Why are coral reefs important, and what are possible explanations for the phenomenon known as “coral bleaching?”
Coral
reefs play a very important part in many ecosystems. They are a home for many
different types of fish. It is said that reef supports about twenty five
percent of all marine life. Reefs
provide spawning, nursery, refuge and feeding areas for large groups of
organisms. Although reefs are very essential, they can be endangered due to
many possible things. Boats and dropped anchors can cause
severe damage to these fragile ecosystems. Frequent human contact and pollution
kills the reefs over time. Silt from eroded soil in runoff water can block
sunlight. Without sunlight, photosynthesis does not occur and reefs gradually
die and begin to diminish. Untreated or improperly treated sewage promotes
the growth of algae, which harms coral reefs. Some
fishermen stun fish by squirting cyanide, a very toxic poison, into reef areas
where fish seek refuge. The poison does not kill, but disorients the fish in
the coral where they hide. Coral reefs are very sensitive and need to be well
maintained in order for organisms to survive.
Warmer
water temperatures can result in coral bleaching. When water is too warm,
corals will expel the algae “zooxanthellae” living in their tissues causing the
coral to turn completely white, the term for this is called coral bleaching.
When a coral bleaches, it is not dead. Corals can survive a bleaching event, but
they are under more stress and have a higher risk of becoming unhealthy. When
corals bleach they commonly lose 60-90% of their “zooxanthellae” and each
zooxanthella may lose 50-80% of its photosynthetic pigments. Coral bleaching is
very harmful and stressful to all organisms living in the environment.
