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Download Coral Reefs - Mater Academy Lakes High School
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What is a Coral? Animal, vegetable or mineral? It’s an animal which may live with a plant and makes a mineral-based skeleton. Illustration by Geoff Kelley in JEN Veron (2000) Corals of the World, AIMS, Townsville Coral structure Individual animals are called polyps Several polyps make up a colony Corals are closely related to jellyfish and sea anemones—they all contain stinging cells called nematocysts. Coral reefs Reef-building corals require clear, warm water Shallow areas Most reefs are between 26° N and S latitude There are corals found off Alaska and other cold waters, but they grow very slowly and do not form reefs Symbiosis E.C. Peters Many hard and soft corals (and some jellyfish and sea anemones) contain a symbiotic single-celled brown dinoflagellate (algae) called zooxanthellae This is a mutualistic symbiosis Bleaching occurs when corals lose their zooxanthellae Coral Bleaching Response to stress Temperature UV Oxygen Darkness Sedimentation Who initiates bleaching? Can corals recover? J. Hoggesteger Patterns of bleaching Seasonal—usually in summer Geographically, often begins in the Caribbean and spreads northwards Physically, there are often bleached patches on the sides of large coral heads (especially Montastraeas) Zooxanthellae “clades” Three groups of zooxanthellae have been identified Each group has different environmental tolerances and is found in different locations on the coral head Photo by Scott R. Santos, SUNY Buffalo Where do zooxanthellae go? “Free” zooxanthellae are rarely found in plankton samples May become benthic, sessile May go into dormant stage Presumably free zooxanthellae do exist Status of coral reefs Globally, coral reefs are generally in decline Increasing human population (especially in coastal areas) increases the impacts on coral reefs Human impacts on coral reefs Overfishing Sedimentation Nutrient enrichment Chemicals/oil Physical damage (anchors, fishing, groundings) Overfishing Changes trophic structure Many large predators are no longer present Grazing fish species are being collected as food fish May allow algal overgrowth of corals NOAA Nutrient enrichment Nutrients are elements needed for growth If there are not enough of certain types of nutrients, they are said to be limiting nutrients Most common limiting nutrients in the marine environment are N and P Nitrogen Available in water as nitrate, nitrite, ammonium or organic nitrogen (e.g. urea, plant or animal tissues) Phosphorus Available in water as dissolved inorganic phosphate or organic phosphorus (dissolved or particulate) How does nutrient enrichment occur? Septic tanks/sewage Leaks Pumping into the ocean Fertilizer runoff Agricultural Homeowners Golf courses Effects of increasing nutrients Cause increase in plant (algae) growth Macroalgae Microalgae (phytoplankton) Effects of increased nutrients on corals Cause decrease in coral growth Direct chemical interference with skeleton formation Result of overshading by algae Jennifer M. Smith Chemicals/oil Non point-source pollution – 51% of the oil entering the oceans is from runoff – 5% is from big spills – 19% is from routine maintenance – 2% is from offshore drilling – 13% is from burning fuels (e.g. car exhaust) – 10% is from natural seeps Physical damage Thomas Heeger, Philippines Fishing techniques in the South Pacific include dynamiting or poisoning reefs to collect aquarium fish for export Boat anchors and boat/ship groundings cause damage that can take thousands of years to re-grow Natural impacts Marine debris Suffocation risk Balloons/bags Entanglement/entrapment Fishing line/ropes Old nets Abandoned traps/pots What can you do? Reduce, reuse, recycle Motor oil Fishing line Read and follow instructions on chemicals, including fertilizers Fix automotive leaks What does the future hold? The answer is up to you… 1988 USGS 1998 USGS Restoring of Reefs A process being done in areas where high coral bleaching has occurred or coral population is in danger. Many methods such as: Coral Tree Nurserys, Artificial reefs, Biological restoration Advantages to each method??? Your turn! Choose your method of restoration (designed to improve coral growth!) Choose materials Create a design based on researched methods. Write all dimensions and materials list! (INCLUDING DESIRED SPECIES) Options:
