Ciliates and Other Microorganisms in the Plankton from Al-Sammaliah Island- Arabian Gulf-United Arab Emirates

Abstract

Al-Sammaliah Island is one of more than 200 islands belonging to United Arab Emirates in the Arabian Gulf. This inshore shallow island lies at the north east coast of Abu Dhabi and is connected to the Arabian Gulf through Khor Laffan. It has a surface area of about 24 km2. The abundance of ciliates at Al-Sammaliah Island water showed an annual cycle with the highest numbers (23 ml"1) in the spring, and the lowest values (5 ml'1) in the summer. The ciliate community generally was dominated by non-loricate oligotrichs, tintinnids. Other planktonic forms also in abundance. Nanoflagellates that could provide a food supply for the filter - feeding ciliates were especially numerous in the spring, but this was not the case for bacteria. The high populations of ciliates and flagellates reflect the productivity of the water column of the island while the production of bacteria will presumably be the important component at the base of the food chain at the island water. Total nanoflagellates, heterotrophic nanoflagellates and bacteria were enumerated to gain some indication of the food resources for ciliates. In this connection the filtration activities of the heterotrophic flagellates and ciliates are compared with the population densities of bacteria, flagellates and filterfeeding ciliates. The time required for the whole water body to be filtered by flagellates and ciliates was estimated.