Characterization of seasonal and inter-annual changes in the abundance of species of marine Cladocera on the Turkish coast of the northeastern Levantine Basin

Abstract

The purpose of this study was to describe temporal variations in the abundance of cladocerans in the Mediterranean Sea in relation to environmental parameters. The study was conducted between 2008 and 2011 at five sampling stations located in the coastal waters of İskenderun Bay. Zooplankton samples were seasonally collected for four years using a 200-μm mesh WP-2 zooplankton net. The contribution of cladocerans to the total zooplankton community was 22.8% in 2008 and 9.3% in 2009. In 2010 (59.4%) and 2011 (63.4%), the annual mean abundance of cladocerans increased markedly from 473 ind. m−3to 3917 ind. m−3and accounted for more than half of the zooplankton population. A total of five species of Cladocera were found:Penilia avirostrisDana, 1849,Pseudevadne tergestina(Claus, 1877),Evadne spiniferaP. E. Müller, 1867,Pleopis polyphaemoides(Leuckart, 1859) andPodon intermediusLilljeborg, 1853.Penilia avirostriswas the most abundant species during all seasons, especially in April and July, for all four years of the study. The abundance of total cladocerans andP. avirostriswas negatively correlated with salinity () and picoplankton abundance ().P. avirostrisalso exhibited a positive correlation with phytoplankton abundance (), as well as withE. spinifera. In addition, the abundance ofE. spiniferaandP. tergestinawas positively correlated with temperature (), butP. tergestinacorrelated negatively with chlorophyll a. In conclusion, species composition and abundance of cladocerans seems to be greatly affected by the amount of available food and other environmental factors, such as temperature and salinity.