Gareth here. Welcome back to the Charismatic Microfauna Blog. Today our team set sail on the Scripps Institution of Oceanography’s Research Vessel New Horizon for a 25-day cruise to the northeast Pacific. This is the second cruise in our Ocean Acidification Pteropod Study (OAPS), in which we’re trying to understand how pteropods, a group of shell-forming plankton also known as sea butterflies, will respond to ocean acidification — the process by which the ocean is becoming more acidic as a consequence of the oceans absorbing excess CO2 released into the atmosphere through the burning of fossil fuels.

The OAPS logo (designed by Peter Wiebe)

Last year our inter-disciplinary team of biologists, chemists, and engineers conducted a cruise between the latitudes of 35N and 50N in the northwest Atlantic (check out last year’s posts!), sampling pteropods and other plankton with nets, sonar, and video camera systems, at the same time as we measured the chemistry of the water column they inhabited.

This year we’ll be doing the same kind of sampling but now in the northeast Pacific, where the ocean’s chemistry is very different. Global patterns of flow in the deep waters that fill the ocean basins lead to waters in the Pacific being much more acidic than in the Atlantic (more on this in a later post). We are capitalizing on these differences between the oceans as what we call a ‘natural experiment’ — unlike in a laboratory experiment where we can manipulate the conditions experienced by lab animals, manipulating conditions in the ocean is much harder. Biologists therefore often look for cases where nature provides different kinds of conditions in order to compare how animals respond. By comparing how pteropods respond to the seawater chemistry of the Pacific relative to the Atlantic, and at different latitudes within each of those oceans, we hope to gain some insight into how pteropods might respond to the changing chemistry of the ocean predicted for coming decades.

Right now we’ve made a course for the starting point of our survey at 50N 150W, which is about 675 nautical miles (about 776 regular miles) due south of Anchorage, Alaska. From there we’ll run our survey towards the southeast, ultimately ending at 35N 135W and heading in to San Diego where our cruise will end on September 2. It will take us 5 days to cover the 1105 nautical miles to the transect’s starting point, giving us lots of time to get the instruments ready and overcome any seasickness.

Over the next few weeks we’ll be posting about pteropods and marine ecology, chemistry and ocean acidification, and life at sea generally, along with plenty of photographs and hopefully some video. Tune back in soon!