Shallow-water benthic habitats of St. John, U.S. Virgin Islands

Coral reef ecosystems of the Virgin Islands Coral Reef National Monument, Virgin Islands National Park and the surrounding waters of St. John, U.S. Virgin Islands are a precious natural resource worthy of special protection and conservation. The mosaic of habitats including coral reefs, seagrasses and mangroves, are home to a diversity of marine organisms. These benthic habitats and their associated inhabitants provide many important ecosystem services to the community of St. John, such as fishing, tourism and shoreline protection. However, coral reef ecosystems throughout the U.S. Caribbean are under increasing pressure from environmental and anthropogenic stressors that threaten to destroy the natural heritage of these marine habitats. Mapping of benthic habitats is an integral component of any effective ecosystem-based management approach. Through the implementation of a multi-year interagency agreement, NOAA’s Center for Coastal Monitoring and Assessment - Biogeography Branch and the U.S. National Park Service (NPS) have completed benthic habitat mapping, field validation and accuracy assessment of maps for the nearshore marine environment of St. John. This work is an expansion of ongoing mapping and monitoring efforts conducted by NOAA and NPS in the U.S. Caribbean and replaces previous NOAA maps generated by Kendall et al. (2001) for the waters around St. John. The use of standardized protocols enables the condition of the coral reef ecosystems around St. John to be evaluated in context to the rest of the Virgin Island Territories and other U.S. coral ecosystems. The products from this effort provide an accurate assessment of the abundance and distribution of marine habitats surrounding St. John to support more effective management and conservation of ocean resources within the National Park system. This report documents the entire process of benthic habitat mapping in St. John. Chapter 1 provides a description of the benthic habitat classification scheme used to categorize the different habitats existing in the nearshore environment. Chapter 2 describes the steps required to create a benthic habitat map from visual interpretation of remotely sensed imagery. Chapter 3 details the process of accuracy assessment and reports on the thematic accuracy of the final maps. Finally, Chapter 4 is a summary of the basic map content and compares the new maps to a previous NOAA effort. Benthic habitat maps of the nearshore marine environment of St. John, U.S. Virgin Islands were created by visual interpretation of remotely sensed imagery. Overhead imagery, including color orthophotography and IKONOS satellite imagery, proved to be an excellent source from which to visually interpret the location, extent and attributes of marine habitats. NOAA scientists were able to accurately and reliably delineate the boundaries of features on digital imagery using a Geographic Information System (GIS) and fi eld investigations. The St. John habitat classification scheme defined benthic communities on the basis of four primary coral reef ecosystem attributes: 1) broad geographic zone, 2) geomorphological structure type, 3) dominant biological cover, and 4) degree of live coral cover. Every feature in the benthic habitat map was assigned a designation at each level of the scheme. The ability to apply any component of this scheme was dependent on being able to identify and delineate a given feature in remotely sensed imagery.

Moderate-depth benthic habitats of St. John, U.S. Virgin Islands

The National Oceanic and Atmospheric Administration’s (NOAA) Center for Coastal Monitoring and Assessment’s (CCMA) Biogeography Branch and the U.S. National Park Service (NPS) have completed mapping the moderate-depth marine environment south of St. John. This work is an expansion of ongoing mapping and monitoring efforts conducted by NOAA and NPS in the U.S. Caribbean. The standardized protocols used in this effort will enable scientists and managers to quantitatively compare moderate-depth coral reef ecosystems around St. John to those throughout the U.S. Territories. These protocols and products will also help support the effective management and conservation of the marine resources within the National Park system.

St. John, USVI mission report, NOAA/NOS/NCCOS/CCMA/Biogeography Branch, July 6 - July 17, 2009

The intent of this field mission was to continue ongoing efforts: (1) to spatially characterize and monitor the distribution, abundance and size of reef fishes, and the abundance of macroinvertebrates (conch, Diatema, lobster) within and around the waters of the Virgin Islands National Park (VIIS) and newly established Virgin Islands Coral Reef National Monument (VICR), (2) to correlate this information to in-situ data collected on associated habitat parameters, (3) to use this information to establish the knowledge base necessary for enacting management decisions in a spatial setting and (4) to establish the efficacy of those management decisions. An additional focus this year, was to evaluate a new habitat data collection method for RHA sites (MSR and some Coral Bay sites). There are concerns that the cylinder habitat data are not reflective of the fish transect habitat. To address this, we collected habitat data at 5x4 m increments along the transect in addition to data collected using the cylinder method. We are currently assessing the potential differences between these methods and preliminary results indicate that the average difference of coral cover estimates between the two methods was 4.1% (range 0-11%) based on 16 sample sites. In addition, Erinn Muller, a Nancy Foster Fellowship recipient, collaborated with the Biogeography Branch to examine the spatial distribution of coral diseases, to provide baseline information on disease prevalence over varying spatial scales and to establish spatial distributions of coral diseases around St. John.

