UC San Diego
Foraging ecology, biogeography, and population biology of seabird and toothed whale predators in the Anthropocene
- Author(s): Joyce, Trevor William
- Advisor(s): Ballance, Lisa T
- Dayton, Paul K
- et al.
The human capacity to expand niche breadth through cultural evolution has propelled humans into keystone ecological roles in many ecosystems. In particular terrestrial animal assemblages have experienced radical reductions in diversity and size distribution. Oceanic habitats have experienced shorter histories of exploitation and typically retain faunal assemblages that more closely resemble pre-human Pleistocene assemblages. Although the direct harvest of many marine mammal and seabird species has diminished in recent decades, these assemblages now face an onslaught of novel human impacts in marine and oceanic island habitats. Stressors range from noise and chemical pollution to the introduction of invasive mammalian predators on oceanic islands. To develop a better understanding of how these disparate effects will impact the ecologies and conservation statuses of wide-ranging, dynamic, and patchy seabird and marine mammal populations, this dissertation leveraged the use of two extensive observational datasets collected by and in collaboration with the NOAA-NMFS Southwest Fisheries Science Center. In the first section (Chapters 1-3) I used satellite tag and biopsy sampling 1) to describe vertical habitat use and biogeographic distribution patterns, and 2) to develop a systematic framework to better understand foraging ecology trade-offs in seven species of toothed whales from the Bahamas. In the second section (Chapters 4-5) I have applied innovative modeling techniques to estimate population abundance and growth rate parameters using an extensive time series of seabird transect surveys. These parameters play critical roles in assessing population status and developing strategic management decisions.