Contaminants & Toxins

1995 Abstracts

Oyster and Sediment Contaminant Levels and Trends in South Florida

A. Y. Cantillo, G. G. Lauenstein, T. P. O'Connor, NOAA/NOS/ORCA, Silver Spring, MD

During the past 50 years, the South Florida ecosystem has been subject to a increase in human population and anthropogenic activity. One large environmental concern has been the reduction of freshwater flow into the Bay from the Everglades, because of drainage canals built to meet the demand for dry land imposed by increasing population and agricultural interests. Oyster and sediment samples were collected in South Florida from 1986 to 1994 as part of the NOAA National Status and Trends (NS&T) Program which is designed to assesses the current status of, and changes over time in the environmental health of the estuarine and coastal waters of the United States. Analytes quantified include 24 polycyclic aromatic hydrocarbons, 20 polychlorinated biphenyl congeners, DDT and its metabolites, 9 other chlorinated pesticides, organotins, 4 major elements, and 12 trace elements. The quality of the NS&T analytical data is overseen by the NS&T Quality Assurance Project. The concentrations of organic and inorganic contaminants in sediments and mollusks collected in South Florida from 1986 to 1994 show temporal and spatial trends that reflect anthropogenic influence in areas removed from large population centers. There is evidence of relatively high levels of man-made chemicals, such as endosulfan, at the NS&T sites in Florida Bay. High levels of Hg and As in oysters were also observed. Contaminant levels found in South Florida sites are compared to those found nationwide at other NS&T sites.

An Ecotoxicological Assessment of Pesticide and Urban Nonpoint Source Runoff into Florida Bay and Surrounding Environments

G. I. Scott, M. H. Fulton, J. R. Kucklick, National Marine Fisheries Service, Southeast Fisheries Science Center, Charleston Laboratory, PO Box 12607, Charleston, SC 29422-2607; G. Thayer, National Marine Fisheries Service, Southeast Fisheries Science Center, Beaufort Laboratory, Beaufort, NC 28516-9722.

Recent concerns about declining environmental conditions in Florida Bay, have helped focus research to address the status of living marine resources residing in the bay. The high salinity conditions now existing in Florida Bay may be in part responsible for the declining environmental conditions. Recent agreements have been reached which would increase freshwater inflows into the Everglades and eventually into Florida Bay. Most of this increased freshwater inflow will be diverted from water management districts in south Florida, which may contain surface water runoff from a variety of sources, including urban and agricultural nonpoint sources. Thus, under this new management plan, the potential exists for pesticides and other contaminants to be released into the Everglades and be eventually discharged into Florida Bay. To address this issue, the U.S. National Marine Fisheries Service, Southeast Fisheries Science Center, Beaufort, Charleston and Miami Laboratories conducted studies to measure pesticide levels in surface water and sediments in Florida Bay and adjacent inland, agricultural watersheds. The long-term goal of this research is to assess the risk presented by water and sediment-associated contaminants in south Florida to marine and estuarine living resources.

In 1993, an initial study was conducted at 34 sites which were sampled for surface water quality measurements (temperature, salinity, dissolved oxygen, and pH) and pesticide residues (500 mL samples). Station latitude and longitude coordinates were determined by Global Position Systems (Trimble and Magellan GPSs). Several sites were also sampled for sediment pesticide levels. Stations were classified as agricultural watershed (n=6), land-sea interface (n=10), and bay stations (n=18). Additional stations were sampled in 1994 and 1995 in both Florida Bay and at inland areas near vegetable farms. The sites selected in Florida Bay were also long-term ecological monitoring sites sampled by the NMFS and Beaufort Laboratories so that ecological data from each site could be used in conjunction with contaminant monitoring data. Pesticide levels in surface waters were initially screened by polyclonal antibody test kits (triazine herbicides and cyclodiene insecticides). Samples testing positive were further analyzed for pesticides (atrazine, azinphosmethyl, endosulfan, and fenvalerate--pesticides commonly used on vegetable farms) by capillary-column gas chromatography using both electron-capture (GC-ECD) and nitrogen-phosphorus detection (GC-NPD). Endosulfan is a supertoxic (96h LC50 for aquatic organisms < 1 ug/L) insecticide which has caused more coastal fish kills from 1980-89, than any other pesticide. Also, toxicity tests have been conducted with mosquito fish (Gambusia affinis) from different localities to assess the sensitivity of fish, which may be chronically exposed to endosulfan, in terms of cyclodiene pesticide resistance. In situ bioaccumulation and ecophysiological studies have been conducted with the oyster, Crassostrea virginica, at selected sites within Florida Bay.

Results from the 1993 study, indicated that 14.4% (5/34) of the 34 stations sampled had detectable levels of pesticides in surface water samples. Initial screening by polyclonal antibody test kit indicated detectable levels of cyclodiene insecticides (6 stations) and triazine herbicides (7 stations). Subsequent GC-ECD and GC-NPD analysis indicated only the presence of the organochlorine insecticide, endosulfan, at five stations. Endosulfan concentrations as high as 0.170 ug/L were detected. The State of Florida Regulatory limit for marine waters is 0.0085 ug/L for endosulfan. Only a few stations which had detectable endosulfan levels had concentrations that exceeded the 0.0085 ug/L state regulatory limit. Results from surface water monitoring from 1994-95 and laboratory and in situ field toxicity tests conducted to date will be discussed along with long term ecological monitoring data from sites within Florida Bay. Research planned for 1995-96 will also be discussed including planned laboratory toxicity tests on crustaceans (grass shrimp and copepods) to determine the impacts of the pesticide endosulfan, which is potentially an endocrine disrupting chemical, on survival, growth, development and reproduction.

