Corals are sessile animals, but their larvae make active habitat selection choices that can determine their future competition, growth, and survival to adulthood. These processes that determine the success of newly-settled corals can have strong impacts on coral reef communities. I study how coral larvae select settlement habitats, and how these choices affect their future success.

To study how coral larvae select habitats we first have to collect coral gametes and raise them in the lab. We do this by "tenting" corals (shown on the right) just before they spawn, which happens once per year. Released coral gametes float to the top of the tent and into a collection cup. We collect gametes from multiple corals and cross fertilize them on the boat. After fertilization, embryos develop into planulae over several days, and planulae begin to swim after about a week. We can then use planulae in experiments!

A tented colony of the mountainous star coral, Orbicella faveolata, releasing gametes during coral spawning in the Florida Keys.

The lumpy blobs are developing embryos, the smooth spheres are unfertilized eggs.

Raising one million coral babies becomes a full time job

Using a series of settlement experiments I showed how benthic communities influence whether or not and where coral larvae settle. My work suggests that coral larvae make complex settlement choices at the scale of millimeters (Speare et al. 2023, MEPS). Additionally, I have investigated how  sediment trapped in algal turfs, which is commonly found on degraded coral reefs, can strongly suppress coral settlement rates ​​(Speare et al. 2019, ​Marine Pollution Bulletin).

Experimental chambers for a coral settlement experiment in the wet lab.