I work on a number of aspects of symbiosis between invertebrates and
algae. I am particularly interested in the metabolism of the partners,
and the ways in which they exchange organic nutrients.
In many associations, the translocation of photosynthetic products
from the algae to their host is controlled by the host animal, which
produces a "host release factor". This stimulates the algae to release
photosynthates. The targets of the release factor are specific,
in that only a sub-set of the soluble metabolites that are available
in the algae is exported to the host. We are purifying, characterising,
and studying the mode of action of the host release factor of the
widespread reef-building coral, Plesiastrea versipora. This
changes algal metabolism so that the translocated products are over-produced
and then released.
We recently discovered a photosynthetic inhibitor in P. versipora.
We are now purifying this inhibitor, and determing how it inhibits
photosynthesis, and how this affects the interactions between P.
versipora and its photosynthetic symbionts.
Although symbioses between sponges and macroalgae are common,
there has never been a detailed study of their ecophysiology or
biochemistry. We are studying the population dynamics, productivity,
physiology and biochemistry of a tropical symbiosis between a sponge,
Haliclona cymiformis, and a red seaweed, Ceratodictyon
spongiosum, in the field at One Tree Island (Great Barrier Reef).
This sponge affects the development of the red alga, so that its
morphology changes from a loose, tufty form (upper picture) to a
rigid, upright structure which seems to support the thin tissue
of the sponge (lower picture). We are studying the nature and mode
of action of the red algal morphogen produced by H. cymiformis.
Ceratodictyon spongiosum
Haliclona cymiformis
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