Animal behavior

The Sargassum community is comprised of a unique and diverse assemblage of organisms. Habitat detection by two of the most common invertebrates, Latreutes fucorum and Leander tenuicornis , was investigated. Results of this study do not support that either L. fucorum or L. tenuicornis respond to chemical cues released by the Sargassum habitat in the absence of other information. Habitat selection of both shrimp species was examined as well. Both L. fucorum and L. tenuicornis selected live Sargassum over artificial Sargassum . Moreover, L. fucorum selected Sargassum natans over Sargassum fluitans when only visual cues were available, whereas large-sized L. tenuicornis selected S. fluitans under the same conditions. Conversely, habitat selection trials combining both chemical and visual cues resulted in no preference between the two Sargassum species by either shrimp species. Additional ecological factors that possibly influence habitat location and selection are discussed as well as the importance of Sargassum in terms of pelagic fisheries management.

Investigation of the spatio-temporal movements of leatherback sea turtles (Dermochelys coriacea) and ocean sunfishes (family Molidae), as well as analyses of their prey, support the hypothesis that they may occupy similar ecological niches. This study examined the spatial and temporal occurrences of sunfishes (Mola mola and Masturus lanceolatus) and leatherbacks in the western Atlantic Ocean and assessed dietary overlap. Analyses of leatherback and sunfish distributions, estimated from aerial surveys, showed greater spatial and temporal overlap along the Northeast coast of North America than in the Gulf of Mexico. Both species co-occur more often during warmer months. Pelagic longline fisheries bycatch data and aerial survey data revealed slightly different trends in spatio-temporal distributions. Nematocysts found within gastrointestinal tract contents of stranded animals indicate that they may feed on similar prey, including cnidarians in the classes Scyphozoa, Hydrozoa, and Cubozoa.

This study's objectives were to determine if coastal (shallow-water, oceanic reef) aggregations of juvenile green turtles (Chelonia mydas L.) in Palm Beach, Florida occupied distinct home ranges and how these home ranges compared in size and resource availability with those studied elsewhere. Six immature green turtles were captured, measured, and subjected to esophageal lavage to determine diet. Each turtle was returned to its initial capture site within 24 h with an ultrasonic transmitter used to track movements. All turtles were <65 cm SCL, had ingested similar macroalgae, and occupied markedly small home ranges (mean = 2.38 +/- 1.78 km 2), largely restricted to the reef itself. Diving and feeding activity peaked during the day; at night, activity was minimal. The food and sleeping site resource distribution at this specific location coincides with the turtles' home range size and shape, with considerable overlap of core areas.

Changes in activity related oxygen consumption and energy partitioning were measured in leatherback and olive ridley sea turtle hatchlings over their first month after nest emergence. Leatherbacks emerge with about 75--90 KJ of energy in the residual yolk at their disposal for growth and movement. In comparison, the residual yolk energy reserves for the olive ridley are estimated to be much less (45 KJ). In leatherbacks resting specific oxygen consumption rates decreased by 53% over the first post-hatching month (0.0065 ml O2 min-1 g-1--0.0031 ml O2 min-1 g-1), while for ridleys the fall was 32% (0.0038 ml O2 min-1 g-1--0.0026 ml O2 min-1 g-1). Greater differences were seen in aerobic scope. For olive ridleys the factorial aerobic scope doubled over the first month but there was no significant increase in the leatherback's factorial aerobic scope. Leatherback hatchlings gained on average 33% body mass (10 g) over the first week however 70 to 80% of this increase was due to water accumulation. The differences in aerobic scope and energy reserves are related to differences in early life ecological stratagems of these species.

Discipline was implemented by mothers and alloparent spotted dolphins (Stenella frontalis) mothers and alloparents on Little Bahama Bank, Bahamas. Disciplinarians were significantly more likely to be adults than juveniles. Although most disciplinarians were female, males were also observed to perform discipline. The recipients of discipline were male and female, and significantly more likely to be calves than juveniles. Pursuit, contact, and display behaviors were used in discipline, however pursuit behaviors were most often observed. Variables such as age class, sex, and parity were not found to influence how discipline was implemented. The durations of all disciplinary pursuits were under thirty seconds, and successful pursuits had slightly shorter duration than unsuccessful pursuits. Disciplinarian success was not significantly influenced by age class, sex, parity, or behavior used.

Pelagic Sargassum was used to determine the effects of habitat architecture for one species of shrimp (Leander tenuicornis) and two species of fish (Stephanolepis hispidus and Histrio histrio). Inter-thallus spacing (low, medium, and high) and depth (shallow versus deep) were manipulated independently to test whether the spatial components of habitat architecture. Two differing habitats (Sargassum versus seagrass species) were tested for the structural component of habitat architecture. There were no significant results for inter-thallus spacing experiments for L. tenuicornis and S. hispidus. H histrio selected habitats with medium inter-thallus spacing in two treatments. Large individual H. histrio contributed mostly to the significant effects. All three species selected habitats with a greater depth aspect. Finally, L. tenuicornis and H. histrio selected habitats with greater structural complexity (i.e., Sargassum). These results demonstrate clearly that habitat architecture of Sargassum influences habitat selection by these shrimp and fishes.

The Sargassum community consists of a unique and idverse assemblage of fauna critical to pelagic food chains. Associated organisms presumably have adaptations to assist in finding Sargassum. This study investigated cues used for habitat location and selection by the Sargassum crab, Portunus sayi. Chemical detection trials were conducted with a two-chamber choice apparatus with Sargassum spp. and Thalassia testudinum as source odors. Visual detection trials (devoid of chemical cues) and habitat selection trials were conducted in which crabs were given a choice of habitats. Results showed that P. sayi respoded to chemical odors from Sargassum spp. Crabs visually located habitats but did not visually distinguish between different habitats. In habitat selection trials, crabs selected Sargassum spp. over artificial Sargassum and T. testudinum. These results suggest that crabs isolated from Sargassum likely use chemoreception from longer distances ; within visual proximity of a potential patch, crabs use both chemical and visual information.

The photopollution of beaches caused by artificial light sources can interfere with sea turtle hatchlings' ability to orient properly towards the sea. Exhaustion due to extended disorientation crawling may then increase hatchling mortality. This study evaluated the energetic consequences of long-distance crawls in green and loggerhead sea turtle hatchlings. Turtles crawled for 200 m or 500 m on a treadmill, followed by a 30 minute evaluation of swim performance. Metabolic activity was quantified via measures of blood glucose, blood lactate, and oxygen consumption. No significant changes in metabolism resulted from long-distance crawling activity in loggerheads ; however, loggerheads rested for extended periods of time during the crawl trials, often unresponsive to stimuli. This behavior implies that loggerhead hatchlings would be vulnerable to predation or temperature stress due to exhaustion from extended periods of crawling. Further data is required to draw any significant conclusions about long-term disorientatin crawling in green hatchlings.

Previous research into people's perceptions of animals suggests that people view animals most favorably when they perceive them as being mentally like humans. This thesis examined whether animals perceived as threatening are still seen to be mentally similar to humans, but more likely to experience mental states associated with anger and aggression. Using three separate measures of people's perceptions of animals, including one designed for this study, it was found that participants did indeed view the mental lives of animals differently when those animals were perceived to be threatening. Examination of the effect of the animal chosen showed that some animals are inherently seen as more threatening and less-human like. The implications of these findings for animal conservation efforts, reduction of human-animal conflict, and anthropomorphism in the study of animal cognition were discussed.