Exploring Coral Reefs: a Virtual Dive in the Bermuda Triangle!

Join us as we dive and explore reefs around the Caribbean.

Coral reefs are amazing diverse ecosystems constructed by coral algae, sponges and many other groups of organisms.

This presentation will take you through many of the important aspects of a modern coral reef. It includes examples from Bermuda, Lee Stocking Island in the Bahamas and the Florida Keys.

(modified from Google Earth)1.

Coral reefs are only found at low latitudes, generally within 30° of the equator.

•Corals need:•Clear, warm water (18-30°C)•Shallow water (mostly less than 20 meters)•Near normal salt content (salinity) (25-35 parts per thousand)•Low nutrient levels

This photo shows the eastern edge of the Bermuda volcanic atoll. The brownish areas in the light blue water are coral reefs that average 15 meters in diameter. The dark blue water marks the edge of the atoll and reaches depths of more than 3 kilometers. 2.

This is the best classroom ever,I can’t wait to get in the water!

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Clear water on top of the Bermuda atoll, east side. Dark areas are small reefs in about two meters of water and light blue water areas have white sand on the ocean floor.

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North RockLighthouse

Reef that is about three meters in diameter in Bermuda with only a few centimeters of water covering it.

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Photo showing the underside of the water surface and a large colony of elkhorn coral (Acropora palmata), Lee Stocking Island, Bahamas.

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Corals are colonial animals that have photosynthesizing organisms called zooxanthallae in their skin. This is a reef from near Lee Stocking Island, Bahamas.

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Close-up showing a branch of elkhorn coral (Acropora palmata), Lee Stocking Island.

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2 mm

Corals are animals. Photo above shows coral polyps of the finger coral (Porites porites) with its tentacles extended. The diagram on the upper right is a simplified cross section of a coral polyp.

1 cm

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The photo above shows elkhorn coral (Acropora palmata), that has grown within a few centimeters of sea level.

The photo to the right shows the same species but in this case in about two meters of water.

Both examples are from Lee Stocking Island.

Relative amount and colors of light absorbed

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Broken branch of elkhorn coral (Acropora palmata), near Lee Stocking Island, Bahamas

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Branching staghorn coral (Acropora cervicornis), in three meters water depth, Lee Stocking Island.

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I can’t count the number of organisms on this reef!

What high biodiversity!

In Bermuda above the coral reef in the next slide.

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Coral reef in Bermuda below the students in the previous slide.

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Small patch reef crest in Bermuda

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Small patch reef crest in Bermuda

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Top of a small coral reef in Bermuda with a blue terminal phase stoplight parrot fish(Sparisoma viride) peaking out from behind two brain coral colonies (genus = Diploria).

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Photo above shows a large colony of mountainous star coral (Montastrea annularis). Upper right shows many colonies of mountain star coral with green algae. Lower right, large brain coral (Diploria strigosa) colony. All from the Florida Keys.

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Reefs are home to many organisms like the great barracuda (Sphyraena barracuda) (above left from the Florida Keys) and the moon jellyfish (Aurelia aurita) (above right from Bermuda), and occasionally students, like Holly (Homo sapiens)(right, in Bermuda).

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Sea whips (octacoral coral) and a shelter created by a now dead coral colony gives shelter to small fish, Bermuda.

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A queen angel (Holacanthus ciliaris) taking shelter in a coral reef, Lee Stocking Island

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A purple-tipped sea anemone lives permanently attached in a rocky shelter on the reef along with a brown, encrusting sponge (left), Bermuda.

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Sea fans (right) are a type of soft corals called gorgonians. Sea fans, such as this common sea fan (Gorgonia vendalina) in the right photo shelter for fish, especially during the night when predators, such as sharks, patrol the reef.

The photo below shows a large school of French grunts (Haemulon flavolineatum) accompanied by a few jacks (gray)(Seriola rivoliana) and sergeant majors (Abudefduf saxatilis).

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Patch reef dominated by soft octacorals (sea whips and sea fans) with a school of blackear wrasses (Halichoeres poeyi), Bermuda.

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A young hawksbill sea turtle (left) (Eretmochelys imbriocota) swims toward a reef seeking protection from large, threatening-looking students. The hawksbill is 0.5 meter long; Lee Stocking Island, Bahamas.

A Caribbean spiny lobster (Panulirus argus) also depends on the reef for shelter (right). The lobster is 35 centimeters long; Lee Stocking Island, Bahamas. 25.

Blue terminal phase stoplight parrot fish (Sparisoma viride) and two young initial phase stoplight parrot fish grazing on a reef, Bermuda.

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Young initial phase stoplight parrot fish (Sparisoma viride) grazing on a reef and, Lee Stocking Island, Bahamas.

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A gray angel fish (Pomacanthus arcuatus) grazing on algae on the flanks of a coral reef, Lee Stocking Island.

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Deep water (22 meters deep) reef dominated by soft octacorals (left) and sponges (below), Lee Stocking Island, Bahamas.

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A small colony of staghorn coral (Acroporoa cervicornis), near Key Largo, Florida Keys. The white tips of the branches are new growth.

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Stresses on Reefs:

Reefs around the world are experiencing environmental stress from increasing temperatures, nutrients, and sediment.

Large brain coral (Diploria strigosa) colony approximately one meter in diameter, Bermuda.

The left half of the colony is dead with only its underlying white skeleton exposed. The black line is a zone of tissue infected with a flesh-eating bacteria that causes blackband disease.

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A sergeant major fish (Abudefduf saxatilis) swims over a large brain coral (Diploria strigosa) colony approximately one-half meter in diameter, Bermuda.

The top of the colony is dead and eaten away. This is likely due to damage to the living colony caused by a boat anchor. Once the living tissue is damaged, the underlying skeleton is attached by snails, clams, worms, sponges, and other organisms.

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Reefs Glossary

Bacteria and cyanobacteria: single-celled prokaryotic organisms; cyanobacteris, also called blue-green algae, photosynthesize

Biodiversity: a measure of the biological variety or number of different organisms in an environment.

Hermatypic Corals: corals that have rigid skeletons and build coral reefs.

Nutrients: compounds or elements dissolved in sea water that organisms use for metabolism and growth.

Oligotrophic conditions: water that has very low nutrient levels -- any nutrients that are present in the environment are tied up in the living tissues of the organisms. Corals are adapted to live in oligotrophic conditions.

Photosynthesis: the process in which some bacteria, plants, and some protozoans use energy from the sun to drive the transformation of carbon dioxide into simple sugars and oxygen: 6CO2 + 6H2O --> C6H606 + O2

Protozoan: Single celled eukaryotic organisms of the phylum Protista; many protozoans are able to photosynthesize and were orignially calssified as a type of single-celled algae.

Volcanic atoll: An extinct volcano in the ocean that is capped with coral reefs.

Zooxanthallae: microscopic, single-celled protozoans that form symbiotic relationships with corals that produce energy by photosynthesis.

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