Hudson River Fishes and their Environment

Patterns of Habitat Utilization by Resident Nekton in Phragmites and Typha Marshes of the Hudson River Estuary

David T. Osgood, David J. Yozzo, Randolph M. Chambers, Seth Pianka, Christina LePage, and Jason Lewis


Abstract.—We compared nekton density and benthic prey availability over a range of flooding conditions within common reed Phragmites australis and narrowleaf cattail Typha angustifolia at a mesohaline and an oligohaline marsh on the Hudson River Estuary. Nekton were sampled using lift nets at high and low elevations. Marsh surface nekton sampling occurred on 16 high tide events from May–October 1999 and 2000. Hydrology (depth, duration, and frequency) was simultaneously measured. Benthic macroinvertebrate density and richness were measured from sediment cores in June, August, and October, coincident with lift net collections. A total of 690 individuals representing nine species, mostly mummichog Fundulus heteroclitus and daggerblade grass shrimp Palaemonetes pugio were captured within both vegetation types. Mean nekton density (individuals 6 m-2 ± SE) on the marsh surface was not significantly different among reed at the mesohaline marsh (4.1 ± 1.3) and reed (3.4 ± 0.6) and cattail (4.1 ± 0.9) at the oligohaline marsh. Nekton density did not vary predictably across the measured range of flooding depth and duration. Nekton density was also not predictably related to benthic macroinvertebrate density or taxonomic richness. Significantly more juvenile mummichog were collected within cattail relative to reed, suggesting that spawning success of this species may be lower in reed. Adult resident fish and macrocrustacean species are distributed similarly within and between reed and cattail when they experience comparable flooding regimes. The present study represents one of the first direct measures of nekton density within reed and corroborates previous patterns for nekton abundance between reed and nonreed vegetation stands across a wide salinity regime.