Bronx River Education

Life in the Bronx River Estuary

August 11, 2009

On a visit to Hunts Point Riverside Park, I decided to try my luck in the water with a seine net. I could see the small fish flashing along under the surface, but I was not sure that I would be able to sample any since they seemed to sense my presence well before I approached the river’s edge. But one short walk parallel with the shore brought up the bounty of the sea.

These silversides (maybe Rough Silversides?), also known as sand smelt, are one of the most abundant fishes in our coastal waters. As Tarleton Hoffman Bean in his 1903 work Catalogue of the fishes of New York writes, these fish are not of great importance as a human food source, but they are a food source for the larger fish that inhabit local waters, as well as the wading birds that are regular visitors.
Silversides begin to spawn in May and, after a gestation period of just eight days, their young begin feeding on zooplankton before graduating to detritus, algae and even small fish and insects. The schools follow the tides up the river to feed in the salt marshes or  other protected river banks, swimming in tight shoals that serve as a form of protection against predators. Over the summer the populations swell, creating a migrating energy source that will move out to deeper water in the fall, sharing the productivity of the estuary and the salt marsh with the greater oceans.
Unfortunately the picture below did not turn out as planned, but the jellyfish shown, most likely a comb jelly, also came up in my net.   One of 90 species in phylum Ctenophora, some are able to glow with a slight phosphorescence as this example shows. The color that appears in the photo was not visible to my eye at the park, but appeared when I cropped the shot. Comb jellies are all carnivores and, though they have no tentacles, have tremendous mouths under their bell and can even eat prey larger than themselves.

Entry Filed under: Water Quality Monitoring, sighted. Tags: bronx river, Bronx River Wildlife, estuaries.