Written by Rosanna Milligan
It’s the end of another successful cruise and we’ve collected thousands of animals and taken hundreds of physical and chemical measurements across the northern Gulf of Mexico. My job is now to take these data, integrate them with the data from our previous research cruises, and analyze them all to try to find patterns in them that will help us understand how the deep pelagic fish communities are structured.
Understanding how animals are distributed through different environments is one of the key questions in ecology, because the answers can tell us important information about which areas might be particularly valuable. This might be because they contain particularly high biodiversity and are important to conserve, or they might be areas that might contain particularly high abundances of animals that we might want to target for fisheries or drug development for example.
While it’s easy to imagine different terrestrial environments, like deserts, forests or mountain ranges, it’s much harder to imagine what the different environments that might exist in the open oceans are, because, frankly, one patch of seawater looks much the same as any other at first glance. But, when we start looking with scientific instruments like CTDs, or using satellite imagery, we can start to see how the oceans are structured by gradients and boundaries in the physical and chemical properties of the oceans like temperature, salinity or water currents. However, we still don’t really understand is how much this environmental variability influences the animals that live in the deep pelagic oceans. Do they care about different conditions or are they happy to live anywhere? Are they just pushed around randomly by water currents or do they actively swim against them to stay in the best locations?
CTD Instrument used to measure the physical properties of water and to collect water samples from different depths.
Our work with the DEEPEND project is starting to disentangle some of these ideas. For example, we’ve been working hard to figure out how to identify different water masses in the Gulf of Mexico in an ecologically-meaningful way, and separate out how and why different water types affect different deep-sea animals and their distribution patterns. We’re working with teams of geneticists, chemists and oceanographers too, to match up all the different research strands into a coherent story. All of this will be really important in understanding how resilient or vulnerable different organisms might be to human impacts in the Gulf of Mexico, in case something like the Deepwater Horizon disaster ever happens again.
So all the work we do at sea is really just scratching the surface of the work we do when we get back. We’ve got lots more work to do and many more questions to answer!