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Biogeography And Change Among Regional Coral Communities Across The Western Indian Ocean

Following the major 1998 coral bleaching event between 2004 and 2011, 291 coral sites from 11 Western Indian Ocean (WIO) countries were surveyed to evaluate regional biogeographic patterns of coral communities along latitudinal gradients and in relation to biogeography and fisheries management. Coral reef abundance, biodiversity, and susceptibility to bleaching were assessed during that period to develop an extensive database on coral reef communities and researchers aimed to evaluate possible impacts such as fishing and fishing closures on reef patterns and status. Patterns show that coral communities are influenced by large-scale interactions between biogeographic factors and temperature abnormalities but not so much by fisheries management. All coral reefs in the WIO are experiencing climate change and coral bleaching since the early 1980s, but at variable rates, timing and scale depending on the geography. The region was characterized by a complexity of a large number of significant interactions among variables tested. The northern Mozambique Channel demonstrated the strongest signs of resilience to climate disturbances.

Author: McClanahan, T.R., M. Atewberhan, E.S. Darling, N.A.J. Graham, and N.A. Muthiga
Year: 2014
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PLoS ONE 9(4): e93385. doi: 10.1371/journal.pone.0093385

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Coral Reefs On The Edge? Carbon Chemistry On Inshore Reefs Of The Great Barrier Reef

This study presents broad-scale carbon chemistry data from Great Barrier Reef (GBR) inshore coral reefs to test for regional and season differences between inorganic carbon system parameters in coastal waters. Spatial and temporal variations in sea surface carbon dioxide concentrations on a large-scale were examined to better understand the carbon cycle for predicting future increases in CO2. Data was collected from a large latitudinal range six times over a two-year period at 14 nearshore fringing reefs at islands in the GBR that experience terrestrial runoff. Carbon chemistry of inshore reefs was compared from smaller sample sets from mid- and outer-shelf reefs and historical data 18 and 30 years ago. Water samples were taken to analyze various parameters for oceanographic and water quality that serve as proxies for total alkalinity (TA) and dissolved inorganic carbon (DIC). Overall it was found that regional variability in carbon system parameters is relatively small; of variation in inshore reefs, the largest contributor was seasonal variation. Inshore reefs are subjected to elevated levels of partial pressure of CO2 (pCO2) as well as decreased light, increased sedimentation and higher nutrient levels compared to offshore reefs. The study found that the rate of increase of pCO2 in coral reef waters is increasing faster than in the atmosphere, likely due to other human-caused impacts on water quality, with higher values during the wet seasons. Thermodynamic effects contributed to higher aragonite saturation on inshore reefs and lower pCO2 than on offshore reefs, with land-based runoff contributing. The authors conclude that inshore GBR reefs could be more vulnerable to ocean acidification compared with offshore reefs.

Author: Uthicke, S., M. Furnas, and C. Lonborg
Year: 2014
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PLoS ONE 9(10): e109092. doi: 10.1371/journal.pone.0109092

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Community Change and Evidence For Variable Warm-Water Temperature Adaptation Of Corals In Northern Male Atoll, Maldives

This study is a descriptive analysis of coral reef communities in North Male, Maldives seven years after the major 1998 coral bleaching event with the goal of evaluating ongoing changes and ability for adaptation. The study looked at coral community composition, recruitment community, evidence for recovery and responses to corals to a subsequent thermal anomaly in 2005. Eleven shallow reef areas consisting of hard calcium carbonate were assessed using benthic field measurements and bleaching surveys. Maldivian coral recovery showed considerable spatial and taxonomic variability, with dominant taxa characterized by stress tolerance and several previously common taxa now still quite rare. Compared to other Indian Ocean islands, the Maldivian coral response was considerably more variable and complicated. The authors conclude that natural selective processes are in progress with responses showing potential for adaptation.

Author: McClanahan, T.R. and N.A. Muthiga
Year: 2014
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Email for the full article: resilience@tnc.org

Marine Pollution Bulletin 80(1-2): 107-113

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Persistence and Change in Community Composition of Reef Corals through Present, Past and Future Climates

This study looked at long-term data from fossil and modern coral reefs to test for variation among coral genera over time, both in rates and directions of change in abundance. Data was synthesized from seven extant reefs, creating 78 trajectories of changing coral cover by genus in the Caribbean and 153 trajectories in the Indo-Pacific. Fossil records from 70 localities from late Miocene to late Pleistocene were used to understand the temporal nature of changes affecting current coral reef communities. A model was developed to evaluate potential coral reef composition of the future under increased thermal stress predicted by climate change. The model suggested that coral mortality and adult coral growth were the most important ecological indicators of coral persistence; thermal tolerance became increasingly important when looking at severe climate change. Overall, corals most likely to persist in future climate scenarios are characterized by rapid growth and moderate mortality but changes in the genera of coral composition in the future are likely to occur.

Author: Edmunds, P.J., M. Adjeroud, M.L. Baskett, I.B. Baums, A.F. Budd, et al.
Year: 2014
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PLoS ONE 9(10): e107525. doi: 10.1371/journal.pone.0107525

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Coral reefs work as nature’s sea walls – It pays to look after them

A group of researchers found that intact coral reefs reduce wave energy by 97% and wave height by 84%. The study, published recently in the journal Nature Communications found that the risk reduction provided by reefs is relevant to some 200 million people worldwide.

