The nighttime bongo tows (see The Scoop from the Zooplankton Nets) provide a wealth of organisms for the biologists aboard the NOAA Ship Ronald H. Brown to study. From krill and crabs to copepods and pteropods, researchers aboard the Brown are interested in one unifying question: How will ocean acidification change the distribution and abundance of these organisms? We seek to answer this question because these marine organisms have very few options to combat changes in their environment; they can either move to a more favorable environment or adapt to the new conditions.
Changing distributions and abundances of phytoplankton and zooplankton can provide evidence that an organism is moving from one environment to another; however, the ability to adapt to a new environment can be more challenging to detect. One method we are employing aboard the Brown involves looking at how the organism is using its molecular machinery – its genes – to adapt to these changes. All organisms have genes that turn on in response to stress; many of these genes fall into a category known as the cellular stress response genes. By measuring the activity of these cellular stress response genes, we can approximate the level of stress that different environments have on an organism.
Using this information, we are specifically interested in how pteropods respond to both future ocean acidification (see Nina Bednarsek’s earlier post) and present-day pH variability. To do this, we are collecting pteropods from a variety of different environmental conditions and will be measuring changes in gene activity. By looking at what genes pteropods have turned on or turned off, we can determine the level of stress created by the environment they were collected from. This work, of course, is only possible thanks to the group of oceanographers aboard the Brown who work tirelessly to measure the chemical composition of samples collected at each sampling station, including pH, salinity, temperature, alkalinity, and oxygen content. These data will help us interpret the molecular signs of stress in contemporary populations, and further understand how pteropods will cope with ocean acidification in the future.
Author: Kevin Johnson