Coral Reefs

• Basics

• Among the oldest and most diverse ecosystems on Earth
• All populations in this ecosystem are interdependent and part of a global food web
• Closely related to anemones, jellyfish, and other animals in the Phylum Cnidaria

• Feeding Habits

• Filter Feeders

• Capture zooplankton from the water column
• Require some regular water movement (i.e., slow currents) to bring them their preferred food

• Photosynthesis

• Only shallow-sea coral
• Use energy from light and absorption of carbon dioxide to produce food

• Cockscomb Cup Coral

• Tropical to sub-polar latitudes in the Atlantic and Pacific oceans
• Found on deep seamounts and other deep-sea habitats
• Normal depth range is greater than 3300 feet
• Stony coral

• builds a skeleton of calcium carbonate

• Lives in the deep sea and in cold-water fjords
• Provides habitat for several other species of invertebrates and fishes

• Elkhorn Coral

• Caribbean Sea and adjacent waters including Florida and the Gulf of Mexico
• Shallow water
• Stony coral

• Builds a skeleton of calcium carbonate

• Colonies of several genetically identical animals living together
• One of the most important reef-building species in the Caribbean
• Keystone species and ecosystem engineer

• Numerous species directly rely on elkhorn coral as their primary habitat
• Caribbean spiny lobsters, parrotfishes, tube blennies

• Hermaphroditic

• Each animal produces both eggs and sperm

• Critically endangered (highly vulnerable to extinction)

• Result of disease, pollution, coral bleaching, and storm damage, populations of elkhorn corals have crashed

• Grooved Brain Coral

• Caribbean Sea and Adjacent Waters Including Florida, Bermuda, and the Gulf of Mexico
• Shallow water
• May be hundreds of years old
• Large, reef-building coral
• Forms large, circular structures that can reach more than 6 feet (nearly 2 m) in diameter
• Only the outer few millimeters represent living tissue, while the rest is a calcium carbonate skeleton

• Lobe Coral

• Tropical latitudes of the Indian and Pacific oceans and adjacent seas
• Shallow water
• Grows very large

• Only grow a few centimeters each year

• May be hundreds of years old
• Are either male or female, not both
• Have symbiotic algae living within their cells
• Depleted in some areas as a result of a combination of local stressors and climate change
• Near threatened with extinction

• Lophelia Coral

• Tropical to sub-polar latitudes in the north Atlantic and Pacific oceans
• Deep sea coral

• Found down to depths of approximately 3300 feet (1000 m), but it has been observed or collected from depths of nearly 10,000 feet (3000 m)

• Builds structure that provides habitat for many kinds of invertebrates and fishes
• Can be enormous, stretching for several miles and rising to at least 100 feet (30 m) above the seafloor.
• Slow growing and are known to live for more than 1000 years
• Threatened by

• Ocean acidification
• Destructive fishing practices, most notably bottom trawling

• Bottom trawling has destroyed one third to one half of all lophelia coral reefs in Norway

• Yellow Cup Black Coral

• Tropical warm temperate latitudes in the eastern Pacific Ocean
• Deep-sea coral reefs
• Black corals grow extremely slowly, so any excessive harvest can quickly drive populations down
• Black coral skeletons are a beautiful, shiny black and resemble a gemstone
• For centuries, they have been the raw material for making jewelry and other trinkets
• This practice has threatened several species in some areas

• Dangers to Coral

• Ocean acidification

• From increased CO2 absorption (carbonic acid)
• Deep waters naturally more acidic than shallow
• May eventually become acidic enough to literally dissolve deep sea coral skeletons

• Coral Bleaching

• Occurs when coral polyps expel algae that live inside their tissues
• The algae is crucial for the health of coral and reef
• Leading cause of coral bleaching is rising water temperatures
• Oxygen starvation, sedimentation, salinity changes

• Fishing practices

• Most notably bottom trawling
• Threaten deep-sea coral reefs by scraping corals right off of the bottom and flattening the three-dimensional habitat

• Great Barrier Reef

• One of the original Seven Natural Wonders of the World
• Largest coral reef system in the world

• Visible from outer space
• 1,430 miles long

• Climate change has caused an 89% reduction in new coral

• Mass bleaching due to warmer temperatures
• May never recover

• Half of the Great Barrier Reef has died since 2016