Biology 105 Module 5 1

Module 5.The Coral Reefs of Florida

Coral Reef EcosystemsWhere are Coral Reefs?ResourcesEnergy Flow

Symbiotic AssociationsReef Ecosystem Problems

Changes in Resources, Changes in CommunitiesCoral Bleaching

World Distribution of Coral Reefs

Coral reef development is restricted to the low-latitude areas where watertemperature remains above 18oC (64oF). In each ocean basin, the coral reef belt iswider and the diversity of coral genera is greater on the western side of the oceanbasins.

wysiwyg://21/http://www.cgiar.org/iclarm/reefbase/frameg/rbmap.htm

Biology 105 Module 5 2

Coral Reefs in the United States

wysiwyg://21/http://www.cgiar.org/iclarm/reefbase/frameg/rbmap.htm

Coral Reef EcosystemsWave energy, light, salinity & temperature create zonation

concepts:• abiotic factors control community composition • temperature, salinity, wave energy, and light are major factors

controlling coral growth

Incidentlight

60%

20%

4%

Coralzonation

Massive branching corals dominatebuttress zoneMassive head corals grow in high energy zone

Delicate plate corals dominate wherewave energy in low

Where light is too low, no corals grow

Depth

20 m

50 m

150 m

island

lagoon

Biology 105 Module 5 3

BiodiversityThe high productivity of reef ecosystems fosters biodiversity

concepts:• high resource cycling leads to high productivity • high heterogeneity provides diverse habitats• reefs cover 0.2% of the ocean but contain 25% of ocean species

Symbiotic AssociationsForm the heart of a healthy coral reef

Polyps of a reef coral extend theirtentacles to capture tiny planktonicorganisms from the surroundingwater. However, for many reef-building corals, most of theirnourishment is provided bysymbiotic algae, zooxanthellae, thatlive in the coral tissue.

http://www.geology.iupui.edu/classes/g130/reefs/images/f1521ath.gif

Biology 105 Module 5 4

Symbiotic AssociationsCooperation between organisms enhances productivity

alga photosynthesis providesenergy source to coral (up to 90%)

coral provides a “home” andinorganic nutrients to alga

Threats to Coral ReefsLocal and distant activities affect reef health

pollution:nutrients & sediment

coastline development

coral harvest &indirect damage

fishing practice

concepts:• human activity directly & indirectly affects coral ecosystems• reef health is integrally linked to the health of other ecosystems

global warming

Biology 105 Module 5 5

Population Distribution - Florida

Coastal DevelopmentDamages coastal boundaries & alters land-sea interactions

Location: St. Augustine Inlet, Florida Photographer: Marge Beaver

Biology 105 Module 5 6

Mangrove Coastal BoundaryControls terrestrial-marine transfers

Red mangroveJohn PennekampState Park, Florida

Photographer: Richard B. Mieremet, NOAA OSDIA

concepts:• coastal mangrove forests filter water moving to sea• root systems provide habitat for fish, especially for reproduction

Seagrass BedsA critical and overlooked ecosystem

concepts:• seagrass beds filter water moving to sea• provide habitat and nursery ground for many species

Biology 105 Module 5 7

Changes in Resources ChangeCommunity Structure

nutrient levels in seawater

low

corals(symbiosis)

high

suspensionfeedersfleshy algae

phytoplankton

Nassau GrouperPredators control population dynamics

Epinephelus striatus, Nassau grouper

http://www.nova.edu/ocean/dna/picture.htm#Myinter

Biology 105 Module 5 8

Loss of Grazers or PredatorsChanges ecosystem balance

f-Sea urchins eat algae and keepcorals clean

Top predators may keeppopulations of coral-eatingstarfish in check

f-

algae corals thorn of stars grouper

sea urchin

Problems In The Florida Keys

• Loss of biological diversity• Too many algae• Decreased freshwater flow from

the Everglades to the Florida Baywhich has resulted in extremelyhigh salinity

• Increased ocean temperatures aredestroying the corals

• Rise in bleaching & black banddisease

Biology 105 Module 5 9

Coral BleachingChange in the physical environment eradicates zooxanthellae

Photograph of a bleaching hard coral (Goniopora sp) from Pohnpei, Micronesia.!Notice that the entire coral is not bleached, the polyps around the edges are stillhealthy. Photo taken by J Hoogesteger.

http://www.marinebiology.org/

Global Climate ChangeTemperature & CO2 are implicated in coral bleaching

surface temperatureCO2

Above 30oC,zooxanthellae nolonger fix carbon

Enhanced CO2dissolution acidifieswater, leading to coral degradation

concepts:• global change factors alter fundamental ecosystem variables• these changes act as selective forces against coral reefs