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Habitat and fish populations in the deep-sea Oculina coral ecosystem of the western Atlantic

Abstract and Figures

The growth form of the scleractinian ivory tree coral Oculina varicosa (also known as fused ivory tree coral) that occurs on the shelf edge off Florida's eastern coast is unique for this species. Here, the branching coral colonies coalesce into thickets supporting high vertebrate and invertebrate biodiversity and high densities of economically important reef fish. In 1984, the South Atlantic Fishery Management Council took the first step to protect the area from trawling and other disruptive bottom activities. Despite these protective measures, however, there is evidence that trawling has damaged previously intact coral habitat. In this paper, we describe results from mapping studies conducted in 2001 and improvements to reef fish populations that have occurred in the last few years. We find that less than 10% of the area contains intact Oculina coral thickets, which we continue to attribute primarily to trawling. In addition, we find increased grouper density and male abundance inside the protected area, suggesting population recovery, and the appearance of juvenile speckled hind Epinephelus drummondhayi (family Serranidae), suggesting nursery function for this and possibly other commercially important species.
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American Fisheries Society Symposium 41:795–805, 2005
© 2005 by the American Fisheries Society
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Habitat and FHabitat and F
Habitat and FHabitat and F
Habitat and Fish Pish P
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Department of Biological Science, Florida State University, Tallahassee, Florida 32306-1100, USA
NOAA Undersea Research Program, University of North Carolina at Wilmington,
5600 Marvin Moss Lane, Wilmington, North Carolina 28409, USA
Harbor Branch Oceanographic Institution, 5600 U.S. 1 North, Fort Pierce, Florida 34946, USA
Department of Biological Science, Florida State University, Tallahassee, Florida 32306-1100, USA
Oregon Institute of Marine Biology, Post Office Box 5389, Charleston, Oregon 97420, USA
National Marine Fisheries Service, 3500 Delwood Beach Road, Panama City, Florida 32408, USA
U.S. Geological Survey, 384 Woods Hole Road, Woods Hole, Massachusetts 02543, USA
Abstract. The growth form of the scleractinian ivory tree coral Oculina varicosa (also known as
fused ivory tree coral) that occurs on the shelf edge off Florida’s eastern coast is unique for this
species. Here, the branching coral colonies coalesce into thickets supporting high vertebrate and
invertebrate biodiversity and high densities of economically important reef fish. In 1984, the South
Atlantic Fishery Management Council took the first step to protect the area from trawling and other
disruptive bottom activities. Despite these protective measures, however, there is evidence that
trawling has damaged previously intact coral habitat. In this paper, we describe results from mapping
studies conducted in 2001 and improvements to reef fish populations that have occurred in the last
few years. We find that less than 10% of the area contains intact Oculina coral thickets, which we
continue to attribute primarily to trawling. In addition, we find increased grouper density and male
abundance inside the protected area, suggesting population recovery, and the appearance of juvenile
speckled hind Epinephelus drummondhayi (family Serranidae), suggesting nursery function for this
and possibly other commercially important species.
Deep-sea coral species are subject to both increased in-
terest and increased pressure (Malakoff 2003). The ivory
tree coral Oculina varicosa (also known as fused ivory
tree coral) is a case in point. This species, common in
small (<30 cm), isolated, shallow water (2–30 m) colo-
nies from the West Indies to North Carolina and Ber-
muda, occurs off Florida’s eastern coast in deep (60–
120 m), species-unique reefs as 2-m high azooxanthellate
thickets on the slopes and crests of pinnacles (Reed et al.
1982; Reed 2002). These reefs, the Oculina Banks, ex-
tend 67 km along the outer shelf (Avent et al. 1977;
Virden et al. 1996; Figure 1). Healthy Oculina reefs
support a diverse invertebrate assemblage (Reed et al.
1982; Reed 2002), dense populations of fishes (G.
Gilmore, Dynamac Corporation, Kennedy Space Cen-
ter, unpublished data), and important spawning sites for
many economically important reef fish species (Gilmore
and Jones 1992; Koenig et al. 2000).
Interest in these unique Oculina thickets set in mo-
tion a series of protective measures by the South Atlantic
Fishery Management Council (SAFMC), starting in 1984
with the designation of the Oculina Habitat Area of Par-
ticular Concern (OHAPC; 316 km2) to prohibit the use of
bottom gear. In 1994, the area became the Experimental
Oculina Research Reserve (EORR), extending the prohi-
bition to bottom fishing for 10 years to explore the use of
marine protected areas (MPAs). In 2000, the OHAPC
was expanded to 1,029 km2. More recently (2003), the
EORR closure was extended indefinitely.
Our 1995 observations in the EORR confirmed pre-
vious findings by Reed (1980) of extensive coral rubble
(Koenig et al. 2000). We also found trawl damage to coral
habitat known to be intact 20 years earlier and severely
reduced reef fish populations. Jeff’s Reef, a small (4-ha)
area in the southern EORR (Figure 1), appeared to be the
only intact area, although the biomass and number of
economically important fish were much lower than they
had been in the 1970s. The objectives of this study were
to estimate the relative proportion of intact and rubble
Oculina habitat on high relief sites in the OHAPC based
on knowledge that intact coral habitat occurred predomi-
nantly on high relief and to evaluate reef fish use of both
natural and artificial structure in the EORR.
The data presented here were derived from the National
Oceanic and Atmospheric Administration’s 2001 Islands
in the Stream expedition. In 8 d (30 August–6 Septem-
ber), we completed 13 remotely operated vehicle (ROV)
dives (Phantom S4, National Undersea Research Center,
Wilmington, North Carolina) and 16 submersible dives
(Clelia, Harbor Branch Oceanographic Institution, Ft.
Pierce, Florida) in the EORR and other portions of the
OHAPC (Figure 1), producing more than 70 h of under-
water videography. The ROV made line transects over
large areas of the seafloor to determine the relative abun-
dances of coral habitat on the ridges and pinnacles. The
submersible made belt transects to quantify habitat type
and fish density within habitat types.
Habitat ConditionHabitat Condition
Habitat ConditionHabitat Condition
Habitat Condition
We used a base map derived from side-scan sonar images
(Scanlon et al. 1999) and the ship’s echo sounder to set
sampling sites. Collection site coordinates and transect
lengths were determined with differential global position-
ing system navigation (Magnavox MX 200 global posi-
tioning system [GPS], accurate to within ± 5 m) and
ArcView software. Plots of the submersible tracks and
specific sample sites were made with the Integrated Mis-
sion Profiler (Florida Atlantic University, Boca Raton)
linked to the ship’s GPS.
Remotely Operating Vehicle Sampling
The ROV was tethered near the bottom to a 100-kg down
weight by two parallel lines: (1) the first 20 m of the ROV
umbilical, extending beyond the down weight to allow
limited ROV movement at approximately 1.85 km/h (1.0
knot) northerly (i.e., with the Florida Current); and (2) a
19-m polypropylene tension-relief line to tow the ROV.
The remaining ROV umbilical extended vertically to the
vessel and was attached along its length. Transect posi-
tions were recorded while the ROV was under way to
allow location of changes in geomorphology, habitat, and
Manned Submersible Sampling
Habitat types identified by the ROV were further character-
ized by submersible with an underwater video (Insite-Tritech
high sensitivity [0.0003 lux], high-resolution monochrome
1.23-cm charge coupled device). Video imagery on statisti-
cally random belt transects was recorded with laser-equipped
downward-looking and forward-looking cameras. The
downward-looking camera’s two parallel lasers (25 cm
apart) provided the scale for standardizing quadrat size and
measuring coral colonies. The forward-looking camera’s
three inline lasers (10-cm intervals) provided the scale (two
adjacent parallel beams) and distance (the third beam con-
verged on the other two at 5 and 10 m), allowing determi-
nation of transect width at a selected distance from the
camera. Laser dots were visible at approximately 5 m in the
lower half of the camera’s field of view.
Quadrats were derived from 16 to 20 randomly se-
lected video frames from each downward-looking transect.
Each quadrat was standardized relative to the laser metric
and overlain with 100 randomly distributed dots to deter-
mine percent cover of each habitat type. The mean percent
cover was calculated for each transect (averaging ran-
domly selected frames) and compared within a given site
for each habitat type using analysis of variance (ANOVA;
arcsine transformation). A Shapiro–Wilk test for normal-
ity and Duncan’s Multiple Range test were used to iden-
Figure 1. igure 1.
igure 1. igure 1.
igure 1.
Map of
Banks Habitat Area of Particular Concern (OHAPC, shaded area in
left locator map), includes the Experimental
Research Reserve (EORR, inset box on
left, expanded on right). Dots in OHAPC are historic dive sites visited in the 1970s and 1980s.
Expanded EORR shows hard and soft bottom, high and low relief (Scanlon et al. 1999), and
location of 2001 remotely operated vehicle (ROV) transects and submersible dives.
Map Key:
High Relief Hard Bottom
Low Relief Hard Bottom
Low Relief Soft Bottom
ROV Transects
Submersible Dives
tify homogeneous subsets among transect means. Ran-
domly selected coral colonies within each transect were
Fish DensitiesFish Densities
Fish DensitiesFish Densities
Fish Densities
Fish densities (numbers per ha) were determined during
submersible belt transects in each habitat type. Transects
were run without lights to avoid affecting fish behavior.
Belt transect quantification of fish populations provides a
statistical basis for spatial and temporal comparisons, mea-
suring relative rather than absolute abundance and requir-
ing that interannual comparisons account for temporal
activity patterns.
Natural Habitat
Estimating belt transect area from submersible videos re-
quired determining the effective distance (D), the camera’s
horizontal angle of view (A = 92°), and the length (L) of
the transect. The effective distance is the distance from the
camera within which fish are counted and identified with
high certainty rather than the limits of visibility (typically
< 5 m, which was used as the standard distance; fish
occurring beyond 5 m were excluded).
The field of view width (W) at distance D was calcu-
lated by:
W = 2 [tan (0.5A)] (D).
The area of the transect (TA) was calculated by:
TA = (L × W) – 0.5(W × D).
Estimating the transect area allowed calculating
the average density and standard error of observed fish
species within each habitat type. Species tending to
follow or circle the submersible (e.g., greater amber-
jack and almaco jack) were not counted each time they
appeared on the video. Rather, their total abundance
was determined by observers in the submersible. Den-
sity differences among habitats were determined for
numerically dominant species, economically important
groupers, and pelagic species using ANOVA.
Habitat Modules
Reef balls (Reef Ball Foundation, (N
= 105)—perforated concrete domes 1 m across and 0.7 m
high—were deployed in 2000 to simulate the size and
aspect of Oculina coral colonies and serve as larval re-
cruitment surfaces, centers for Oculina thicket restoration
through transplant growth, and structure replacement for
reef fish (Figure 2; Koenig, Coleman, Brooke, and
Brusher, unpublished data). They were distributed among
nine areas (each 500 m2) in clusters of 5, 10, or 20, with
three replicates of each cluster size in a randomized block
design to determine the most efficient density for attract-
ing fish.
Habitat ConditionHabitat Condition
Habitat ConditionHabitat Condition
Habitat Condition
Seven ROV line transects were made over high relief pin-
nacles and ridges in the EORR (Chapman’s Reef: N = 3;
Sebastian Reef: N = 4). Transect lengths ranged from 424
to 2,867 m, covering 7,645 m of high-relief seafloor (Fig-
ure 1). Three coral cover levels were identified: (1) dense—
relatively undisturbed, large live and dead coral thickets
with multi-scale structural complexity; (2) sparse—small
colonies widely distributed in expanses of consolidated
(rubble with identifiable coral branching) and unconsoli-
dated rubble (fine coral debris), providing little structural
complexity; and (3) no coral cover—sand, rock, and un-
consolidated rubble, providing essentially no structural com-
plexity. The relative proportion of each coral cover type
was estimated as the proportional distance traversed by the
ROV over that habitat type.
Of the total high relief pinnacle ridges transected, 464
m (6%) contained dense coral cover, 302 m (4%) contained
sparse cover, and 6,877 m (90%) contained no cover. The
only additional dense thickets identified during this study
(Jeff’s Reef having been located in 1995) were approxi-
mately 4 ha on the western bank of Chapman’s Reef
(Chapman’s Reef West), one of three banks in Chapman’s
Reef (Figure 1). The only sparse habitats occurred on the
south face of Chapman’s Reef East and on the slope bases
of Jeff’s Reef and Chapman’s Reef West. Three additional
random transects covering 2,041 m of high relief just north
of the EORR within the OHAPC revealed only unconsoli-
dated rubble. Sparsely distributed, small (5–20-cm diam-
eter) colonies of Oculina were associated with some of the
rubble and with large boulders on low relief rocky bottom.
Sixteen belt transects were made in the EORR with
the submersible (N = 8 at Jeff’s Reef, N = 5 at Chapman’s
Reef West, N = 3 at Sebastian Reef; Figure 1), revealing
four habitat types: intact live coral, intact dead coral, coral
rubble, and bare rock and sand (Figure 3). Intact live coral
only occurred on Jeff’s Reef and Chapman’s Reef West.
Sebastian Reef was mostly coral rubble. Within each reef,
the mean live coral coverage varied considerably among
transects (ANOVA, P < 0.01). For Jeff’s Reef, mean live
coral coverage ranged from 9% to 21% and for Chapman’s
Reef West, 7% to 22% (Table 1). Coral colony diameter on
Chapman’s Reef West ranged from 8 to 143 cm, with a
mean of 47.4 cm (SE = 4.75 cm, N = 43). Coral colony size
on Jeff’s Reef was not measured due to a laser malfunc-
Fish Pish P
ish Pish P
ish Populationsopulations
Natural Habitat
Population densities for the dominant fish species cor-
related highly with habitat type (Figure 4). Only one
economically important species was observed on coral
rubble (Table 2). Highly cryptic juvenile speckled hind
Epinephelus drummondhayi associated with intact habi-
tat at average densities of 3–5 per ha. Male gag
Mycteroperca microlepis occurred on Jeff’s Reef.
Habitat Modules
Surveys of reef ball clusters occurred thirteen months after
reef ball deployment. Surveys were easy to do because
each cluster covered a small area (12.6-m radius). The
mean species richness and abundance of economically im-
portant fish were greater for reef ball densities of 10 per
cluster than for 5 but did not increase further at densities of
20 per cluster (Figure 5; Table 3). Male gag and scamp
Mycteroperca phenax occurred near reef ball clusters.
Submersible observations around habitat modules
and coral-transplant modules revealed module pieces miss-
ing and littering the bottom, suggesting impact by strong
Figure 2. Figure 2.
Figure 2. Figure 2.
Figure 2.
Habitat modules deployed on Sebastian Reef within the
Oculina Research Reserve
off the east coast of Florida
in 2000. A wooden cross attached to the top of each reef ball with
jute line (both substances being biodegradable) provided sufficient
drag to make the reef balls land upright on the bottom.
Figure 3. igure 3.
igure 3. igure 3.
igure 3.
Percent cover of habitat types in intact coral habitat (Jeff’s and
Chapman’s West Reef) and in unconsolidated rubble habitat (Sebastian Reef)
within the Experimental
Research Reserve off the eastern coast of
Florida. Bars = standard error.
Live coral Dead intact Unconsol.
Rock and sand
Benthic habitat
Percent cover
mechanical means. Apparent trawl tracks in the rubble
were noted near the damage.
Habitat CharacterizationHabitat Characterization
Habitat CharacterizationHabitat Characterization
Habitat Characterization
During this study, we specifically targeted high-relief
sites in the OHAPC known in the 1970s to have either
intact coral thickets (e.g., Jeff’s Reef and Chapman’s
Reef) or extensive coral rubble (e.g., Sebastian Reef;
Reed 1980; Koenig et al. 2000). We used direct observa-
tion rather than acoustic methods because the latter does
not distinguish among live coral, dead intact coral, or
unconsolidated rubble. Rubble is a major component on
high-relief features. The concern is that so few high
relief sites had intact thickets. Indeed, about 90% of the
habitat surveyed was unconsolidated rubble; less than
10% contained intact coral colonies. No additional coral
thickets were found within the EORR. Areas of the
OHAPC north of the EORR known to contain thickets
20 years ago contained only coral rubble.
Ten percent intact coral on high relief features is
likely a high estimate. If one assumes the EORR’s only
intact habitat is on Jeff’s Reef and Chapman’s Reef West,
a lower estimate results. Roughly 3% (947 ha) of the
EORR is high relief (Scanlon et al. 1999) and therefore
suitable for Oculina thicket growth. With only 8 ha known
to contain intact habitat, less than 1% of the intact habitat
occurs on high relief sites. The more accurate estimate is
likely somewhere in between. Although the ROV line
transects targeted areas that once supported Oculina thick-
ets, transposing old long-range navigation coordinates to
GPS introduces uncertainty about historic site locations,
and there was no way to anticipate which features would
contain rubble and which would contain intact colonies.
In intact habitat, live coral coverage was less than
half that of dead standing coral coverage, and both types
of coverage were highly variable among transects. Ob-
servations of small coral colonies within coral rubble
(primarily on high relief sites, occasionally on low relief
sites) and extensive coral colonies on 60-year-old ship-
wrecks just outside of the EORR (M. Barnette, National
Marine Fisheries Service, personal communication) sug-
gest that coral colonization and growth occur but are
insignificant. The presence of small dead standing colo-
nies in low relief sites suggests that these may be mar-
ginal sites for survival.
Fish Pish P
ish Pish P
ish Populationsopulations
In the past 30 years, the size, age, and proportion of
male gag and scamp have declined throughout the south-
eastern United States (Coleman et al. 1996; McGovern
et al. 1998; Koenig et al. 2000). The results of this study
suggest that protecting aggregation sites and resident
populations within MPAs can help reestablish historical
fish populations. Indeed, gag and scamp, including males,
occur on coral thickets within the EORR but not on sites
outside of the EORR. They also suggest some nursery
function, based on the observation of juvenile speckled
hind on Jeff’s and Chapman’s reefs. This is significant
because the SAFMC considers this species threatened
(Coleman et al. 2000). Density estimates of small fish or
young individuals of typically larger species are prob-
ably low, especially in structurally complex habitats
where these fish are often cryptic.
Unlike the typical artificial reef, which provides habi-
tat and attracts reef fish to areas where neither previously
existed, the reef ball modules replace destroyed habitat
and serve as bases for reestablishing Oculina thickets.
Observations thus far on restoration sites show promise
only for reestablishing fish populations. All grouper spe-
cies observed in 1980 on intact reefs (see Koenig et al.
2000), except warsaw grouper Epinephelus nigritus, as-
sociated with reef balls 1 year after their deployment. The
reef balls may eventually support spawning, based on the
presence of both gag and scamp males (typical of spawn-
ing aggregation sites, per Coleman et al. 1996), with scamp
exhibiting presumed courtship behavior (described in
Gilmore and Jones 1992).
Table 1. able 1.
able 1. able 1.
able 1.
Mean live coral cover and standing dead coral cover (in parentheses) determined from belt
transects made with submersible on Jeff’s Reef and Chapman’s Reef in the
Experimental Research
Reserve. Thick horizontal lines indicate homogenous groupings of live coral (based on Duncan’s multiple
range test).
Transect number
Reef 1 2 345678
Jeff’s Reef 8.9 (8.4) 9.2 (3.2) 11.1 (17.7) 12.9 (8.4) 13.6 (7.4) 13.6 (10.4) 20.0 (46.2) 21.3 (49.8)
Chapman’s 7.0 (12.7) 7.7 (0) 9.2 (16.0) 11.0 (24.8) 22.3 (727.1)
Figure 4. Figure 4.
Figure 4. Figure 4.
Figure 4.
Mean population densities of (A) dominant basses
(Anthiinae; roughtongue bass
Holanthias martinicensis
and red
Hemanthias vivanus
), (B) dominant groupers (Epinephelinae;
scamp, gag, and speckled hind), and (C) pelagic species (greater
Seriola dumerili
and almaco jack
S. rivoliana
) in three
levels of coral habitat condition. Bars = standard errors. Scamp
density in intact habitat was significantly greater (
= 0.05) than in
other habitats.
Possible Causes of Habitat Declineossible Causes of Habitat Decline
ossible Causes of Habitat Declineossible Causes of Habitat Decline
ossible Causes of Habitat Decline
Natural, wholly unmanageable events that damage coral
include extreme temperatures (Fitt et al. 2001), excessive
nutrient input (Szmant 2002), strong currents (Lugo et al.
2000), and disease (Porter et al. 2001). Oculina is relatively
tolerant of changes in temperature and nutrient and sedi-
ment input that occur during episodic deep-sea upwelling
events (Reed 1983), although this tolerance may not persist
in the face of global warming or increased nutrient loads
associated with ocean dumping. Although no studies of
Roughtongue bass
Red barbier
Rubble Sparse Dense
Speckled hind
Rubble Sparse Dense
Greater amberjack
Almaco jack
Rubble Sparse Dense
Most of the evidence for Oculina habitat destruc-
tion points to human-induced impacts. While it is pos-
sible that World War II exchanges between U.S. and
German vessels west of the OHAPC (Cremer 1986)
caused some damage, these encounters ended about 60
years ago, allowing sufficient time for habitat recovery.
