Effects Of Different Salinities On Maturation Period Of Acartia Clausi Copepod Of Caspian Sea

Abstract

The present study was conducted to evaluate the effects of salinity on maturation rate of Acartia clausi which is a copepod in Caspian Sea. The experiment was done during March to April 2007 and the referred zooplankton was collected from southern coast of Caspian Sea via plankton net. The gathered zooplankton was introduced to culture tanks for mass production. Afterwards Acartia clausi nauplius was isolated from tanks and transferred to four different salinities (07, 13, 18, 24psu) with three replicates in separate glass dishes in order to obtain growth and maturation. An equal mixture of Isochrasis galbana and Chaetoceros sp. alga were used for nauplii daily feeding. Statistic analysis indicated significant differences among the salinity treatments in the time of maturation (p<0.05). However, maturation period in salinities of 7, 13, 18 and 24psu was prolonged to 285.6, 268.8, 288 and 396 hours respectively. In addition, the results of Duncans averages comparison test showed that the 13psu salinity caused the lowest time for the maturation of 50% of the population, and this salinity obtained the first rank (a) among other salinity groups.