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Publication year : 0
Thematic : Climate Change and Biodiversity
Language : English
Note
Coral reefs are critically important for
the ecosystem goods and services
they provide to maritime tropical and
subtropical nations (1). Yet reefs are in
serious decline; an estimated 30% are already
severely damaged, and close to 60%
may be lost by 2030 (2). There are no
pristine reefs left (3–4). Local successes
at protecting coral reefs over the past
30 years have failed to reverse regionalscale
declines, and global management of
reefs must undergo a radical change in
emphasis and implementation if it is to
make a real difference. Here, we review
current knowledge of the status of coralreefs, the human threats to them now and in
the near future, and new directions for research
in support of management of these
vital natural resources.
Until recently, the direct and indirect
effects of overfishing and pollution from
agriculture and land development have
been the major drivers of massive and accelerating
decreases in abundance of coral
reef species, causing widespread changes in
reef ecosystems over the past two centuries
(3–5). With increased human populations
and improved storage and transport systems,
the scale of human impacts on reefs
has grown exponentially. For example, markets
for fishes and other natural resources
have become global, supplying demand for
reef resources far removed from their tropical
sources (6) (Fig. 1). On many reefs, reduced
stocks of herbivorous fishes and added nutrients
from land-based activities have caused
ecological shifts, from the original dominance
by corals to a preponderance of fleshy
seaweed (5, 7). Importantly, these changes to
reefs, which can often be managed successfully
at a local scale, are compounded by the
more recent, superimposed impacts of global
climate change.
The link between increased greenhouse
gases, climate change, and regional-scale
bleaching of corals, considered dubious by
many reef researchers only 10 to 20 years
ago (8), is now incontrovertible (9, 10).
Moreover, future changes in ocean chemistry
due to higher atmospheric carbon dioxide
may cause weakening of coral skeletons
and reduce the accretion of reefs, especially
at higher latitudes (11). The frequency and
intensity of hurricanes (tropical cyclones,
typhoons) may also increase in some regions,
leading to a shorter time for recovery
between recurrences (10). The most pressing
impact of climate change, however, is
episodes of coral bleaching and disease that
have already increased greatly in frequency
and magnitude over the past 30 years
(9–14).
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Encoded by : Pauline Carmel Joy Eje
