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Open Access Publications from the University of California

Habitat Partitioning by Three Species of Dolphins in Santa Monica Bay, California

  • Author(s): Bearzi, Maddalena
  • et al.

Despite scientific advances and increases in public interest in whales and dolphins, much information is still lacking to properly understand these animals living in an environment often threatened by human activities. Previously not investigated, the Santa Monica Bay is a heavily impacted area occupied year-round by various marine mammals, including threatened species. The purpose of this proposal is to provide a means to fill the need for critical information in the area.

This study takes a “precautionary approach” which may identify potential problems thereby preventing the disappearance of this and other species from the Bay. Project methodology involves weekly field surveys from a powerboat using laptop data collection, photo- and video-recording, plankton net tows, GIS, remote biopsy sampling, and a recently developed “computer-assisted system” for use in identifying dolphins.

By building upon research begun in 1996, this project will provide an important framework on the composition, distribution, and abundance of cetacean species. This will also illustrate the likely indirect changes in marine mammal populations during the 1997-98 El Niño event and the subsequent La Niña. This framework represents a valuable opportunity to investigate how significant these events are on cetacean populations and their prey, and how populations may shift in relation to changes in oceanographic conditions.

A second phase of this project will look at bottlenose dolphin behavior and habitat use with relation to human activities in the nearshore habitats of the Bay and collect data on pollutant levels in the animals. Dolphins are apex predators in a coastal ecosystem sensitive to fluctuations of temperature, with corresponding changes in the populations of zooplankton and fish. Gathering data on dolphins, known as bio-indicators of the status of the environment, and monitoring trends in their populations, is an excellent way of protecting all marine organisms living in the local ecosystem.

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