Abstract Many Caribbean reefs have experienced a phase-shift in community structure, the principle features being a decline in coral cover and an increase in macroalgal biomass. However, one Jamaican reef-Dairy Bull on the north shore near Discovery Bay-is once again dominated by scleractinian corals and several key species have returned. Living coral cover at 6-8 m depth at Dairy Bull has doubled over the past 9 years and is now $54%. The absolute cover of Acropora cervicornis was &lt;1% in 1995, but increased to $11% by January 2004. During this time the cover of macroalgae decreased by 90%, from 45 to 6%. We speculate that long-lived colonies of Montastraea annularis may have facilitated the recovery of this reef by providing structural refugia

A E Laurie

Allen-Requa Peter

J Edmunds

John F Bruno

Joshua A Idjadi Ae

Sarah C Lee Ae

William F Precht

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Joshua A. Idjadi Æ Sarah C. Lee Æ John F. Bruno
William F. Precht Æ Laurie Allen-Requa
Peter J. Edmunds
Rapid phase-shift reversal on a Jamaican coral reef
Received: 27 April 2005 / Accepted: 22 November 2005 / Published online: 15 March 2006
 Springer-Verlag 2006
Abstract Many Caribbean reefs have experienced a
phase-shift in community structure, the principle
features being a decline in coral cover and an increase
in macroalgal biomass. However, one Jamaican
reef—Dairy Bull on the north shore near Discovery
Bay—is once again dominated by scleractinian corals
and several key species have returned. Living coral cover
at 6–8 m depth at Dairy Bull has doubled over the past
9 years and is now 54%. The absolute cover of Acro-
pora cervicornis was <1% in 1995, but increased to
11% by January 2004. During this time the cover of
macroalgae decreased by 90%, from 45 to 6%. We
speculate that long-lived colonies of Montastraea
annularis may have facilitated the recovery of this reef
by providing structural refugia.
Keywords Acropora cervicornis Æ Coral reef Æ
Montastraea annularis Æ Phase-shift
Introduction
Since the 1980s, the community structure of most
Caribbean reefs has changed dramatically (Gardner
et al. 2003). A phase-shift from coral- to macroalga-
dominated benthic reef communities has been caused by
a variety of factors, of which two of the most important
have been the drastic reduction in abundance of Acro-
pora spp. (Aronson and Precht 2001) and the decline in
herbivory (Hughes 1994).
This phase-shift from coral to macroalgal dominance
is widely accepted as a model for the recent dynamics of
Caribbean reefs in general and Jamaican reefs in par-
ticular (Hughes 1994). Indeed, Jamaican coral reefs of-
ten are depicted as a classic example of reef degradation
in the Caribbean, in part because multiple agents have
acted in concert to create widespread and persistent
macroalgal dominance.
Materials and methods
Surveys were performed on the fringing reef at Dairy
Bull, located 2 km east of Discovery Bay, Jamaica.
This reef is 500 m long and 100 m wide and is part of
a discontinuous reef system that spans most of Jamaica’s
north coast. We conducted our surveys on this reef in
1995, 2003, and 2004.
To estimate the coverage of benthic components
such as corals and macroalgae, three transects each
30 m in length were haphazardly placed parallel to
depth contours at 6–8 m depth. Benthic community
structure was quantified with standard photographic
survey techniques. We photographed the substratum
within 0.25 m2 quadrats positioned at random locations
along transects (n=37 quadrats in 1995, 73 in 2003,
and 38 in 2004). Statistical comparisons of benthic
cover components were made between 1995 and 2004
data using unpaired t-tests. All data are reported
±1 standard error.
Communicated by Ecology Editor P.J. Mumby
J. A. Idjadi
Department of Biological Science, University of Delaware,
Newark, DE 19716, USA
S. C. Lee Æ J. F. Bruno
Department of Marine Sciences,
The University of North Carolina at Chapel Hill,
Chapel Hill, NC 27599-3300, USA
W. F. Precht (&)
Ecological Sciences Division, PBS&J,
2001 NW 107th Avenue,
Miami, FL 33172, USA
E-mail: bprecht@pbsj.com
Tel.: +1-305-5143488
Fax: +1-305-5949574
L. Allen-Requa Æ P. J. Edmunds
Department of Biology, California State University,
18111 Nordhoff Street, Northridge, CA 91330-8303, USA
Coral Reefs (2006) 25: 209–211
