The invertebrate fauna of Texas Coast jetties; a preliminary survey.

An ecological survey of the marine invertebrate fauna was conducted on the jetties of the Texas coast during the months of June and July in 1938, 1939 and 1940. The jetties guard five passes to inland bays which are maintained as navigable waterways, but the actual rocky area constitutes a minor percentage of the total coast line, which is a sandy beach 400 miles long. The passes guarded by these jetties are subject to an annual temperature variation from 9 to 30 C. The study was confined primarily to the fauna of the intertidal community of the Texas jetties. This community, considering the coast as a whole, is composed of three speices of barnacles, one limpet, one littorine, one mussel, a Thais, an anemone, the isopod, Ligyda, and hermit crab. There are indicators of a north to south change in the relative abundance of these species, which may be correlated with mean annual salinity of the respective areas, and possibly also with wave action. Jetty fauna represents a composite colonization from various habitats, including the oyster reef, the sand and mud bottom of adjacent areas, the salt march, and possibly the sargassum. A few species, found principally on the rock works on the Texas coast, probably owe their colonization to their free living larvae.