Coral community decline at a remote Caribbean island: marine no‐take reserves are not enough

Abstract

1. Coral reefs around the world have been deteriorating over decades owing to anthropogenic pressure. In the Caribbean recent rates of decline are alarming, particularly for coral reefs under high local human impact, many of which are severely degraded, although regions with lower direct anthropogenic influence seem less affected.2. Little Cayman is a relatively undeveloped island, with less than 150 permanent residents. About 20% of its reefs have been protected by no-take marine reserves since the mid-1980s. We analysed the dynamics of coral communities around the island from 1999 to 2004 in order to test the hypothesis that a lack of major local anthropogenic disturbances is enough to prevent decline of coral populations.3. Live hard coral coverage, coral diversity, abundance, mortality, size, and prevalence of disease and bleaching were measured using the Atlantic and Gulf Rapid Reef Assessment methodology (line transects) at nine sites. Despite the apparent undisturbed condition of the island, a 40% relative reduction of mean live coral coverage (from 26% to 16%, absolute change was 10%) was recorded in five years. Mean mortality varied from year to year from 23% to 27%. Overall mean diameter and height have decreased between 6% and 15% on average (from 47 to 40 cm for diameter, and from 31 to 29 cm for height).4. The relative abundance of large reef builders of the genus Montastraea decreased, while that of smaller corals of the genera Agaricia and Porites increased. Disease prevalence has increased over time, and at least one relatively large bleaching event (affecting 10% of the corals) took place in 2003.5. Mean live coral cover decline was similar inside (from 29% to 19%) and outside (from 24% to 14%) marine no-take reserves. No significant difference in disease prevalence or clear pattern in bleaching frequency was observed between protected and non-protected areas. It is concluded that more comprehensive management strategies are needed in order to effectively protect coral communities from degradation.Coral reefs around the world have been deteriorating over decades owing to anthropogenic pressure, but recent rates of decline in the Caribbean are particularly alarming. The main causes of deterioration have been attributed to overfishing, pollution, increased sedimentation, climate change and disease (Harvell

Coral disease following massive bleaching in 2005 causes 60% decline in coral cover on reefs in the US Virgin Islands

“…However, documented coral cover losses were of smaller magnitude (e.g., from 20 to 13% at Yawzi Reef due to Hurricane Hugo, Rogers et al 1997) and very localized. Recent monitoring (post-2000, but prior to 2005 bleaching) at the study reefs showed two sites within VINP with significant increases in coral cover suggesting that while MPAs are not a panacea for coral reefs (see Coelho and Manfrino 2007), a synergy of ecology and management could facilitate positive coral growth. The severity and duration of the 2005 coralbleaching event and subsequent disease outbreak superseded management and political boundaries affecting reefs within and outside national parks and eliminated any prebleaching gains in coral cover.…”

Coral Community Decline at Bonaire, Southern Caribbean

“…Multivariate analyses were performed using PRIMER v6 (Clarke and Gorley 2006) to examine trends in the biotic (scleractinian corals, hydrocorals, gorgonians, sponges, macroalgae, coralline algae, other benthos) and abiotic (dead coral, cemented coral rubble, coral rubble, pavement, sand) data. Replicate transect data were used for all multivariate analyses except non-metric multidimensional scaling (nMDS) ordination for which mean biotic data (means across four replicate transects for each depth by location) were used to better visualize patterns in two dimensions.…”

The utility of repeated presence data as a surrogate for counts: a case study using butterflies

“…Often, though, abundance measurements are desired to monitor the longer-term dynamics of a population or focal suite of species. In particular, relative abundance data are important in identifying species in decline (Browne and Hecnar 2007;Doody et al 2009), the rise of invasive species (Engeman and Whisson 2006;Harrington et al 2008), the success of management strategies (Coelho and Manfrino 2007;Homyack and Haas 2009), as well as geographical differences in population dynamics (Okuda et al 2009). Presence data are already used to predict abundance in gridded plot surveys (Conlisk et al 2009).…”