In coastal environments, many abiotic and biotic factors can influence daily movement patterns and behaviors of marine predators including foraging efforts, refuging from their own predators, and mating success. California horn sharks (Heterodontus francisci) are demersal, nocturnally active sharks, resident to temperate rocky reef communities. While they are a relatively small, sedentary and abundant species, little is known about their behavior and ecology. This study used active acoustic tracking methods and accelerometers to quantify the diel, fine-scale spatial movements, activity patterns, and sheltering behaviors of horn sharks to better understand their ecological role in rocky reef habitats. Results indicate horn sharks exhibit central place foraging behaviors, resting in a central place (i.e., shelter) during the day, and increasing activity space while navigating to different reefs at night. During nighttime travels, horn sharks exhibited area restricted search patterns, which identified the locations of potentially profitable habitat, or ‘activity hotspots’. While refuging in shelters during the day, horn sharks were vertically distributed by size and mature sharks were sexually segregated, which may partition conspecific resources and allow for a larger resident population. Limited resources during El Niño conditions reduced horn shark body condition and den fidelity. I hypothesize that individual resource preferences (i.e., prey, shelter habitat) could be driving intra-specific differences in patch use, reef fidelity, and sheltering behaviors. By understanding how horn sharks partition their resources and respond to changing climatic conditions, my data provide new insight to how a kelp bed meso-predator spatially and temporally uses its habitat and maximizes ecological fitness.
|Advisor:||Lowe, Christopher G.|
|Commitee:||Allen, Bengt, Papastamatiou, Yannis|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 81/3(E), Masters Abstracts International|
|Subjects:||Biology, Ecology, Biological oceanography|
|Keywords:||Accelerometer, Acoustic telemetry, Area restricted search, El Niño, Horn shark, Sheltering behavior|
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