Dissertation/Thesis Abstract

Effectiveness of marine protected areas for top predators along the central West African and US west coasts
by Maxwell, Sara M., Ph.D., University of California, Santa Cruz, 2010, 218; 3421299
Abstract (Summary)

Marine protected areas (MPAs) are a popular tool to manage marine resources, but determining the effectiveness of boundaries and management strategies is critical for effective conservation, particularly as MPAs are increasingly being used in ecosystem-based management and marine spatial planning processes. Similarly, satellite telemetry has been heralded as a powerful tool in marine conservation and I apply satellite telemetry to determine MPA effectiveness using two case studies.

In the first chapter, I use telemetry to determine the nesting ecology of olive ridley sea turtles (Lepidochelys olivacea) in Gabon, Africa. Applying a state-space model to filter and determine animal behavior (n = 18), I found that olive ridleys distributions were confined to a small area; renesting events often occurred within 10 km of the original nest, and they were most frequently found within 30 km of the original nesting site between nests. The findings of this study are in keeping with those of olive ridleys studied in other parts of the world, but represent the first comprehensive study of this species in the Eastern Atlantic. Additionally, movements of this species during the internesting period suggest that because of their limited internesting movements, relatively small marine protected areas can be effectively used to protect this species during a critical life stage.

In the second chapter, I examine how olive ridleys (n = 18) use the boundaries of Mayumba National Park (MNP) in Gabon, which was created in part to protect them during the interesting period. By applying home range analyses and a predictive habitat model, I found that the boundaries of MNP incorporate only between 55.6 and 81.4 percent of high-use areas, but that if the park was expanded to include the proposed Transboundary Park (TBP) between Gabon and the Republic of Congo, between 97.3 and 100.0 percent of high-use areas would be protected. We found that the driving factors for habitat preference during the interesting period include sea surface temperature, chlorophyll a concentrations, depth, distance to coast and distance to nesting site. This model can be applied to other nesting sites along the African coast. Overall we found that satellite telemetry was an effective tool for delineating effective boundaries and management strategies of an MPA, and we support the designation of the TBP.

In the third chapter, I shift focus to the West Coast of the US and the distribution of top predators in relation to the National Marine Sanctuaries which are among the largest MPAs in the US. By examining home ranges of individual species (blue whales (Balaenoptero musculus) (n = 51), humpback whales (Megaptera novaeangliae) (n = 15), California sea lions (Zalophus californianus) (n = 111), Laysan albatrosses (Phoebastria immutabilis) (n = 33), black-footed albatrosses (Phoebastria nigripes) (n = 72), and sooty shearwaters ( Puffinus griseus) (n = 25)), I determine that the Sanctuaries incorporate significant levels of high-use areas for humpback whales, blue whales and male California sea lions, but less so for female California sea lions, black-footed albatrosses and sooty shearwaters. No high-use areas for Laysan albatrosses were found within the Sanctuaries. Top predator distribution changed considerably between years and biological seasons, with animals using the Sanctuaries in greater abundance during foraging seasons, and during cooler or more 'normal' oceanographic years. During warmer oceanographic years, animals distributed further offshore, as well as further north as foraging effort likely increased during these years. The Sanctuaries did not encompass these wider ranges during anomalously warm years, indicating a need for wider boundaries if animals are to be protected from interannual and global scale oceanographic variability.

In the fourth chapter, I examine the distribution of these same top predators in relation to the entire West Coast of the US as it relates to the California Current System. Again applying home range analyses, I determined high-density and high-use multi-species areas across years and oceanographic seasons. The upwelling and Davidson seasons had the largest density of top predators and the National Marine Sanctuaries encompassed a number of high-use and high-density areas, but we also identified under-protected areas. These areas include south of Cape Blanco and Cape Mendocino, between the Monterey Bay and Channel Islands National Marine Sanctuaries and offshore of Central California. These regions are unique oceanographic regions that result in increased productivity that is persistent across years, making them prime candidates for additional protected areas or areas that should receive special consideration in the marine spatial planning process.

Overall, I was able to show that satellite telemetry can be an effective tool in determining both effectiveness of current MPA boundaries, and in helping to determine where additional protected areas should be considered. Though an expensive conservation tool compared to other types of behavioral studies, when used appropriately, it can help to significantly guide and streamline marine resource management.

Indexing (document details)
Advisor: Moore, Andrew M.
School: University of California, Santa Cruz
School Location: United States -- California
Source: DAI-B 71/09, Dissertation Abstracts International
Subjects: Wildlife Conservation, Physical oceanography, Environmental management
Keywords: Lepidochelys olivacea, Marine protected areas, Predators, Sea turtles
Publication Number: 3421299
ISBN: 978-1-124-20354-6
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