Monitoring Changes in the Estuaries of the United States: The Environmental Monitoring and Assessment Program in Florida Bay

J. Kevin Summers, National Program Manager, EMAP, U.S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, FL; John M. Macauley, Michael A. Lewis, U.S. EPA, Gulf Ecology Division, Gulf Breeze, FL

The purpose of the Environmental Monitoring and Assessment Program/ Estuaries (EMAP-E) is to estimate the current status, extent, changes, and trends in ecological indicators of the condition of the nation's coastal resources (intertidal, subtidal, and offshore) on a regional and national basis. Initial monitoring activities have been initiated or completed in approximately 70% of the nation's estuarine waters, including Florida Bay, and focus on suites of ecological measurements describing the benthic community, the fish community, water quality, levels of sediment and tissue contamination, sediment toxicity, and SAV extent/condition. Estuarine monitoring is based on a probability-based sampling design implemented over a 60-day window during July-September of each year. The use of statistical tools developed for the program show that 25% ± 4% of the sediments of the nation have degraded biological conditions while 29% ± 4% of the area show degraded conditions in relation to human uses of the resource (e.g., water clarity, tissue contaminants, and the presence of marine debris). Biological degradation is characterized by significantly less than expected number of benthic species and diversity, high numbers of pollution-tolerant species, and low numbers of pollution-sensitive species, incidence of fish pathologies, and increased levels of selected biomarkers in target fish species. Human use degradation is characterized as decreased water and sediment quality, potential for decreased consumptive use, and incidence of characteristics limiting non-consumptive use.

Monitoring and research activities in Florida Bay began in the spring of 1995 with five separate activities: (1) a baseline characterization of the ecological condition of Florida Bay, (2) a seasonal characterization of Florida Bay to examine changes in condition due to seasonal variation, (3) a characterization of the flux of materials from the primary canals and creeks draining into Florida Bay and the conditions at the mouths of these canal/creek outlets, (4) a baseline characterization of ecological condition of the terrestrial region draining into Florida Bay (Everglades National Park, Big Cypress Swamp, and the Water Conservation Areas), and (5) assistance to other existing monitoring programs in Florida Bay with regard to statistical design and analysis.

The baseline characterization of Florida Bay began in July 1995, is based on sampling at 45 probabilistic sites, and is intended to be a "snapshot" of ecological condition against which changes over the next decade can be gauged. The program focuses on sediment condition, biotic condition, level of eutrophication, and SAV condition as the primary indicators of condition. Sediment condition is measured through the use of chemical analysis of contaminants (125 contaminants including mercury and endosulfan) and basic sediment characteristics (e.g., total organic carbon, acid volatile sulfides). The biotic condition indicators include multiple indicators of benthic communities, incidence of fish pathologies and levels of bioaccumulation of contaminants, and SAV indicators discussed below. Eutrophication is gauged by water quality parameters (e.g., light penetration and dissolved oxygen), nutrient concentrations, and productivity. Submerged aquatic vegetation condition is determined from abundance and density, abundance of epiphytic biomass, and age-structure of SAV sites. Using these same parameters, the seasonal variability of ecological condition will be described for spring-fall 1995 and winter 1996. Data from these surveys will be available in mid-1996.

The measurement of the flux of contaminants from five canals and creeks into the northeastern portion of Florida Bay consists of two time periods; summer 1995 and winter 1995-96 to characterize the wet and dry periods of runoff. The study is designed to address two primary issues: (1) Does the runoff characterized by these water bodies include significant levels of contaminants and nutrients, and (2) What are the contaminant and toxicological condition of the areas directly adjacent to the mouths of these creeks/canals. The characterization includes the C-111 Canal, Trout Creek, Shell Creek, McCormick Creek, and Taylor River. There is some discussion regarding expanding the program to include the Shark River in late 1996. Chemical results for these studies will not become available until mid-1996 but early toxicological studies suggest significant toxic responses to sediment collected from the mouths of these water outlets to plant development and the survival rates of benthic target species.

The baseline characterization of the landward system will begin in October/November 1995 and will include 75 probabilistic locations throughout the parks, natural areas, and water conservation areas. To date, we have assisted several other monitoring programs in Florida Bay to develop probabilistic sampling designs for their programs.

While little data is available as yet, EMAP Phase II will, dependent on available funding, begin: (1) the development of an intensive monitoring site network within Florida (3-5 sites) to characterize short-term mechanistic behaviors; (2) initiate direct hypothesis-testing studies to evaluate the effects of mercury and endosulfan contamination of fish, shellfish, and bird populations; (3) initiate hypothesis-testing studies to assess the effects of eutrophication and fresh-water flow reductions on the estuarine communities of northern Florida Bay, and (4) conduct intensive surveys designed to strengthen our understanding of the role of spatial scale in controlling the mechanisms of estuarine dynamics.

 

Last updated: 06/15/98
by: Monika Gurnée
gurnee@aoml.noaa.gov