Life in Shallow Marine Water:Kelp Forests and Coral Gardens. Albert Zheng Keystone College
Introduction • Kelps can grow over 40m in some places. • Resembles submarine forests. • Example: Coast of California • Coral Reefs are diverse in colors. • Resembles gardens • Example: Coast of Egypt
Geography • Marine environment and its inhabitants vary with latitude. • In temperate to subpolor regions: • Enormous amount of kelp growth • The closer you go towards the equator region, the kelp will slowly be replace by coral reefs. • Corals are confined to low latitudes, 30°N and 30°S.
Coral Reef Distribution Corals are absent from shores and grow in H20 temperature averaging about 23°C to 25°C along the equator Kelp Forest Distribution Kelps grow along rocky shores in regions with max H2O temperature is < 20°C
Structure • In 1842, Charles Darwin was the 1st to place coral reefs into 3 categories • Fringing reefs – are along the shores of the continent or island • Barrier reefs – stretches for nearly 2000km off the coast • Coral Atolls – consist of coral that have built up from a submerged oceanic island. Barrier reefs Atolls Fringing reefs
Structure • Kelp forests, mainly the larger kelps, have structural features similar to terrestrial forests. • On the surface of the water is canopy, which can be 25m above seafloor. • Stems or stipes of kelps extend from canopy to the bottom and the anchoring to the ground is called holdfast.
Physical Condition • Light • Both kelp and reef building corals grow only to the surface water where there is enough light to support photosynthesis. • Light penetration can be read from a few meters to almost 100m, sufficient enough to support the kelp and coral • Varies with local conditions. • Temperature • Kelps are limited to temperate shores. • Corals are restricted to warm waters averaging 23°C to 25°C
Water Movement • Coral reefs and kelp beds are continuously being washed by ocean currents that will deliver oxygen and nutrients and remove waste product. • However extreme strong currents and waves can detach entire kelp forests and flatten coral reefs.
Chemical Conditions • Salinity • Coral reefs grow only in stable salinity H2O • Kelp beds appear to be more tolerant in fresh H2O runoffs and will grow well along temperate shores. • Oxygen • Coral reefs and kelp beds occur where water is well oxygenated.
Biology • Coral reefs face intense biological disturbances • Outbreaks of predatory crown-of-thorn sea star, will eat corals which has devastated large area of coral reefs in the Indo-Pacific region. • The center of diversity for reef building corals is in the western pacific and eastern Indian Ocean • 600 coral species and over 2000 species of fishes can be found
Biology • In a Caribbean coral reef community, population of sea urchin, Diadema antillarum will eat both algae and corals. • But these urchins benefit the corals by reducing algal population that will compete for space with the young corals