Biologists at Rutgers University are studying the behavioral changes of marine life in New Jersey estuaries – two polluted, one relatively clean -- to determine if these conditions will create long-term ecological consequences.
Judith Weis, a professor of biology at Rutgers-Newark, and graduate student researchers, has studied five species of marine life living in parts of the Hackensack Meadowlands and Piles Creek (which runs into the Arthur Kill between New Jersey and Staten Island), in northern New Jersey, and in Great Bay, near Tuckerton in southern New Jersey. The Hackensack Meadowlands and Piles Creek are polluted with metals, dioxin, PCBs and other toxic chemicals. Great Bay is relatively clean.
All five species are negatively affected by the polluted environment, Weis and her colleagues found, but the three crustaceans they studied – grass shrimp, fiddler crabs and blue crabs – seem to be more successful than the two finfish species, killifish and bluefish.
Weis’s research, published recently in BioScience, illustrates the long-term effects of pollution on the behavior of interconnected species in an ecosystem.
“If your predator is worse affected by the pollution than you are, you can do well,” says Weis.. “Put another way, if your predator is leaving you alone for some reason, or is just a lousy predator, you can do okay.”
The crustaceans are affected by pollution. Fiddler crabs spend more time in their burrows and less time feeding in polluted habitats than they do in clean estuaries, the researchers found. Grass shrimp also eat less food and are less active. But
their predators, killifish, are much worse off. Killifish prey on grass shrimp, but in polluted waters they swim slower, hunt less efficiently and cannot catch them well. Instead, they eat a lot of what Weis calls “junk food” – detritus and sediment – which isn’t nutritious for them. The reduced predation by killifish allows the grass shrimp to become larger and more abundant, despite the poor environment. The blue crabs are also poor predators in polluted waters; they cannot capture active prey well, and also eat a lot of “junk food,” but seem to grow bigger anyway and more aggressive. This may be because blue crabs live longer: due to the fact that their predators, human beings, are forbidden to catch and eat them in the northern polluted waters.
Bluefish have it worst of all, and their plight has an impact on human beings, who eat them. Bluefish spawn at sea, but spend their first summer in estuaries. If the estuaries are polluted, the bluefish that live in them end up less active, eating less, and growing more slowly. Furthermore, they may eat more contaminated killifish because they swim slower and are easier to catch. Young bluefish from such estuaries are so contaminated that they are unsafe for humans to eat.
“The phenomenon of catching the easier-to-catch, more contaminated prey is
likely to happen with birds also, which will accumulate more in their
tissues also,” Weis says.
