Scartella cristata - Amazon S3

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time. A similar pattern has been observed in demographically distinct local populations of the parrotfish
Chlorurus sordidus from widespread locations on Australia’s Great Barrier Reef (Dudgeon et al. 2000).
Analysis of blennies from a larger number of sample sites will be needed to fully explore the plausibility
of this scenario.
Biogeography of Blennies on Texas Jetties
A transition in the species composition of blenny assemblages appears to occur on the middle
Texas coast. This area may represent a biogeographic break for several blenny species due to current
patterns and environmental tolerances of these taxa. The Texas coast receives a convergence of northward
and southward flowing longshore currents (Fig. 25). The exact location of this convergence varies by
season; it is located near Matagorda Bay in summer and near the mouth of the Rio Grande throughout the
rest of the year (Cochrane and Kelly 1986, Britton and Morton 1989, Cho et al. 1998). The Texas coast
also provides transition between subtropical and temperate climatic regimes (Britton and Morton 1989).
Two species, Labrisomus nuchipinnis and Hypleurochilus geminatus, appear to reach the limits of their
distribution on the Texas coast near Port Aransas. Failure to encounter L. nuchipinnis north of Port
Aransas conforms to previous descriptions (Springer 1958, Hoese and Moore 1998) of this tropicalsubtropical
species’ range. H. geminatus, a more temperate species (Hoese and Moore 1998), was rarely
encountered south of Port Aransas. These distributional patterns may be indicative of these species’
environmental tolerances and/or probable sources of initial recruits to Texas jetties. Even though L.
nuchipinnis occur on hard shores of the eastern Gulf, they are more typically associated with warmer
waters of the Caribbean and southern Atlantic (Hoese and Moore 1998). Their observed distribution on
Texas jetties suggests that the original source population(s) is located in the southern Gulf or Caribbean.
Whether environmental conditions are favorable to this species’ colonization north of Port Aransas may be
irrelevant if prevailing current patterns prevent transport of their larvae. H. geminatus is common along
the southeastern U.S. coast (Lindquist and Chandler 1978, Hoese and Moore 1998) and is a frequent
inhabitant of Florida jetties (Hastings 1979). Based upon its distribution on Texas jetties, the most
probable source population for H. geminatus would be from the eastern Gulf of Mexico. If H. geminatus
recruits to Texas jetties originated in the southern Gulf or Caribbean then South Padre Island should host a