Coral Reefs Outcome: To understand where coral reefs are distributed, examine the symbiotic relationships within coral reefs, compare/contrast the three reef types, and understand the danger corals face

Tropical Paradise In the waters in tropical paradises (bottom left) what do you notice that would be different from Ocean City (bottom right)?

Coral Reef Distribution Coral waters are relatively nutrient poor giving them a clear blue coloration. How is the diversity of the coral supported in such a nutrient poor community? Zooxanthellae!! (ZOH-oh-zan-thel-ee)

Zooxanthellae Zooxanthellae are dinoflagellates the make up a large part of the reef system. Zooxanthellae are symbionts for jellyfish, corals, and molluscs. Zooxanthellae are photosynthetic algae providing food (sugar), O2, and lipids (fats) for their host organism and the host (coral) provides CO2, H2O, and shelter for them.

Coral Reefs Coral reefs are massive structures made of calcium carbonate secreted by corals living within the reef. Although thousands of species inhabit coral reefs, only a fraction produce the limestone that builds the reef. The most important reef-building organisms are the corals.

What is Coral? Coral is often mistaken for a rock or a plant, but these fragile animals are called coral polyps. When people say coral, they are referring to these little animals and the skeletons they leave behind after they die.

Coral Polyp A coral polyp is an invertebrate that ranges in size from the size of a pinhead up to a foot in diameter. Coral polyps are cousins to anemones and jellyfish

Coral Reefs A polyp has a saclike body and an opening, or mouth, encircled by stinging tentacles called nematocysts. Coral polyps are usually nocturnal hunters and only have their paralyzing tentacles out at night. This is because the zooxanthellae do NOT photosynthesize at night

Coral Polyp Stomach and digestive filaments make up most of the polyps structure Polyps take in and expel waste from their mouth The coensarc connects the polyps together to form a colonial organism

Coral Polyps

Coral Colony One coral branch or mound is covered by thousands of coral polyps called a coral colony. Thus, each coral branch or mound is one colony of coral polyps.

Formation of Coral Colonies Larva attaches to hard surface Larva develops in to a polyp Polyp reproduces asexually by budding The shape is genetically determined New polyps continue to bud

Formation of Coral Reefs There are three types of coral reefs: Fringing reefs: project seaward directly from the shore (10,000 years) Barrier reefs: move outward from shore to create a lagoon separation (100,000 years) Atoll: the island/volcano complete submerges and a lagoon center is left (30,000,000 years)

Fringing Reef

Barrier Reef

Atoll

Zooxanthellae in the coral tissue Bleached coral: Healthy coral: Zooxanthellae in the coral tissue Bleached coral: Zooxanthellae expelled from tissue Dead coral: Skeleton covered in filamentous algae

Major Bleaching Events

Danger Facing Coral Reefs Increase water temperatures due to global warming cause coral to release their zooxanthellae and coral bleaching occurs. Hurricanes/typhoons/cyclones cause massive damage by toppling coral formations and removing them from the reef. Human impacts such as coastal development, increased CO2 production, increase sedimentation and encourage overfishing. Coral diseases such as black band disease and white pox can also occur when bacteria attack the coral.

Bleached Coral

Black band and White Pox

Coral Reefs In Decline Day 16 Drill: As you watch the video write down biotic and abiotic factors that affect coral reefs. Outcome: Compare and contrast the biotic and abiotic factors of a coral reef under stress and a coral reef that is not under stress. Hypothesize reasons why coral reefs may or may not be under stress.

Coral Reefs In Decline Your job today will be to form groups (2 to 3) and find corals in our oceans that are stressed and not stress and compare them You will use Google Earth to help find them and identify why they may be stressed You must choose a reef from the list provided, so let’s take a look at what I mean!

Biotic and Abiotic Factors Coral is affected by biotic and abiotic factors daily Some factors can lead to a decline in the population due to coral bleaching. In groups you will go to http://coralreefwatch.noaa.gov/satellite/ge/index.php You will click on Google Earth will open You will choose two reefs from this list: http://www.hhmi.org/biointeractive/coral-temperature-data One reef should be stress free One reef should have stress and be in danger of bleaching You will try to hypothesis what biotic and abiotic factors are different between the two reefs that would cause one to bleach and one to be normal All info will be placed on the back of the map sheet

Reef Life Coral reefs are the rain forest of the waters. The diversity found in coral reefs is what makes them so fascinating and important to protect Molluscs, Echinoderms and Arthropods

Echinoderms Sea urchins, sea stars, brittle stars, and sea cucumbers Can be both sessile, brittle stars, and mobile, sea urchins and sea stars Some sea stars eat the reefs, taking down 1/3 since 1957

Molluscs Clams, sea snails (nudibranchs), octopi, and squid Feed on sponges, anemones, and jellyfish Giant clams, 3 feet, filter feed but also have zooxanthellae

Crustaceans Shrimps, crabs, lobsters and horseshoe crabs Symbiont because they use coral as a cover to attack prey Mantis shrimp’s strike is so powerful it can cut another shrimp in half