At a time when towns, cities and countries are making major investments in climate and weather-related hazard protection, the authors found that coral reef protection makes economic, ecological and practical, risk-reduction sense when compared with artificial solutions such as seawalls.

To dive deeper:

Read a summary of the article and download the full paper. Also, read co-author Mike Beck’s summary of the study and explanation of how implementing better coral reef management and restoration as part of storm risk reduction has become a new field of science and practical application.

Read why Coral Reefs Soften Ocean’s Fury for Millions of Coastal Dwellers and how economics, location, restoration and threat of coral bleaching may all effect healthy reefs and the 200 million people worldwide that rely on them.

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Status and Trends of Caribbean Coral Reefs: 1970-2012, Executive Summary

Since the early 1980s Caribbean coral reefs have suffered massive losses of corals. Impacts from human population growth, overfishing, coastal pollution, global warming and invasive species have resulted in decrease of coral populations, increases of seaweeds, outbreaks of coral bleaching and disease, and failure of corals to recover from natural disturbances. This study analyses the status and trends of reef communities throughout the wider Caribbean. Metadata on the nature of the reef environment, depth and history of human population growth, fishing, hurricanes, coral bleaching and disease was compiled and analyzed. In some cases, biological information for coral and macroalgal cover, abundance of grazing sea urchin Diadema antillarum, and biomass of fishes such as grazing parrotfish was also obtained. Results imply that the three best predictors of the decline in Caribbean coral cover over the past 30 or more years are: (a) outbreaks of Acropora and Diadema diseases (1970s and early 1980s); (b) overpopulation, including increase in tourism; and (c) overfishing of herbivores, particularly parrotfish. Coastal pollution is also significant and increasingly warming seas is also a threat but so far, extreme heating events have had only localized effects.

In summary, the degradation of Caribbean reefs has occurred in three distinct phases: (1) Massive losses of Acropora (mid-1970s to early 1980s) due to White Band Disease; (2) Increase in macroalgal cover and decrease in coral cover following the mass mortality of Diadema (1983) and (3) Continuation of the patterns established in Phase 2 worsened by more overfishing, coastal pollution, tourism, and extreme warming events. Four major recommendations for management emerge from this report:

  1. Adopt conservation and fisheries management strategies to restore parrotfish populations;
  2. Simplify and standardize monitoring of Caribbean reefs and make the results available on an annual basis;
  3. Foster communication and exchange of information;
  4. Develop and implement adaptive legislation and regulations to ensure that threats to coral reefs are systematically addressed.

Author: Jackson, J.B.C.
Year: 2014
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Global Coral Reef Monitoring Network, IUCN, Gland, Switzerland.

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Designing Marine Reserves for Fisheries Management, Biodiversity Conservation, and Climate Change Adaptation

Coral reef ecosystem goods and services, such as fisheries, are threatened by local and global stressors. Effectively designed and managed marine reserve networks (areas closed to all extractive uses) can reduce local threats and build resilience of coral reefs. This paper reviews recent scientific advances in criteria for designing marine reserve networks to achieve multiple objectives such as fisheries management, conservation, and climate change adaptation. The authors provide integrated guidelines regarding habitat representation, risk spreading, protecting critical habitat, incorporating connectivity, allowing time for recovery, adapting to changes in climate, and minimizing local threats. Integration of marine reserve networks into broader management frameworks is also stressed. Although the guidelines were written for the Coral Triangle region, they can be applied to coral reefs worldwide.

Ecological considerations and guidelines for marine reserve design outlined in the paper include:
Habitat representation: protect 20-40% of each major habitat
Risk spreading: protect at least 3 examples of each major habitat and spread them out
Critical areas: protect critical areas such as fish spawning aggregations, nursery, nesting, breeding, and feeding areas
Incorporating connectivity: apply minimum and variable sizes, 0.5-1 km and 5-20 km across, space reserves 1-15 km apart with smaller reserves closer together
Allowing time for recovery: put reserves in place for 20-40 years or permanently, use periodic closures in addition to long-term protection
Adapting to changes in climate: protect refugia of more resilient habitats
Minimizing local threats: place reserves in areas less likely to be impacted by local threats such as land-based pollution

Author: Green, A.L., L. Fernandes, G. Almany, R. Abesamis, E. McLeod, P.M. Aliño, A.T. White, R. Salm, J. Tanzer, and R.L. Pressey 
Year: 2014
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Email for the full article: resilience@tnc.org

Coastal Management 42(2): 143-159. doi:10.1080/08920753.2014.877763

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The Effectiveness of Coral Reefs for Coastal Hazard Risk Reduction and Adaptation

A global meta-analysis revealed that coral reefs reduce wave energy on coastlines by 97% on average, with the reef crest responsible for attenuating 86% of the energy. Coral reef restoration projects were found to cost significantly less, $1290 USD per meter (median cost), compared to $19,791 USD per meter for building artificial breakwaters, making it significantly cheaper to restore reefs rather than build breakwaters in tropical environments. This study supports the role of coral reefs in risk reduction, including shoreline erosion and flooding, and can be used by managers and policy makers to motivate greater reef protection and restoration.

Author: Ferrario, F., M.W. Beck, C.D. Storlazzi, F. Micheli, C.C. Shepard, and L. Airoldi
Year: 2014
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Nature Communications 5(3794). doi:10.1038/ncomms4794

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