JC36: Geology & biology of the Whittard Canyon


 JC36



Cruise diary

4 July 2009
Location: NE Atlantic

Nathan writes:

A week without a winch can last a lifetime at sea, but it allowed for some valuable downtime in which essential repairs and maintenance could be carried out on the ever-improving ROV ISIS.

With the eyes of everyone onboard finally removed from the distinctly alien seafloor 3500 m beneath the ship, there was plenty of time that could now be spent in the lab investigating the delights of the deep-sea in different ways. To some of us here on the James Cook this specifically meant amphipods....

Amphipods are the piranhas of the deep-sea. They are small shrimp like organisms that can smell a decomposing animal from kilometers away and rapidly muster, in the thousands, around any potential food source. Amphipods will eat furiously until only the bones are left. Our amphipods, were collected earlier on JC36 using the surprisingly named ‘amphipod trap’.

The amphipod trap is a baited box with a mesh opening that allows the amphipods to enter but not exit. Once the trap and its bounty are collected from the surface, (the trap can be released with a signal so that it rises from the seafloor) these swarming animals can be easily maintained as long as kept at deep-sea temperatures (< 5 °C) and this makes them perfect for study our onboard lab.

In order to investigate how different species are found more/less often depending on the depth of the seafloor, some of the collected amphipods were subjected to a range of temperatures and pressures. As pressure increases constantly with depth we can mimic different depths by simulating the pressure changes in our lab.

As we change the environment of our amphipods, we recorded the rate at which these organisms were consuming oxygen. The rate of oxygen consumption by each amphipod can be used as an indicator of how healthy they are and can give crucial insights into the environmental conditions to which the species are suited. We are using this knowledge to help determine the abundance of the species throughout our oceans and how this may be affected by global temperature changes.

Amphipod!

The amphipod trap


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