Indeed, U.S. freighters sunk near the OHAPC by Ger-
man U-boats in the 1940s support dense Oculina thick-
ets on their decks (Barnette, personal communication).
Trawling continues to be the greatest manageable
threat to the Oculina reefs (Koenig et al. 2000). Bottom
trawling and dredging worldwide result in severe coral
damage (Jones 1992; Rogers 1999; Fosså et al. 2000;
Koslow et al. 2000; Richer de Forges et al. 2000), re-
quiring long recovery times (Dayton et al. 2002; Johnson
2002). These have occurred off Florida’s eastern coast
for years, involving both foreign and domestic fleets.
Foreign trawling stopped in the late 1970s with devel-
opment of the U.S. Exclusive Economic Zone.
The extent to which domestic trawling persists in the
Oculina banks is unknown. However, circumstantial evi-
dence suggests that it does to some degree. Trawlable
high relief bottom features where Oculina normally oc-
curs show little evidence of coral recolonization, while
Table 2. able 2.
able 2. able 2.
able 2.
Comparison of mean densities of species observed in intact habitat (Jeff’s Reef and
Chapman’s Reef) and unconsolidated coral rubble (Sebastian Reef; presumably coral
destroyed by trawling) within the Experimental
Research Reserve. An asterisk
indicates an economically important species.
Jeff’s Reef Chapman’s Reef Sebastian Reef
Species Number/ha SE Number/ha SE Number/ha SE
Red barbier 7,301 2,757 18,082 3,429 277 277
Roughtongue bass 1,211 410 6,424 3,560 141 89
Greater amberjack* 298 182 284 187
Yellowtail reeffish 60 30 277 111 53 43
Chromis enchrysurus
Almaco jack* 55 29
Scamp* 48 11 47 27
Blue angelfish 39 13 204 72 6 6
Holacanthus bermudensis
Bank butterflyfish 27 10 110 35 19 12
Chaetodon aya
Gag* 16 7
Reef butterflyfish 13 6 102 50 17 11
Chaetodon sedentarius
Specked hind* 3 3 5 5
Serranus phoebe
3 3 27 12 44 12
Spotfin butterflyfish 2 2
Chaetodon ocellatus
spp.* 10 10
Wrasse bass
Liopropoma eukrines
17 13
spp. 17 13
Wrasse Labridae 42 26
Purple reeffish
Chromis scotti
36 18
spp.* 6 6
Figure 5.Figure 5.
Figure 5.Figure 5.
Figure 5.
Mean number of species and individuals
(benthic and pelagic) of economically important reef
fish associated with three reef ball densities, 5 per
500 m2, 10 per 500 m2, and 20 per 500 m2 set over
unconsolidated coral rubble in Sebastian Reef within
the Experimental
Research Reserve off the
east coast of Florida There were 3 replicates of each
disease have been conducted in the Oculina banks, virulent
pathogens would be expected to cause extensive damage to
ahermatypic reefs like Oculina rather than selective elimi-
nation of some reefs but not adjacent reefs.
5 per set 10 per set 20 per set
Cluster size
untrawlable wrecks in the same area support dense thick-
ets. The incidence of trawling is sufficiently high that the
SAFMC requires local trawlers to use vessel monitoring
systems. The council did not alter the penalties for trawl-
ing, however, which currently are relatively light (i.e.,
confiscated catch and moderate fines) and viewed by vio-
lators as a business expense (anonymous commercial fish-
erman, personal communication). This differs significantly
in the Florida Keys National Marine Sanctuary, where,
based on the National Marine Sanctuaries Act (U.S. Code,
Title 16, chapter 32, section 1431 et seq., as amended in
Public Law 106-513, November 2002), those guilty of
destroying coral habitat—for whatever reason—are sub-
ject to fines substantial enough to cover the costs of habi-
tat restoration or mitigation.
While surveillance and enforcement are important
to management of MPAs, compliance indicates that ex-
tractive users perceive MPA boundaries as fair and eq-
uitable. This typically results from knowledge of the
natural resources that occur within reserve boundaries
and the ecological and economic benefits derived from
their protection. Education clearly provides the most ef-
ficient, cost-effective, and powerful stimulus to habitat
We thank J. McDonough (National Oceanic and Atmo-
spheric Administration [NOAA] National Ocean Service
[NOS]), T. Potts (National Undersea Research Center
[NURC], University of North Carolina, Wilmington
[UNCW]), and S. Orlando (NOS) for organizing the
NOAA Islands in the Stream cruise. L. Horn (NURC/
UNCW) served as expert pilot for the ROV. M. Barnette
(NOAA National Marine Fisheries Service [NMFS], St.
Petersburg, Florida) provided information on Oculina
growth on shipwrecks. G. Gilmore (Dynamac Corpora-
Table 3. able 3.
able 3. able 3.
able 3.
Comparison of reef fish found on Sebastian Reef in the Oculina Experimental Research Reserve,
associated with three different densities of reef balls deployed in coral restoration experiments. Asterisk
indicated economically important species.
5 reef balls/cluster 10 reef balls/cluster 20 reef balls/cluster
Species Number/1,500 m2% Number/1,500 m2% Number/1,500 m2%
Greater amberjack* 109 37.72
Roughtongue bass 7 41.18 120 41.52 53 21.9
Red barbier 1 0.35 25 10.33
Almaco jack* 20 6.92 20 8.26
Scamp* 3 17.65 15 5.19 14 5.79
Wrasse 1 0.35 10 4.13
Blue angelfish 3 1.04 5 2.07
Reef butterflyfish 4 1.38 3 1.24
Red snapper* 6 2.08 2 0.83
Lutjanus campechanus
Snowy grouper* 2 11.76 2 0.83
Epinephelus niveatus
Speckled hind* 3 1.24
Tattler 1 5.88 2 0.83
Red porgy* 2 11.76 2 0.83
Pagrus pagrus
Sharpnose puffer 1 0.41
Canthigaster rostrata
Queen angelfish 1 0.41
Holacanthus ciliaris
Bank butterfly 1 5.88 2 0.69
Short bigeye 2 0.69
Pristigenys alta
Twospot cardinalfish 2 0.69
Apogon pseudomaculatus
Spinycheeck soldierfish 2 0.69
Corniger spinosus
Sharpnose puffer 1 0.35
Canthigaster rostrata
Bank sea bass 1 5.88
Centropristis ocyurus
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A. David. NOS and NMFS Southeast Fisheries Science
Center supplied funding for the “Islands in the Stream”
OHAPC study, especially for the use of Harbor Branch
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... Although initially used for determining substrate composition in deep-water biological assessments as a replacement for manned submersibles (Koenig et al., 2005), advancements in video quality and in ROV technology have allowed ROVs to become a more practical and affordable method for providing assessments for a wide variety of flora and fauna, including elasmobranchs (Benz et al., 2007;Henry et al., 2016), teleost fish (Carpenter and Shull, 2011;Haggarty et al., 2016), cephalopods (Smale et al., 2001;Zeidberg and Robison, 2007), gastropods (Butler et al., 2006;Stierhoff et al., 2012), macro-algae (Spalding et al., 2003), corals (Doughty et al., 2014;Etnoyer et al., 2018) and other macroinvertebrates (Grinyó et al., 2016;Hemery and Henkel, 2016). While ROVs can provide in situ observations of fish, their behaviors and habitat-associations that cannot be determined with traditional methods (i.e., trawls, longline) (Adams et al., 1995;Karpov et al., 2004;Linley et al., 2013), ROVbased sampling strategies must account for the unique challenges of surveying mobile organisms that are not applicable in surveys of sessile invertebrates and substrate. ...
