Coral Reefs.

Coral Reefs

What is coral? It’s a living organism! It is an invertebrate
Cnidaria!! Sun Coral Polyps

Where Can You Find Coral Reefs?
Coral is found all over the world: Tropical Temperate Only tropical corals build reefs Coral reefs around the world

Coral Builds Reefs? The animal portion of the reef is called a polyp
The polyp absorbs calcium carbonate out of the water The calcium carbonate is used to build the reef

Coral are Cnidarians Soft bodied Carnivorous
Stinging tentacles arranged in a circle around their mouth Radial symmetry

Cnidarians Usually two life stages: Polyp Medusa

Anatomy of Coral The coral polyps build a calcium carbonate cup called a corallite to live in Coral has stinging cells called nematocysts

Stinging Cells Nematocysts help coral catch food
They also help protect the coral When the cell is stimulated, it releases a sharp barb The barb will fire and catch the food and bring it back towards the mouth Maybe add a slide about how they feed

Coral and Zooxanthella (algae)
Symbiotic relationship Zooxanthella is an algae that lives in the skin of coral Coral provides protection Zooxanthella provides food and color!

Coral is Picky Very specific habitats: Temperature: 73-75F
Depth: Less than 80 ft to 230 feet Salinity: Normal salt levels (35ppt) Light: Zooxanthellae need light to survive Sedimentation: Being covered with silt interferes with photosynthesis Desiccation: being exposed to air. The corals will die if exposed too long

Key Concepts Coral reefs are primarily found in tropical clear water, usually at depths of 60 meters or less. The three major types of coral reefs are fringing reefs, barrier reefs, and atolls. Both physical and biological factors determine the distribution of organisms on a reef. © 2006 Thomson-Brooks Cole

Key Concepts Stony corals are responsible for the large colonial masses that make up the bulk of a coral reef. Reef-forming corals rely on symbiotic dinoflagellates called “zooxanthellae” to supply nutrients and to produce an environment suitable for formation of the coral skeleton. Coral reefs are constantly forming and breaking down. © 2006 Thomson-Brooks Cole

Key Concepts The most important primary producers on coral reefs are symbiotic zooxanthellae and turf algae. Coral reefs are oases of high productivity in nutrient-poor tropical seas. © 2006 Thomson-Brooks Cole

World of Coral Reefs Coral reefs are highly productive, but occur in nutrient-poor waters This is made possible by the symbiotic relationship between coral animals and zooxanthellae © 2006 Thomson-Brooks Cole

Coral Animals Coral nutrition symbiotic zooxanthellae
supply 90% of nutritional needs of stony coral coral polyp provides a suitable habitat and nutrients, absorbed directly through the animal’s tissues zooxanthellae remove CO2 and produce O2 need of zooxanthellae for sunlight limits the depths to which stony corals can grow © 2006 Thomson-Brooks Cole

Coral Animals Coral nutrition (continued) corals as predators
small animals paralyzed by the nematocysts are passed into the digestive cavity © 2006 Thomson-Brooks Cole

Coral Animals Coral nutrition (continued) other sources of nutrition
corals can feed off bacteria living in their tissues, which feed on dissolved organic matter directly from the water © 2006 Thomson-Brooks Cole

Reef Structure Reef front or forereef—portion of the reef that rises from the lower depths of the ocean to a level just at or just below the surface of the water, on the seaward side © 2006 Thomson-Brooks Cole

Coral Reef Distribution
Major factors influencing distribution: temperature – corals do best at 23-25o C light availability – photosynthetic zooxanthellae need light sediment accumulation – can reduce light and clog feeding structures salinity wave action – moderate wave action brings in oxygenated seawater, removes sediment that could smother coral polyps duration of air exposure – can be deadly © 2006 Thomson-Brooks Cole

Coral Reef Ecology Coral provides:
foundation for reef food webs shelter for resident organisms Reefs form a complex 3-dimensional habitat for many beautiful and strange creatures © 2006 Thomson-Brooks Cole

Coral Reef Community Sponges and cnidarians Annelids
sessile organisms, though anemones can move if necessary filter feed; anemones also paralyze and consume small fishes and crustaceans Annelids sessile filter feeders include featherduster and Christmas tree worms fireworms are mobile predators palolo worms burrow through and weaken coral and usually deposit feed © 2006 Thomson-Brooks Cole

Coral Reef Community Crustaceans Molluscs shrimps, crabs and lobsters
vary from parasites to active hunters Molluscs gastropods eat algae from coral surfaces giant clams are filter feeders, but also host symbiotic zooxanthellae octopus and squid are active predators © 2006 Thomson-Brooks Cole

Coral Reef Community Echinoderms Reef fishes
feather stars, sea urchins, brittle stars, sea stars, and sea cucumbers filter feed, scavenge, or eat sediment Reef fishes most prominent and diverse inhabitant diverse food sources, including detritus, algae, sponges, coral, invertebrates, other fish © 2006 Thomson-Brooks Cole

Species Interactions on Coral Reefs
Competition among corals fast-growing, branching corals grow over slower- growing, encrusting or massive corals and deny them light slower-growing corals extend stinging filaments from their digestive cavity to kill faster-growing corals fast-growing corals can also sting and kill using long sweeper tentacles with powerful nematocysts © 2006 Thomson-Brooks Cole

Competition among corals (continued) slower-growing corals are more tolerant of shade, and can grow at greater depths as a result… fast-growing, branching corals on many reefs dominate upper, shallower portions larger, slower-growing corals dominate deeper portions © 2006 Thomson-Brooks Cole

