> For the complete documentation index, see [llms.txt](https://taylor-lindsay.gitbook.io/tl-comps/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://taylor-lindsay.gitbook.io/tl-comps/2.-coral-biology/2.3-growth-and-reproduction.md). # 2.3 Growth & Reproduction ## Process of Reef Growth #### [Asexual budding](https://www.engineeringfordiscovery.org/how-do-corals-reproduce/) * Growth is affected by light intensity, water motion, depth, turbidity, day length, water temp, plankton concentration, predation, competition #### Fragmentation * storms and waves can commonly break coral colonies, causing genetically identical copies of a colony * often contributes to single-species domination of an area * rapid recolonization after a disturbance #### [Polyp Bailout ](https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.7740) #### Skeletal growth * growth rate determined by skeleton density * Average growth 1mm upward and 8mm horizontally per year (marine life book) * depends on balance of deposition and removal of CaCO3 * contributions form calcareous algae, colonial hydrozoans, skeletons of crustaceans, bryozoans, foraminifera, mollusks, echinoderms. * loss of CaCO3 can be caused by grazing/scraping urchins & fish, or etchers (bacteria, fungi, algae) that penetrate skeletons. Infaunal organisms (sponges, bivalves, worms) bore holes into skeletons. ## Sexual Reproduction * strategy linked to taxonomy * Dioecious - only producing male or female gametes * hermaphroditic - possessing both male and female sex organs #### Brooders * eggs remain in gastrovascular cavity where they are fertilized by motile sperm cells. developing zygotes are eventually released to settle nearby * commonly small-polyped species #### Spawners * millions of gametes released into water column for external fertilization * commonly large-polyped species #### Mass spawning events * induced by specific dark periods & the cycle of the moon * seasonality driven by temperatures * multi-speceis spawning may satiate predators by overwhelming them with food #### Larvae & recruitment * planula larvae - at first they swim towards brighter light (stay at surface where currents can facilitate dispersal), then after some development they swim away from light to settle on sea floor * Single-polyp recruits metamorphose into a juveline byt developing a CaCO3 skeleton, mouth and tentacles * Develop to maturity in 7-10 years ## References See [Morphology](/tl-comps/2.-coral-biology/2.4-morphology.md) section for all growth papers #### Harriott 1983 Reproductive ecology of four scleractinian species. Describes patterns of coral reproduction. Histology.