Stable Isotope and Biochemical Composition of White Perch in a Phragmites Dominated Salt Marsh and Adjacent Waters

Tissue stable isotopes and biochemical condition were compared in two populations of white perch, Morone americana, residing in a Phragmites australis-dominated tidal salt marsh and adjacent open waters of Haverstraw Bay, in the Hudson River estuary, USA. As reported previously for other taxa in this system, stable isotope composition of M. americana was influenced by the dominant vegetation present, in this case a near monoculture of P. australis and other C-3 vegetation, mainly deciduous trees, that lined the immediate upland shoreline of the marsh. However, all three stable isotopes, delta C-13, delta N-15, and delta S-34, differed significantly between the two populations, with all three parameters displaying enrichment in the open water collections. Both fish populations exhibited the expected allometric relationships among mass components (total protein, total lipids, dry weight) but energy reserves in the form of triacylglycerols and total lipids were significantly greater in the Haverstraw Bay population. These results were interpreted to not only be a function of fish size but also to originate from differences in habitat quality at the two locations.