Interactions in Marine Ecosystems
Chapter 3: Interactions in Marine Ecosystems
3.1 Interactions
Ecological interactions describe relationships between organisms in a community.
Symbiosis: Close relationships between different species.
Relationship | Description | Example |
|---|---|---|
Mutualism | Both species benefit | Clownfish and sea anemone |
Commensalism | One benefits, other unaffected | Barnacles on whales |
Parasitism | One benefits, other is harmed | Isopod on fish |
3.2 Feeding Relationships
Producers: Autotrophs that make their own food, forming the base of the food web.
Photosynthesis: Uses sunlight, , and to make food (e.g., algae, plants).
Chemosynthesis: Uses chemical energy (from compounds like hydrogen sulfide) to make food (e.g., bacteria near deep-sea vents).
Consumers: Heterotrophs that get energy by eating others.
Trophic Levels:
Primary (Herbivores: eat producers)
Secondary (Carnivores/Omnivores: eat primary consumers)
Tertiary (Eat secondary consumers)
Quaternary (Top carnivores)
Only about of energy transfers to the next trophic level.
Decomposers: Break down dead material, recycling nutrients.
Predation: One organism (predator) kills and eats another (prey). It helps balance populations (e.g., starfish controlling mussel populations).
Food chains (linear energy flow) vs. food webs (complex network of feeding relationships).
3.3 Nutrient Cycles
Nutrient cycles (e.g., carbon, nitrogen, phosphorus) are vital for life, moving elements through ecosystems.
Nutrients exist as ions, gases, or in sediments.
Biotic Phase: Nutrients move through living organisms via feeding.
Abiotic Phase: Nutrients are stored in non-living parts and returned to producers after decomposition.
Key Nutrients and Roles:
Nitrogen: Essential for proteins and DNA.
Carbon: Base of all organic compounds.
Phosphorus: Used in bones, DNA, and energy transfer (ATP).
Calcium: Forms bones and shells ().
Phytoplankton are crucial for the carbon cycle, absorbing and transporting it to ocean sediments (biological pump).