Coral Reef - Ecological Interactions Flashcards
how do corals reproduce?
brooding and spawning
what is brooding?
internal fertilization - retains egg, planula larva is released
what is spawning?
release packets of eggs and sperm, fertilization is external - both separate sexes and hermaphroditic species exist
- shoots up into enviro and floats into a column
what is used to determine when to spawn?
season - spring or early fall
moonlight - evening and slack tide -> full moon triggers spawning, tides affect the moon, slack tide: brief period between tidal flows
smell - chemicals - pheromones
weather - low wave action
why do corals start spawning at different times?
lessen the competition
when does sperm lose its viability?
within 30 min of spawning - prevents hybrids
what types of corals can form a hybrid?
montastraea annularis and montastraea franksi
what is darwin’s paradox?
highly productive but low in nutrients
where do corals get nutrients from?
- algal symbionts
- recycling nutrients
- animals feed and excrere
- land plants and birds on atoll
- algae of reef flat
- upwelling of deep water
where is diversity the greatest?
indo pacific more than atlantic
why are there more habitats?
- competition: leads to specialized adaptations, branch out niches so there is less competition
- lottery: fish are not specialized, local success depends on what is available, what they acquire in order to succeed
- predation-disturbance: disturbance keeps fish pop low, competition not an issue, adds balance, no speecies can overtake the reef
- recruitment limitation hypothesis: larval supply low - adult pop reflects differences in larval supply
what is key to keeping algal growth in check?
grazing
what animal grazes more selectively than sea urchins?
fish
what fish species can let too much algae grow?
damsel fishes
what are the challenges for coral reefs?
- crown of thorns starfish “plagues” - digest large areas of reef - overtake the reef, predate and digest reefs
- episodic
- few predators
what causes bleaching?
- increased temp
- bacterial infection
- UV
- bleaching reduces immunity and food meaning there is a higher chance of disease
- expel zooxanthellae when they die from stress
what happened in 2002?
seawater temp reached highest
54% bleached and of the 54 -> 25% bleached
what is protective in zooxanthellae and coral tissue?
fluorescent pigments
what are multi-cultures?
species are acclimated to diff light levels
- diff corals have diff tolerances to bleaching
- variability in bleaching is due to diff species of algae in tissue
- spit out algae that are dying so tolerances change
what dissipates excess energy at benign wavelengths?
FPs
- diffuse harmful light at less harmful wavelengths
- mostly blue
what is pocilloporins?
- pigment in coral tissue
- homologous to GFP - luciferins
- do not luminesce
- diffuse harmful light
what does bleaching do to algae?
allow exchange of algae with diff FPs
- by bleaching and removing one type of zooxanthellae can coral take up another that works better at a diff temp
-> transplantation of coral colonies from shallow to deep and deep to shallow showed a change in algal community
where does carbonate ions steal calcium from?
shells
what are the conservation problems for reefs?
- low gamete density -> too few corals result in too few gametes - Allee effect, leads to success of brooders, low density means low reproduction
- disease -> pathogens weaken coral’s resistance to increased water temp
- shifting ecological balance -> predation, Diadema and Acanthaster
- eutrophication (increased nutrients) - upsets the balance, algae covers the coral meaning no photosynthesis and death
