Abstract

In August of 1997 approximately 400 common murres (Uria aalge) were found dead in a relatively confined area of the southern end of the Monterey Bay National Marine Sanctuary, California. This dieoff occurred at a time when there was a "red tide" event in the area. The primary gross lesions were serosanguinous rhinitis and pulmonary edema. Immunohistochemical staining showed presence of brevetoxin within lung tissue in patterns similar to those seen in manatees dying of brevetoxicosis. This is the first report of inhaled brevetoxin killing birds on the Pacific coast. In retrospect, brevetoxicosis is suspected in several previous common murre dieoffs in Monterey Bay, California, each involving hundreds of murres and each occurring during months with warmer ocean temperatures. Changes in seawater temperature and quality, which may be related to human activity within the near shore environment, as well as global climate change, El Nino events and natural ocean cycles may influence algal species and abundance.