Biological productivity associated with the serpulid reefs of Baffin Bay, Texas

The upper Laguna Madre and Baffin Bay-complex has long been noted for its abundant finfish populations despite its generally persistent hypersaline condition. The purpose of this present study was to determine the contribution of the serpulid worm reefs to the productivity of Baffin Bay. The primary focus of this thesis was to test the hypothesis that fish were larger and found in higher concentrations near the serpulid worm reefs in Baffin Bay, and to quantify the abundances of potential prey items associated with the reefs. In addition, I measured the productivity (by O2 evolution) of the epiphytic algae growing on the reefs and compared it to published seagrass studies in the upper Laguna Madre. Lastly, I examined the dependence of consumers on carbon fixed by these primary producers using stable carbon isotope ratios as tracers.

A total of 5,396 individuals representing 35 fish species, were collected by trammel net during the study. Seven fish species (Mugil cephalus = 27.3 o/q Pogonias cromis = 20.2 %, Cynoscion nebulosus = 15.2 %, Leiostomus xanthurus = 12.1 %, Arius felis = 10.7 %, Lagodon rhomboides = 2.3 %, and Sciaenops ocel/atus = 1.1 %) comprised 89.0 % of the total catch. The overall ichythyofaunal catch rate was not significantly different between reef and non-reef sites and only a seasonal effect in the catch rate data was observed. Seasonal differences can be explained by the recruitment of fish into the bay in Spring and Summer. These seasonal peaks can be attributed to three species: Arius felis, Pogonias cromis, and Leiostomus xanthurus. No strong evidence was found to support the hypothesis that larger fish congregate around the serpulid worm reefs.