[Coral-List] Coral reproduction questions

[Sangeeta Mangubhai]

Dear Colleagues,

I am looking at spawning patterns in Kenyan corals focusing on the
genera Acropora, Platygyra and Echinopora. I collect coral tissue samples
from tagged colonies in the field and spawning is inferred from the
disappearance of mature gametes from sequential samples. I am doing
dissections on my samples (not histology) to collect data on the size of
gametes as a means of documenting gametogenic cycles in 5 species. I have a
couple of 'issues' that have come up that I would like to share to see how
others have addressed these.

1) In some of my samples I am finding that the male spermaries have
disappeared, but there are still large strings of ripe eggs throughout the
sample. Have others seen this? Is this an example of partial spawning or
some type of 'premature spawning' as a result of stress? My experience with
premature spawning is that both the eggs and spermaries are released in a
bundle under stress, rather than just the spermaries or just the eggs.
Alternatively, the spermaries could have become re-absorbed by the coral due
to stress - has anyone documented this in similar or other genera/species?

2) When using dissections as a means of documenting spawning patterns
(rather than in situ observations) the difficult issue is how to confirm
that 'partial spawning' has occurred. I have a number of colonies of
Acropora spp., Platygyra daedalea and P. sinensis that appear to have
partially spawned. I would be interested in emailing with others who have
tried to address this issue to share ideas.

Regards

Sangeeta Mangubhai
____________________________
Sangeeta Mangubhai
P.O. Box 10135
Bamburi 80101
Mombasa
KENYA
Tel/Fax: +254 (41) 5486 473 (w)
Mobile: 0733 698 771
smangubhai at africaonline.co.ke