The occurrence and distribution of hydroids in the Galveston Bay, Texas area.




Defenbaugh, R.

Journal Title

Journal ISSN

Volume Title



Study materials were collected at approximately monthly intervals, from June 1968 to September 1969, in the Galveston Bay area. Collecting locations included the front beaches of Galveston Island and Bolivar Peninsula, East Bay, West Bay, San Luis Pass, Lower Galveston Bay, and East Lagoon. Nearshore dredge samples collected by other workers were also examined. Specimens were narcotized with magensium sulfate, preserved on 4% formalin, and stored in 70% ethanol. Salinities, temperatures, and offshore depths were recorded. Verifications and corrections were made by Miss Joann Allwein, of the Zoology Department, North Carolina State University. Only 29 species are represented in the 210 collections examined. Nine are new to the Texas coast (), one is new for the Gulf of Mexico(), and one is new for the Atlantic coast(). Three species are believed to be new. Three hydroid faunas, based on substrate, are recognized. The typical hydroid fauna consists of species occurring on any suitable substrate (pilings, rocks, submerged debris, etc. ) and includes Bimeria franciscana, Bougainvillia inaequalis, *Eudendrium exiguum, *E. eximium, Stylactis n. sp., Ectopluera gradis, Tubularai crocea, Clytia coronata, C.cylindrica, ***C. longitheca, Gonothyraea gracilis, Obelia bicuspidata, O. dichotoma, *Lovenella grandis, and *Halecium bermudense. The sargassum fauna includes species commonly or exclusively occurring on floating sargassum weed: Zanclea costata, *Perigonimus jonesi Clytia cornoata, C. cylindrica, *C. johnstoni, C. noliformis, Gonothyraea gracilis, Obelia bicuspidata, O. dichotoma, O. geniculata, *Sertularia mayeri, *Plumularia floridana, and Aglaopheniz latecarinata. The invertebrate epifauna includes species common on other invertebrates (e.f., other hydroids, worm tubes, bivalves, gastropods, barnacles, hermit crabs, swimming crabs, etc.): Bougainvillia inaequalis **Perigonimus repens, Hydractinia echinata, Podocoryne carnea, Clytia coronata, C. cylindrica, Gonothyraea gracilis, Obelia bicuspidata, O. dichotoma, Lovenella n. sp., *L. gracilis, and Campalecium n. sp. The monthly occurrence, distribution in the Galveston Bay area, and literature reports of each species are mentioned. The relative paucity of hydroids in the Galveston Bay area (when compared to other areas which have been well studied) is attributed to lack of previous collecting effort, intolerance to widely fluctuating salinity and temperature conditions common in shallow Texas bays, and failure to repopulate following Pleistocene decimation. A comparison with species reported from the southern Atlantic coast and in the Caribbean indicates affinities with both regions, but slightly closer to the former. Limitations of the study included limited collecting effort and limited availability of offshore samples. Samples from other areas in the Gulf of Mexico are solicited, for inclusion in a later study.


p. 387-388.


hydroids, ecological distribution, dredged samples, monthly distribution, vertical distribution, temporal distribution