2. Recent Investigations
2.1. La Parguera, southwest Puerto Rico
The first quantitative assessment of reef substrate cover by benthic communities from deep
hermatypic reefs of the upper insular slope of PR was produced by Singh et al. (2004) using
the SeaBED Autonomous Underwater Vehicle (AUV) off the La Parguera shelf-edge. The
SeaBED AUV is a modern imaging platform designed for high resolution optical and
acoustic sensing (Singh et al., 2004). The main purpose of the deployment was to perform
engineering tests of the vehicle and to build initial photomosaics of shallow-water reef sites.
However, one deep transect along the insular slope south of La Parguera starting at 20 m
over the shelf-edge to 125 m depth was included in the scope of work. The UPRM
Department of Marine Sciences 42’ R/V Sultana was used as the support vessel.
Scleractinian corals were the dominant sessile-benthic invertebrate at depths down to 30 m,
with maximum reef substrate cover (25 %) at the 24 – 30 m depth interval. Below 30 m
sponges were the dominant sessile-benthic invertebrate with a substrate cover of less than
10% (Plates 1-2). Benthic algae, sand and other abiotic substrates prevailed down the
insular slope of La Parguera to a maximum depth of 125 m. Black corals (Antipathes sp.
and Cirrhipathes sp.) were reported from the deepest section of the transect (90-100 m).
This was a preliminary study designed primarily as an equipment test and not to provide a
comprehensive biological characterization of the benthic communities. The single transect
obtained constrains the analysis of variability associated with the vertical distribution of
substrate categories. Identification of benthic organisms from the photography was
impaired by the large, up to 4 m distance between the camera lens and the substrate, due in
part to the high angle of the insular slope. Still, this work provided an unprecedented
quantitative assessment of the benthic communities off southwestern Puerto Rico.
2.2. Hind Bank Marine Conservation District (USVI)
The Hind Bank Marine Conservation District (MCD) is located at the shelf-edge, 12 km south
of St. Thomas, USVI (Figure 1). It is a known spawning aggregation site for the Red Hind
(Epinephelus guttatus), and a closed fishing area since 1999 (Nemeth (2005). Beets and
Friedlander (1997) described the spawning site and provided an assessment of the Red
Hind population at the MCD. An evaluation of the effectiveness of the fishing closure as a
22
2.1. La Parguera, southwest Puerto Rico
The first quantitative assessment of reef substrate cover by benthic communities from deep
hermatypic reefs of the upper insular slope of PR was produced by Singh et al. (2004) using
the SeaBED Autonomous Underwater Vehicle (AUV) off the La Parguera shelf-edge. The
SeaBED AUV is a modern imaging platform designed for high resolution optical and
acoustic sensing (Singh et al., 2004). The main purpose of the deployment was to perform
engineering tests of the vehicle and to build initial photomosaics of shallow-water reef sites.
However, one deep transect along the insular slope south of La Parguera starting at 20 m
over the shelf-edge to 125 m depth was included in the scope of work. The UPRM
Department of Marine Sciences 42’ R/V Sultana was used as the support vessel.
Scleractinian corals were the dominant sessile-benthic invertebrate at depths down to 30 m,
with maximum reef substrate cover (25 %) at the 24 – 30 m depth interval. Below 30 m
sponges were the dominant sessile-benthic invertebrate with a substrate cover of less than
10% (Plates 1-2). Benthic algae, sand and other abiotic substrates prevailed down the
insular slope of La Parguera to a maximum depth of 125 m. Black corals (Antipathes sp.
and Cirrhipathes sp.) were reported from the deepest section of the transect (90-100 m).
This was a preliminary study designed primarily as an equipment test and not to provide a
comprehensive biological characterization of the benthic communities. The single transect
obtained constrains the analysis of variability associated with the vertical distribution of
substrate categories. Identification of benthic organisms from the photography was
impaired by the large, up to 4 m distance between the camera lens and the substrate, due in
part to the high angle of the insular slope. Still, this work provided an unprecedented
quantitative assessment of the benthic communities off southwestern Puerto Rico.
2.2. Hind Bank Marine Conservation District (USVI)
The Hind Bank Marine Conservation District (MCD) is located at the shelf-edge, 12 km south
of St. Thomas, USVI (Figure 1). It is a known spawning aggregation site for the Red Hind
(Epinephelus guttatus), and a closed fishing area since 1999 (Nemeth (2005). Beets and
Friedlander (1997) described the spawning site and provided an assessment of the Red
Hind population at the MCD. An evaluation of the effectiveness of the fishing closure as a
22