Bourne, Godfrey R.

Rock and coral reef fishes are known to select their habitat, and selection oftentimes involves the settlement of pelagic larval stages. Thus, I examined the short-term temporal relationship between artificial reef morphology and the composition of warm-water reef fish assemblages 30 m offshore of the Town of Palm Beach, Florida. Correlations were found between reef height and total fish abundance and species richness. Reef height was also correlated with log transformed numbers of juveniles. Horizontal opening size showed an inverse correlation with species richness and a weak inverse trend with juvenile abundance. Furthermore, vertical openings were directly proportional to juvenile and total fish abundance, and to species richness. Piscivore abundance was weakly influenced by presence and dimensions of vertical crevices. Thus, artificial reefs with many varied-sized vertical crevices are most desirable for attracting juvenile warm-water reef fishes.

Dolphins emit distinct vocalizations in the contexts of stressful situations, such as when captured in nets. It has been assumed among animal rights groups that the presence of human swimmers causes stress in captive Atlantic bottlenose dolphins (Tursiops truncatus). Stress may be expressed in dolphin vocalizations and the associated visual behaviors before, during, and after swim sessions with humans. Thus, these behaviors were recorded to elucidate quantitative vocal patterns suggestive of conspecific stress. Significant differences among vocalization types within sample sessions were found only for whistles between During II and After sessions. Other comparisons indicated no significant differences for vocalization production frequencies between the presence or absence of human swimmers. Additionally, correlations found among the seven vocalization types and all five sample sessions indicated only that one variable, i.e. the presence or absence of human swimmers, was being measured in several different ways (by the different vocalization type production frequencies). Thus, conspecific stress, if indeed it can be measured by vocalization production frequency, does not appear to occur more often in the presence of human swimmers.

Small clear and blackwater streams of the neotropics are economically important because they may be nursery grounds for important food and aquarium fishes. At present, these ecosystems are being negatively impacted by current logging, and gold and diamond mining practices. Thus, the role of biotic and abiotic factors in fish community structure was examined in three unimpacted streams in Guyana, South America. These streams had relatively low fish species diversity, but complex feeding guild structure. No significant correlations between abiotic factors and fish species diversity and feeding guild diversity were determined due to small sample size. However, principal component analysis suggested an association between pH and species diversity, and conductivity and guild diversity. Biotic factors, such as competition and predation may be the primary determinant of fish community structure and organization in neotropical blackwater streams.

The relationship between patterns of association, and the rates and distribution of behaviors that are considered stressful in Atlantic bottlenose dolphins (Tursiops truncatus) in a swim program with humans is poorly understood. This relationship was elucidated by measuring stress indirectly through the occurrence of behaviors previously reported when dolphins were captured in nets. Comparisons of patterns of association, and behavioral repertoires recorded before, during, and after swim sessions with humans, indicated no significant change in patterns of association due to human swimmers. There were no correlations between frequencies of interaction, behavioral repertoires, and position in the dominance hierarchy for dolphins that interacted more with humans. Furthermore, rates of air inspiration, and aggression did not increase in the presence of humans. These findings suggest that swimming with humans does not appear to induce stress in dolphins.

The relationship between heterospecific aggression and dispersion in sea anemones is poorly understood. This relationship was elucidated for Bartholomea annulata Leseur and Aiptasia pallida Verrill at a quarry in the Florida Keys. Laboratory experiments indicated that B. annulata was the aggressor. Individuals of both species moved to avoid contact under both laboratory and field conditions. Field assessment of dispersion revealed aggregated patterns, as well as vertical segregation between the species. Bartholomea annulata was most abundant at a depth of 0.75 m, while A. pallida dominated at the surface. Heterospecific aggression may be just one but probably an important one of several factors mediating the spatial distribution of these two sea anemones.