... In a study comparing the abundances and lengths of fish collected by ROV and manned submersible surveys across different habitats and depths in California, manned submersibles were able to record a greater number of species, body length estimates, and abundances of species that were found closer to the seafloor (Laidig and Yoklavich, 2016). While the number of studies comparing these methods are limited, ROVs are a more practical and inexpensive tool for monitoring (Koenig et al., 2005), and possess greater maneuverability than AUVs and manned submersibles. ...
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Anthropogenic activities and greater demands for marine natural resources has led to increases in the spatial extent and duration of pressures on marine ecosystems. Remotely operated vehicles (ROVs) offer a robust survey tool for quantifying these pressures and tracking the success of management intervention while at a range of depths, including those inaccessible to most SCUBA diver-based survey methods (~>30 m). As the strengths, limitations, and biases of ROVs for visually monitoring fish assemblages remain unclear, this review aims to evaluate ROVs as a survey technique and to suggest optimal sampling strategies for use in typical ROV-based studies. Using the search engines Scopus™ and Google Scholar™, 119 publications were identified that used ROVs for visual surveys of fish assemblages. While the sampling strategies and sampling metrics used to annotate the imagery in these publications varied considerably, the total abundance of fish recorded over strip transects of varying dimensions was the most common sampling design. The choice of ROV system appears to be a strong indicator of both the types of surveys available to studies and the success of ROV deployments. For instance, larger, more powerful working-class systems can complete longer and more complex designs (e.g., swath, cloverleaf, and polygonal transects) at greater depths, whereas observation-class systems are less expensive and easier to deploy, but are more susceptible to delays or cancelations of deployments. In more severe sea state conditions, radial transects, or strip transects that employ live-boating or a weight to anchor the tether to the seafloor, can be used to improve the performance of observation-class systems. As these systems often employ shorter tethers, radial transects can also be used to maximize sampling area at greater depths and on large vessels that may rotate substantially while anchored. For highly mobile species, and in survey designs where individuals are likely to be recounted (e.g., transects along oil and gas pipelines), relative abundance (MaxN) may be a more robust sampling metric. By identifying subtle, yet important, differences in the application of ROVs as a tool for visually surveying deep-water marine ecosystems, we identified key areas for improvement for best practice for future studies.
... At deeper shelf depths, O. varicosa forms large individual colonies that create significant habitat for invertebrates and fishes (Reed et al. 1982;Reed and Mikkelsen 1987;Reed 2004). On the edge of the continental shelf (70-152 m), this species forms massive reef structures that support an extremely diverse and abundant invertebrate fauna, and provides spawning habitat for economically valuable fish species (Reed et al. 1982;Reed and Mikkelsen 1987;Reed 2004;Reed et al. 2005;Koenig et al. 2005). The Oculina Banks were designated a Habitat Area of Particular Concern (HAPC) in 1984 by the South Atlantic Fish Management Council . ...
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Along the east Florida coast, 602 species of invertebrates have been identified on nearshore reefs. Ecological functions of invertebrates in this area include those organisms that: (1) increase local diversity of fishes and invertebrates via enhancing shelter availability, and/or (2) serve as predators or prey in local food webs. Generally, the highest community biomasses occur in reef areas with higher abundances of foundation invertebrate species that enhance local shelter and reduce environmental stress. A major example is the reef-building polychaete, Phragmatopoma lapidosa (caudata), which can be abundant along the central sections of the Florida coast and creates important structure that supports high diversities of invertebrates and fishes. In some areas, hard and soft corals, sponges, tunicates, mollusks, and barnacles function similarly. In contrast, many invertebrates also function as predators, prey, or both. In this capacity, they can be important in local food webs. Taxonomic groups that serve this function are sponges, crabs, polychaetes, echinoderms, and shrimp. Both functions likely vary dramatically with depth and latitude along the east Florida coast. Additional research is needed to better understand such spatial variability as well the dispersal and connectivity of important foundation species along the coast.
... Van Dover et al. (2014) evaluated hypothetical scenarios of ecological restoration of the deep sea but lacked empirical data from active restoration studies, bringing to light a major gap in applied scientific knowledge. Although experimental restoration of the deep-sea corals Lophelia pertusa (∼ 500 m in depth) and Oculina varicosa (∼60-120 m) has been somewhat successful in the Gulf of Mexico (Koenig et al., 2005;Brooke et al., 2006;Brooke and Young, 2009), studies examining the sensitivity of multiple coral taxa to differential handling and processing remain a gap in knowledge for all deep-sea efforts. However, insights gained from these initial efforts, in combination with information from coral reef restoration studies from shallow habitats (<30 m), may serve as a more comprehensive guide to expanding mitigation strategies for the deep sea. ...
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Corals and sponges in rocky deep-sea environments are foundation species postulated to enhance local diversity by increasing biogenic habitat heterogeneity and enriching local carbon cycling. These key groups are highly vulnerable to disturbances (e.g., trawling, mining, and pollution) and are threatened by expansive changes in ocean conditions linked to climate change (acidification, warming, and deoxygenation). Once damaged by trawling or other disturbances, recolonization and regrowth may require centuries or longer, highlighting the need for stewardship of these deep-sea coral and sponge communities (DSCSCs). To this end, the sustainability of DSCSCs may be enhanced not only by protecting existing communities, but also repopulating disturbed areas using active restoration methods. Here, we report one of the first studies to explore methods to restore deep-sea coral populations by translocating coral fragments of multiple coral species. Branches of deep-sea corals were collected by ROV from 800 to 1300 m depth off central California and propagated into multiple fragments once at the surface. These fragments were then attached to "coral pots" using two different methods and placed in the same habitat to assess their survivorship (n = 113 total fragments, n = 7 taxa, n = 7 deployment groups). Mean survivorship for all translocated coral fragments observed within the first 365 days was ∼52%, with the highest mortality occurring in the first 3 months. In addition to an initial temporal sensitivity, survival of coral fragments varied by attachment method and among species. All coral fragments attached to coral pots using zip ties died, while those attached by cement resulted in differential survivorship over time. The latter method resulted in 80-100% fragment survivorship after 1 year for Corallium sp., Lillipathes sp., and Swiftia kofoidi, 12-50% for the bamboo corals Keratoisis sp. and Isidella tentaculum, and 0-50% for the bubblegum corals Paragorgia arborea and Sibogagorgia cauliflora. These initial results indicate differences in sensitivities to transplanting methods among coral species, but also suggest that repopulation efforts may accelerate the recovery of disturbed DSCSCs.
