Biology and ecology of athecate hydroids in Biscayne Bay, Florida: Potential use as bioindicators

This dissertation is a study evaluating the use of athecate hydroids as water quality bioindicators according to current EPA guidelines. The hydroid fauna of Biscayne Bay was examined to ascertain the relative abundance and distribution of taxon present. Both thecate and athecate hydroids were found within the bay; however, the distributions of the hydroids differed drastically. Athecate hydroids were found in great abundance in the eastern and western halves of the bay, while thecate hydroids were found predominantly in the eastern portions of the bay. The most abundant athecate hydroids were Eudendrium carneum and Halocordyle disticha. Reproduction and recruitment of both athecate hydroids was variable throughout the year.; The distribution of E. carneum in Biscayne Bay suggested the ability of the hydroid to persist and adapt to the highly variable environmental conditions found in the western portions of the bay. Reciprocal transplants of E. carneum and H. disticha demonstrated competitive exclusion coaction and the ability to maintain exclusion in non-preferred habitats for both hydroids. Experimental laboratory testing using nutrients, Atrazine, Malathion, and Coppercide demonstrated E. carneum responded to alterations in ambient water quality on the time scale of 1 week by changes in overall colony size. Eudendrium carneum placed in various locations throughout Biscayne Bay responded with different changes in total colony size of to various water qualities found within the bay. Recommendations for further study and increased sensitivity analysis are included.