Determination of δ15N in Anemonia sulcata as a pollution bioindicator

delta N-15 concentration can reveal the anthropogenic pollution of an ecosystem. To study this pollution level, this isotope can be analyzed from water or animal tissue. Sewage pipes pour anthropic waters, rich in delta N-15, to the sea. In the sewage pipes surroundings live several organisms, like the cnidarian Anemonia sulcata (Pennant, 1777). As anemones have zooxanthellae, they incorporate nitrogen from the environment. To test for the possible effects of wastewater effluents on the coastal ecosystem through the content of the isotope delta N-15, A. sulcata specimens were collected near a sewage pipe in North Tenerife (Spain), in contiguous zones to look for a delta N-15 gradient. The obtained results show that there is a gradient of delta N-15 concentration, and the highest levels were found nearest the sewage pipe (mean = 5 delta N-15 parts per thousand) and the lowest in the control zone (mean = 3.26 delta N-15 parts per thousand). Being so, A. sulcata has proven to be a sensitive organism whose delta N-15 concentration can be used as bioindicator for pollution and human involvement in the ecosystem in which it lives.