Coral spawn sensitivity

6 posts / 0 new
Last post
Dominiquest
Dominiquest's picture
Coral spawn sensitivity

I am working on a small hypothesis which involves the sensitivity of corals to varying climatic conditions and the transportation of spawn during and after the spawning season. Approximately how long does the planula take to change into a recruit? Does it depend on the availability of substratum or is it time bound?

g a
g a's picture
Hi Dominiquest

Hi Dominiquest

Planulae are ciliated larvae. the manner in which they under go metamorphosis is species specific.
It is also known that planulae of anthozoans, hydrozoans and several scyphozoans are substrate specific as they grow into polyps upon finding a hard surface only.

Dominiquest
Dominiquest's picture
So in that case do the

So in that case do the planulae stay the way they are until they find the substratum? Approximately how long would they last in this condition, provided that nutrients are available in the water? By nutrients I mean what ever makes up the feed of the planulae.

g a
g a's picture
Hi

Hi

I am not aware of the exact chronological clock in that regard but what i know for sure is that the planulae donot undego metamorphosis until they are attached to a suitable substratum. You can refer to any elementary zoology book for the details of the same.

reefSTA
reefSTA's picture
The planulae larvae can

The planulae larvae can generally be produced in two ways by corals, firstly those that are brooded internally and release as fully formed planulae. These can often be able to settle almost immediately, provided there is some suitable substrate. However, if there is no substrate it has been shown for at least some species that can survive in the plankton for weeks or months. The more common mode of reproduction in corals is to broadcast the eggs and sperm into the water during seasonal spawning periods. After fertilisation the embryo devlops into a planula larvae over  a couple of days and cannot settle during this period. For most broadcast spawning coral species the larvae become competent to settle  2-4 days after spawning. This depends a little on the species and also the seawater temperature. It is very common for species to require 3-4 days before a significant percentage of the larvae are able to setltle, but generally most would be able to settle within a week. Again this depends on the availability of a suitable substrate and if  no suitable place is available the larvae from broadcast spawning species can also survive for weeks or even months in the plankton. But I think on average  most dispersal will be during a period of 3-10  days after spawning. One other factor in broadcast spawners is that most species, except those in the genera Montipora and Porites, do not have symbiotic zooxanthellae  in the eggs, so they need to acquire them afterwards, usually once they have settled.

Dominiquest
Dominiquest's picture
So if these planulae are

So if these planulae are carried by the water, do they settle on any suitable substratum? By this I mean that if the water column is a little polluted, will they still settle or will they move on till they find clean water?