We are assessing the scope and extent of land-based sources of chemical contaminants in the marine waters surrounding Cocos Island, Guam. Previous NCCOS studies identified a gap in polychlorinated biphenyls data, which this project will fill to better inform management decisions about the island and its marine waters. NOAA’s Coral Reef Conservation Program is funding this study.
Why We Care
Cocos Lagoon is an atoll-like coral reef lagoon located off the southwestern coast of the island of Guam. A series of fringing reefs and barrier islands surround the lagoon, of which Cocos Island is the largest. Cocos Lagoon is a popular area for recreational activities such as fishing, boating, and diving, along with subsistence fishing.
Between 1944 and 1963, the U.S. Coast Guard (USCG) operated a Long Range Navigation (LORAN) station on Cocos Island. People have found components from this LORAN station, including several transformers and capacitors containing polychlorinated biphenyls (PCBs), both on land and in nearby waters. The Coast Guard has since removed the PCB containing transformers and capacitors, along with a substantial amount of contaminated soil, but there is evidence that these chemicals have migrated into several marine matrices, including fish and nearshore sediments, which concerns local natural resource managers and the public.
Exposure to PCBs can lead to a range of toxic responses according to animal studies, including reduced growth, reproductive impairment, and vertebral abnormalities. PCBs have also caused cancer in animals. In 2006, following USCG-funded research that detected PCBs in fish, Guam agencies issued a fish consumption advisory for Cocos Lagoon. In 2015, local natural resource managers asked NCCOS for help in assessing chemical contaminants in sediments and fish to understand the extent of contamination in Cocos Lagoon.
What We Are Doing
In September of 2017, NCCOS scientists and their partners from the Guam EPA deployed polyethylene devices (PEDs) in Cocos Lagoon. These PEDs remained in situ for approximately one month to reach equilibrium with any hydrophobic organic compounds (HOCs) present in the water column. The research team recovered these PEDs, and is currently analyzing them for a suite of organic chemical contaminants, including PCBs.
Benefits of Our Work
Data generated from this study will fill the gap identified by previous NCCOS studies in the area. Previous studies identified elevated levels of PCBs in fish tissues caught in the area. However, sediment samples from the region were unable to give a good spatial distribution of PCB concentrations, due to the coarse nature of the sediment not binding organic contaminants well. In conjunction with the results from the previous study, the data products from this study will help inform future management decisions about the lagoon by identifying spatially where PCB and other chemical contaminants may be entering the environment.
The team is currently analyzing the PEDs deployed during the September 2017 field mission for a suite of organic and inorganic contaminants. Once we complete this analysis, project data will be available online via the National Status and Trends database, and will be synthesized, including statistical and geospatial analysis, in a technical memorandum.