تاثير نوع بستر بر نشست كشتي چسب (Amphibalanus improvisus (L.، 1758 در سواحل جنوبي درياي خزر

Effect of substratum type on Amphibalanus improvisus settlement in the southern coast of the Caspian Sea

كشتي چسب ها از جمله مهمترين و فراوان ترين جانوران چسبنده بسترهاي سخت مخصوصاً در نواحي جزرومدي هستند. در اين پژوهش تاثير نوع بستر بر ميزان نشست كشتي چسب Amphibalanus improvisus در طي يك سال به صورت ماهانه در منطقه بندر اميرآباد درياي خزر در سال 93-92 مورد بررسي قرار گرفت. در اين مطالعه، پنج نوع بستر شامل پنل هاي PVC، چوب، پلكسي (شيشه پلاستيك) آغشته به عصاره كشتي چسب بالغ، پلكسي صاف و پلكسي خشن در ابعاد 10×10 سانتي متر انتخاب شد. پنل ها با 10 تكرار براي هر نوع بستر به صورت افقي در عمق يك متري از سطح آب قرار داده و ماهانه با بسترهاي جديد جايگزين شدند. تعداد كشتي چسب هاي چسبيده شده بر روي هر بستر شمارش و سپس زيتوده (وزن خشك)، ميزان رشد (وزن به ازاي هر فرد) و ميزان ماده آلي و غيرآلي نمونه ها در هر ماه ثبت و محاسبه شد. نتايج نشان داد كه تراكم كشتي چسب ها بر روي پنل هاي PVC با اختلاف معني داري بيشتر از ديگر بسترها است (0/01

Barnacles are among the most important and abundant sessile animals on hard substrates, particularly in tidal areas. In this study, effect of substratum type on settlement of the bay barnacle, Amphibalanus improvisus, was investigated in Amirabad Port, Southern Caspian Sea, from August 2013 to July 2014. Five substrates (10×10 cm) including PVC, wood, Plexiglas sheets treated with barnacle adult extract, smooth sheet and roughed sheet were used. Ten replicates per substratum were horizontally deployed at 1m depth. The substrates were then monthly retrieved and replaced with new panels. Subsequently, number of settled barnacles (abundance), biomass (dry weight), growth (weight per individual) and organic to inorganic material ratio of the barnacles were recorded. The results showed that the number of the settled barnacles on the PVC panels were significantly higher compared to the other substrates (p<0.01). Furthermore, the highest density of barnacles were observed in December, while there were almost few settlers in February. The highest growth rate of barnacles occurred in July. The highest and the lowest organic to inorganic ratio were observed in December and July, respectively. Regression analysis showed that temperature is a significant factor in the growth rate of barnacles. Besides the knowledge on the temporal distribution of barnacle larvae, the results of this study have implications in selecting the material type for construction of marine infrastructures.