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REPRODUCTION IN CORALS. Life history -sequence of developmental stages from birth to death Growth, Reproduction, Senescence, Mortality.

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Presentation on theme: "REPRODUCTION IN CORALS. Life history -sequence of developmental stages from birth to death Growth, Reproduction, Senescence, Mortality."— Presentation transcript:

1 REPRODUCTION IN CORALS

2 Life history -sequence of developmental stages from birth to death Growth, Reproduction, Senescence, Mortality

3 All of this activity takes energy - must be apportioned Different investment patterns

4 Death recruitment Aclonal Life History Sexual reproduction

5 Death recruitment Clonal Life History Fission Sexual reproduction

6 Concept of the Individual in Corals 1. Morphological - Polyp (= ramet)

7 Concept of the Individual in Corals 2. Physiological - Groups of connected polyps

8 Concept of the Individual in Corals 3. Genetic - All polyps and colonies derived from the same zygote (Genet)

9 Asexual reproduction in corals - Budding Intratentacular Extratentacular

10 Asexual reproduction in corals - Budding Intratentacular Extratentacular Can stay in place = growth Can detach and grow elsewhere = asexual reproduction

11 Asexual reproduction in corals - Budding

12 Asexual reproduction in corals - Fragmentation

13 Partial colony mortality Dead areas Three colonies but one genetic individual

14 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

15 Asexual reproduction in corals - Polyp Bailout Coral Budding

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

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

18 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 ?

19 Strategies Revisited All life functions can be seen as competing with each other for energy 1. Growth rate and reproduction Size Growth rate

20 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

21 Strategies Revisited All life functions can be seen as competing with each other for energy 2. Polyp size

22 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

23 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

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

25 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

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

27 Gametogenesis

28

29 Release of sperm and egg packets

30 Coral Spawning

31 Release of sperm and egg packets

32

33 Free spawning coral

34 Synchrony in spawning Sea temperature Tidal cycle Photoperiod

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

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

37

38 Development Patterns 1. Brooders2. Spawners -effects on planula larva - immediately competent- lag time until competence - larger- smaller - have all zooxanthellae- must acquire zooxanthellae

39 Predation on spawned gametes

40 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

41 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


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