Distribution pattern and a new coverage range index identification of zoanthids in littoral zone of Hormuz Island, Persian Gulf

Abstract

This study aimed to investigate the spatio-temporal changes in zoanthids abundances and to assess the influences of sea water parameters on their distribution. According to this, 2 sites in littoral zone of Hormuz Island were monthly studied from June 2015 to June 2016. Coverage range index (CRI) was also introduced as a new index in this study to assess the influence of the substrate composition on distribution of zoanthids. Line intercept transect method was performed to assess the zoanthid coverage along 6 transects. The results indicated significant relationship between substrate composition and coverage range of zoanthids. Hence, CRI proved to be a reliable index because of its strong fluctuations resulting mainly from total abundance of zoanthids. Also, the results indicated that zoanthids tended to colonize in low-littoral and mid-littoral zones, which are least exposed to air. Apparently, Zoanthus sansibaricus can tolerate desiccation conditions better than Palythoa cf. mutuki and Palythoa tuberculosa. From the results obtained, the abundances of 3 zoanthids during winter season showed an increasing trend, while during spring season it showed a reverse trend. Seasonal variations of sea water parameters were correlated with ecological attributes of species; where dissolved oxygen showed a positive significant correlation with mean seasonal abundance of each zoanthids at different study sites. Consequently, based on the findings of this study, zoanthids could be utilized as a bioindicator species of various environmental conditions in coastal waters.

Keywords

• abundance
• cri
• littoral zone
• substrate composition
• zoanthids