Long-Term Monitoring of Ecological Conditions In Gray’s Reef National Marine Sanctuary: Comparison of soft-bottom benthic assemblages and contaminant levels in sediments and biota in Spring 2000 and 2005 Item Type monograph Authors Bathis, W. L.; Hyland, J. L.; Cooksey, C.; Fulton, M. H.; Wirth, E.; McFall, G. Publisher NOAA/National Ocean Service/National Centers for Coastal Ocean Science Download date 27/09/2021 18:32:44 Link to Item http://hdl.handle.net/1834/19977 Long-Term Monitoring of Ecological Conditions In Gray’s Reef National Marine Sanctuary: Comparison of Soft-Bottom Benthic Assemblages and Contaminant Levels in Sediments and Biota in Spring 2000 and 2005 NOAA Technical Memorandum NOS NCCOS 68 This report has been reviewed by the National Ocean Service of the National Oceanic and Atmospheric Administration (NOAA) and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for their use by the United States government. Citation: Balthis, W.L., J.L. Hyland, C. Cooksey, M.H. Fulton, and G. McFall. 2007. Long-Term Monitoring of Ecological Conditions In Gray’s Reef National Marine Sanctuary: Comparison of Soft-Bottom Benthic Assemblages and Contaminant Levels in Sediments and Biota in Spring 2000 and 2005. NOAA Technical Memorandum NOS NCCOS 68. 29 pp. + Appendices. Cover photo credit: Greg McFall Long-Term Monitoring of Ecological Conditions In Gray’s Reef National Marine Sanctuary: Comparison of Soft-Bottom Benthic Assemblages and Contaminant Levels in Sediments and Biota in Spring 2000 and 2005 W.L. Balthis, J.L. Hyland, C. Cooksey, M.H. Fulton, E. Wirth, G. McFall NOAA, National Ocean Service National Centers for Coastal Ocean Science Center for Coastal Environmental Health and Biomolecular Research 219 Fort Johnson Road Charleston, South Carolina 29412-9110 NOAA Technical Memorandum NOS NCCOS 68 September, 2007 United States Department of National Oceanic and National Ocean Service Commerce Atmospheric Administration Carlos M. Gutierrez Conrad C. Lautenbacher, Jr. John (Jack) H. Dunnigan Secretary Administrator Assistant Administrator Table of Contents Abstract........................................................................................................................ iii 1.0 Introduction..............................................................................................................1 2.0 Methods....................................................................................................................2 3.0 Results......................................................................................................................5 3.1 Spring 2005 Sampling.........................................................................................5 3.2 Comparison with results of the spring 2000 survey..........................................18 4.0 Conclusions............................................................................................................23 5.0 Acknowledgements................................................................................................25 6.0 References..............................................................................................................26 Appendix......................................................................................................................30 i ii Abstract As part of an ongoing program of benthic sampling and related assessments of sediment quality at Gray’s Reef National Marine Sanctuary (GRNMS) off the coast of Georgia, a survey of soft-bottom benthic habitats was conducted in spring 2005 to characterize condition of macroinfaunal assemblages and levels of chemical contaminants in sediments and biota relative to a baseline survey carried out in spring 2000. Distribution and abundance of macrobenthos were related foremost to sediment type (median particle size, % gravel), which in turn varied according to bottom-habitat mesoscale features (e.g., association with live bottom versus flat or rippled sand areas). Overall abundance and diversity of soft-bottom benthic communities were similar between the two years, though dominance patterns and relative abundances of component species were less repeatable. Seasonal summer pulses of a few taxa (e.g., the bivalve Ervilia sp. A) observed in 2000 were not observed in 2005. Concentrations of chemical contaminants in sediments and biota, though detectable in both years, were consistently at low, background levels and no exceedances of sediment probable bioeffect levels or FDA action levels for edible fish or shellfish were observed. Near-bottom dissolved oxygen levels and organic-matter content of sediments also have remained within normal ranges. Highly diverse benthic assemblages were found in both