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Research Voyages

Voyage to the Gulf of Carpentaria

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REPORT 5 - Seeing sea shells

Sunset over the Gulf of Carpentaria.

Part of the science team enjoys a good laugh while in transit to the first sampling station.

Frigatebirds look for opportunities.

A varied catch. These larger creatures are supported by tiny plants and animals that live on the sea floor.

One of these isopods, which measure about one centimetre in length, bit the author and made him bleed.

Tom Okey notes patterns in sea-floor shell debris that may reflect habitat disturbance

If you are fortunate enough to have spent time at sea, you might have noticed that its texture and appearance changes constantly. Change is the enduring rule of the sea, but if you have the patience for observation, you will find that patterns begin to emerge.

Since embarking from Cairns a fortnight ago, our research voyage to the Gulf of Carpentaria on the RV Southern Surveyor has become a voyage of true discovery.

The Gulf of Carpentaria contains a variety of sea-floor habitats, and we are finding that the assemblage of organisms in any given place varies strongly according to that habitat. This should not surprise an ecologist, but the empty space of this gulf as seen on most maps gives one the misleading impression that the floor of this shallow sea is featureless.

One conspicuous pattern we are finding is that the amount of shell debris (from clams and other seafloor animals) varies among different types of soft bottoms, possibly reflecting differences in the types of disturbance that the areas experience.

I suggested a "softening bottoms" hypothesis, and this triggered some very good jokes, usually related to how good the meals are on the Southern Surveyor. But joking aside, this triggered alternative hypotheses, debate, and excitement among the science team members and the ship's crew (many of whom are keen observers of the sea).

A plethora of life surrounds us every day, including abundant schools of bonito or tuna chasing smaller fish to the surface, where seabirds such as terns and boobies can catch them. But frigatebirds, the pirates of tropical ocean skies, are often overhead and ready to steal hard-earned meals. Dolphins and sharks, and even sea snakes and other animals, partake in this ongoing feast in their own special ways.

These food webs are supported by phytoplankton and zooplankton, but they are also supported by tiny plants and animals that live on the sea floor. One of our goals is to try to understand just how important this "benthic" component is to such food webs.

We have difficult tasks ahead of us, but the growing excitement is palpable and the Southern Surveyor voyage has provided the time and the facility for us to begin to understand how this special ecosystem functions. If you ask me what I think, it is that our journey has just begun.

About Tom Okey
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Updated: 29/03/07