Stable isotope ratios and contaminant concentrations in a sewage-distorted food web

Concentrations of selected neutral organic contamlnants and stable isotope ratios of carbon nltrogen and deu tenudhydrogen In invertebrates and fish were compared from near a large, 60m deep municipal waste outfall near Los Angeles Cahforn~a, where waste has a measurable influence on the structure of the marlne food web, and from a reference area off Santa Barbara, Cahfomia Oblect~ves were to investigate (1) the degree of utilization of sewage organlc matter in the food web especially by 3 species of fish, (2) l f ferences in contaminant accumulahon between these benthophagous fish and (3) the behavior of organic contamlnants relat~ve to each other and to organlc matter through several t rophc levels Isotopically lighter carbon and nitrogen and h g h e r concentrations of most chlorinated hydrocarbons were found in t~ssues of organisms from near the outfall On the basis of the 6I3C and 6I5N of the fishes, the estimated contnbution of nitrogen and carbon from sewage was about 15 to 20% of their requirements for these elements The 613c and 6 1 5 ~ values increased in the fishes In the order of M~crostomus paclficus, Clthanchthys sordldus and Zaruolep~s lahplnnls The Cs/K rat10 of the latter species was also sign~ficantly h ~ g h e r than the former 2 species also ind~cahng its h g h e r t roph~c posihon C sordldus had the highest wet-weight concentrations of chlonnated hydrocarbons and phthahc a c ~ d esters, intermed~ate concentrat~ons of these compounds were found in Z lahplnnls and the lowest concentrations were found In M paclficus Concentrations of chlonnated hydrocarbons on a 11pid-weight basis changed this order so that ~t more closely resembled the t roph~c structure revealed by the stable isotope ratio and Cs/K rat10 data Increases of both XDDT and Aroclor 1254, from deposit-feeding invertebrates through fish were evldent In foodwebs of the outfall and reference areas as posit~ve correlations w t h 6I3C A large degree of correlahon was evldent between contaminants in Z lahpinnls but not in the other 2 fish species These correlations were apparently not a function of liver lipid concentration, but the strengths of the correlations were dependent on the similarities of log KO, values of the correlated compounds