Marine Ecology Flashcards
What are the three major types of tropical coastal ecosystems
Mangroves, seagrass meadows, and coral reefs
What two coastal habitats are important carbon sinks
Mangroves and seagrass meadows – they store large amounts of carbon in their biomass and soils
What makes coral reefs unique among the tropical coastal ecosystems
Extraordinary biodiversity, but vulnerable to overfishing, warming seas, and pollution
Why are many tropical ocean areas low in productivity
Due to the permanent thermocline, which prevents vertical mixing and nutrient return from deep water
What are hotspots of productivity in nutrient poor tropical oceans
Upwelling zones and specialised primary producer communities, like coral reefs
Where do mangroves grow
In coastal brackish or saline habitats
What genus do true mangroves belong to
Rhizophora (flowering plants adapted to marine conditions)
What adaptations so mangroves have for oxygen-poor soils
Pneumatophores and lenticels for gas exchange
How do mangroves deal with salt
Root exclusion and/or salt glands on leaves for excretion
What are seagrasses
The only marine angiosperms, successful in both temperate and tropical zones
What allows seagrasses to absorb nutrients from the sediment
They have true roots and a vascular system (unlike algae)
What’s the main species in temperate seagrass beds
Zostera marina (eelgrass)
What makes tropical seagrass beds important ecologically
High productivity and biodiversity, and nursery grounds for fish
How do seagrasses reproduce
Both vegetatively (rhizomes) and sexually (flowers/pollen/seeds)
How do seagrass beds interact with adjacent ecosystems
They trap sediment protecting reefs, and receive wave protection from nearby reefs
What did Van der Zee et al. (2016) show about habitat modifiers
Seagrass (primary) and burrowing crab (secondary) both enhanced habitat structure, increasing species richness and food web complexity as succession progressed
What is blue carbon
Carbon stored in coastal and marine ecosystems, especially in soils of wetlands like mangroves and seagrasses
Why aren’t coral reefs or phytoplankton considered blue carbon sinks
They do not provide long-term carbon sequestration like coastal wetlands do
How do wetlands keep carbon locked in the soil
Tidal inundation keeps soil wet/anoxic, slowing decomposition
Why are wetlands key to climate change mitigation
They have a limitless carbon sequestration capacity and can keep pace with sea-level rise
What are the two main coral reef regions
Indo-Pacific
Western Atlantic
What do coral reefs need to thrive
Clear, warm water (18–30°C)
High light, low turbidity, and low nutrients (oligotrophic)
How do coral reefs form
- Fringing reef on volcanic island
- Island subsides → barrier reef
- Island sinks below sea → atoll
What phylum and class do reef-building corals belong to
Cnidaria, class Anthozoa, order Scleractinia
