Paper No. 6
Presentation Time: 9:00 AM-6:00 PM
NEKPON IN PIERMONT MARSH: DISTRIBUTION, DIVERSITY AND DEPENDENCE
Piermont Marsh, located approximately 40 kilometers north of the Battery Park in New York City, is a brackish system along the western bank of the Hudson River (Montalto, 2006). The marsh acts as a shelter to marine life, especially the most abundant fish species, the Fundulus heteroclitus. The F. heteroclitus diet consists primarily of diatoms; a major group of algae frequently seen among the phytoplankton of the Hudson estuary. The marsh is inundated relatively infrequently, about 10-12 times a month (Montalto 2006). These high-high tides provide opportunity for exchange of nutrients and biota, including juvenile fish, between the marsh interior and the surrounding streams and estuary. Colonization of the marsh by an invasive genotype of Common Reed, Phragmites australis, is thought to have significantly shifted the hydroperiod; in particular, it may have further isolated interior pools. We have sampled between 9 and 24 sites for juvenile nekton during each of the past 7 summers. The interior pools are often nearly barren, but occasionally stocked with orders of magnitude more minnows than the surrounding waters. In this contribution, we show the population levels and diversity in a 7- year time series of nekton samples and explore the impact of P. australis colonization of the Marsh interior on fish populations. Invasive Reed typically spreads at a rate of 1% to 6% annually and today covers at least 85% of Piermont Marsh. In addition to decimating flora diversity in the Marsh interior, P. australis is having a profound effect on the fish by limiting communication with the open waters. We investigate the extent to which Fundulus make up for the loss of their preferred habitat by utilizing rivulets at the Marsh edge, as well as correlations between fish abundance and diatom blooms. All data collection and sample processing was performed by NYC public high school students working in the Lamont Doherty Earth Observatory’s Secondary School Field Research Program.