|
Effects of Coastal Pollution and Importance of Oceanographic Features
for Marine Mammals in the Waters off Los Angeles, California
 
Many species of marine mammals worldwide are impacted by anthropogenic threats (e.g., pollutants, plastic debris) that cause harm to these animals indirectly by degrading the areas in which they live. Gathering data on the effects of coastal pollution on dolphins and pinnipeds living in L.A. waters and monitoring trends in their populations is an important first step toward devising conservation strategies that protect the entire ecosystem.
This study focuses on the effects of coastal pollutants on the abundance and distribution of several species of dolphins and pinnipeds in Los Angeles waters. Behavioral descriptions and photo identification of dolphin groups, the use of GIS technology and satellite images form the key methods of answering questions about the distribution and abundance of these dolphin populations in areas of pollution.
 |
 |
 |
| Researcher using GIS to log dolphin positions |
|
Harbor seal atop a rock in Malibu |
The first phase of this project uses satellite imagery of water color and sediment concentrations to identify and “localize” zones of coastal pollution allowing us to target those zones for survey at the time in which they occur. By taking data in and around these zones, the positive or negative effects on marine mammals can be ascertained. By conducting surveys immediately following major rainstorms we can determine the effects of pollution plumes originating from increased urban runoff on marine mammals. To obtain a historical perspective, the data collected in this study will be added to a database of satellite images and marine mammal data collected by the LADP in the years 1997-2002, which forms an excellent foundation for comparison.
Phase II of the project will implement biopsy sampling to further understand the effects of contaminants, in particular POPs, on dolphins inhabiting the Los Angeles waters. By comparing pollutant levels in tissue samples taken from identified inshore and offshore bottlenose dolphin populations, we can learn whether animals that frequent the inshore waters are at a greater risk than those who do not.
- Evaluate the severity and impact of pollutants along the coast (including the polluted waters off the port of Los Angeles and along the shipping lanes) on marine mammal abundance and distribution.
- Galvanize efforts to preserve the environment as a whole by focusing on one long-lived top-predator - the bottlenose dolphin - that considering its coastal distribution and high exposure to the effects of human activities in the Los Angeles waters is a valuable indicator of ecosystem health and problems
- Encourage an interdisciplinary approach to cetacean conservation by prompting local scientists with different specializations to work together in developing conservation and management strategies for a heavily impacted area in which various marine mammal species occur year-round.
 |
| |
Several dolphin and pinniped species seem to have a preference for specific bathymetric features, and the abundance and diversity of marine mammals is typically higher along regions of strong bathymetric gradients, as also shown for Santa Monica Bay. To what extent top predator distributions are determined by "fixed" geographic features (e.g., ocean depth) versus dynamic water mass properties (e.g., salinity, temperature, chlorophyll) associated with these bathymetric features remains unclear.Understanding the linkages between marine mammals and their physical environment is key to protecting them and their prey resources.
This study, conducted in collaboration with Dr. N. Nezlin, visiting professor at UCLA and expert in Satellite Oceanography, focuses on the effects of frontal zones and other oceanographic features on the abundance and distribution of several species of dolphins and pinnipeds in the Los Angeles waters, California.
The location of frontal zones can be estimated from sea surface temperature maps and, consequently, by on-the-water observation and data collection, we can test the hypothesis that frontal zones may influence the distribution of dolphins and pinnipeds; the analysis of inter-annual variability of marine mammal populations will be compared to the inter-annual variability of the ocean environment, including data collected during the last strong 1997-1998 El Niño event.
 |
|
Satellite charts show sea surface temperatures (NOAA) |
|
© 2005 Ocean Conservation Society.
All Rights Reserved. |
