The setting stage of a Montastraea coral. Coral bundles
swell inside the polyps as they move upward. This stage lasts about
20 minutes. Photo by Raphael Williams.
Spawning of coral bundles from a Montastraea coral. Bundles
are released almost silmutaneously across the entire coral head,
and float up to the surface where they break apart. |
Broadcast spawning organisms depend on water motion to bring sperm
and eggs together. Diffusion models of gamete mixing can give insight
into spawning behavior and patterns of fertilization success. Some
taxa, such as sea urchins, emit gametes over a period of time in
a plume, a process for which theoretical models have been developed
and verified experimentally in marine systems. However, analogous
models for broadcast spawners who release gametes in an explosive
puff have not been applied to natural systems.
I have been working with my advisor, Don Levitan, on a model of
turbulent diffusion from a point source, which is time dependent
as sperm rapidly diffuse from the source. We use the model to estimate
how sperm diffuse from gamete bundles, and how gamete bundles diffuse
from the coral, Montastraea franksi. Combining these models
allows us to examine the resulting sperm cloud from a single coral
head as a function of time, and predicted sperm concentrations are
within those observed during a spawning event.
The parameters of the model were easily established by videotaping
the diffusion of materials in the field, and using these vidoes
to calculate diffusion coefficients. |