years, supporting the premise that GRNMS serves as an important reservoir of marine biodiversity. A total of 353 taxa (219 identified to species) were collected during the spring 2005 survey. Cumulatively, 588 taxa (371 identified to species) have been recorded in the sanctuary from surveys in 2000, 2001, 2002, and 2005. Species Accumulation Curves indicate that the theoretical maximum should be in excess of 600 species. Results of this study will be of value in advancing strategic science and management goals for GRNMS, including characterization and long-term monitoring of sanctuary resources and processes, as well as supporting evolving interests in ecosystem-based management of the surrounding South Atlantic Bight (SAB) ecosystem. iii iv 1.0 Introduction In April 2000, the National Centers for Coastal Ocean Science (NCCOS) and the Office of National Marine Sanctuaries (ONMS) began a partnership with the purpose of augmenting the management of National Marine Sanctuaries (NMS) through increased scientific understanding of sanctuary sites (ONMS/NCCOS 2004). An ongoing program of benthic sampling and related assessments of sediment quality was initiated at Gray’s Reef National Marine Sanctuary (GRNMS) to help address strategic science and management goals, including long-term monitoring of environmental conditions and characterization of basic oceanographic processes. Such activities are important to fulfilling key research and monitoring goals for GRNMS to “support, promote and coordinate scientific research and long-term monitoring to enhance the understanding of the Sanctuary environment and to improve management decision-making” (NOAA 2006). Figure 1.1. Location of Gray’s Reef National Marine Sanctuary. GRNMS is a marine protected area located 32 km offshore of Sapelo Island, Georgia (Fig. 1.1), encompassing 58 km2 of “live bottom” habitat and associated sandy substrate. Named in recognition of Milton B. Gray, a taxonomist and curator who studied the area in the 1960s to obtain collections of reef-associated fauna for the University of Georgia Marine Institute (Hunt 1974), Gray’s Reef was designated a National Marine Sanctuary in January, 1981. It is one of the largest near-shore rocky reefs off the southeastern United States, and lies in a transition zone between temperate and tropical waters. Located at the boundary between the inner and mid- continental shelf portion of the South Atlantic Bight (SAB), which extends from Cape Hatteras, 1 North Carolina to Cape Canaveral, Florida, Gray’s Reef is influenced by freshwater inflow, winds, and tides, with some influence from the Gulf Stream, which flows along the shelf edge (NOAA 2006). Water depths throughout the sanctuary average approximately 20 m. The bottom consists of extensive but discontinuous rock outcroppings of moderate height (2-3 m) interspersed with unconsolidated sediments of sand and shell hash (ONMS/NCCOS 2004). An initial characterization of GRNMS was conducted in spring 2000 (3-6 April) to evaluate the condition and distribution of benthic macroinfauna, including sediment-associated stressors, to provide a quantitative benchmark for tracking any future changes due to natural or human disturbances. The results of the spring 2000 survey suggest that soft-bottom habitats associated with GRNMS support highly diverse infaunal assemblages, a finding that contradicts a commonly-held assumption that these relatively featureless expanses of substrate surrounding “live bottom” habitat are biological voids (Cooksey et al 2004, Hyland et al. 2006). Levels of man-made, chemical contaminants were found at low, but detectable, concentrations in sediments and edible tissues of target species (black sea bass, zebra ark), suggesting background conditions while highlighting the need for future monitoring to track potential changes in levels of these substances. This report presents the results of a follow-up survey, conducted in spring 2005 (3-7 May), to assess ecological conditions associated with soft-bottom benthic habitat in GRNMS relative to the initial spring 2000 baseline study. The objectives of this study were to characterize benthic macroinfaunal assemblages and concentrations of chemical contaminants in sediments and biota (black sea bass, Centropristis striata, and zebra ark, Arca zebra) comparing 2005 survey data to the baseline study results to see how conditions may have changed. Results are intended to address sanctuary goals as noted above. Additionally, in assessing the linkages of ecological condition across multiple species in relation to a variety of environmental controlling factors and processes, this study supports evolving interests within NOAA and other institutions to move toward ecosystem-based approaches