Temporal trends in reef fish assemblages inside Virgin Islands National Park and around St. John, U.S. Virgin Islands, 1988-2006

This report is a result of long-term fish monitoring studies supported by the National Park Service (NPS) at the Virgin Islands National Park since 1988 and is now a joint NPS and NOAA collaboration. Reef fish monitoring data collected from 1988 to 2006 within Virgin Islands National Park (VINP) and adjacent reefs around St. John, U.S. Virgin Islands (USVI) were analyzed to provide information on the status of reef fishes during the monitoring period. Monitoring projects were initiated by the National Park Service (NPS) in the 1980s to provide useful data for evaluation of resources and for development of a long-term monitoring program. Monthly monitoring was conducted at two reef sites (Yawzi Point and Cocoloba Cay) starting in November 1988 for 2.5 years to document the monthly/seasonal variability in reef fish assemblages. Hurricane Hugo (a powerful Category 4 storm) struck the USVI in September 1989 resulting in considerable damage to the reefs around St. John. Abundance of fishes was lower at both sites following the storm, however, a greater effect was observed at Yawzi Point, which experienced a more direct impact from the hurricane. The storm affected species differently, with some showing only small, short-term declines in abundance, and others, such as the numerically abundant blue chromis (Chromis cyanea), a planktivorous damselfish, exhibiting a larger and longer recovery period. This report provides: 1) an evaluation of sampling methods, sample size, and methods used during the sampling period, 2) an evaluation of the spatial and temporal variability in reef fish assemblages at selected reef sites inside and outside of VINP, and 3) an evaluation of trends over 17 years of monitoring at the four reference sites. Comparisons of methods were conducted to standardize assessments among years. Several methods were used to evaluate sample size requirements for reef fish monitoring and the results provided a statistically robust justification for sample allocation.

Status of coral reef ecosystems in a marine managed area in St. Croix, USVI [poster]

This poster presents information on the status and trends of coral reef ecosystems in St. Croix, US Virgin Islands (USVI). Data were collected by NOAA’s Center for Coastal Monitoring and Assessment Biogeography Branch (CCMA-BB) from 2001-2006 at 1,275 random locations in and around Buck Island Reef National Monument (BIRNM). The main objective was to quantify changes in fish species and assemblage diversity, abundance, biomass and size structure; to provide spatially explicit information on the distribution of key species or groups of species; and to compare community structure inside versus outside of BIRNM.

Mission report: a strategy to inventory, characterize, and monitor the marine region within and around the National Park and Monument boundaries of St. John, USVI, July 21- July 31, 2008

The intent of this field mission was to continue ongoing efforts: (1) to spatially characterize and monitor the distribution, abundance and size of both reef fishes and conch within and around the waters of the Virgin Islands National Park (VIIS) and newly established Virgin Islands Coral Reef National Monument (VICR), (2) to correlate this information to in-situ data collected on associated habitat parameters, (3) to use this information to establish the knowledge base necessary for enacting management decisions in a spatial setting and to establish the efficacy of those management decisions. This work is supported by the National Park Service and NOAA’s Coral Reef Conservation Program’s Caribbean Coral Reef Ecosystem Monitoring Project. The report highlights the successes of this mission.

Movement of American lobster (Homarus americanus) in the southwestern Gulf of St. Lawrence

A total of 42,445 American lobsters (Homarus americanus) were tagged in thirty-one sites throughout the southwestern Gulf of St. Lawrence between 1980 and 1997. Results from the recapture of 8503 tagged lobsters showed small distances traveled between the release and the recapture position for animals ranging in size from 51 to 152 mm carapace length. The average distance traveled ranged from 2 km in parts of Baie des Chaleurs and western Cape Breton to 19 km in central Northumberland Strait. Lobsters moved generally along the shore (93% of the dispersion was in areas between the shore and the 20-m bathymetric contour). As a result, lobsters traveled longer distances in sites characterized by a gradually sloping bottom where the distance between the shore and the 20-m contour line was extensive in contrast to areas characterized by rapidly changing depths and by a relatively small amount of habitat shallower than 20 m. In the majority of sites (14 of 19) there was no significant difference between males and females in the average distance they traveled. In four of the five sites females moved farther than males. In general, the average distance traveled by berried females was shorter than that traveled by males or nonberried females. No relationship was observed between the distance traveled and the size of the animal. There was no strong evidence of a relationship between the average distance traveled and the number of days at liberty. In general, lobsters in the southwestern Gulf of St. Lawrence traveled short distances and dispersion was restricted to the nearshore habitat. Further, the distance traveled was not correlated to size, sex, or years at large. These findings show that there is little interaction between American lobsters from different fishing areas at the benthic level and that American lobster movements should have minimal consequences for management of the species in the southwestern Gulf of St. Lawrence.