Jackson2013-Status and Trendsof Caribbean Coral Reefs

2b. ECOLOGICAL EXTINCTION OF
FORMERLY DOMINANT SPECIES
Three taxa of formerly very great ecological
significance on Caribbean reefs suffered
massive declines up to several decades
before the first quantitative surveys at the
vast majority of the 90 locations in Table
2. Understanding the subsequent decline
of Caribbean reefs hinges upon a clear
understanding of the magnitude of these
early changes that in most places have hardly
left a trace.
Decline of Acropora palmata and A. cervicornis
Acropora palmata and A. cervicornis were
among the most abundant and ecologically
dominant corals on Caribbean reefs in depths
down to 20 m for the last one million years
until the 1970s and 1980s (Goreau 1959;
Geister 1977; Lewis 1984; Jackson 1992,
1994; Aronson and Precht 2001; Pandolfi
and Jackson 2006; Johnson et al. 2008).
Both species experienced intense mortality
due to White Band Disease (WBD) since
the mid to late 1970s until today (Gladfelter
1982; Porter and Meier 1992, Aronson and
Precht 2001, Porter et al. 2001, Patterson et
al. 2002, Weil and Rogers 2011). Hurricanes
and outbreaks of predators also devastated
acroporids in Jamaica and the USVI in the
1980s (Knowlton et al. 1981, 1990; Woodley
et al. 1981; Rogers et al. 1991; Rogers and
Miller 2006), and there is paleontological
evidence for die-offs several decades earlier
in Barbados (Lewis 1984), Bocas del Toro
Panama (Cramer et al. 2012), and more
broadly throughout the region (Jackson et al.
2001).
Unfortunately there are remarkably few
quantitative data on the abundance of
either species until they were already greatly
diminished by disease, a spate of hurricanes
in close succession, and degrading water
quality to be reviewed in the next section.
To address this, we compiled a very large
qualitative database on the occurrences of
both species back into the 19 th century to
supplement the quantitative data (Appendix
3). The proportion of reef sites with presence
and dominance of Acropora palmata and A.
cervicornis was computed for the time period
from 1851-2012. Data include qualitative
and quantitative information from the primary
peer-reviewed scientific literature, government
reports, and less commonly historical
literature as well as quantitative data received
directly from contributors to this study and
compiled in the larger GCRMN database.
Quantitative data include percent cover for
either Acropora species, while qualitative
data include presence/absence and relative
abundance data, as well as descriptions of
relative abundance categories (Appendix
3). Data are primarily from underwater field
surveys, although a small number are from
boat-based observations and high-resolution
aerial photographs. Data from the literature
were extracted from texts, tables, figures, and
maps.
Only data from “reef crest” and “midslope”
reef zones were included in the analysis.
Generally, reef crest data spanned 0-6m
water depth and midslope data spanned
between 6-20m, as 6m was the depth at
which dominance typically shifted from A.
palmata to A. cervicornis in the quantitative
data. However, the distinction between reef
crest and midslope was made on a reef siteby-site
basis, taking into account additional
information on reef zone or reef morphology,
if available. For some locations, the cutoff
was closer to 10m, the same value used in
Jackson et al. (2001). Data were not included
if determination of the reef zone could not be
made. Data were recorded at the reef site level
and computed by averaging over replicates
within the same reef site and reef zone. In
total, 1,863 reef sites from 79 locations were
compiled for the reef crest zone and 4,569
reef sites from 83 locations for the midslope
zone. These included locations that were not
represented in the master GCRMN quantitative
database (Table 2).
Results are presented in Figs. 20 and 21 for
A. palmata and A. cervicornis respectively.
Sample size is small before 1950, and the
locations represented in various time bins are
not consistent. Nevertheless, the data confirm
the remarkably great abundance of both
species before the 1970s. Acropora palmata
was present at more than 80% of all areas
surveyed in depths less than 10 m throughout
the wider Caribbean region and was recorded
as “dominant” at 60% of these localities.
42 STATUS AND TRENDS OF CARIBBEAN CORAL REEFS: 1969-2012