Final: Tropical reefs and their fishes Flashcards
distribution on globe
Less than 2% distribution across the globe
why so rare
Need stable and warm water temperatures usually around 21-29 C
Clean, clear water, shallow depths(<50 m)
Corals are colonial animals but only grow with help of endosymbiotic autotrophs called zooxanthellae
Zooxanthellae play role in coral’s production of CaCO3
environmental conditions required
Need stable and warm water temperatures usually around 21-29 C
Clean, clear water, shallow depths(<50 m)
zooxanthellae
-tiny algae
-endosymbiotic autotrophs (colonial animal)
cnidarian
Colonial cnidarians with endosymbiotic autotrophs
coral polyp
cnidarian
functional roles of fishes
plankton harvesting
turf algae removal
microalgae removal
sediment transport
detritus removal
observations about reef fish communities
Most reef fish are highly specialized
* complex adaptations to complex
environment, and competition
2. Species richness and pop’n densities
very high
3. Species composition varies among
reefs
4. Reef fish produce millions of pelagic
larvae
lottery
Steady rain of recruits but only lucky ones settle onto vacant space and survive, a random process
threats: climate change
can change water temp which kills coral
predation/disturbance
Plenty of recruits arrive to fill vacancies but intense subsequent mortality prevents saturation, therefore predation limits competition
recruitment limitation
Mortality of larvae so high reef never reaches saturation (never at K) and colonization varies with recruitment success (density, species composition in constant flux)
ocean acidification
The oceans absorb about 25% of the CO2 humans release into atmosphere every year
Initially scientists focused on the benefits of the oceans removing this greenhouses gas from the atmosphere
Acid dissolves coral skeletons 30% drop in ocean pH since industrial revolution, tipping point in 30 years
Consumption of carbonate ions impedes calcification
coral bleaching
prolonged warm water causes corals to expel aglaw
how to help save reef ecosystems
Be informed consumer- boycott wild-
harvested “live rock”, reef products,
fish, and seafood unless harvest is
sustainable
2. Support creation, maintenance of
Marine Protected Areas, parks and
reserves
3. Support conservation orgs
4. Practice “sustainable diving” and
snorkeling
5. Support reef-friendly businesses
(e.g., “green” cruise ships, eco-
resorts)
6. Learn more about coral reefs- and
educate others about their fragility
and value
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