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Research Technical Report

A Comparison of Nutrient Concentration, Enteric Bacteria, and Phytoplankton Biodiversity between Carmel Bay and Monterey Bay

Carmichael, S., A. DeVogelaere, K. Coale, E. McPhee-Shaw, and M. Los Huertos (April 2008)

Poster presentation at the 2008 Sanctuary Currents Symposium, Seaside, CA


Enteric Bacteria, and Phytoplankton Biodiversity between Carmel Bay and Monterey Bay Coastal waters near developed areas are often plagued with two common pollutants, elevated nutrients and harmful pathogens (Brown 2001). Monterey and Carmel bays are located in the Monterey Bay National Marine Sanctuary and experience similar impacts from anthropogenic input and terrestrial sources. The deep canyons bring nitrogen rich water to both bays during times of upwelling. At a steady state concentrations of phosphorous (P) and nitrogen (N) approximate the Redfield ratio of 1:16 in marine ecosystems (Libes 1992; Jackson 1977). Excess nutrients in the coastal marine environment can cause high-density phytoplankton growth (Liu W et al 2007). A hypoxic area can follow large blooms from decomposition (Chang et al 2002, Turner and Rabalais 2003). Enteric bacteria live in the intestines of mammals and enter the marine ecosystem through farm and urban run off. Fecal coliform and E. coli bacteria are used as indicators of harmful pathogens in water. Surface samples were collected at both locations. Bacteria assays were done using EPA method 1604 for detecting E. coli and total coliform. Phytoplankton groups in each sample were identified and enumerated. In order to compare the biodiversity between both sites the Shannon-Weiner Index was used. Nutrient analysis methods were automated using a Lachat Instruments QuikChem 8500 Series flow injection analyzer (FIA). The biodiversity index tended to be lower at the Carmel Bay site. Total coliform and E. coli averages were higher at the Carmel Bay site. The phosphate nitrate ratio did not tend to follow the Redfield ratio of 1 P: 16 N. The nutrient ratio indicates nitrate depletion and the possibility of a terrestrial phosphate source.