Characteristics of Coral Reef Ecosystems
- An ecosystem is a community of interacting biotic and abiotic organisms
- All ecosystems, whether on land or in water function in the same way
- All survive by nutrient cycling around three stores:
- Biomass
- Litter
- Sea Water
Nutrient Cycle of a Coastal Ecosystem
Nutrient Cycle of Coastal Ecosystems
Overview of Coastal Nutrient Cycling
Mangroves | Sand Dunes | Salt Marsh | Coral | |
Nutrient Store |
Mud /Sand |
Mud /Sand |
Mud / Sand |
Sea Water Rivers Entering On-Shore Currents |
Biomass Store |
Plants Animals |
Plants Animals |
Plants Animals |
Coral Polyps Seaweed Fish, Crustaceans & Invertebrates |
Litter |
Plants Animals |
Plants Animals |
Plants Animals |
Dead Coral Polyps Seaweed Fish, Crustaceans & Invertebrates |
Degrades In |
Water |
Water |
Water |
Sea water |
Transfers |
Water |
Land |
Water |
Tidal & Ocean Currents |
Exam Tip
Make sure you understand nutrient cycling in these ecosystems, particularly the difference between abiotic & biotic factors. You may be asked to identify one or both of them from a list.
Biotic Components of a Coral Reef
- A coral reef is a well-organized food web comprising of:
- Producers
- Consumers
- Scavengers
- Decomposers
- Producers in a coral reef include seaweed, seagrass, and phytoplankton. zooxanthellae are also producers that provide the nutrients from photosynthesis to coral
- Consumers are organisms that eat other organisms to gain energy. There are three main types of consumers in a food web: primary, secondary, and tertiary
- Primary consumers only eat producers - the green sea turtles graze on seagrass
- Secondary consumers eat primary consumers - stingrays, octopuses, squid, and larger fish for example
- Tertiary consumers, also called apex predators, are carnivores that do not prey upon themselves. These consumers help maintain the balance of the ecosystem - sharks, dolphins, tuna, barracuda, etc.
- Scavengers feed on dead and decaying plants and animals - crabs and lobsters scavenge for food
- Decomposers bring nutrients back into the ecosystem to support another cycle - examples include bacteria, sea cucumbers, and fungi
Abiotic Features of a Coral Reef
- Light: Corals need some sunlight to survive:
- Too little, then the zooxanthellae will not be able to photosynthesize and produce food for corals.
- Too much may cause corals to expel zooxanthellae, causing bleaching
- Depth: As corals need light, they are typically found at approximately 25 meters
- Water temperature: Corals thrive in the warm waters of the tropics. They prefer a temperature range of 23-25°C but will survive at lower and higher temperatures for short periods of time
- Salinity: Corals need salty water
- Air: Can survive out of water for very short periods of time
- Water: Corals need clean, clear water