Chemical control agents are often being used in Connecticut’s wetlands for wetland restoration and pest control purposes. In the later end of the summer of 1999, an outbreak of West Nile Encephalitis prompted aggressive widespread spraying of mosquito breeding areas, while continued wetlands restoration efforts continue to use herbicides to reduce invasive plant populations. This ecological risk assessment evaluated the potential ecological risks to Pandion haliaetus (osprey) and Acipenser brevirostrum (shortnose sturgeon), chosen due to their state and federally listed status, associated with the application of Rodeo?, an herbicide used in the control of the invasive reed Phragmites australis, and resmethrin, a pesticide from the pyrethroid chemical family used for mosquito control in the Connecticut River wetlands. The chosen areas of interest were the wetlands and waters in the estuarine and tidal river complex of the lower Connecticut River, with its extensive, high-quality tidal freshwater and brackish marshes and remarkable clustering of rare and endangered species, waterfowl, and anadromous fishes. There is a tremendous degree of ecological interaction and interdependence among these tidal waters, tidal wetlands, adjacent uplands, and species populations within an ecosystem or watershed framework. It is this degree of interaction and dependence, as well as the intentions of controlling populations of species through chemical means, that prompted the necessity of this ecological risk assessment (ERA).

The ecological risk assessment was based on a hypothetical model, not site specific toxicity data and followed the recently released USEPA 1998 guidelines for ecological risk assessment. Even though this assessment did not use site specific data, it outlined all assumptions relating to how assumptions used in this assessment may skew the results. Toxicity data for the chemicals of potential ecological concern (COPECs) were found using USEPA approved database information, the most defensible level of reviewed information. The toxicological effects, potential routes of exposure, and application procedures in Connecticut wetlands were used to determine the potential ecological toxicity to the species of concern in this ERA. Exposure concentrations were estimated from application concentrations listed in Connecticut Department of Environmental Protection literature, and exposure-response was estimated from literature research results.

Assessment Conclusions:
It was found that resmethrin will most likely produce a significant risk to shortnose sturgeon, while posing relatively low risk to osprey populations. For both shortnose sturgeon and osprey, glyphosate will most likely not add a considerable increase in risk in combination with resmethrin. However, if it is shown that osprey prey species ingest large enough quantities of glyphosate to either biotransfer glyphosate to the osprey or cause a reduction in the availability of the prey species, then the combined risk of glyphosate and resmethrin will increase considerably. A site-specific analysis should be conducted to better estimate concentrations and residence times of the COPECs in the Connecticut River wetlands. Additionally, fish tissue studies should be collected to estimate concentrations of toxins, as well as to determine the potential of the chemicals for bioaccumulation and bioconcentration. Care must be taken in the application of both resmethrin and glyphosate, given their potential for both aerial drift and infiltration into nearby water bodies if risks to shortnose sturgeon and osprey prey species are to be reduced. Given that resmethrin will most likely produce a medium to high risk on shortnose sturgeon populations, its application near shortnose sturgeon habitat may want to be reconsidered.

This ecological risk assessment provides a rudimentary assessment of the potential impacts of the combination of chemical reed control and the emergency widespread chemical spraying of mosquitoes in Connecticut. The threats of Eastern Equine Encephalitis and West Nile Virus are of very significant concern to both local and state governments, and are acted upon as a severe threat to the health of the human population. Given the results of this ERA, it would seem prudent to evaluate the potential effects of the spraying not only to the chosen species of concern in this risk assessment, but also to other species and the human population as well.

CONCEPTUAL MODEL BELOW