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2 2022

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Effects of fishing and environmental parameters on the commercial bony fish assemblage in the southern Caspian Sea

Fazli Hasan, Kaymaram Farhad, Daryanabard Gholam Reza

Oceanological and Hydrobiological Studies

2022

Vol. 51, No. 1

90--99

Since the 1990s, anthropogenic activities have been the major direct or indirect threats to the structural and functional organization of the unique ecosystem of the Caspian Sea (CS). This study attempts to investigate the relationships between fish community structure and environmental parameters and to analyze the Abundance Biomass Comparison (ABC) in the CS. The input data, including catch data by species and environmental parameters, were collected from 1996 to 2017. Of the 13 bony fish species identified, only two species Rutilus kutum and Chelon aurata accounted for 47.14% and 62.65%, and 40.80% and 29.34% of CPUE and NPUE, respectively. DisTLM revealed that five environmental variables showed a significant linear relationship with the NPUE resemblance matrix. Based on the AIC criteria, the combination of year, precipitation, SST_Apr, SSL, SST, GTA, Iranian rivers, and Volga discharges explain 80.3% of the total variability. Based on the ABC curves and W statistics, it was concluded that the fish assemblage was environmentally stressed from 1996 to 2003. The Shannon diversity index (H′) showed a decreasing trend, suggesting that fish species have been exposed to increasing stress over the past 22 years. Considering the current environmental conditions (downward trend in SSL river discharge and increase in SST) and anthropogenic activities, it appears that the downward trend will continue in the future.

Comparative physiological aspects of plasma hemostasis of some commercial fish species

Alobaidy Holya, Saleem Hayder Dawood, Al-Dhalimy Aiman Mohammed Baqir

Journal of Water and Land Development

2022

no. 54

239--242

The hemostasis system is designed to ensure the integrity of the body’s internal environment, stop bleeding, and maintain a liquid state of blood in the vascular channel. Modern biological and veterinary science presents highly fragmented and scarce data containing clinical and diagnostic clotting characteristics in different fish species. An essential point emphasising the practical component of such studies is spontaneous thrombus formation in fish farming described in the literature. The present research is devoted to the study of the functional state of plasma hemostasis in some ray-finned commercial fishes: phylogenetically more ancient cartilaginous ganoids - sturgeon Acipenser baerii and hybrid of sterlet A. ruthenus and starred sturgeon A. stellatus, as well as bony fishes - carp Cyprinus carpio and tilapia Oreochromis niloticus. It should be noted that the current study was performed at the aquaculture development center “AquaBioCenter” of VSDFA from 2015 to 2020. Species-specific features of clotting were revealed: activation by common and extrinsic pathways, characterised by thrombin time (TT), prothrombin time (PT), and fibrinogen concentration, is several times faster in cartilaginous ganoids than in both bony fish species; hemostasis with activation of the intrinsic pathway, characterised by activated partial thromboplastin time (APTT), is faster in hybrids and tilapias, in contrast to carps and sturgeons. Content of soluble fibrin monomer complexes (SFMC) in all fish was higher than in dogs and humans but lower than in cattle. The highest amount of SFMC was detected in carps, the lowest - in cartilaginous ganoids.