Morphometric features of the branchiopod belonging to Artemia Leach, 1819 genus in Sivash Bay
Authors:   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”), Semik A. M. , Zamyatina E. A. ,   Russian Federal Research Institute of Fisheries and Oceanography (FSBSI “VNIRO”), Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”)
Published: December 2024

Background. The increase in the catch volumes of Artemia (brine shrimp) in the 21st century exacerbated the need for development of the measures for conservation and rational exploitation of this valuable aquatic living resource. Relevance. The Republic of Crimea, due to the favorable environment in Sivash Bay, is in possession of considerable Artemia stocks. The variation in the water and salinity regime of Sivash Bay over the last decades necessitates a thorough examination of the biology of these crustaceans in the changing environment, as well as investigation of their morphometric characteristics. The aim of this study is to investigate the morphometric parameters of the brachiopod brine shrimp (Artemia Leach, 1819) of Sivash Bay. Methods. A correlation analysis of the morphometric parameters (9 morphological characters and 3 meristic characters) of Artemia males and females has been conducted. Collection and laboratory processing of the hydrobiological samples have been carried out following the standard practices. For plankton sampling, the Apstein plankton net has been used. Water salinity has been identified with refractometric salinometer, and water temperature has been measured with Kelilong thermometer. The samples have been fixed with 4 % formaldehyde; their laboratory processing has been conducted using a stereoscopic microscope; the weight of the investigated organisms has been measured with analytical balances accurate to 0.0001 g. Results. Water and salinity regime of some Sivash Bay areas has been identified; it is found to be determined by the geographical features of the bay and seasonal precipitation. Geographically, the water salinity increases from east to west in the Western Sivash Bay and from north to south in the Eastern Sivash Bay. In Sivash Bay, both parthenogenetic and bisexual populations of brine shrimp have been identified. The female individuals are characterized by a greater body length as compared to the male ones. The furcal values in the females and the abdominal values in the males have been found to be the most variable parameters. Conclusion. Comparative analysis of the morphometric parameters in the mature Artemia individuals has shown their dissimilarity for males and females. The normal distribution has been recorded for the total body length (tl) and the abdomen length (al), the head capsule width (hw), the eye diameter (ed), and the cephalothorax length (cl), while the bimodal distribution has been recorded for the furca length (fl), the relation of the furca length to the abdomen length (fl/al), and the relation of the cephalothorax length to the abdomen length (cl/al). No relation has been found for the abdomen length and the abdomen width in females (r=0.01); the relation of the abdomen length to the total body length shows strong correlation (r=-0.97). In females, contingency of the morphometric parameters was strong in 25.7 % out of all compared pairs; it was average in 18.2 % of cases, weak in 45.5 %, and absent in 10.6 %. In males, it was strong in 39.4 % out of all compared pairs, average in 31.8 %, weak in 9.1 %, and absent in 19.7 %.