Corals Landlords of the Reefs

What should you know about corals? They are animals Plants live inside of them Two kinds Soft corals Hard corals (These build reefs!) They are made of tiny polyps (which look like upside-down jellyfish)

Hard Corals The Reef Builders Polyps build hard limestone cups around their bases Polyps build hard limestone cups around their bases The cups cement together to make a coral colony The cups cement together to make a coral colony Reefs are made of hundreds of hard coral colonies next to and on top of each other Reefs are made of hundreds of hard coral colonies next to and on top of each other

What’s a Polyp? Tentacles release stinging cells when something brushes by them Polyps make their own limestone cup to hide in during the day At night, polyps come out to catch plankton floating by.

Zoo-what!?! Algae, Coral Polyps’ Tenants Inside polyps live zooxanthellae, which are algae. Inside polyps live zooxanthellae, which are algae. Zooxanthellae give corals their color. Zooxanthellae give corals their color. Since algae are plants, they use sunlight and CO 2 to make food (the process known as photosynthesis). Since algae are plants, they use sunlight and CO 2 to make food (the process known as photosynthesis).

Zooxanthellae -Symbiotic dinaflagellate algae (Pyrophyta) -Symbiotic dinaflagellate algae (Pyrophyta) Benefits for coral: Benefits for coral: -fixed carbon -fixed carbon -enhanced calcification -enhanced calcification -nutrient efficiency -nutrient efficiency Benefits for zooxanthellae: Benefits for zooxanthellae: -nutrient supply from host -nutrient supply from host -stay in photic zone -stay in photic zone -UV protection -UV protection

Symbiosis: So Happy Together Two organisms living together and helping each other is called symbiosis. Two organisms living together and helping each other is called symbiosis. Zooxanthellae make oxygen, remove the polyp’s wastes, and make food for the polyp from photosynthesis. Zooxanthellae make oxygen, remove the polyp’s wastes, and make food for the polyp from photosynthesis. Coral polyps protect the zooxanthellae, release CO 2, and provide it with necessary nutrients from their own waste. Coral polyps protect the zooxanthellae, release CO 2, and provide it with necessary nutrients from their own waste.

3 forms of Symbiosis Mutualism- Both organisms benefit Mutualism- Both organisms benefit Commensalism- one organism benefits and the other is not affected Commensalism- one organism benefits and the other is not affected Parasitism- one organism benefits while the other is harmed. Parasitism- one organism benefits while the other is harmed.

Mutually Beneficial Symbiosis A Win-Win Situation Egyptian Plover bird and crocodile Egyptian Plover bird and crocodile Bumblebee and flowers Bumblebee and flowers Your intestine and bacteria Your intestine and bacteria

Parasitic Symbiosis A Win-Lose Situation Tapeworms and intestines Tapeworms and intestines Ticks and dogs Ticks and dogs

How are these mutually symbiotic? Drivers and passengers in a carpool Drivers and passengers in a carpool Tenants and landlords Tenants and landlords

Which form of symbiosis is this? Why? Mutualism

How about this? Why? Parasitism

And last. WHY? Commensalism

Reef Ecology Trophic Structure – Primary producers: zooxanthellae and macroalgae – Primary Consumers: coral and invertebrates – Tertiary consumers: predators Keystone Species – Sea urchins, Crown of Thorns Sea Star

What is a keystone species? A keystone species is a species that has a disproportionate effect on its environment relative to its biomass. Such a species affects many other organisms in an ecosystem and help to determine the types and numbers of other species. So why were the sea urchin and the crown of thorn sea star keystone species?

One third of all marine species live in coral reef systems

Coral Colonies – Butterflies, damsels, wrasses, velvet fishes, gobies, puffers, filefishes, hawkfishes, triggerfishes, and squirrelfishes

Conditions for coral Sunlight Low nutrient levels Certain salinity Water temperature between 18 and 29 Celsius Water circulation

What is coral bleaching? Coral bleaching is caused by stress Poll question: what might be stressful for a coral? Healthy coral Bleached coral

What can stress a coral? - High light or UV levels - Cold temperatures - Low salinity and high turbidity(cloudiness of water) from coastal runoff events or heavy rain - Exposure to air during very low tides - Major: high water temperatures Photos: AIMS and GBRMPA

Man made threats to coral reef systems Global warming leading to coral bleaching Runoff from chemicals and nutrients from land Sedimentation Overfishing Physical damage from tourists and fishing pollution

What turns the coral white? - As a stress response, corals expel the symbiotic zooxanthellae from their tissues - The coral tissue is clear, so you see the white limestone skeleton underneath Healthy coral with algae Bleached coral with no algae

Can corals recover? - Yes, if the stress doesn’t last too long - Some corals can eat more zooplankton to help survive the lack of zooxanthellae - Some species are more resistant to bleaching, and more able to recover Photos: AIMS and GBRMPA

Does bleaching kill corals? - Yes, if the stress is severe - Some of the polyps in a colony might die - If the bleaching is really severe, whole colonies might die - Bleaching in Puerto Rico killed an 800-year-old star coral colony in 2005

What does it really matter if coral die or not? What’s the impact of bleaching?

Your answer!!! (The short version) If coral reefs were to become bleached and die it would have a domino effect of the ecosystem. Many fish that rely on the reef for camouflage would be exposed and eaten by predators. Many animals lay their eggs on the reefs. As their breeding grounds diminish their population will decline. Before the coral completely die they will be eroded and/or eaten (parrotfish). Human rely on the coral reef for food. Overall, less coral equals less food for us.