... The majority of research related to this topic has focused on scleractinian corals. For example, an estimated 5-52% of the total area covered by Lophelia pertusa in Norwegian waters was damaged by fishing activities , and researchers attributed destruction of all but 10% of Oculina spp. in a Florida reserve to illegal trawling activity (Koenig et al., 2005). However, trawl survey data, showed highest abundances of gorgonians (and deep-water corals, in general) in areas with little to no past trawling along the eastern Grand Banks and Flemish Cap (Murillo et al., 2010). ...
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Keratoisis grayi is one of the most abundant large gorgonian corals found off Newfoundland and Labrador, yet we know little regarding the factors influencing its distribution, abundance, and condition. We employed remotely operated vehicle (ROV) transect data collected in three canyons off the Grand Banks, Newfoundland to quantitatively examine the influence of depth, bottom type, canyon, and trawling intensity on K. grayi abundance, height, and condition at small spatial scales. While surveying 105 km of seafloor with a ROV, we observed 5770 K. grayi colonies and 167 trawl marks. We found that K. grayi were significantly more likely to occur in boulder areas than in cobble or gravel. Bottom depth related positively and significantly with colony height and our models predict that the largest bamboo coral colonies occur in boulders in Halibut Channel, and in boulders and cobble in Haddock Channel. The majority of colonies observed were alive and undamaged, but tipped, broken, dead and partially dead colonies were also recorded. K. grayi were more likely to occur in trawled areas, but these colonies were more likely to be damaged, broken, smaller in size, and less abundant than colonies outside trawled areas. These results demonstrate a negative impact of bottom trawling on K. grayi colonies off Newfoundland and Labrador and that fishers may specifically target areas where these corals occur.
... Structurally complex habitats, including coral gardens and reefs, sponge aggregations and boulder fields can influence the distribution of demersal fish species (Söffker et al., 2011;Komyakova et al., 2013;Trebilco et al., 2015). Fish may prefer structurally complex habitats as they provide shelter (Auster et al., 2003;Koenig et al., 2005), or serve as spawning or nursery grounds (Fosså et al., 2000;Costello et al., 2005;Baillon et al., 2012;Miller et al., 2012). Habitat complexity may also influence fish feeding behaviour (Weber et al., 2010), especially when fish use different habitats for foraging than for shelter (e.g. ...
The association between fish assemblages and cold-water coral habitats was evaluated based on analysis of longline catches in the Lónsdjúp trough, SE-Iceland. In 2009 and 2010, longlines were set in locations with varying coral cover within the trough. The study site is characterised by a depression (50-100 m deep), intersected by several ridges. Colonies of the cold-water coral Lophelia pertusa and other coral species were mainly found on the ridges. Among the fifteen fish species recorded, tusk (Brosme brosme) contributed ∼80% to the total fish abundance in both surveys and their catch per unit effort was twofold greater on the ridges than in adjacent flat areas. Multivariate analyses showed differences between the structure of fish communities on and off the ridges. Constrained redundancy ordinations followed by variance partitioning revealed that the structure of the fish community varied with seabed complexity, cold-water coral coverage and geographical position. It was not possible to separate between the effects of seabed complexity and coral cover, as these were strongly correlated.
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Deep-water environments make up 64% of the world’s oceans (nearly 202 million km2). In the past, the belief that this environment represented one of the most stable and unproductive ecosystems on the planet has been refuted by scientific research and the interest of potential productive sectors evaluating seabed resources. Human activities that threaten the health of deep-sea threats are uncontrolled and unregulated fishing, deep-sea mining, oil spills, marine litter, and climate change. With recent advances in technology, the study of deep-sea coral communities is a growing subject. The deep-sea corals are long-lived, slow-growing, and fragile systems, making them especially vulnerable to physical damage. In the last 40 years, Colombia has discovered these communities’ existence scarcely distributed in its territorial waters. A representative and irreplaceable sample of deep-sea coral formations triggered in 2013 the establishment of the Corales de Profundidad National Natural Park, a Marine Protected Area (MPA), which holds 40% of the marine biodiversity known in the Colombian Caribbean continental shelf-slope break. The MPA’s essential ecological value is the Madracis myriaster species’ presence as a primary habitat-forming organism, a unique habitat for the Caribbean and the world. Here we describe the MPA creation process in three phases. Firstly, in the provisioning phase, three main threats from human activities are identified. Secondly, in the preparation phase, the area’s conservation objectives and management category are defined, and the negotiation process with the fishing, communications, and oil and gas economic sectors is described. Lastly, in the designation phase, three MPA scenario proposals were evaluated, assessing the minimum distance, the possible effects of activities in the area as the main criteria for the buffer zone and the management of possible future impacts. As a result, the most extended boundary was adopted, guaranteeing these communities’ conservation despite the limited information to carry out a complete planning process. The MPA designation is considered the first experience of deep communities in the Southern Caribbean and an example that it is possible to have effective conservation agreements with economic sectors.
The Pourtalès Terrace is an exposed hard-bottom platform located south of the Florida Keys in 200–450 m depth with a diverse deep-sea coral ecosystem dominated by stylasterid hydrocorals, octocorals, and sponges that supports recreational and commercial fisheries. Portions of the Terrace have been designated as managed areas in the absence of detailed habitat maps, which hampers identifying ecological benefits derived from such management actions. Here we report analyses of historic Terrace physiographic and geologic data with more recent high-resolution bathymetric and benthic data to statistically derive a benthic community characterization across the Terrace. Multivariate analyses of faunal density from 42 standardized sites showed spatially distinct communities: East Terrace, West Terrace, Upper Terrace Edge, Sinkholes and Lophelia Coral Mound (the southernmost record of this habitat in the continental U.S.). These corresponded to physiographic divisions into an Upper Terrace comprised of Central and Karst-like regions, and Lower Terrace. A detailed description of these communities is provided. This study presents new insights into the Terrace benthic community spatial arrangement and is a necessary step towards facilitating benthic mapping. Our recommendations highlight the information needed for benthic habitat map creation and collecting data to determine if current conservation boundaries match management goals.
Marine animal forests (MAFs) are constituted by dense aggregations of epibenthic and emergent animals, chiefly members of Porifera (sponges), Cnidaria (hydrozoans and anthozoans, including corals), and Bryozoa. Their three-dimensional structure and collective spatial complexity provide a diversity of habitats for associated fauna. Dispersed throughout the ecological literature are examples of the functional role that MAFs play in terms of nursery functions for vagile species of ecological and economic importance. However, a holistic approach for identifying the time and space domains for the ecological role of MAFs is not a trivial task. MAFs are biodiversity hotspots, with juvenile life-history stages of a diversity of species co-occurring in such habitats. Unfortunately, co-occurrence is not enough to discriminate a functional linkage between species and thus properly define the function and role of these biogenic habitats as nurseries. Applying ecological theory based on habitat selection models for different species is the first step toward this discrimination, with subsequent field sampling to test and refine models based on patterns of survivorship, density, and fitness (e.g., size, weight). Such fieldwork aims to define important elements for delineating MAFs as nursery habitats and developing conservation alternatives in a conservation and fisheries context. Overfishing and habitat degradation have profoundly altered populations of taxa that form MAFs. Currently, a great portion of species subject to exploitation across the globe is overfished. In this negative context, however, the good news is that humanity holds the power to attenuate or even reverse this trend. Fundamentally, this goal relies on a more holistic approach that conserves habitats designated as “essential” for, at least, a crucial part of marine organisms’ life cycles. In this regard, nursery habitats enhance populations of some species through adjacent habitats; hence, their conservation becomes a buffer against overexploitation. The aim of this chapter is to present a synthesis of the role of the nursery functions of MAFs, link MAF species to patterns of use as nurseries, describe approaches and tools to identify such habitats, and provide guidance for future research and conservation planning.
