Superfund Research Program
Sentinel Species: Xenobiotics, Toxicity, and Reproduction
Project Leader: Ian P. Callard
Grant Number: P42ES007381
Funding Period: 1995 - 2000
The approach to this project changed over the past year in response to input from geochemists and ecologists working on the Ashumet remediation, the Superfund site where this project's field studies are located. Concern developed that insights gained from groundwater tests would not necessarily be relevant to predicting impacts on surface dwelling organisms. Therefore, the sentinel species approach was expanded by validating an innovative new assay using aquatic plants that has not previously been applied in this context. This assay, chlorophyll fluorescence induction, examines the quantum yield of photosystem II, and identifies damage to several biochemical sites of electron transport inhibition. In the past year, laboratory toxicity tests using the alga Selenastrum capricornutum were performed to describe its responses to toxins present in the Ashumet plume (anthracene, TCE, aluminum). The assay was highly sensitive as a bioassay endpoint, and differentiated between the impacts of metals as opposed to organic chemicals. The rooted macrophyte Gratiola aurea was also used in preliminary field surveys to examine whether fluorescence induction could detect sites of contamination, and/or the identity of the chemicals. Stress was observed in populations closest to the presumed discharge locations of 2 different groundwater plumes, and the responses suggested that different chemical classes from each plume were responsible. In the upcoming year, laboratory experiments and field surveys will be continued to further validate this assay as a means of identifying locations and types of biologically significant xenobiotics in the field.
Parallel sentinel-species work was continued with higher organisms in the same field location. Several fresh-water species have been used, including the eastern painted turtle, Chrysemys picta, as a bioindicator species. It has been shown: (a) that a single organism appears to segregate heavy metal sequestration in different organs to a significant degree (in the turtle, cadmium in the liver, and lead in the kidney) regardless of sex; (b) that there are sex differences in cadmium being significantly higher in animals from a site impacted by contaminated plumes than in animals from a control site. These data suggest a potential for sex differences in the impact and detoxification of heavy metals which may be important for germ line effects as well as organ specific damage based on primary sequestration site.