toxicity effect of Satureja rechingeri On barnacle Amphibalanus amphitrite

The life cycle of many marine invertebrates has a larval period, during which the animals usually most susceptible to environmental stress. As sensitivity is of prime concern when conducting toxicity tests, many studies have compared the sensitivity of different larval stages of the same species. Barnacles are crustacean arthropods. Barnacles are found on hard substrates in virtually all marine habitats and on all levels of the shore, often in vast numbers. This, coupled with the fact that they have a typical marine life cycle with an easily identifiable, planktonic larval stage, has made them a model study organism. The life cycle of a typical barnacle includes two stages a free-swimming larval stage and a sessile adult stage. stage In this study the toxicity effect of S.rechingeri on the larval stages of barnacles was investigated. Barnacles are a good model for toxicity studies, because have many reproduction and their larvae always are available.This test was done based on the determined LC50 in a 24 hours period on larvae of barnacles stages. The results showed the essential oil from plan (S. rechingeri) in hight concentration have the toxicity effect on larvae of barnacles.(LC50-6/20 µg/ml stage VI and LC50-28/66µ g/ml stage II). among the naupliar stages of Balanus amphitrite, stage VI is the most sensitive stage(P