Temporal dynamics of the ichthyoplankton assemblages in the central Aegean Sea during one year and the effects of ecological factors

Abstract

In this investigation, vertical and horizontal sampling was performed monthly, covering a year, from 16 stations situated in Sığacık Bay. In ichthyoplankton sampling, a standard-type plankton net with a 350-micron mesh size for vertical sampling and a 500-micron mesh size for horizontal sampling was used. This study aimed to investigate temporal changes in the ichthyoplankton assemblages in Sığacık Bay and their relationship with ecological factors. A total of 113 fish taxa belonging to 42 families were identified. The Sparidae, Engraulidae, and Labridae families were found to be the most dominant among the eggs and larvae, with Engraulis encrasicolus, Coris julis, Mullus barbatus, and Gobius niger being the most prevalent species. The highest biodiversity index values were observed in April and May. The cluster analysis revealed the existence of three distinct groups.Based on the SIMPER analysis, S. aurata emerges as the indicator species for months characterised by lower water temperatures, G. niger stands as the indicator species for warm months, and E. encrasicolus represents the indicator species for the hottest months group. Both distance-based linear modelling (DistLM) and distance-based redundancy analysis (dbRDA) highlighted that water temperature, salinity, and chlorophyll-a were the main variables that influenced the temporal variation of the ichthyoplankton assemblage. The results of this study will be of great significance in comprehending the responses of the ichthyoplankton assemblages residing in analogous ecosystems to ecological variables.