Transcript Coral Reproduction

REPRODUCTION
IN
CORALS
Life history
-sequence of developmental stages
from birth to death
Growth, Reproduction, Senescence, Mortality
All of this activity takes energy - must be apportioned
Growth
Reproduction
Respiration
Feeding
Mate Seeking
Defense
Growth
Reproduction
Respiration
Feeding
Mate Seeking
Defense
Different investment
patterns
Aclonal Life History
recruitment
Sexual reproduction
Death
Clonal Life History
Sexual reproduction
recruitment
Fission
Fission
Fission
Death
Concept of the Individual in Corals
1. Morphological - Polyp (= ramet)
Concept of the Individual in Corals
2. Physiological - Groups of connected polyps
Concept of the Individual in Corals
3. Genetic - All polyps and colonies derived from the same zygote (Genet)
Asexual reproduction in corals - Budding
Intratentacular
Extratentacular
Asexual reproduction in corals - Budding
Intratentacular
Can stay in place = growth
Extratentacular
Can detach and grow elsewhere
= asexual reproduction
Asexual reproduction in corals - Budding
Asexual reproduction in corals - Fragmentation
Three colonies but one
genetic individual
Partial colony mortality
Dead areas
Costs and Benefits of Fragmentation
Benefit - risk of genet mortality
-spread over several colonies
Costs
-disrupt physiological function
- possible decrease in fecundity
- possible postponement of sexual reproduction
Asexual reproduction in corals - Polyp Bailout
Coral Budding
Sexual Patterns
1. Gonochoristic (dioecious)
2. Hermaphroditic (monecious)
Development Patterns
1. Brooders
-retain embryo
2. Spawners
-free-spawning
Development Patterns
Can these patterns be related to life history/structure/habitat?
1. Related to whether species is r- or K- selected?
X
2. Related to depth?
-shallow should brood, deeper should spawn
X
3. Related to the size and structure of the coral?
-small, branched corals should brood,
larger massive corals should spawn
X
4. Related to habitat stability?
-corals in predictable habitats should brood
?
Strategies Revisited
All life functions can be seen as competing with each
other for energy
1. Growth rate and reproduction
Growth rate
Size
Strategies Revisited
All life functions can be seen as competing with each
other for energy
1. Growth rate and reproduction
Growth rate
or calcification
rate
Pavona
Breeding season
Time of year
Strategies Revisited
All life functions can be seen as competing with each
other for energy
2. Polyp size
Strategies Revisited
All life functions can be seen as competing with each
other for energy
3. Allocation of energy (within reproduction)
Pavona
25-50% of colony biomass as planulae
50 – 180% of colony biomass as planulae
Strategies Revisited
All life functions can be seen as competing with each
other for energy
3. Allocation of energy (within reproduction)
Across species
planulae
eggs
Mean diameter
(µm)
Fecundity / year
Strategies Revisited
All life functions can be seen as competing with each
other for energy
4. Temporal variation in fecundity
Brooders
Size
Spawners
Time
Strategies Revisited
All life functions can be seen as competing with each
other for energy
4. Temporal variation in fecundity
Age or size?
Goniastrea
-complex interaction
Montastrea
Gametogenic cycles
gametogenesis
ovogenesis
spermatogenesis
spawn
quiescence
gametogenesis
Correlated with a. Change in sea temperature
b. Lunar/tidal cycles
c. Photoperiod
Time
Gametogenesis
Gametogenesis
Release of sperm and egg packets
Release of sperm and egg packets
Coral Spawning
Release of sperm and egg packets
Release of sperm and egg packets
Free spawning coral
Synchrony in spawning
Sea temperature
Tidal cycle
Photoperiod
Synchrony in spawning
- Low tide, late afternoon
Goniastrea
- Low tide, evening
Synchrony in spawning
-grind up male polyps
-expose female polyps to extract
Caryophyllia
-egg release by exposed females
Development Patterns
-effects on planula larva
1. Brooders
2. Spawners
- immediately competent
- lag time until competence
- larger
- smaller
- have all zooxanthellae
- must acquire zooxanthellae
Predation on spawned gametes
Larval Settlement
-success depends on ability to identify site for settlement and metamorphosis
Substrate type
Salinity (>32 ppt)
Illumination
Water motion
Sediment level
Chemical signals from
algae, biofilms,
conspecifics
Settlement & metamorphosis
Summary
Planulae
Sample and assess
subtrate: prepare to
settle
Young
primary
polyp
Planulae released
from individual
polyps
Zygote
Brooders internal
fertilization
Asexual
colony
growth
Broadcasters external fertilization