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!
3.
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.
North Rock
Lighthouse
4.
Reef that is about three meters in diameter in Bermuda with only a few centimeters of water
covering it.
5.
Photo showing the underside of the water surface and a large colony of elkhorn coral
(Acropora palmata), Lee Stocking Island, Bahamas.
6.
Corals are colonial animals that have photosynthesizing organisms called zooxanthallae in
their skin. This is a reef from near Lee Stocking Island, Bahamas.
C
A
B
D
7.
Close-up showing a branch of elkhorn coral (Acropora palmata), Lee Stocking Island.
8.
1 cm
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.
9.
Relative amount
and colors of
light absorbed
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.
10.
Broken branch of elkhorn coral (Acropora palmata), near Lee Stocking Island, Bahamas
11.
Branching staghorn coral (Acropora cervicornis), in three meters water depth, Lee Stocking Island.
12.
What high biodiversity!
I can’t count the number of
organisms on this reef!
In Bermuda above the coral reef in the next slide.
13.
Coral reef in Bermuda below the students in the previous slide.
14.
Small patch reef crest in Bermuda
15.
Small patch reef crest in Bermuda
G
A
E
C
F
B
16.
D
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).
17.
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.
18.
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).
19.
Sea whips (octacoral coral) and a shelter created by a now dead coral colony gives shelter to
small fish, Bermuda.
20.
A queen angel (Holacanthus ciliaris) taking shelter in a coral reef, Lee Stocking Island
21.
A purple-tipped sea anemone lives permanently attached in a rocky shelter on the reef
along with a brown, encrusting sponge (left), Bermuda.
22.
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).
23.
Patch reef dominated by soft octacorals (sea whips and sea fans) with a school of
blackear wrasses (Halichoeres poeyi), Bermuda.
24.
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.
26.
Young initial phase stoplight parrot fish (Sparisoma viride) grazing on a reef and,
Lee Stocking Island, Bahamas.
27.
A gray angel fish (Pomacanthus arcuatus) grazing on algae on the flanks of a coral reef,
Lee Stocking Island.
28.
Deep water (22 meters deep) reef
dominated by soft octacorals (left)
and sponges (below), Lee Stocking
Island, Bahamas.
29.
A small colony of staghorn coral (Acroporoa cervicornis), near Key Largo, Florida
Keys. The white tips of the branches are new growth.
30.
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.
31.
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.
32.
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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33.