DOI 10.1007/s00338-006-0088-7
Results and discussion
Benthic cover surveys revealed drastic changes in coral
and macroalgal cover from 1995 to 2004. The rapid shift
from macroalgal to coral dominance is demonstrated by
an inversion in relative percent cover (Fig. 1). Between
1995 and 2004 scleractinian cover nearly doubled from
23.0±3.5 to 53.5±3.5% while macroalgal cover was
reduced by nearly 90% from 44.9±2.8 to 5.7±1.6%. Of
the scleractinians Acropora cervicornis showed the most
dramatic increase in cover from 0.6±0.4 to 10.5±3.2%,
appearing in thickets between massive colonies of
Montastraea annularis reminiscent of the fore-reef
community structure that was present at Discovery Bay
prior to Hurricane Allen (Rylaarsdam 1983; Fig. 2a).
There were no significant differences among sampling
periods in cover of M. annularis; however, the cover of
other reef-building coral species increased significantly,
especially Agaricia agaricites and Porites astreoides
(Fig. 2b).
The benthic community at Dairy Bull in 2004 is
similar to benthic structure on pre-phase-shift Jamaican
reefs of the 1970s when average coral cover was 55%
(Huston 1985). The dramatic reduction in the abun-
dance of macroalgae to only 5.7±1.6% cover in 2004 is
even more striking and is similar to the cover recorded
prior to the Diadema mortality of 1983–84 (Hughes
1994). The presence of residual populations of living
coral at Dairy Bull in the 1990s (Edmunds and Bruno
1996), especially long-lived colonies of M. annularis,
maintained a high degree of habitat complexity. While
habitat complexity was not directly measured in this
study, massive corals of the M. annularis species com-
plex have been shown to withstand hurricane damage
(Woodley et al. 1981), and contribute substantially to
topographic complexity (Aronson and Precht 2001).
This is a striking contrast to intermediate depths
(6–20 m) on the Discovery Bay west fore-reef, where
topographic relief has been reduced by coral mortality
and bioerosion. At these intermediate depths, coral
cover presently is 5–15%, and macroalgae occupy
>60% of the substratum (Cho and Woodley 2002).
M. annularis-generated high structural complexity of the
Dairy Bull reef is likely to be an important difference
compared to nearby reefs (Bechtel et al. 2006), and it
may be that reefs without it are less resilient. If this
scenario is accurate, M. annularis species complex may
function as a foundation taxon (sensu Bruno and
Bertness 2001) that facilitated the recovery of the Dairy
0
25
50
75
%
 c
ov
er
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
coral
macroalgae
Fig. 1 Percent cover of dominant benthic components in 1995,
2003, and 2004. Data are means ± 1 SE
Fig. 2 Underwater photographs of Dairy Bull Reef, Jamaica in
February 2003. aUnderwater photograph of a Acropora cervicornis
thicket filling in the areas between large, long-lived colonies of
Montastraea annularis at 6 m depth at Dairy Bull. View is
reminiscent of the coral community of Jamaica in the 1960s and
1970s. b Abundance of brooding species Agaricia agaricites and
Porites astreoides within and between large M. annularis colonies
that form the foundation species of the Dairy Bull Reef complex
210
Bull reef. At present, the role of Diadema as a factor in
reef recovery at Dairy Bull is unclear because of high
temporal and spatial variance of the data. However, the
possibility of high rugosity favoring Diadema popula-
tions, and hence increased herbivory, could be usefully
investigated in future studies (see Bechtel et al. 2006).
While our study is the first to report a phase-shift
reversal on a Caribbean reef, our results are spatially
restricted to the reef at Dairy Bull. However, when
interpreted in conjunction with other studies (i.e.,
Edmunds and Carpenter 2001; Carpenter and Edmunds
2006), they appear to provide some important clues
about the factors responsible for promoting coral reef
recovery along the north coast of Jamaica and
throughout the Caribbean. This is Discovery Bay Mar-
ine Lab publication number 715, and contribution
number 128 of the marine biology program of California
State University, Northridge.
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211


Rapid phase-shift reversal on a Jamaican coral reef

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