Use of delta(13)C and delta(15)N, and carbon to nitrogen ratios to evaluate the impact of sewage-derived particulate organic matter on the benthic communities of the Southern California Bight.

We measured stable isotope ratios (delta(13)C and delta(15)N) of particulate organic matter (POM) sources and benthic organic matter compartments as well as sediment C to N ratios from the coastal area of the southern end of the Southern California Bight (SCB). We used the isotopic values to evaluate the relative importance of the major POM sources to the sediment and two benthic macroinvertebrates. Application of a simple model to sediment delta(13)C values suggested that sewage-derived POM (SDPOM) supplies an average of 48% of the organic C to study area sediments.