Climate change in the UKOTs an overview of the ... - JNCC - Defra

Mangrove in the British Virgin Islands
Credit: BVI National Trust
from agriculture, industry and human settlements
in the coastal zone. The intensity
of hurricanes is also placing stress on
corals. The region’s reefs have experienced
a massive decline from approximately
50 per cent coral cover to less than
10 per cent (Jones, 2004). Reefs are likely
to be affected by a higher incidence of
bleaching and die-out due to higher water
temperatures. Additionally, changes in
ocean chemistry that are the result of
higher levels of carbon dioxide in the
atmosphere are contributing to the weakening
of coral skeletons (Jones, 2004).
Across the region, mangroves are threatened
by development in the coastal zone
and conversion to other uses. Mangroves
are an important element of the coastal
defence system. They provide protection
against cyclones, storm surges, and tides.
They are also nurseries and habitats for
many marine species and play a role in filtering
run-off from the land. Mangroves are
sensitive to the threat of sea level rise, particularly
from increased salination of the
ecosystem. This sensitivity is heightened
by the pressures they are already facing.
Over time, higher sea levels are likely to
change the size and distribution of coastal
wetlands and increase the risk of flooding
(Wall, 1998 and Nicholas et al., 1999 cited
in Sear et al., 2001).
Climate change is expected to have longterm
impacts on biodiversity in the
Caribbean, particularly in marine and
coastal ecosystems. Climate change is not
the only threat to the region’s biodiversity,
but it intensifies the effects of other threats
and vulnerabilities.
A 0.5 m increase in sea level is expected to
result in the loss of just over one third of
marine turtle nesting sites in the
Caribbean (Fish et al., 2005, cited in
Mimura et al., 2007). This is not the only
potential threat to turtles. Sea level rise,
increases in water temperature, storminess
and rainfall could also damage reefs
and sea grass beds, the foraging habitats
of sea turtles. Temperature also plays a
role in determining turtle sex: eggs incubated
in warmer waters produce females
and those nurtured in cooler temperatures
produce males. According to the Marine
Conservation Society in the UK, natural
sex ratios and reproduction could be
affected if marine turtles do not change
their nesting seasons (Marine Conservation
Society, 2008).
Commercially valuable fish species such
as tuna (Thunnus albacares), and parrotfish
(Scaridae), would not survive a 1°C
rise in Caribbean Sea temperature and
would migrate further north as formerly
cold waters become milder. Loss of the
parrotfish would affect coral reef health as
well as fisheries. This favourite on
Caribbean tables plays an important role
in keeping corals free of algae. Without it,
unchecked algae could smother the reefs
and cause them to die (Moxam, 2008).
3.2.4 British Indian Ocean Territory
The British Indian Ocean Territory has one
of the largest and most isolated coral reef
and island systems. Because it is largely
uninhabited, it is one of the few remaining
tropical areas that could be used as a reference
location for observing the impacts
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