The basic premise of this component is that cross-habitat movements of organisms play a vital role in the structure and function of coral reef systems, that is, fish act as important vectors for the transport of nutrients, organic matter and energy, and that this transport is nonrandom, leading to hotspots of productivity. Secondary premises that derive from this include contentions that: (i) Movement and distribution of organisms are determined by the types, amounts and distribution of different habitats; (ii) Movements of organisms play a vital role in the health of coral reef ecosystems; (ii) Fish diversity and abundance, as well as age-class diversity within fish species, will be maximum where there is maximum habitat diversity; (iii) Deep-water and muddy bottoms are ecological barriers to reef fish movements; and (iv) regional fisheries may benefit from the cross-shelf movements of commercial fish and invertebrates between MPAs and nonMPAs. Coral reef degradation will impact the strength of ecological linkages and how species utilize particular habitats. By the same token, the breakdown of these ecological linkages through overfishing and alteration of community structure, will lead to a decline in coral reef productivity and health.
Habitat Utilization & Energy Transport
This work, led by NOAA's National Centers for Coastal Ocean Science (NCCOS), aims to provide an understanding of reef fish habitat utilization patterns and energy transport. By understanding the connection between species and habitat as well as movements between habitats managers will better understand the consequences of a particular management action (e.g., setting up a Marine Protected Area, designating Essential Fish Habitat, evaluating coastal development). To contribute to this understanding NCCOS will employ multiple survey methodologies including underwater visual censuses of the fish community and associated habitat using SCUBA as well as deployment of passive fishing gear.
To evaluate species' habitat utilization patterns, sampling locations are randomly chosen over hard-bottom habitats throughout St. John and southwestern Puerto Rico . This random selection ensures statements made are applicable over the entire region of interest. Additional sites are selected inside and outside the recently created Virgin Islands Coral Reef National Monument , an MPA south of St. John . The hard-bottom regions have been previously delineated and geo-referenced in a series of benthic habitat maps (NOAA 2001) and all site selection is done using ArcView GIS software. Habitat data is analyzed to determine which of a suite of variables best quantifies the state of reef degradation. These variables are then related to metrics of fish community structure to determine how the state of reef health influences fish communities throughout the study region. Data is further explored to determine if patterns of fish habitat utilization differ within and outside of the MPA.
To evaluate the role fish species take in energy transport between habitats, adult and sub-adult fishes are collected at habitat boundaries during migration movements associated with foraging. Sampling locations are again chosen utilizing the habitat maps (NOAA 2001) which are stratified into four habitat boundary classes: seagrass/reef; seagrass/mangrove; seagrass/unconsolidated sediments; and mangrove/unconsolidated sediments; as well as three zones: lagoon; outer lagoon; and bank shelf. Fish movement is inferred by noting fish orientation in the net and gut contents are removed in the laboratory and preserved for identification. Gut contents are identified to the lowest possible taxonomic level and weighed. Results are then evaluated to determine the type and direction of energy transport.
The results of this particular project will be integrated with concurrent studies under the same proposal. Within the "Reef Processes" component of the proposal PIs are working on mark and recapture and acoustic tagging studies. These studies are designed to examine the patterns of movement of adult fish species and evaluate home range size. The energy flow work being conducted by NCCOS will allow interpretation of these movements. Furthermore, by utilizing the habitat utilization information gathered by NCCOS in conjunction with these other studies, proposed MPAs can be evaluated based on the health of their reefs and their size.
Work is also being conducted on the CRES grant to consider socioeconomic factors in the delineation of MPAs and to identify how best to include the public in the delineation process. In combination with the biological analyses this work will aid significantly in the evaluation of proposed MPAs.
All results obtained as part of this study will be made available to other PI's via the Database Management System as well as to other researchers via a website and peer-reviewed publications.
Year 1 -3 Sampling
Year 4 Sampling
Completed
2005
Technical Contact:
Chris Caldow
1305 East-West Highway
SSMC-IV, N/SCI-1
Silver Spring, MD 20910
301-713-3028, Ext. 164
chris.caldow@noaa.gov
