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 Different investment patterns

Death recruitment Aclonal Life History Sexual reproduction

Death recruitment Clonal Life History Fission Sexual reproduction

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 Extratentacular Can stay in place = growth Can detach and grow elsewhere = asexual reproduction

Asexual reproduction in corals - Budding

Asexual reproduction in corals - Fragmentation

Partial colony mortality Dead areas Three colonies but one genetic individual

Costs and Benefits of Fragmentation Costs -disrupt physiological function - possible decrease in fecundity - possible postponement of sexual reproduction Benefit - risk of genet mortality -spread over several colonies

Asexual reproduction in corals - Polyp Bailout Coral Budding

Sexual Patterns 1. Gonochoristic (dioecious)2. Hermaphroditic (monecious)

Development Patterns 1. Brooders2. Spawners -free-spawning -retain embryo

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 Size Growth rate

Strategies Revisited All life functions can be seen as competing with each other for energy 1. Growth rate and reproduction Time of year Growth rate or calcification rate Breeding season Pavona

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) 25-50% of colony biomass as planulae 50 – 180% of colony biomass as planulae Pavona

Strategies Revisited All life functions can be seen as competing with each other for energy 3. Allocation of energy (within reproduction) Across species Mean diameter (µm) Fecundity / year planulae eggs

Strategies Revisited All life functions can be seen as competing with each other for energy 4. Temporal variation in fecundity Time Size Brooders Spawners

Strategies Revisited All life functions can be seen as competing with each other for energy 4. Temporal variation in fecundity Age or size? Goniastrea Montastrea -complex interaction

Gametogenic cycles gametogenesis ovogenesis spermatogenesis spawn quiescence gametogenesis Time Correlated witha. Change in sea temperature b. Lunar/tidal cycles c. Photoperiod

Gametogenesis

Release of sperm and egg packets

Coral Spawning

Release of sperm and egg packets

Free spawning coral

Synchrony in spawning Sea temperature Tidal cycle Photoperiod

Synchrony in spawning Goniastrea - Low tide, late afternoon - Low tide, evening

Synchrony in spawning Caryophyllia -grind up male polyps -expose female polyps to extract -egg release by exposed females

Development Patterns 1. Brooders2. Spawners -effects on planula larva - 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

Planulae Sample and assess subtrate: prepare to settle Young primary polyp Asexual colony growth Broadcasters - external fertilization Zygote Planulae released from individual polyps Brooders - internal fertilization Summary