2. Birds Pollute Dungeness Watershed in Washington
Birds are the predominant source of fecal coliform pollution in the Dungeness watershed, both in the freshwater and marine environment, according to a 2009 microbial source tracking (MST) studyconducted by Battelle for the Jamestown S?Klallam Tribe in Washington.
The result is not much of a surprise as more than 250 species of birds live some parts of the year in the Dungeness National Wildlife Refuge that encompasses Dungeness Bay. In particular, migrating shorebirds are present in the spring and fall while flocks of waterfowl are present during the winter months. Other MST studies have also noted the widespread influence of birds, particularly gulls, along coastal and lake waters.
In this study, two MST approaches were used: ribotyping method, which is a cultivation-dependent, host-library dependent approach; and Bacteroides target-specific method, which is a cultivation-independent approach that doesn?t require the development of a host-reference library for comparison.
For the ribotyping method, water was collected from two marine and four freshwater stations. Samples representing the distribution and variety of animals, birds, marine mammals, and human sources that occur in the Dungeness watershed were also collected. Test sampling of water, marine sediment and marine vegetation occurred on a monthly basis between May 2006 and May 2007, a total of 13 months, from each of the 6 study stations.
For the bacteroides target-specific polymerase chain reaction (PCR) analysis, samples were collected on December 2, 2008 (10 marine stations, 6 seep stations), December 12, 2008 (9 freshwater stations), and January 6, 2009 (5 marine stations, 11 freshwater stations). Fourteen of these stations were sampled on two of the three dates.
Birds, in total, represented the largest source group, accounting for approximately 42% of the isolates collected and analyzed throughout Phase 1 of the study. They also occurred most frequently throughout the course of the study. They were the dominant presence in Dungeness Bay and all freshwater stations, except one, in the lower watershed (i.e. Matriotti Creek, Meadowbrook Creek, and Golden Sands Slough).
Human and ruminant markers were targeted in the Phase 2 study. A total of 42 samples were collected, not including blind or quality control samples, during three sampling events. Overall there were relatively few samples that were identified as a ruminant or human source. Twenty samples tested negative for the Bacteroides screening test (48%), and 17 samples (40%) contained the general Bacteroides-only marker indicating a source other than human or ruminant were present.