engleski

TWO FRESHWATER SHRIMPS (DECAPODA, CRUSTACEA) AND THEIR HABITAT CONDITIONS IN THE NERETVA DELTA, CROATIA

Two decapod species Atyaephyra desmaresti and Palaemonetes antennarius, and their representative habitats in the Neretva Delta were investigated in 1995. The aim was to cđmpare habitat conditions for these two species. Salinity oscillations, water temperature, composition of submerged vegetation as microhabitat, and seasonal breeding dynamics were observed. Both species were present in the limnic water of different habitat types in the Neretva Delta, such as springs, rivers, channels and lakes. However, both species are known to be tolerant of medium salinity oscillations. In this study, P. antennarius was found to inhabit limnic and oligohaline water (0-5), while A. desmaresti was found in habitats with larger salinity oscillations, which, occur in mesohaline water (0-9). Only A. desmaresti was observed in occasions of increased marine influence due to low seasonal freshwater inflow in dry periods. In case of exceptionally strong influence of high tide, only the marine species Palaemon adspersus was noticed in the Neretva River. Due to the influence of marine thermodynamics on freshwater thermodynamics in the delta seasonal breeding period of researched species was noticed to be longer. Therefore A. desmaresti, which occur in sites under stronger marine influence, has longer breeding period and gravid females appeared earlier (March or April to August) than P. antennarius (May or June to August). Composition of submerged vegetation in which mentioned species were found is shared, although Ceratophyllum demersum was found as microhabitat only for P. ahtennarius.

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