On the hunt for elusive calcifying zooplankton … Victoria Peck , January 14 , 2013
Today ’ s plankton catch – on some days the bucket is swarming with krill and other plankton but today it was almost empty . @ Vicky Peck
On a non-bioassay day onboard the cruise , scientific deployments begin at 05.15 with the bongo nets . These twin nets , made of a fine nylon mesh are lowered down to 200 m beneath the sea surface and hauled vertically through the upper ocean catching anything that doesn ’ t have the ability or foresight to swim out of its way … i . e . plankton and the odd hapless fish . To investigate the potential consequences of ocean acidification on zooplankton , we are primarily interested in the calcifiers , the plankton that make their shells from calcium carbonate , namely foraminifera and pteropods – see images . As well as observing the condition of their shells in the their natural environment , we will also incubate certain species in water manipulated to simulate water chemistry under future pCO2 .
As Toby reported of our ‘ catch ’ at Station 1 , we recovered more pteropods than I could have ever dreamt for , unfortunately , since we were fresh out of the Falkland ’ s and north of the polar front with temperatures in the heady heights of 6 C , they were not the polar species we were looking for . Since passing the polar front and the notable drop in sea and air temperature the pteropods have become somewhat elusive . A handful , well , a micropipetteful , of the polar species Helicina limacina were caught yesterday morning , but were too few to be added to the bioassay experiment . Foraminifera on the other hand were massively abundant , apparently feeding on the abundant phytoplankton community dominated by siliceous diatoms .
19