Scartella cristata - Amazon S3

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the biotic community continues to evolve on Texas jetties. Other studies on Florida and South Carolina
jetties have noted dominance of H. geminatus (Hastings 1979, Van Dolah 1984, 1987), but may not have
been sufficient in duration to observe the colonization of S. cristata. The latter species appears to be
tolerant of the entire spectrum of environmental conditions (temperature, salinity, turbidity, and habitat
complexity) along the Texas coast. A lack of more detailed information on the biology of other
constituent species for comparison, particularly H. geminatus, makes it difficult to explain why S. cristata
is so successful on Texas jetties.
Scartella cristata’s total dominance of other blenniids through competitive exclusion may be
possible only under the environmental conditions and habitat quality of the central and lower Texas coast.
Woodland (1999) found this type of exclusion and dominance based on differences in local condition
demonstrated by the Family Signidae, a family of herbivorous reef fishes in the western Pacific.
Conversely, the more temperate species such as Hypleurochilus geminatus may not compete as well as
Scartella cristata in the more subtropical waters of the central and lower Texas coast. Clarke (1989, 1992)
found that the higher metabolic rate of Acanthemblemaria spinosa, a tube dwelling chaenopsid blenny,
allowed it to displace a congener, Acanthemblemaria aspera, from preferred, higher quality habitat and
facilitating a higher growth rate in A. spinosa. A more tropical species, such as S. cristata, may have a
higher metabolic rate giving it an advantage in agonistic interactions as seen in A. spinosa (Clarke 1992).
Differential growth rates between species may be an important underlying explanation for why
certain species dominate (Jones 1991) or a result of competive interactions between species (Clarke 1992).
With growth, fishes typically decrease their vulnerability to predation, increase their fecundity, and, in
territorial species such as blennies, increase the size of territory they can or need to defend (Stephens et al.
1970, Phillips and Swears 1979, Jones 1991, Goncalves and Almada 1998). A blenniid species reaching a
large size quicker than a competing species has the edge in not only holding more territory, but also
producing more offspring. Consequently, a faster growing species has the potential to exclude a slower
growing species from a given area over time. Further work with additional blenniid species, particularly
Hypleurochilus geminatus, will determine if this is the case on Texas jetties.
The Genetic Structure of Scartella cristata on Texas Jetties