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Geology topics

Christopher C. Koenig

Publications and source records attributed to Christopher C. Koenig.

7 recordsLinked to original sources
USGS2011

Groupers on the edge: Shelf edge spawning habitat in and around marine reserves of the northeastern Gulf of Mexico

The northeastern Gulf of Mexico contains some of the most diverse and productive marine habitat in the United States. Much of this habitat, located on the shelf edge in depths of 50 to 120 m, supports spawning for many economically important species, including groupers. Here, we couple acoustic surveys with georeferenced videography to describe the primary spatial and geologic features of spawning aggregation sites for four economically important species: gag ( Mycteroperca microlepis ), scamp ( M. phenax ), red grouper ( Epinephelus morio ), and red snapper ( Lutjanus campechanus ), with notes on fish distribution and abundance and spawning activities. We provide information on movement patterns of reef fish determined using acoustic telemetry. Finally, we discuss the possible coupling of geomorphology with hydrographic features to influence the overall productivity of the region and the importance of spatial fishery management in sustaining that productivity.

Northeastern Gulf of Mexico↗
USGS2003

Importance of geology to fisheries management: Examples from the northeastern Gulf of Mexico

Seafloor mapping of shelf-edge habitats in the northeastern Gulf of Mexico demonstrates how sidescan-sonar imagery, seismic-reflection profiling, video data, geologic mapping, sediment sampling, and understanding the regional geologic history can enhance, support, and guide traditional fisheries research and management. New data from the Madison Swanson and Steamboat Lumps Marine Reserves reveal complex benthic habitats consisting of high-relief calcareous pinnacles, low-relief karstic hardbottom, rocky outcrops several kilometers in length, and variable thickness of fine-grained and apparently mobile coarse-grained sediments. Our data also show that certain fish alter the landscape by clearing sediment from hardbottom areas (e.g., red grouper Epinephelus morio) and by burrowing extensively in fine-grained sediment (e.g., tilefish Lopholatilus chamaeleonticeps). The seafloor imagery and geologic maps show that (a) sea level fluctuations played a dominant role in the development of the present-day regional geology, and (b) habitats (and benthic communities) are tied closely to geologic character. Understanding the geologic setting allowed for efficient and representative sampling of the biology. The geologic data can be used to set meaningful boundaries for fishery reserves and to help predict habitats in areas that are not well mapped. This interdisciplinary work added value to traditional research disciplines by providing management with integrated tools to make better decisions.

American Fisheries Society Symposium↗
USGS2000

Protection of fish spawning habitat for the conservation of warm-temperature reef-fish fisheries of shelf-edge reefs of Florida

We mapped and briefly describe the surficial geology of selected examples of shelf-edge reefs (50–120 m deep) of the southeastern United States, which are apparently derived from ancient Pleistocene shorelines and are intermittently distributed throughout the region. These reefs are ecologically significant because they support a diverse array of fish and invertebrate species, and they are the only aggregation spawning sites of gag ( Mycteroperca microlepis ), scamp ( M. phenax ), and other economically important reef fish. Our studies on the east Florida shelf in the Experimental Oculina Research Reserve show that extensive damage to the habitat-structuring coral Oculina varicosa has occurred in the past, apparently from trawling and dredging activities of the 1970s and later. On damaged or destroyed Oculina habitat, reef-fish abundance and diversity are low, whereas on intact habitat, reef-fish diversity is relatively high compared to historical diversity on the same site. The abundance and biomass of the economically important reef fish was much higher in the past than it is now, and spawning aggregations of gag and scamp have been lost or greatly reduced in size. On the west Florida shelf, fishers have concentrated on shelf-edge habitats for over 100 yrs, but fishing intensity increased dramatically in the 1980s. Those reefs are characterized by low abundance of economically important species. The degree and extent of habitat damage there is unknown. We recommend marine fishery reserves to protect habitat and for use in experimentally examining the potential production of unfished communities.

Florida↗
USGS2000

Protection of fish spawning habitat for the conservation of warm temperate reef fish fisheries of shelf-edge reefs of Florida

We mapped and briefly describe the surficial geology of selected examples of shelf-edge reefs (50–120 m deep) of the southeastern United States, which are apparently derived from ancient Pleistocene shorelines and are intermittently distributed throughout the region. These reefs are ecologically significant because they support a diverse array of fish and invertebrate species, and they are the only aggregation spawning sites of gag ( Mycteroperca microlepis ), scamp ( M. phenax ), and other economically important reef fish. Our studies on the east Florida shelf in the Experimental Oculina Research Reserve show that extensive damage to the habitat-structuring coral Oculina varicosa has occurred in the past, apparently from trawling and dredging activities of the 1970s and later. On damaged or destroyed Oculina habitat, reef-fish abundance and diversity are low, whereas on intact habitat, reef-fish diversity is relatively high compared to historical diversity on the same site. The abundance and biomass of the economically important reef fish was much higher in the past than it is now, and spawning aggregations of gag and scamp have been lost or greatly reduced in size. On the west Florida shelf, fishers have concentrated on shelf-edge habitats for over 100 yrs, but fishing intensity increased dramatically in the 1980s. Those reefs are characterized by low abundance of economically important species. The degree and extent of habitat damage there is unknown. We recommend marine fishery reserves to protect habitat and for use in experimentally examining the potential production of unfished communities.

Florida↗
USGS1999

Oculina Bank: Sidescan sonar and sediment data from a deep-water coral reef habitat off east-central Florida

The Experimental Oculina Research Reserve (EORR) is located along the shelf edge off east-central Florida in water depths of about 60 to 100 meters. It is about 7.5 km wide and 43 km long and encompasses numerous high-relief rocky pinnacles where Oculina varicosa , a fragile deep-water coral, grows. These coral reefs have historically been the sites of prolific grouper spawning aggregations and have supported a large variety of other reef fish (Gilmore and Jones, 1992). Serious decline of the fishery in the area prompted the establishment of the EORR. The data presented in this open-file report were collected as part of a cooperative project between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program and the National Marine Fisheries Service (NMFS) of the National Oceanographic and Atmospheric Administration (NOAA). The project’s goal was to provide reconnaissance geologic maps of the Experimental Oculina Research Reserve and an unprotected control area north of the reserve to support the NMFS studies of grouper spawning aggregations. To accomplish this, we collected sidescan sonar data and sediment samples throughout both study areas and used video and observations from a manned submersible at selected sites. This report includes digital mosaics of the sidescan sonar data, tabulated sediment data, and interpretative maps of the seafloor geology. The video and submersible observations are not included in this report, but were used in the interpretation of the sidescan data.

Open-File Report↗