using the reconnaissance tools were then surveyed with the AUV platform, which
resolved cold-water coral fields at 0.5–3 m resolution. The AUV maps detected
mounds as small as 81 m
2 and revealed fine-scale coral ridges up to 20 m high that
were not resolved by the reconnaissance maps. The AUV maps, and other
remotely acquired data, were ground-truthed with submersible dives to produce an
integrated, geo-referenced dataset. Spatial and quantitative analyses were applied
to this dataset in order to characterize the morphology and distribution of coralbuilding features in each surveyed site. In the Miami Terrace site, where corals
build low-relief ridges, a habitat classification map and spatial analyses show that
coral patches preferentially grow on and along the northern sides of the ridges. A
southward flowing bottom current, measured by the AUV, dictates the observed
asymmetrical coral distribution. In the site on the lower slope of Great Bahama
Bank, where corals form individual mounds, morphometric analyses show a lack
of correlation between bottom current regime and mound morphology. Results
from these analyses indicate that the two cold-water coral sites in the Straits of
Florida are highly variable in terms of coral distribution, spatial parameters, and
current regime. Given its high-resolution, the approach presented here is ideal for
determining the biophysical processes that underlie these and other remote, fragile
ecosystems. Assessment and monitoring of coral distribution and mound abundance based on geophysical data is crucial for managing cold-water coral habitats
and is an important research priority.
10.1 Introduction
Scleractinian (stony) cold-water corals are branching, colonial organisms
(Fig. 10.1) that are distributed throughout aphotic water depths of 50–3,000 m
(Freiwald et al. 1997; Roberts et al. 2006). These corals can baffle and trap mobile
sediments to form large mounds, which in addition to corals contain numerous
organisms such as sponges, hydroids and anemones (Mullins et al. 1981; Roger
1999; Reed et al. 2006; Roberts et al. 2006). Mounds are also habitats for mobile
species including economically important populations of fishes (Fosså et al. 2002;
Reed 2002; Costello et al. 2005). Cold-water coral mound fields differ among
geographic locations in terms of their size-frequency distribution, morphology,
spatial pattern, and the relative exposure or burial of the mounds they contain
(Neumann et al. 1977; Del Mol et al. 2002; Huvenne et al. 2003; Wheeler et al.
2007; Correa et al. 2011). Within a given field, individual mounds can also vary
significantly in height from 1 to 300 m, and in shape from individual cone-like
forms to elongated features (Van Weering et al. 2003; Wheeler et al. 2005a;
Grasmueck et al. 2006). This variability is the result of local hydrodynamics,
antecedent topography, and/or other factors, such as sedimentation rate (White
et al. 2005; Mienis et al. 2007; Dorschel et al. 2007; Correa et al. 2011).
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T. B. S. Correa et al.
resolved cold-water coral fields at 0.5–3 m resolution. The AUV maps detected
mounds as small as 81 m
2 and revealed fine-scale coral ridges up to 20 m high that
were not resolved by the reconnaissance maps. The AUV maps, and other
remotely acquired data, were ground-truthed with submersible dives to produce an
integrated, geo-referenced dataset. Spatial and quantitative analyses were applied
to this dataset in order to characterize the morphology and distribution of coralbuilding features in each surveyed site. In the Miami Terrace site, where corals
build low-relief ridges, a habitat classification map and spatial analyses show that
coral patches preferentially grow on and along the northern sides of the ridges. A
southward flowing bottom current, measured by the AUV, dictates the observed
asymmetrical coral distribution. In the site on the lower slope of Great Bahama
Bank, where corals form individual mounds, morphometric analyses show a lack
of correlation between bottom current regime and mound morphology. Results
from these analyses indicate that the two cold-water coral sites in the Straits of
Florida are highly variable in terms of coral distribution, spatial parameters, and
current regime. Given its high-resolution, the approach presented here is ideal for
determining the biophysical processes that underlie these and other remote, fragile
ecosystems. Assessment and monitoring of coral distribution and mound abundance based on geophysical data is crucial for managing cold-water coral habitats
and is an important research priority.
10.1 Introduction
Scleractinian (stony) cold-water corals are branching, colonial organisms
(Fig. 10.1) that are distributed throughout aphotic water depths of 50–3,000 m
(Freiwald et al. 1997; Roberts et al. 2006). These corals can baffle and trap mobile
sediments to form large mounds, which in addition to corals contain numerous
organisms such as sponges, hydroids and anemones (Mullins et al. 1981; Roger
1999; Reed et al. 2006; Roberts et al. 2006). Mounds are also habitats for mobile
species including economically important populations of fishes (Fosså et al. 2002;
Reed 2002; Costello et al. 2005). Cold-water coral mound fields differ among
geographic locations in terms of their size-frequency distribution, morphology,
spatial pattern, and the relative exposure or burial of the mounds they contain
(Neumann et al. 1977; Del Mol et al. 2002; Huvenne et al. 2003; Wheeler et al.
2007; Correa et al. 2011). Within a given field, individual mounds can also vary
significantly in height from 1 to 300 m, and in shape from individual cone-like
forms to elongated features (Van Weering et al. 2003; Wheeler et al. 2005a;
Grasmueck et al. 2006). This variability is the result of local hydrodynamics,
antecedent topography, and/or other factors, such as sedimentation rate (White
et al. 2005; Mienis et al. 2007; Dorschel et al. 2007; Correa et al. 2011).
254
T. B. S. Correa et al.