Competition between corals and other reef organisms sponges, soft corals and algae can overgrow stony corals and smother them algae outcompete corals at shallow depths unless grazers control the algae growth © 2006 Thomson-Brooks Cole

Effect of grazing grazing of larger, fleshier seaweeds permits competitively inferior filamentous forms or coralline algae to persist herbivory decreases with depth damselfish form territories where they exclude grazers and permit abundant algal growth provides habitat for small invertebrates overgrows corals; fast-growing, branching corals are most successful near damselfish © 2006 Thomson-Brooks Cole

Coral Reef Ecology Coral reefs - marine habitats with greatest diversity/abundance of fishes Seems to defy competitive exclusion principle, which suggests that no 2 species can occupy the same niche 60-70% of reef fishes are general carnivores about 15% are coral algae grazers or omnivorous © 2006 Thomson-Brooks Cole

Threats to Coral Reefs Effect of physical changes on the health of coral reefs hurricanes and typhoons topple and remove coral formations El Niño Southern Oscillation (ENSO) changes winds, ocean currents, temperatures, rainfall and atmospheric pressure over large areas of tropical and subtropical areas can cause massive storms © 2006 Thomson-Brooks Cole

Threats to Coral Reefs Coral bleaching
a phenomenon by which corals expel their symbiotic zooxanthellae most often associated with warming of the ocean water by or global warming if the stress is not too severe, corals may regain zooxanthellae and recover if the stress is prolonged, corals may fail to regain zooxanthellae and die © 2006 Thomson-Brooks Cole

Threats to Coral Reefs Human impact on coral reefs
overfishing may occur human-sewage bacteria cause white pox nutrient-rich runoff (eutrophication) increases algal growth, which covers and smothers corals e.g. Kane’ohe Bay in Hawaii © 2006 Thomson-Brooks Cole

Evolutionary Adaptations of Reef Dwellers
Role of color in reef organisms color for concealment and protection countershading disruptive coloration camouflage (bright colors in reef environment) © 2006 Thomson-Brooks Cole

Symbiotic relationships on coral reefs cleaning symbioses cleaner wrasses, gobies, etc. feed on parasites of larger fishes cleaning organisms set up a cleaning station Other symbiotic relationships clownfishes and anemones conchfish and the queen conch gobies and snapping shrimp crustaceans and anemones © 2006 Thomson-Brooks Cole

Coral Reefs http://tools.coralreef.org/content/
objects/view.acs?object_id=545 mccarty_and_peters/coral/C-intro.htm

Importance of Coral Reefs
0.2% of world’s oceans Habitat for 1/3 of marine fishes Habitat for tens of thousands of other animals The rainforests of the oceans

PROTECTION TO COASTLINES ECONOMIC RESOURCES BIODIVERSITY NATURAL BEAUTY

PROTECTION TO COASTLINES absorb energy of ocean waves reduce erosion of shoreline storm damage flooding

ECONOMIC RESOURCES Fisheries for food Fisheries for jobs Tourism Building materials Aquarium trade

BIODIVERSITY The rainforests of the sea Genetic diversity Pharmaceuticals

NATURAL BEAUTY florida2/background/coralspawning.html

$375 billion in environmental goods and services
Reefs at Risk 1998 (

Caribbean reef values (annual net benefits in 2000)
Fisheries: $310 million Dive tourism: $2.1 billion Shoreline protection: $ billion Total: $ billion

REEFS WORLDWIDE ARE THREATENED
11% of reefs have been lost 16% of reefs severely damaged ~60% of studied reefs threatened by human activities No pristine reefs left

CARIBBEAN REEFS DECLINING
1970s: ~50% coral cover Present: ~10% coral cover =80% reduction in coral cover over last 30 years Gardner et al Science 301:

Threats to coral and coral reefs:
1) Natural 2) Anthropogenic of human origin

Natural disturbances that affect corals and coral reefs?
Hurricanes Tsunamis Volcanoes Earthquakes Predators & competitors Bleaching Pathogens

Hurricanes Smothering Freshwater poisoning
Physical damage Smothering Freshwater poisoning 1989hugo.html Destruction of other ecosystems upon which coral reefs depend

Tsunamis Physical damage Erosion
Possible disruption of reproduction and recruitment

Volcanoes Depends upon where volcano occurs Heat
smothering and sedimentation current_volcs/montserrat/montserrat.html

Earthquakes Little direct impact Indirect impacts triggers tsunamis
coastal landslides

Predators crown of thorns starfish snails parrotfish butterflyfish
cot-starfish/pages/cot-q07.html

Competitors algae

Bleaching Loss of zooxanthellae causes
higher than usual ocean temperature sharp changes in salinity heavy UV light exposure mccarty_and_peters/coral/Bleach.htm

Pathogens Diseases on the rise new pathogens (8+)
land pathogens (Aspergillus) occurring at all depths More susceptible when stressed homepages/mccarty_and_peters/ coral/Bbd.htm

Anthropogenic threats to coral reefs:
Overfishing Development Mining and dredging Recreation

Overfishing Ecological imbalance

Overfishing Destructive fishing practices

Development Sediment  smothering Freshwater input
Pollutants & nutrients (sewage, pesticides, fertilizer, heavy metals, pathogens)

Development

Mining for construction materials and dredging
Destruction of reef structure stirs up sediment

Recreation Anchors, boats, flippers, hands, feet Kill animal tissue
Skeleton breakage

Global climate change Reduced reef building
Increase in frequency and intensity of hurricanes Increases in bleaching Increased in disease

Coral Reefs.

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