[Coral-List] Post by Nicole Crane and others

Clive Wilkinson clive.wilkinson at rrrc.org.au
Thu Aug 8 05:37:40 UTC 2019


The Global Coral Reef Monitoring Network was tasked by the International Coral Reef Initiative to report on the status and trends in the world's coral reefs.

Back in 2004, a colleague from WWF US (Brooks Yeager) suggested we list the major stressors to coral reefs as a 'Top 10'. Thus we went through the status reports from 240 coral reef scientists and managers from 96 countries or states to come up with the list below; but not listed in any order of priority. On any damaged reef, many of the stressors in this list will be contributing factors. I doubt that much has changed in the following 15 years, but others may wish to add to this list - please do!.

Clive Wilkinson
THREATS AND STRESSES TO CORAL REEFS

This Status Report focuses on 'The Top Ten' threats and stresses to coral reefs around the world. They are listed in an order that does not necessarily reflect the degree of damage they cause to coral reefs. The rank of these threats will change considerably in different areas of the world; pollution is greater threat in some areas, whereas over-fishing is more destructive in other areas; while on remote reefs, the threat of global climate change will be the major threat. However, poor awareness of the problem and insufficient political will is usually a causal agent behind damage to coral reefs and a threat to their future survival.

Global Change Threats:
o       Coral bleaching - caused by elevated sea surface temperatures due to global climate change;
o       Rising levels of CO2 - increased concentrations of CO2 in seawater decrease calcification rates in coral reef organisms;
o       Diseases, Plagues and Invasives - increases in diseases and plagues of coral predators that are increasingly linked to human disturbances in the environment.

Direct Human Pressures:
o       Over-fishing (and global market pressures) - the harvesting of fishes and invertebrates beyond sustainable yields, including the use of damaging practices (bomb and cyanide fishing);
o       Sediments - from poor land use, deforestation, and dredging;
o       Nutrients and Chemical pollution - both organic and inorganic chemicals carried with sediments, in untreated sewage, waste from agriculture, animal husbandry and industry; includes complex organics and heavy metals;
o       Development of coastal areas - modification of coral reefs for urban, industrial, transport and tourism developments, including reclamation and the mining of coral reef rock and sand beyond sustainable limits.

The Human Dimension - Governance, Awareness and Political Will:
o       Rising poverty, increasing populations, alienation from the land - increasing human populations put increasing pressures on coral reef resources beyond sustainable limits;
o       Poor capacity for management and lack of resources - most coral reef countries lack trained personnel for coral reef management, raising awareness, enforcement and monitoring; also a lack of adequate funding and logistic resources to implement effective conservation; and
o       Lack of Political Will, and Oceans Governance - most problems facing coral reefs are tractable for solutions if there is political will and effective and non-corrupt governance of resources. Interventions by, and inertia in, global and regional organisations can impede national action to conserve coral reefs.

The true natural threats are not considered further as coral reefs generally have strong potential to recover from tropical cyclonic storms, fresh water inundation, geological events, like earthquakes and volcanoes, and low levels of plagues and diseases. The caveat about recovery is that additional anthropogenic stresses are not imposed on the reefs, and the level of these natural disturbances does not increase in future; this, however, is one of the predicted scenarios of global climate change. It is predicted that tropical storms could increase in frequency and severity, and the major global ocean currents may change.

Direct human damage pressures are summarised below; as they have been discussed in more detail in previous 'Status of Coral Reefs of the World' reports, and there is detailed treatment in many of the regional chapters.

The third category is more contentious: those stresses that are natural in origin, but are probably exacerbated by human activities. This category includes: stresses arising from global climate change, with coral bleaching and the potential that coral calcification will be reduced by rising concentrations of CO2 in seawater; diseases of corals and other reef organisms; plagues of coral predators and other damaging animals; and invasive species that threaten to disturb the ecological balance on coral reefs by out-competing local species. These stresses are the theme for Chapter 1 Global Threats to Coral Reefs: (P. 67).
[reference: Wilkinson, C. (2004). Status of Coral Reefs of the World: 2004. Global Coral Reef Monitoring Network & Australian Institute of Marine Science, Townsville, 2 volumes, p. 553]

-----Original Message-----


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