UC Santa Cruz

Species interactions are at the center of every ecosystem, determining ecosystem functioning. More frequent disease outbreaks and species range shifts due to climate change can alter species interactions, leaving lasting impacts on ecosystems. Current conservation practices concentrate on single-species plans, not incorporating species interactions into management decisions. In this dissertation, I focus on the endangered black abalone, Haliotis cracherodii, and the recovery of the California Channel Islands population from fatal Withering Syndrome, a disease that depleted roughly 90% of the southern California population. Review of the population is necessary as southern sea otters, a natural abalone predator and threatened species, are shifting ranges to the islands for the first time in 100 years, creating a policy conundrum with no direct answer. In the following chapters, I explore the potential for recovery, restoration and management through a multidisciplinary approach linking together science and policy. In my first chapter, I examine the Northern Channel Island black abalone populations through field surveys, determining population size, size distribution, density, and vulnerability to otter predation. The data reveals a mix of positive indicators for reproductive and recovery success, including aggregation and recruitment, as well as some negative markers, such as over 50% susceptibility to otter predation and low population density, possibly impeding further recover. In my second chapter, I record community structure of abalone habitat on Santa Cruz Island through a point-intercept method. I compare communities of different habitat quality, sites, and presence or absence of abalone, as well as assess patterns of specific species in abalone habitat. Results show a difference in community structure of varying habitat qualities and sites, but not those with and without abalone. Examination of species patterns suggests an association of communities of better quality with crustose coralline algae and bare rock, and of those of lower quality with barnacles and the fouling sand-castle worm. These results point to strategies for future abalone recovery efforts at the community level. In my third chapter, I take the ecological reality of two protected species interacting and determine what type of management and policy strategies exist to solve issues from co-listed species interactions. I find that while there are many examples of these interactions and management and policy agencies are moving toward ecosystem management, there is no given solution, prompting a need for collaboration between policy-makers, managers and scientists to come up with creative conservation solutions that avoid conflicting recovery strategies. Finally, I conclude with key insights of this work, suggesting the collection and application of the best scientific evidence available to guide recovery, management and policy for protected species. The use of multiple strategies to gain knowledge from different viewpoints is necessary to attain a comprehensive picture of recovery that can be implemented to achieve conservation goals.