Harter et at: Assessment of fish populations and habitat on Oculina Bank 
203 
compared areas not only within the OECA but 
also included the OHAPC and open areas, and 
examined an expanded range of habitats. 
While it is well known that deep coral habitat 
supports a high diversity and densities of fish 
species (Costello et al., 2005; Koenig et al., 2005; 
Parrish, 2006; Stone, 2006; Ross and Quattrini, 
2007), it is unclear whether fish are attracted 
to live coral or just structure made by corals. 
Our study addressed this question by comparing 
fish assemblages, densities, and diversity among 
several structure-forming habitat types includ- 
ing coral. We found no significant difference in 
the composition of fish assemblages or diversity 
among all hardbottom habitat types. Grouper 
densities were significantly higher on the most 
structurally complex habitats (live O. varicosa, 
standing dead O. varicosa, and rock outcrops) 
compared to the less complex ones (pavement 
and rubble). Therefore, higher grouper densities 
were not exclusive to coral habitats. Accord- 
ing to Auster (2005), one of the ways to define 
functionally equivalent habitats is those that 
support a similar density of fishes, therefore, 
we conclude that O. varicosa was functionally 
equivalent to the other hardbottom habitats on 
the Oculina Bank. Similar results were found in 
the Gulf of Maine (Auster, 2005). No difference 
in fish communities was found between habitats 
dominated by dense corals and those dominated by 
dense epifauna with or without corals. In addition, 
Tissot et al. (2006) concluded that fishes in south- 
ern California were associated with sponges and 
corals, but no functional relationship was pres- 
ent. In Hawaii, fish densities were higher in areas 
with deep-water corals, but when bottom relief and 
depth were accounted for, these densities were not 
higher than those for surrounding areas without 
corals (Parrish, 2006). Ross and Quattrini (2007) 
concluded that deep slope reefs function much like 
shallow corals reefs, hosting a unique, probably 
obligate, ichthyofauna, however other hardbottom 
habitats were not examined. 
Even though our study demonstrated that O. 
varicosa serves a similar role for fishes as other 
hardbottom habitats, corals are still important 
and are major contributors to deep-sea habitat 
complexity and structure (Roberts et al., 2006). 
Significant numbers of gag and scamp aggregate 
on and use O. varicosa for spawning habitat and 
juvenile speckled hind use the coral for shelter 
suggesting a nursery value of the coral (Gilm- 
ore and Jones, 1992; Koenig et ah, 2000; Koenig 
et al., 2005). Intact coral is not only valuable 
for fish, but invertebrates as well. As long as 
the coral is standing (live or dead), living space 
within the colony branches supports dense and 
diverse communities of associated invertebrates (Reed 
et al., 2002a, 2002b; Reed et al., 2007). However, once 
reduced to unconsolidated coral rubble, little living 
50-, 
45 
40- 
35 
30- 
25- 
20 - 
15- 
10 - 
l ill 
pavement 
rubble 
rock outcrops 
standing dead live 
O. varicosa O. varicosa 
Figure 4 
Average grouper densities (no. /hectare) (±SE) for each man- 
agement area by habitat type observed from remotely operated 
vehicle (ROV) transects conducted on the Oculina Bank during 
April/May 2003 and October 2005. Average grouper density for 
pavement in the open area was 0.0 fish/hectare, however, there 
were no live or standing dead Oculina varicosa transects for 
the open area. 
70- 
60- 
o) 50 - 
40- 
a> 
cn 
co 
5 
> 
< 
30- 
20 - 
10 - 
[ii 
rf 
pE 
ig 
.Jfl 
L 
* 
* 
pavement rubble 
rock 
outcrops 
standing dead 
O. varicosa 
live 
O. varicosa 
Figure 5 
Average percent cover (±S.E.) of habitat types in each of 
the three management areas (open = any area outside the 
OHAPC open to fishing, OHAPC = areas where all bottom 
gear except hook and line are restricted, i.e., excluding the 
OECA, and OECA = inside the MPA where all bottom gear, 
including hook and line fishing, are restricted) from analysis 
of digital stills taken during remotely operated vehicle (ROV) 
transects on the Oculina Bank during April-May 2003 and 
October 2005. 
space is left except for infauna (George et al., 2007). A 
hypothetical trophic model of the O. varicosa ecosystem 
indicates significant loss of habitat, in particular intact 
