercial invertebrates. The aim of this work has been to assess the resource potential of commercial invertebrates for the period 2000–2022 and make a forecast of its dynamics under various salinity conditions of the Azov Sea up to 2030. Analytical data characterizing the status of the exploitable resources of commercial invertebrates in the Azov Sea were originally collected during expeditionary surveys in 2000–2022. To characterize the Azov Sea stocks of commercial invertebrates, standard methods of collecting and analyzing the field samples indicative of the state of their populations have been used. A retrospective analysis of the species composition of commercial invertebrates in the Azov Sea indicates an expansion of the list of commercial species, an increase in their stocks and catch volumes, as well as the potential for further additions to the list of commercial species by involving new ones, currently not targeted by fisheries. The development of the invertebrate fishery creates a crucial alternative to the deteriorated catches of commercial fish species and may facilitate the preservation of a small fishing fleet in the Azov Sea, preventing its decline. In the case if salinity remains in the 14.5–16.5 ‰ range or increases to 18.5 ‰, there will be maintained the favorable conditions for increasing the catches of molluscs (veined rapa whelk, mussels, unequal arc), crustaceans (shrimps, Gammarus, Artemia), insects (chironomids), and jellyfish.