The overexploitation of natural resources by human beings in recent centuries has had serious consequences for biodiversity. In freshwater aquatic environments, organisms suffer from various degradation processes, which involve pollution, environmental fragmentation, introduction of invasive species, among others. The construction of dams and reservoirs for energy production is among one of the biggest reasons for the degradation of these environments, as this fragments the water body, preventing connectivity between sites, in addition to transforming the lotic environment into a lentic one, completely changing the dynamics of the local. As an aggravating factor, there are reservoir cascades, which consist of a sequence of reservoirs built on the same river, enhancing the negative effects of a single reservoir. In highly fragmented environments, physical-chemical changes occur, which harm the local biological communities. Thus, in this work, analyzes of the spatial and temporal beta diversity of fish were carried out in a very fragmented river in northeastern Brazil, the São Francisco River. For spatial beta diversity, we calculated the Local Contribution to Beta Diversity (LCBD), taxonomic and functional, at 28 points along the six reservoirs and in a lotic stretch downstream of the reservoirs, up to the mouth. We performed a beta regression model to verify the relationship between LCBD values and environmental variables collected in the same period. As a result, we found that the points of the initial reservoirs and the points closest to the mouth of the river were the ones that most contributed to beta diversity, both taxonomic and functional, and turbidity was the variable that was most positively associated with LCBD values. For the temporal beta diversity analysis, we used five reservoirs, and compared the beta diversity between pairs of months over years. A correlation was also made between the results of temporal beta diversity and the variation of environmental variables. There was no relationship between environmental variables and temporal beta diversity. However, it was possible to observe that the reservoirs that operate as a trickle of water had the most unstable and unpredictable temporal beta diversity values, while the reservoir that operates as an accumulation followed the pattern of seasonal variation of the dry-flood dynamics. We recommend the proper management of the reservoirs of a waterfall, monitoring the variations in the parameters and regulating the flow and water level according to the expected natural variations, mainly the initial ones that function as sources of species and functional traits, and also the preservation of the rivers tax. We conclude that deeper studies covering other periods must be carried out, to complement the existing data and provide greater assertiveness in decision-making and conduction of reservoir operations.

Life history and electrophoretic data were collected for an iso1ated, lacustrine popu1ation of rainbow trout from Packwood Lake, Washington. Spawning activity peaked in the lake outlet in late May and tributaries in mid-June. Eighty-four percent of the spawners were age IV or V. Females represented 63 percent of the total run. Only one of the 16 enzyme loci examined in Packwood Lake rainbow trout was polymorphic, LDH-4. Genetic comparisons indicated that Packwood rainbow are more similar to "inland" steelhead (rainbow) stocks than they were to "coastal" steelhead (rainbow) stocks. This unanticipated finding was hypothesized as evidence that colonization of Packwood Lake by an "inland" form of rainbow trout took place shortly after the last Pleistocene ice retreat. Further, that isolation from invading "coastal" stocks occurred due to subsequent geologic events. It is suggested· that Packwood rainbow are unique and that their genetic integrity be preserved for future reference and study.

The relevance of this research is conditioned by the absence of industrial utilization of the waste discarded while processing the veined rapa whelk (shells), despite the fact that this mullusc is caught in the Azov and Black Sea Fishery Basin annually. As a result of processing 2,746.1 tonnes of rapa whelk caught in the Azov Sea in 2019, almost 2,000 tonnes of shells were derived. The microbiological safety indicators of the calcium feed additive derived from veined rapa whelk have been investigated, which was necessitated by the parts of mollusc viscera remaining in 50 % of shell cones after their processing. Samples of the calcium feed additive were prepared in 5 ways, differing in temperature (20, 80, 105 °C) and duration of drying (12 and 24 hrs, 3 and 9 months), as well as the presence/absence of viscera remains. The total bacterial load in all samples did not exceed the established norms (no more than 5×105 CFU/g); E. coli bacteria, Staphylococcus aureus and pathogenic microorganisms, including salmonella, have not been detected. Thus, the investigated methods of calcium feed additive production can be considered as alternative ones, ensuring the microbiological safety of this type of product with a shelf life of at least 3 months, while in paper bags.

Content: 1)From the Editorial Board; 2) NF-POGO Visiting Fellowship for Shipboard Training; 3) NANO Research Project; 4) Research contributions; 5) Scientific event announcements

Morphological features of the Pacific oyster (Crassostrea gigas, Thunberg) oogenesis in the course of two-year cultivation cycle in Donuzlav Liman have been studied. The data on morphophysiological characteristics of this species (diameter and volume of acini, oocytes, nuclei, nucleoli, as well as the nucleoplasmic index) are given for different seasons. Quantitative changes in the size of oocytes (D) are presented in relation to water temperature (T, °С), which is described by the logistic function equation. It is shown that the dynamics of oogonia number (Nо) is linked to water temperature (T) with an inverse relation and is described by an exponential equation. The synchronicity of the changes in volumes of acini, oocytes and cell nuclei in the course of the reproductive cycle is shown, as well as the interrelationship between the volumes of these components. There was found to exist an asynchronicity in nuclei functioning and the nucleoplasmic index in the process of reproduction, which is linked with the synthesis of ribosomal proteins. Following the obtained data, 1-to-6 score of the maturity stages for the Pacific oyster females in the course of annual reproductive cycle is presented: passive state; beginning of oogenesis; active oogenesis; pre-spawning state; maturation and spawning; post-spawning transformation. The months, during which each maturity stage was the most prevalent, are given.

