Coral
reefs are complex and important features of the marine environment. They have
the highest biodiversity of any marine ecosystem. Coral reefs are often
referred to as the “rainforest of the sea” due to their rich in biodiversity. Reefs provide important ecosystem services
such as feeding and breeding ground for large number of fish, invertebrates and
marine mammals. Apart from that, coral
reefs also protect shorelines from erosion by becoming natural breakwater which
minimize wave impacts from storms and hurricanes in coastal areas. However, the
coral reefs coverage around the world is in decline. Worldwide declines in
coral coverage and overall reef degradation can be attributed to a variety of
anthropogenic and natural causes. These include climate changes, coral
bleaching, diseases and biological infestation, coral mining, tourism, habitat
loss from development and suspended sediment. Human intervention is still seen
as the major causes of corals death. The anthropogenic impacts might be caused
by near shore dredging and the unplanned human occupation of the coastal zone.
Coral reef ecosystem under siege of various stress |
One of
the most prominent stressor in coral decline is suspended sediment. Suspended
sediment is very fine soil particles which suspended in the water as a result
of erosion in streams or on beaches, or from wave-induced re-suspension of
particles from the bottom. These fine particles can smother the coral mucus
surface which can reduce larval replenishment and impede their ability to
persist. Corals can be additionally stressed due to the allocation of energy
required to remove sediment particles, sites for new coral recruitment can be
eliminated, and coral colonies can be buried under conditions that permit
sediment accumulation. Thus, it can be justified that suspended sediment is
indeed a vital factor which may inhibit the growth and survival of corals.
At the
moment, the rate of suspended sediment or sedimentation rate in coral reef
areas has increased due to human activities such as coastal development and
tourism. Sediment accumulation rate or sedimentation rate of 10mg.cm-2.day-1
seems to be critical limit for coral to grow. It is reported that up to a rate
of sedimentation deposition of 15mg.cm-2.day-1, the reefs
start to decline. Hence, continuous monitoring of sedimentation rate and other
threatening factors should be done in order to assess the health of the coral
reef.
High concentration of suspended sediment may results in coral death |