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Deep Coral Physiology

Most of the world's reefs lie below a depth of 50 meters, and normally continue to 150 meters, particularly in the Indo-Pacific realm.  This means that most of the reef has never been thoroughly investigated due to technological limitations.  Recently, due to advancements in SCUBA technology (namely, more accessible and affordable TRIMIX and rebreather systems)   it has become possible to study the coral reefs at these depths in Eilat.  Because this is an entirely new research area, there is a substantial amount of work underway analyzing and understanding the basic physiology of the organisms living in those deep reefs.

Our findings include the description of a totally new photosynthetic pathway and organization.  Deep corals and also macroalgae seem to have an extremely low photosynthetic rate and an almost complete absence of PS1 functional response.  In the case of corals, this makes this symbiosis questionable in terms of the benefit of the hosts.  We believe that the host is actually contributing carbohydrates to the algal symbionts.  If this is true, it redefines the nature of the symbiosis between corals and their algal symbionts.

Surprisingly, the photosynthetic organisms that dwell at those depths have not lost their ability to produce high rates of photosynthesis at high light intensities, and do not show the characteristic non-photochemical quenching evident from corals and macro algae living in shallower depths.

We are currently in the final stages of fortifying and retesting these results using different techniques prior to publishing.  Because of the novelty of this research, in the process of analysis we have developed new techniques and machinery that enable us to acquire data.  For example, we have now a membrane inlet mass spectrometer that is linked to both a fast repetition rate fluorometer and a pulse-amplitude modulated fluorometer, especially modified for this purpose.  I believe that this is a promising new research direction that will be the foundation for a wide range of studies in the future.