Conservation ecology of the Cape clawless otter, Aonyx capensis, in an urban environment

Coastal cities have impacted negatively on freshwater and marine ecosystems - primarily through habitat loss, fragmentation and pollution. Globally, it has been found that otter's dependence on these ecosystems exposes them to a myriad of threats, including loss of habitat, human-wildlife conflict and the bioaccumulation of toxic pollutants. The Cape clawless otter, Aonyx capensis, is the most widely distributed otter species in southern Africa and persists in human-modified habitats, including large cities. The Cape Peninsula provides a unique opportunity to study the impacts of urbanisation on otters as it presents a gradient from densely populated urban areas in the north (City of Cape Town) to sparsely populated areas interspersed with large expanses of natural habitat (Table Mountain National Park) in the south. In this thesis, I investigate the distribution, diet and threats to otters living on the Cape Peninsula. I use sign-based occupancy surveys to determine both broad and fine scale drivers of otter presence within the Peninsula's river systems and predicted that otters would avoid densely populated urban areas and rivers or sections thereof that are heavily transformed and polluted. I collected spraint from living otters and vibrissae from dead otters to investigate their diet. I predicted that otters would show an increased reliance on marine foods in areas where freshwater habitats were degraded in addition to seasonal variation in diet associated with the marked seasonal variation in rainfall and primary productivity typical of temperate Mediterranean ecosystems. I explored both immediate and long-term threats to otters by collating all records of conflict, injury and mortality reported over 5 years in addition to determining PCB levels from road-killed otters. Contrary to my predictions, otters did not avoid urban areas, and were more frequently detected in transformed lowland freshwater river systems close to Marine Protected Areas (MPA). Within rivers otters avoided the relatively pristine, yet ...