Studying the Jellyfish Invasion

In the last couple of years, millions of jellyfish have invaded New Jersey’s Barnegat Bay, leading biology professors Paul Bologna and Jack Gaynor to study their potential impact to aquatic food webs.

Funded by the New Jersey Department of Environmental Protection, the researchers will study the effects that the jellyfish—technically known as sea nettles—are having on the bay’s ecosystem. One effect is clear: The sea nettles are now a major nuisance to humans in this heavily populated area of the Jersey Shore. “They’ve become a real problem,” says Bologna, director of Aquatic and Coastal Sciences for the Department of Biology and Molecular Biology. “The sea nettles are literally chasing beachgoers out of the water.”

There are several reasons for the sea nettle population explosion and they all stem from the changes occurring in and around the bay. As more people build homes in the area, there is more nitrogen in the water – caused by runoff from lawn fertilizer and from acid rain created by increased burning fossil fuels. More nitrogen creates algae blooms that lower the oxygen levels.

Aquatic species that can’t survive in low-oxygen environments are driven away allowing sea nettles, which are not affected by these conditions, to flourish. “Because sea nettles are adapted to low oxygen conditions, they can survive where other organisms cannot,” says Bologna. “Basically, they are winners by default.”

Also working in the sea nettles’ favor is the increase in floating docks, bulkheads and other hard surfaces that come with development. These hard surfaces provide a perfect place for sea nettle larvae to settle and develop into polyps, a critical stage its life cycle. The polyps can bud, creating more of themselves, adding to the eventual increase in the number of adult sea nettles. As adults, sea nettles are top predators of zooplankton and fish larvae, further depleting populations of other aquatic species.

“Our research will involve field sampling to assess the distribution of zooplankton and the settling of the sea nettle polyps as well as assessing the diets of the sea nettles through dissection and molecular analysis,” says Bologna. “We need to know more about the distribution and feeding impacts of the sea nettles in Barnegat Bay.”