Day 04 S/V Kaisei: Dr. Andrea Neal’s Multi-Tiered Filtration System

Friday, 7 August 2009

Lat: 32° 22’ N

Lon: 129° 37’ W

We started day four with a midnight trawl that took usinto the early morning. Our night trawl was aimed to catch small mesopelagic fish called myctophids (lanternfish) and zooplankton. Myctophids are small mid-water fish that dwell between 200-1000 meters in depth during the day and feed at the surface at night. One of our goals is to examine the incorporation of small marine debris into lower trophic levels of the food web. Myctophids are prevalent throughout the world and representative of zooplanktivores. However, the recent full moon may have provided enough light for them to escape the manta trawl provided by Dr. Marcus Ericson from Algalita Marine Research Foundation. Heather Coleman (soon to be Dr. Coleman) identified the abundance of small fish, baby squid, jellyfish and a plethora of by-the-wind-sailors trapped within the manta trawl. We found a considerably greater amount of marine debris compared to the previous trawl. The haul consisted mostly of plastic and some Styrofoam, and the size dispersion was relatively consistent with the last capture (approximately 100µm – 5mm). Dr. Margy Gassel, from the California (EPA) Office of Environmental Health Hazard Assessment, documented the live specimens and froze them for future analysis.

Later in the day, Dr. Neal started a multi-tiered filtration system to examine the size structure of marine debris. Using polycarbonate filters made by Millipore, this system will capture plastic in size ranges as low as 50 nm (in the nano-particle size range). We will examine the accumulation and characterization of these fine particles in our respective labs when we return. We will also compare our findings with oceanographic data from long-term monitoring sites established by CalCOFI (California Cooperative Ocean Fisheries Investigation). Tomorrow we will we reach our first CalCOFI site, which will mark the first nano-particle collection on our research route. Tonight we will be doing another midnight trawl analysis and kick off tomorrow with a wide spectrum of water sampling experiments in our first CalCOFI collection location.