The food habits of four kelp-bed rockfishes (Scorpaenidae, Sebastes) off Santa Barbara, California

The diets of four common rockfishes from the kelp beds near Santa Barbara, California, were determined by gut contents analysis, and related to feeding strategies. The guts of one hundred specimens of each species were examined, and the importance of prey evaluated by their frequency of occurrence, numbers, and volumes. The volumes of stomach contents were standardized for the size of specimen. Estimates of overlap in diet between the species were made. Sebastes atrovirens fed primarily on small animals from the kelp canopy, and may have employed a browsing rather than pursuing strategy of feeding. It showed low overlap in diet with the three bottom-dwelling species, S. carnatus, S. chrysomelas, and S. vexillaris, all of which preferred larger types of prey and seemed more like pursuers. The closely related S. carnatus and S. chrysomelas were quite similar in diet, eating primarily medium sized demersal invertebrates, especially crabs and shrimp. S. vexillaris ate fewer crabs and shrimp but more large-sized fish and octopus than the latter two species. Its more active life style indicates that it may react to prey at greater distances and have a larger home range than these species, as has been predicted for pursuers feeding on larger (and rarer) prey.

Body shape variation and colour change during growth in a protogynous fish

Protogynous sequential hermaphroditism is very common in marine fish. Despite a large number of studies on various aspects of sequential hermaphroditism in fish, the relationship between body shape and colour during growth in dichromatic species has not been assessed. Using geometric morphometrics, the present study explores the relationship between growth, body shape and colouration in Coris julis (L. 1758), a small protogynous labrid species with distinct colour phases. Results show that body shape change during growth is independent of change in colour phase, a result which can be explained by the biology of the species and by the social control of sex change. Also, during growth the body grows deeper and the head has a steeper profile. It is hypothesized that a deeper body and a steeper profile might have a function in agonistic interactions between terminal phase males and that the marked chromatic difference between colour phases allows the lack of strict interdependence of body shape and colour during growth.

Geographical and morphological variation within and between colour phases inCoris julis(L. 1758), a protogynous marine fish

The possible differences between sexes in patterns of morphological variation in geographical space have been explored only in gonochorist freshwater species. We explored patterns of body shape variation in geographical space in a marine sequential hermaphrodite species, Coris julis (L. 1758), analyzing variation both within and between colour phases, through the use of geometric morphometrics and spatially-explicit statistical analyses. We also tested for the association of body shape with two environmental variables: temperature and chlorophyll a concentration, as obtained from time-series of satellite-derived data. Both colour phases showed a significant morphological variation in geographical space and patterns of variation divergent between phases. Although the morphological variation was qualitatively similar, individuals in the initial colour phase showed a more marked variation than individuals in the terminal phase. Body shape showed a weak but significant correlation with environmental variables, which was more pronounced in primary specimens.

Traditional and geometric morphometrics detect morphological variation of lower pharyngeal jaw inCoris julis(Teleostei, Labridae)

In the present study, variation in the morphology of the lower pharyngeal element between two Sicilian populations of the rainbow wrasse Coris julis has been explored by the means of traditional morphometrics for size and geometric morphometrics for shape. Despite close geographical distance and probable high genetic flow between the populations, statistically significant differences have been found both for size and shape. In fact, one population shows a larger lower pharyngeal element that has a larger central tooth. Compared to the other population, this population also has medially enlarged lower pharyngeal jaws with a more pronounced convexity of the medial-posterior margin. The results are discussed in the light of a possible more pronounced durophagy of this population.