Tropical coasts Flashcards
(23 cards)
What defines a tropical region?
It lies within 23 degrees latitude on either side of the equator.
What are the main interconnected habitats in a tropical seascape?
Land → mangroves → seagrasses → coral reef → offshore waters
Ecosystems ecologically linked and support diverse marine life
Why are coral reefs considered biodiversity hotspots?
They provide habitat structure, create ecological niches, and support fisheries, tourism, and coastal protection
Among most diverse ecosystems of earth
What are ecosystem engineers, and why are corals considered one?
Organisms that build or alter their environment significantly—corals build reef structures that support entire communities.
Where are coral reefs distributed geographically?
Within 30 degrees of latitude around the equator
Minimum average sea temperature of ~20°C
What is the Coral Triangle, and why is it significant?
A region in the Indo-Pacific with the highest coral biodiversity: 76% of coral species and 37% of coral reef fish species and 6/7 marine turtle species
What are the two main coral groups?
Hermatypic (reef-building, tropical) and ahermatypic (non-reef-building, worldwide)
Only hermatypic corals contribute to reef formation
What are major human threats to coral reefs?
Climate change, eutrophication, development, invasive species, and overfishing
Contribute to coral bleaching and habitat degradation = phase shifts
What symbiotic relationship is crucial to corals?
Corals host zooxanthellae (symbiotic algae) that help in photosynthesis and calcium carbonate production
What are the main types of coral reefs?
- Fringing reefs
- Barrier reefs
- Patch reefs
- Atoll
Fringing are coastal; barrier reefs are separated by lagoons; atolls rise from deep waters
What are common coral types?
Staghorn and table coral (Acropora), cabbage coral (Tubinaria), finger and hump coral (Porites), mushroom coral (Fungia)
How do macroalgae affect coral reefs?
They compete for space and light, can damage coral mechanically and chemically, and inhibit coral larvae settlement
What are crustose coralline algae known for?
Cementing and stabilizing reef structures.
What causes phase shifts on coral reefs?
Coral bleaching, storms, crown-of-thorns starfish, eutrophication
Can lead from coral-dominated to algae-dominated reefs
Why are herbivorous fish important on coral reefs?
They control algal growth, preventing it from outcompeting corals
Key to reef resiliance
What are parrotfish known for in reef systems?
Scraping surfaces, removing algae, and transporting sediment
Exposes new areas for coral settlement
What are mangroves?
Dicotyledonous woody shrubs that form dense coastal forests in tropical intertidal zones
54 true species found only in these habitats
What is convergent evolution in the context of mangroves?
Different species evolved similar traits to adapt to similar conditions, despite not sharing a close ancestor
Example of functional similarity
Name four types of aerial root adaptations in mangroves
- Buttress (Pelliciera)
- Knee (Bruguiera)
- Pencil (Avicennia/Sonneratia)
- Prop roots (Rhizophora).
Roots stabilise trees and provide oxygen
How do mangroves cope with high salinity?
Salt exclusion at roots (e.g., red mangrove) or salt excretion via glands (e.g., black and white mangroves)
Na+ and Cl⁻ stored in vacuoles
What are some benefits of mangroves to coastal ecosystems?
Soil stabilization, nutrient cycling, complex habitat structure, and nursery grounds for marine life
Support high primary productivity
Why are mangroves valuable nursery habitats?
They offer shelter, food, and protection for juvenile marine species
Support higher species richness
What are major threats to mangroves?
Natural: storms, tsunamis. Human: deforestation, aquaculture, pollution, urbanisation
Habitat loss can affect coastal stability and biodiversity.