Perna viridis (Green Mussels) is characterized by fast-growing, found in large clusters, ‎one of the dominant bio-fouling organisms, native to West Indo Pacific region and ‎commonly distributed along the Southeast Indian and Asian coast. They are found in ‎the shallow sublittoral water up to a depth of 15 m and be able to tolerate an extensive ‎range of environmental situation i.e. tolerate temperatures range of 15-32.5C. Green ‎mussels were collected from the navigation buoy in Manora Channel and brought to the ‎research laboratory. Samples were washed to remove the sand, vegetation, and other ‎particles. Morphometric measurements were measured to the nearest gram. The result ‎revealed that the shell length ranged between 0.60-7.4 cm, the width range between 0.10-‎‎2.9 cm, and the weight range between 0.037-15.549 g. In all morphometric relationships, ‎the validation of the “b” values was significantly different from the isometric value. ‎Significant correlation variation was observed in all variables whereas the highest ‎correlation values were observed in the length-width (n-224, r2 = 0.966) and the lowest ‎was observed in width-total weight (n-224, r2 = 0.85). The analysis of variance (ANOVA) ‎revealed that all variables showed significantly different (DF=1, p<0.000).‎

Nutritionally, fish meat is identified as healthiest meat all over the world. Nutriments that ‎are essential for healthy diet can be easily drive from fishes. Beside fish meat there are ‎various type of derivatives that we can obtain from them. Economically fish industry is ‎considered as backbone for any country. Approximately, 45,000 species of helminth ‎parasites cause pathogenicity in vertebrate hosts that are known to man. Parasite that ‎belong to family Philometridae usually invade different body organs and cavities of ‎various fishes. Parasite that cause pathogenicity in reproductive organs of fish ultimately ‎cause disturbance in their release of reproductive hormones, mating behavior, difficulty ‎in spawning and ultimately number of fry production is declined.‎ This research was conducted on the nematode parasites of marine fish Epinephelus ‎bleekeri (Vaillant 1878) from Karachi coast during January,2021 to December,2021. In ‎this one year research, a new species of nematode Philometra bleekerii n.sp. was ‎recorded from the reproductive organs of marine fish Epinephelus bleekeri (Vaillant ‎‎1878).‎

The progress in species distribution modeling has brought new insights into biological ‎invasion management. The present study aims to model the potential current geographic ‎distribution and future expansion of silver-cheeked toadfish Lagocephalus sceleratus in ‎the Mediterranean Sea. Coordinates of 98 occurrence records of L. sceleratus in the ‎Mediterranean were used, and marine climatic variables were collected from the global ‎databases. Fifteen modeling techniques were tested, and weighted ensemble averaging of ‎the model replicates was built. AUC values for each model ranged from 0.61 for rpart to ‎‎0.99 for rf, and TSS values varied from 0.41 for mlp to 0.95 for rf. Based on the cutoff ‎values of TSS and AUC, the seven modelling algorithms were used for ensemble ‎modeling. The maximum seawater temperature at minimum depth explained strong ‎biological importance to the current adaptation, and the salinity contributed the most to ‎the future adaptation. The ensemble forecasting of suitable habitats of L. sceleratus for ‎current distribution modeling revealed that L. sceleratus dominantly occurred in ‎the middle and eastern parts of coastal areas of the Mediterranean. The future ‎distribution was extended to the western part of coastal areas of the Mediterranean, ‎classifying the high suitability of these areas for its future distribution. The suitable ‎bioclimatic envelope of L. sceleratus under the present study is predicted to widen ‎because of climate change. The likely regions of invasion and the areas at risk for a ‎potential future invasion of L. sceleratus indicate that prompt, effective practical actions ‎by resource managers should be undertaken to mitigate its impacts and spread.‎

The potential effects of bucket dredging on the fisheries resources in the Delaware River was assessed by evaluating the results of nine water quality monitoring studies conducted ·summer of 1992. The assessment was accomplished first by conducting analysis of variance (ANOVA) to determine if water quality conditions downstream of the dredge site were significantly different from upstream reference locations during the weeks of dredging. A second analysis included a literature review that identified critical levels of dissolved oxygen and turbidity from both a biological and regulatory perspective. Based on the critical values of turbidity and dissolved oxygen, the percentage of measurements that exceeded critical levels during dredging was evaluated. Analysis of variance tests indicated that only two of the nine studies resulted in significantly higher turbidity downstream of the dredging operations and the increase was about 15 nephelometric units (NTUs) over control turbidity (15 NTUs). Significant differences in dissolved oxygen were detected by the ANOVA, but mean downstream DO wa_s actually higher than the upstream reference location by about 0. 1 mg/I. A literature review suggested that concentrations of suspended solids can reach · thousands of milligrams per liter before an acute toxic reaction is expected in fish and that dissolved oxygen concentrations above 4 mg/I is required by striped bass. Based on the literature review and Delaware River Basin Commission's water quality standards, protective critical levels of 150 NTUs for turbidity and 4 mg/I for DO were ~elected. In more than 10,500 measurements, turbidity values greater than the critical level of 150 NTUs occurred only 13 times, and 7 of these observations occurred downstream of the Hog Island dredging operation. Over ninety-nine percent of dissolved oxygen measurements taken in downstream areas during dredging were above 4 mg/I and the percentage of observations below this critical level was not statistically different between the upstream reference and the downstream monitoring locations. Analysis of these data suggest that the bucket dredging carried out in 1992 did not result in adverse, biologically meaningful changes in DO or turbidity in the Delaware River