Bird Microbial Source Tracking Case Studies

Detect General Bird Fecal Load, Quantify % Bird Contamination, Multiple Samples Recommended

Bird MST Case Studies 2017-06-28T20:22:19+00:00

1. Birds Suspected of Contaminating Johnson Creek in Oregon

Large numbers of birds were observed in or near water of Johnson Creek in Oregon. But in a 2014 study by the Johnson Creek Inter-jurisdictional Committee and the Johnson Creek Watershed Council, they found only a few sites with positive results. They consider this result as an anomaly.

Water samples were collected at 70 sites spread throughout the Johnson Creek watershed in late summers of 2012 and 2013. There was a wide range of E. coli concentrations and Bacteroides spp. found in the August 2012 samples, and the overall 2013 data appeared to be a bit higher. The group used microbial source tracking methods to identify the source of the fecal pollution.

Source Molecular Corporation?s laboratory was tapped to help with source identification. Using quantitative Polymerase Chain Reaction (qPCR) methodology, Source Molecular analyzed 50 samples with high E. coli concentrations for total General Bacteroides ID. Forty-eight samples with high General Bacteroides levels were identified as candidate samples for source identification. These samples were tested for Source Molecular?s Bird Fecal ID analysis, which uses a bird-specific indicator bacteria (Helicobacter); and Human-specific markers, the most reliable of which was Bacteroides dorei.

The results of the study showed that the bird marker was found in quantifiable concentrations at only six sites while eight sites had trace concentrations. The group found this puzzling considering many sites with waterfowl present. With regards to human fecal contamination, only eight sites had quantifiable detections of human markers while six samples had trace concentrations indicating human waste.

One of the conclusions reached was that more data is needed to verify the avian sources of E. coli in Johnson Creek.

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.

3. Birds Identified as a Contributor of Pollution at Petrie Island Beach in Ottawa

Birds, together with humans, were identified as contributors to the fecal pollution at Petrie Island Beach in the City of Ottawa. Birds such as gulls and Canada geese are known to occur at Petrie Island Beach and their fecal droppings were observed on each sampling day.

Most of the bird droppings were from gulls, and they were largely deposited on the sand along the beach near the Baie des Sables transect. While these bird droppings would have provided some level of continuous loading of E. coli into the beach sand at Petrie Island Beach, their significance for beach postings in 2007 is uncertain.

The study was conducted by the National Water Research Institute, Environment Canada, to investigate the source of fecal pollution responsible for beach postings at Petrie Island Beach near the City of Ottawa in 2007. Field observations and water samples were collected weekly at the Beach and at upstream Ottawa River locations from May 7 to October 15, 2007.

Water samples and sand pore water samples at the beach were collected. E. coli concentrations in water were determined by filtering water samples. Total genomic DNA was extracted from the filter and then purified. Polymerase chain reaction (PCR) technology was used to identify the source of fecal pollution.