Effect of substrate surface on biofouling communities in the southern coast of the Caspian Sea

Biofouling is applied to the colonization, accumulation and growth of living organisms on different substrata exposed to aquatic environment. These structures include natural and artificial substrates. Biofouling communities are both economically and ecologically important. Biofoulers have basic role in transferring of energy in food chains and ecosystems functioning. Also, these communities by creating multi-dimensional substrates provide different habitats for other organisms. In economic aspects, colonization of these organisms on ship hulls, boats, aquaculture cages and marine structures such as pipelines can cause economic damages (Yebra et al., 2004; Schultz et al., 2011). In spite of all these, there are little information about these communities in the Caspian Sea and there is almost none in the Iranian coast of the Caspian Sea. This study was conducted in May 2015 till May 2016 in Astara port to investigate the effect of substrate surface on temporal variation of biofouling assemblages. Five replicates of PVC panels (12×12×0.3 cm) were deployed horizontally at 1m depth. The panels were retrieved and replaced with new series every 2 months for a period of one year. At each sampling event, upside and underside of the panels were photographed separately and then analyzed using CPCe software (Kohler and Gill, 2006) for cover percent of each surface. The biomass and inorganic to organic ratio were calculated using dry and ash weight. In total, 6 major groups including barnacles, bryozoan, algae, polychaete, mussels and hydroids were identified. Amphibalanus improvisus was the most dominated species in this study and was observed all year round. Cheilostome and Ctenostome bryozoans were the second dominant groups. These two groups mostly derived the temporal variations in studied communities. Two-way ANOVA analysis showed that the period of submersion and the surface have significant effect on cover percent, total biomass and inorganic to organic ratio of fouling communities (p