The Nansen is currently researching microplastics and the neuston, the organisms and inorganic particles floating and living in the surface layers of the seas. Although plastic particles spread throughout the water column, this study focuses on surface microplastics in this unique environment.
The neuston habitat receives high concentration dosages of UV radiation, experiences severe temperature and salinity changes and bears waves’ mechanical force. Meanwhile, predators watch from both above and below. Due to this demanding environment, highly specialized organisms populate the neuston habitat.
For example, fish may practice a type of camouflage called countershading with bottoms mirroring the sun’s reflection and the top half of their bodies blending into the water.
One key area of neuston study is quantifying and identifying visible epibiota, plants and animals like gooseneck barnacles or algae attached to the plastic particles we collect. Identifying these epibiota sometimes requires genetic analysis, for some organisms may carry bacteria or viruses. Our samples will be analyzed at the Marine Biological Laboratory at Woods Hole.
Another question is the relationship between surface plastic distribution and ocean currents. Where are the main transport routes for different sized plastics and where is the material aggregating? Currently, we assume that smaller plastic particles have been in the sea longer than larger ones.
Chris Wilcox from CSIRO (Australia’s national science agency) will examine the collected data to improve his models of marine debris sinks and sources and connect our samples with ecosystems and food chains.
Collecting the samples:
We collect the neuston layer with a manta net which skims the surface and filters material like the manta ray. The net is usually deployed for 15 minute periods at a speed of 3 knots. The net is held at a distance from the hull to avoid contamination from particles left by the vessel.
After a trawl is completed, the net is checked in the CTD lab for poisonous animals like sea snakes or jellyfish. Then, the net is rinsed to collect any residues in the sample bucket. Lastly, researchers place the catch in sieves and store samples on petri dishes.
For more information: Morton Bay Research Station
10/07/2015