Scartella cristata - Amazon S3

50
assemblages and their habitat requirements across the upper, middle and lower Texas coast and to what
degree Galveston, Port Aransas, and South Padre Island are representative of these features. Expansion to
cover a greater amount of potential blenny habitat would allow assessment of how effective stations used
in the present study represent Texas’ jetty system as a whole.
Size Structure
Total length of Scartella cristata and Hypleurochilus geminatus was significantly higher on
jetties on the upper and middle Texas coast than on those of the lower coast. Mean total length was
highest at Port Aransas in the case of H. geminatus and at Galveston for S. cristata. There are several
possible explanations for this pattern in S. cristata. The total n for the Galveston collections was an order
of magnitude lower than that of the other two sites; therefore, any bias toward larger individuals would
have a greater impact on the mean. It is also possible density-dependent effects, such as competition for
food or shelter, might be operating at a reduced level, thus allowing S. cristata to reach a larger size at
Galveston because the density was lower than that at the other two sites. The amount of shelter available
to smaller individuals may be limiting and thereby favor larger individuals because the structural
complexity of the habitat at Galveston was less than that at the other sites. Shelter availability and size
was found to be a determining factor in the size structure of blenny populations in rocky littoral zones of
the western Mediterranean (Patzner 1999), the rocky intertidal zone of California (Stephens et al. 1970),
and on oyster reefs along the east coast of the United States (Swearer and Phillips and Swears 1979,
Crabtree and Middaugh 1982). The precise role of rugosity on the composition and structure of blenny
assemblages is not conclusive. The location with the lowest structural complexity, Galveston, exhibited
the highest species diversity, evenness, and mean TL. There also is the possibility that large S. cristata
were present at Port Aransas and South Padre Island but were concentrated in deeper reaches of the jetty
not sampled during this study.
Stability of Blenny Assmblages
How stable is the structure and composition of blenny assemblages on Texas jetties? The only
other studies that documented blenny assemblages on jetties focused on newly constructed jetties in the
Florida panhandle (Hastings 1979) and South Carolina (Van Dolah et al. 1984, 1987) Blenny assemblages