HABITAT USE OF FUNDULUS HETEROCLITUS IN A MARSH DOMINATED BY INVASIVE PHRAGMITES AUSTRALIS IN THE HUDSON RIVER ESTUARY

The Hudson River estuary extends from the Federal Dam at Troy to the Battery at the southern tip of Manhattan. To tease apart the impacts of natural events and human activities on fish populations within the Lower Hudson’s Piermont Marsh, a comparative study of nekton habitat use and water quality in the marsh and the adjacent Hudson River channel was designed. Although use of salt marshes by nekton is well documented (Rozas, 1995; Bretsch and Allen, 2006; Kimball and Able, 2007; Rozas et al. 1998; Halpin, 2000), few studies of habitat selection and availability have been conducted in Piermont Marsh, one of four reference marshes in the Hudson River National Estuarine Resource Reserve System (NERRS). To assess spatial and temporal distribution of small fishes in Piermont Marsh, un-baited Gee minnow traps with 4-mm wire mesh was used to sample nekton in tidal creeks, rivulets, and an interior pool. At each sampling location, three minnow traps were deployed ~ 1 meter apart and adjacent to the shoreline. Minnow traps were deployed at slack high tide and allowed to collect fish for a period of 24 hours to sample an entire tidal cycle. Mummichogs and other nekton were retrieved from traps and preserved in 10% buffered formalin. In the laboratory, all organisms were identified to the lowest taxonomic level practical, enumerated, and measured to the nearest mm standard length (fishes), total length (shrimp), or carapace width (crabs). Our goals were to 1) describe habitat availability in Piermont, 2) quantify use by nekton during diurnal tidal fluctuations, and 3) describe the impact of Phragmites australis on aquatic fauna in the marsh ecosystem.

All data presented were collected and analyzed as part of Lamont-Doherty Earth Observatory’s Secondary School Field Research Program, which engages NYC public school teachers and students in research projects in the Hudson/Raritan estuarine environment.