The Not-So-Secret Sex Lives of Scleractinian Corals

1. The Not-So-Secret Sex Lives ofScleractinian Corals

2. Asexual Reproduction Modes of asexual reproduction Sexual Reproduction sexuality broadcast spawning versus brooding reproductive effort and fecundity timing and synchrony gamete buoyancy and dispersal during spawning fertilization & early development planula dispersal and settlement

3. Asexual Reproduction colony growth versus formation of new colonies

4. Intratentacular (fission) Extratentacular (budding) Types of Polyp Budding

5. Fission Polyp within calyx

6. Budding Polyp within calyx

7. Modes of Asexual Reproduction accidental fragmentation nonaccidental fragmentation partial colony mortality asexual planulae polyp bail-out

8. Wave Damage AccidentalFragmentation

9. Accidental Fragmentation Turtle Damage of Porites compressa in Kane‘ohe Bay

10. Nonaccidental Fragmentation Radial Division in Cycloseris fragilis

11. Nonaccidental Fragmentation anthocyathus Transverse Division in Fungia scutaria anthocaulus

12. Nonaccidental Fragmentation stalk regenerates new disk Transverse Division in Fungia scutaria

13. Partial Colony Mortality Porites compressa with live branch ends, but dead towards the bases

14. Partial Colony Mortality Parricidal Budding in Fungia scutaria The Phoenix Effect

15. Anthocaulus-like Stalk Grown from a Septal Fragment in Fungia scutaria

16. Tissue Regeneration inFungia scutaria Before Regeneration After Regeneration

17. Partial Colony Mortality The Phoenix Effect in Porites compressa Cut surface of a broken finger showing living tissue beneath the surface of the skeleton P. Jokiel Normal colony next to a colony exposed to freshwater

18. Asexual Planula D. Gulkol

19. Polyp Bail-Out D. Gulko

20. planula larvae zygote egg sperm Sexual Reproduction

21. Sexual Reproduction • Hermaphroditic vs gonochoric • Broadcast spawning vs brooding

22. Hermaphroditism versus Gonochorism Hermaphroditism both sexes in the same individuals Gonochorism sexes are separate Acropora sp., a hermaphoditic coral Fungia scutaria, a gonochoric coral eggs egg cloud sperm packet

23. Location of Gonads in Coral Polyps Ovaries Testes eggs sperm tails nucleus sperm heads

24. Types of Hermaphroditism • Simultaneous Hermaphrodites • male and female gametes mature at the same time in the same individual or colony • Sequential Hermaphrodites • one sex appears first followed by the other sex at a later time

25. Adaptive Considerations • Gonochorism and sequential hermaphroditism ensures outcrossing and maintains genetic diversity in the population. • Simultaneous hermaphroditism may result in inbreeding and a higher frequency of genetic disorders being manifested. • However, “selfing” may be advantageous when the probability of finding an individual of the opposite sex to mate with is low. • Most studies suggest that their are barriers to self-fertilization in corals.

26. Hermaphroditic Corals in Hawai‘i Acropora cytheria Montipora capitata Montipora flabellata Montipora patula Leptastrea purpurea Cyphastrea ocellina

27. Gonochoric Corals in Hawai‘i Pavona duerdeni Pavona varians Cycloseris vaughani Fungia scutaria Pocillopora damicornis Pocillopora meandrina Pocillopora eydouxi Porites compressa Porites lobata Tubastrea coccinea

28. Brooding eggs develop to planula stage in gastrovascular cavity of parent polyp Broadcast Spawning eggs and sperm are shed into the water column where fertilization and development occurs Brooding Versus Broadcast Spawning D. Gulko released gametes planula in polyp Pocillopora damicornis, a brooder broadcast spawner

29. Adaptive Considerations • Broodingtypically produces planula with the immediate capability to settle out after planulation occurs. • Broadcastingrequires developing embryos and planula to spend substantial time in the plankton before settlement can occur.

30. Adaptive Considerations • Broodingrequires a substantial reproductive cost on the parent in order to successfully rear on planula. • Broadcastspawning imposes a lower per-egg reproductive cost.

31. Adaptive Considerations • Brooded planula have a relatively higher probability of settlement and recruitment success. • While many gametes are wasted during broadcast spawning, the shear numbers of gametes released ensures that a few eggs will be fertilized, develop to planulae, and settle out as corals.

32. Brooding Corals in Hawai‘i Cyphastrea ocellina Pocillopora damicornis Tubastrea coccinea

33. Broadcast Spawning Corals in Hawai‘i Cycloseris vaughani Fungia scutaria Pocillopora edouxi Pocillopora meandrina Porites compressa Porites lobata Acropora cytheria Montipora capitata Montipora flabellata Montipora patula Pavona duerdeni Pavona varians Leptatrea pupurea

34. Reproductive Effort and Fecundity • Reproductive Effort • the energy invested into reproduction • Fecundity • the number of eggs a female produces

35. Reproductive Effort and Fecundity Adaptive Considerations • many small eggs versus few large eggs • brooding versus broadcast spawning • number of eggs per polyp • number of eggs per colony • spatial variation across a colony • number of spawning events per year • size/age at first reproduction • reproductive senescence • spatial variation across a population

36. Environmental Stresses Yielding Lower Fecundity in Corals • turbidity & sedimentation • high temperature • low salinity • aerial exposure at low tide • low irradiance • lack of uv light • mechanical damage • intraspecific competition • oil & fuel oil pollution • eutrophication

37. Zooxanthellae Incorporation into Eggs Direct Transmission Montipora capitata Indirect Transmission Fungia scutaria

38. Timing and Synchrony P. Jokiel Monthly periodicity in planula release (planulation) by Pocillorpora damicornis.

39. Reproductive Cycles Observed Seasonal (annual) Lunar (monthly) Day/Night

40. Advantages to Synchronized Spawning • maximizes chance of encounter between sperm & egg • maximizes outcrossing in self-fertile hermaphrodites • minimizes predation by swamping predators • maximizes successful recruitment within natal reef • maximizes dispersal beyond natal reef

41. Proximate Factors Synchronizing Spawning in Corals • Possible Seasonal Cycles Involved • seasonal temperature changes • seasonal changes in day length • seasonal changes in irradiance • seasonal changes in wind & current patterns • seasonal changes rainfall & runoff • latitudinal differences • opposite hemispheres • higher latitudes tend to exhibit shorter breeding season

42. Vernal equinox March 21 Sun vertical at equator Northern Hemisphere Names Winter solstice Dec. 22 Sun vertical at 23.5oS Winter solstice Dec. 22 Sun vertical at 23.5oS Summer solstice June 21 Sun vertical at 23.5oN Autumnal equinox Sep. 23 Sun vertical at equator

43. Earth further from sun Earth closer to sun

44. polar temperate tropic temperate polar Isotherms 60o 30o 0o 30o 60o Lines of equal temperature

45. Sea Surface Temperature

46. Surface temperature

47. Wind-driven surface currents

48. Proximate Factors Synchronizing Spawning in Corals • Possible Lunar Cycles Involved • Lunar light intensities related to lunar phases • May also be correlated spring-neap tide cycles

49. Tides

50. Tides are generated by: • Gravitational pull of the moon and sun • Centripetal force of the rotating Earth