This chapter is a review of studies that present the role of cold-water corals as shelter, feeding and life-history critical habitats for fish species in the Mediterranean Sea and world oceans. Studies in the Mediterranean have been carried out both in Madrepora-Lophelia dominated communities and in coral areas characterised by octocorals and black corals. Most studies in the northeast Atlantic regard Lophelia pertusa reefs, while those in the northwest Atlantic refer to Oculina varicosa, L. pertusa and octocoral species. Octocorals and black corals dominated in the studies from the northeast Pacific. Most studies show that the cold-water coral habitats are important for fish species. In fact, a variety of fish species have been observed and suggested to benefit from shelter and productive feeding in the complex heterogeneous habitats built by corals. This is due to the enhanced density of zooplankton as potential prey for planktivorous fish and high density of invertebrates between and around corals as food for benthos feeders and scavengers. Moreover, several fish species use cold-water coral habitats as a spawning area and nursery. The occurrence of gravid individuals frequently observed in the coral habitats, as well as the presence of egg masses found deposited on coral stalks and egg cases attached to corals or found nested in coral colonies are clear evidence that several fish species rely on coral habitats as a place to spawn and protect offspring. The fish species of families Scyliorhinidae, Sebastidae, Serranidae, Berycidae, Zoarcidae, Lotidae, Moridae, Congridae, Liparidae seem to be more tightly associated to cold-water coral habitats. Some fish species of these families obtain multiple benefits from their association with cold-water coral habitats, despite being facultative inhabitants. Regarding the occurrence of many commercial fish species in cold-water coral habitats, it should be take into consideration that these habitats are highly impacted in the Mediterranean and throughout the oceans in general. Studies on this topic have been reviewed shortly focusing on the Mediterranean Sea where longlining and trawling are the main causes of fishing impact.
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Abstract Widespread shallow coral reef loss has led to calls for more holistic approaches to coral reef management, requiring inclusion of ecosystems interacting with shallow coral reefs in management plans. Yet, almost all current reef management is biased towards shallow reefs, and overlooks that coral reefs extend beyond shallow waters to mesophotic coral ecosystems (MCEs; 30–150 m). We present the first detailed quantitative characterization of MCEs off Cozumel, Mexico, on the northern Mesoamerican Reef in the Mexican Caribbean, and provide insights into their general state. We documented MCE biodiversity, and assessed whether MCEs adjacent to a major town and port, where coastal development has caused shallow reef damage, have similar benthic and fish communities to MCEs within a National Park. Our results show that overall MCE communities are similar regardless of protection, though some taxa-specific differences exist in benthic communities between sites within the MPA and areas outside. Regardless of protection and location, and in contrast to shallow reefs, all observed Cozumel MCEs were continuous reefs with the main structural habitat complexity provided by calcareous macroalgae, sponges, gorgonians and black corals. Hard corals were present on MCEs, although at low abundance. We found that 42.5% of fish species recorded on Cozumel could be found on both shallow reefs and MCEs, including 39.6% of commercially valuable fish species. These results suggest that MCEs could play an important role in supporting fish populations. However, regardless of protection and depth, we found few large-body fishes (greater than 500 mm), which were nearly absent at all studied sites. Cozumel MCEs contain diverse benthic and fish assemblages, including commercially valuable fisheries species and ecosystem engineers, such as black corals. Because of their inherent biodiversity and identified threats, MCEs should be incorporated into shallow-reef-focused Cozumel National Park management plan.
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Over the last twenty years, human exploitation has begun to have an impact in the deep sea, especially in the upper bathyal zone. This has mainly taken the form of deep-sea fishing but more recently oil exploration has extended beyond the continental shelf. Deep-water coral reefs occur in the upper bathyal zone throughout the world. These structures, however, are poorly studied with respect to their occurrence, biology and the diversity of the communities associated with them. In the North-East Atlantic the coral Lophelia pertusa has frequently been recorded. The present review examines the current knowledge on L. pertusa and discusses similarities between its biology and that of other deep-water, reef-forming, corals. It is concluded that L. pertusa is a reef-forming coral that has a highly diverse associated fauna. Associated diversity is compared with that of tropical shallow-water reefs. Such a highly diverse fauna may be shared with other deep-water, reef-forming, corals though as yet many of these are poorly studied. The main potential threats to L. pertusa in the North-East Atlantic are considered to be natural phenomena, such as slope failures and changes in ocean circulation and anthropogenic impacts such as deep-sea fishing and oil exploration. The existing and potential impacts of these activities on L. pertusa are discussed. Deep-sea fishing is also known to have had a significant impact on deep-water reefs in other parts of the world.
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The coexistence of hurricanes, coral reefs, and rainforests in the Caribbean demonstrates that highly structured ecosystems with great diversity can flourish in spite of recurring exposure to intense destructive energy. Coral reefs develop in response to wave energy and resist hurricanes largely by virtue of their structural strength. Limited fetch also protects some reefs from fully developed hurricane waves. While storms may produce dramatic local reef damage, they appear to have little impact on the ability of coral reefs to provide food or habitat for fish and other animals. Rainforests experience an enormous increase in wind energy during hurricanes with dramatic structural changes in the vegetation. The resulting changes in forest microclimate are larger than those on reefs and the loss of fruit, leaves, cover, and microclimate has a great impact on animal populations. Recovery of many aspects of rainforest structure and function is rapid, though there may be long-term changes in species composition. While resistance and repair have maintained reefs and rainforests in the past, human impacts may threaten their ability to survive. The sea was far away in Villavicencio, but curiously I spent a deal of time there thinking about it, reading about it, wondering about the similarities, the biological analogies, between the forest and the sea. There I first began to realize the essential similarities in plan and function among all the diverse living landscapes and seascapes of our planetary surface —the essential unity of the living world. Marston Bates (1)
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Fishers have been complaining about the effects of bottom trawl gear on the marine environment since at least the 14th century. Trawl gear affects the environment in both direct and indirect ways. Direct effects include scraping and ploughing of the substrate, sediment resuspension, destruction of benthos, and dumping of processing waste. Indirect effects include post‐fishing mortality and long‐term trawl‐induced changes to the benthos. There are few conclusive studies linking trawling to observed environmental changes since it is difficult to isolate the cause. However, permanent faunal changes brought about by trawling have been recorded. Research has established that the degree of environmental perturbation from bottom trawling activities is related to the weight of the gear on the seabed, the towing speed, the nature of the bottom sediments, and the strength of the tides and currents. The greater the frequency of gear impact on an area, the greater the likelihood of permanent change. In deeper water where the fauna is less adapted to changes in sediment regimes and disturbance from storm events, the effects of gear take longer to disappear. Studies indicate that in deep water (>1000 m), the recovery time is probably measured in decades.
