[Coral-List] Is DMS/DMSP a stress release factor in corals?

[shashank Keshavmurthy]

Dear Coral Researchers...
Greetings...
I was wondering what is the role of DMS/DMSP in
corals? Especially in Acropora sp.
Whenever I sample and work with particularly
Acropora sp. I get strong smell of DMS/DMSP.

Recent studies have shown that there is
production of
Dimethylsulfide(DMS)/Dimethylsulfoniopropionate
(DMSP) in corals under stress.  DMS is produced
increasingly by micro-algae in marine
environments and the factors controlling its
production are still poorly understood.  It is
believed that dinoflagellates are one of the
largest producers of DMS and high concentrations
of DMSP have been found in cultured
zooxanthellae.  
DMS is believed to serve as an osmolyte,
antipredation agent, has antibacterial activity
and as methyl donor in the synthesis of nitrogen
based metabolites.  And one of the main functions
of DMS is its role in the climate regulation.
It has been found that corals especially Acropora
sp. release large quantities of DMS during
stress.  My previous observations in Kavaratti
Atoll, Lakshadweep Islands, India showed that
Acropora formosa release high quantities of DMS
which was obvious by the strong smell everytime I
sampled this particular species during natural
stress and also in the corals subjected to TBT
stress.  Also to some extent the production was
observed in Porites lutea, which led to
preliminary studies of DMS/DMSP at the National
Institute of Oceanography, Goa, India.  My
observations were further supported by the paper
published during that year on the DMS in corals
and macro algae (Broadbent, A. D. et al.).
Recently I again came across the characteristic
smell of DMS/DMSP in Acropora hyacinthus and
Stlyopora pistillata sampled from corals reefs of
Shikoku, Japan.  Again it is that strong smell in
the samples which compelled me to ask the above
question weather DMS is a stress release factor. 

Simple observations can sometimes lead to better
understanding of the problem.  The samples that I
obtained after series of typhoons (August-October
2003), showed a strong smell of DMS (only in
Acropora hyacinthus).  My recent samples
(obtained in October 2003) again had a very
strong smell of DMS and this time it also
included Stylopora pistillata, though
comparatively very faint smell.
These observations and research of other workers
show that it is not just the temperature stress
that results in the production of DMS, but also
various other stressors play a role, though not
consistently in all corals. 
Why is it that the corals release DMS/DMSP?
　May be it is used as an antibacterial and
antigrazing substance when coral is in stress as
it is prone to bacterial attack.  DMS may also be
released as a result of cell lysis that may be
occurring due increased stress.  

It may be that production of DMS is completely a
normal phenomenon that was overlooked until now. 
Since DMS production may be an overflow
mechanism, a reaction of cell during unbalanced
growth, thereby making the cell better adapted to
the changing environmental conditions2.  It may
be also a way to accumulate nitrogen compatible
solutes and use it as a source of nitrogen during
nitrogen limitation.  The production of DMS/DMSP
is boon for the heterotrophic bacterial
communities in the coral reef ecosystem as it is
a source of Carbon and Sulfur.
The amount in which the DMS/DMSP is released is
not very less to be ignored.  Further study need
to be carried out to;
1. Understand the reason behind the DMS/DMSP
production both in zooxanthellae and subsequent
accumulation in the host. 
2. To understand what makes Acropora sp. to
produce considerably high quantities of DMS/DMSP,
and role of coral reefs in the global climate
regulation. 
3. If there is any relationship between the
chlorophyll pigments and DMS/DMSP.  If it is,
then we can easily quantify the production of DMS
by remote sensing and hence understand the role
played by coral reefs as biological climate
regulators.
Till that I will have to continue my encounter
with the strong smell of DMS/DMSP in Acropora
hyacinthus!!!!!!!!!

This was just a thought from my side.
Cheers!!!
shashank

=====
"the role of infinitely small in nature is infinitely large"-Louis Pasteur                

Keshavmurthy Shashank
Kochi University, Faculty of Agriculture
Lab. of AQUa. Environ. Sci. (LAQUES)
Otsu 200, Monobe, Nankoku-shi
783-8502, Kochi, Japan
alt. id: shashank at cc.kochi-u.ac.jp
phone: 81 090 8285 9012

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