Most of our research focuses on the effects of stressors like environmental contaminants, invasive species, and parasites on the behavior and ecology of estuarine organisms. We are interested in responses at the organismal level, such as changes in development, growth, or behavior; responses at the population and community level, such as the development of tolerance on the part of populations that are chronically exposed to certain pollutants, altered life histories, alterations in predator/prey interactions and trophic transfer of contaminants.
Epifauna that live on stems seem to prefer Spartina, as do mummichogs that utilize the marsh surface at high tide. Some of this work is being done in conjunction with the Meadowlands Environmental Research Institute, MERI, which supports joint research projects of several faculty members and is sponsored by the New Jersey Meadowlands Commission (NJMC).
We are interested in the role of salt marsh plants in providing nutrition and transferring toxicants to animals. We are comparing the native marsh plant, Spartina alterniflora with the invasive reed, Phragmites australis in terms of their use as habitat by fiddler crabs, grass shrimp and larval mummichogs, and their nutritional value to the marsh invertebrates. We are also comparing metal uptake, storage and release by these two plants in the Hackensack Meadowlands. Data gathered thus far indicate that Spartina accumulates and releases greater amounts of metals than Phragmites, and that the two plants seem to be equivalent as food, once they have been converted to detritus, and to serve the same habitat function for some but not all of the animals.
The proximity to the Hackensack Meadowlands and Newark Bay, which is a severely stressed estuary, gives us a convenient "outdoor laboratory." We have found such tolerance to methylmercury in populations of mummichogs (Fundulus heteroclitus), grass shrimp (Palaemonetes pugio) and fiddler crabs (Uca pugnax) from the northern NJ estuaries, but have also found that enhanced tolerance comes at a price. We are currently looking at impaired feeding behavior in these fish. They are less capable of capturing live prey, and consequently eat higher proportions of sediment and detritus, which are not nutritious. The reduced prey capture is associated with lower general activity level and reduced levels of serotonin in their brains. We are also looking into the possible involvement of the thyroid gland in their low activity level. This may be a case of endocrine disruption caused by environmental contaminants. Their poor diet may be partly responsible for their decreased growth and life span. However, their prey organisms, grass shrimp (Palaemonetes pugio), whose predator-avoidance does not seem to be impacted by the contaminants in the polluted environment, may be benefiting from being preyed upon less. They are larger in size as well as more numerous at the contaminated site.