Gag, Mycteroperca microlepis, is a large, slow-growing, protogynous grouper that probably makes annual migrations to specific locations to aggregate for spawning. During 1976-82, male gag constituted 19.6% of the sexually mature individuals taken during fishery-dependent and fishery-independent sampling along the southeast coast of the United States. A similar percentage of males was found in the Gulf of Mexico from 1977 to 1980; however, males made up only 1.9% of the population in the Gulf of Mexico during 1992. To assess the current sex ratio of gag along the southeast U.S. coast, an emergency rule was enacted by the Department of Commerce in January 1995 that required commercial vessels from North Carolina to southeast Florida to land gag with gonads intact. Histological examination of 2613 gonads of sexually mature gag collected from 18 January through 18 April 1995 revealed that 5.5% of the gag from the southeast Atlantic were male. There was a weak trend indicating that females reached maturity at a smaller size in 1994-95 than in 1976-82. Very few transitional specimens were collected during the spawning season. Most transitional individuals (79%) were taken during April through June immediately after the 1995 spawning season. Gag in spawning condition were landed during December through mid-May by fishermen working offshore from North Carolina to southeast Florida. In addition, gag in spawning condition were taken during research cruises documenting the occurrence of spawning north of Florida (off South Carolina and Georgia at depths ranging from 49 to 91 m).
Eighty topographic transects were made off the central Atlantic coast of Florida between Cape Canaveral and Palm Beach, November, 1973 to September, 1974, aboard the Research Vessel Gosnold. Profiles obtained with a precision depth recorder indicated the presence of continuous and discontinuous structures on the outer continental shelf and at the shelf-slope break. Most conspicuous was a band of pinnacles, benches, mounds and troughs extending north from Fort Pierce to Cape Canaveral, Florida, and a massive mound occurring off St. Lucie Inlet. These occurred under the western edge of the Florida Current and along the edge of the continental shelf (about 80° W). From Fort Pierce southward to Palm Beach, these structures almost disappear. Dredgings in two selected areas of pronounced vertical profile, and preliminary visual and photographic observations made with the Johnson-Sea-Link I submersible, confirmed the existence of rich, sessile and motile invertebrate assemblages and fish populations associated with exposed limestone bedrock, talus, and the scleractinian coral Oculina varicosa.
Color variants and behavior of scamp, Mycteroperca phenax, and gag, M. microlepis, are described from 64 submersible dives made on reef structures at depths between 20 and 100 m off the east coast of Florida from February 1977 to September 1982. These dives yielded 146 h of observations augmented with video and 35 mm photography. Both species display a variety of color phases associated with social behavior. They are expressed in each case by an aggressive, dominant territorial individual which displays to a group of smaller subordinates. Social hierarchy is evident in both species, with the alpha individual being a male in the gag and of undetermined sex in the scamp. Although actual spawning was not documented, hierarchical behavior and displays are interpreted as courtship associated with spawning activity. Courtship is further implied based on the similarity of these behaviors to those recorded for a variety of other fishes including serranids. Scamp appear to prefer habitats characterized by maximum structural complexity, such as living Oculina coral reefs, at depths between 70 and 100 m. The gag is a larger species and less dependent on live coral habitats. The significance of the social behavior in illuminating possible functions of protogyny and polygyny in M. phenax and M. microlepis is discussed. Documentation of complex social hierarchies in scamp and gag may have an impact on fishery management in that successful reproduction may prove dependent upon a wide variety of behavioral factors related to the role of individual fish in spawning hierarchies.
Decapod crustaceans associated with living colonies of the scleractinian coral Oculina varicosa were sampled quantitatively for 1 year at 4 reef stations encompassing depths of 6, 27, 42, and 80 m off the central eastern Florida coast. A total of 42 samples of individual colonies yielded over 2,300 decapods in 15 families, 35 genera and 50 species, and was species-rich in xanthid and majid crabs (10, 6 spp., respectively), and alpheid shrimp (9 spp.). The community was predominantly anomuran with two species of hermit crabs (Pagurus carolinensis, P. piercei), a porcellanid crab (Megalobrachium soriatum) and a galatheid crab (Galathea rostrata) comprising four of the six most abundant species which accounted for 70% of all collected individuals. Similarity between stations was low (8%) with only four species present at all stations. A gradient of species assemblages from shallow to deep stations corresponded with a similar gradient in environmental factors, with mean temperatures of 24.6, 18.4, and 16.2°C recorded at 6, 42, and 80 m, respectively. These temperatures and periodic cold-water summer upwelling affected species composition, with several species being lost at 6 m and never occurring at deeper stations. Wave surge and sedimentation, greatest at 6 m, affected trophic partitioning, with a filter feeder (M. soriatum) numerically dominant here, whereas a detritivore (P. carolinensis) dominated deeper, less disturbed stations. The biotope also differed topographically among stations. At 6 m Oculina grew as thick-branched, wave-resistant colonies with encrusting bases and were widely scattered among a cover of algae and sponges on limestone ledges. At 80 m massive coral thickets formed banks composed solely of O. varicosa. Greater heterogeneity of the habitat surrounding the 6-m corals may be one reason this station had the highest species numbers (30) and species distribution (32% occurred nowhere but here). Analyses of the effects of coral age on numbers of decapod species (S) and individuals (N) showed no significant correlation, whereas 48.8% of the variance in Sand 42.9% in N were related to the percentage of dead dry weight of the coral colony (r = .709, P < .001; r = .667, P < .001, respectively). Mean densities of individuals decreased with depth (44.4-7.5 N/100 g dead coral wt) and densities of most dominant species were positively correlated with size of the dead, rather than the live portion of the coral. Densities of the obligate commensals Domecia acanthophora and Troglocarcinus corallicola, however, were independent of coral size.
Data on the distribution and growth-form of the scleractinian Oculina varicosa were compiled from 135 submersible dives with the Johnson-Sea-Link submersibles and 57 dredge and trawl records by the R/V Gosnold and R/V Aquarius. A deep-water form of O. varicosa, lacking zooxanthellae, was found in depths of 50 to 100 m off central eastern Florida. These colonies are arborescent with highly anastomosed, irregular dendritic branches. Over 50 sites were located at which living colonies of O. varicosa from 0.25 to 2 m diameter occur either singly or as sparsely scattered groups. Nine areas were found with massive thickets of contiguous colonies up to 2 m in height. Extensive banks of Oculina thickets were found at five locations. The banks have a relief of 17 to 24 m and steep slopes of 30-45°, especially on the south side which faces into the Florida Current. The structure of these thickets and banks is very similar to deep-water Lophelia prolifera banks. Temperatures on the Oculina banks ranged from 7.5 to 26.5°C and had a yearly mean of 15°C.