To sample and characterize microbial community dynamics and ocean chemistry associated with plastic debris in the North Pacific Subtropical Gyre.
We will visit 10–12 stations during a transit from Honolulu, HI to Port Hueneme, CA. At each station, we will conduct a 1–2 hour long net tow to collect plastic debris using a manta trawl, which was generously provided by the Algalita Marine Research Foundation. We will also sample 288 liters of seawater using a circular, 24-Niskin-bottle array. Finally, we will characterize the optical properties of the water column by performing 20-minute long HyperPro casts at each station.
This plan sounds straightforward, but in fact sampling will be a dynamic process that will be determined by weather, available science time, and location of the plastic debris. We require calm weather to conduct the plankton tows because not only does plastic accumulate at the surface in calm conditions, but the manta trawl works most effectively under a calm sea surface state. Also, the ship must arrive at Port Hueneme on time, so we only have a maximum of 48 hours of sampling time during the 12 day transit. Finally, we want to position ourselves within the North Pacific Subtropical Gyre, where the plastic is thought to be the most abundant. Therefore, we have to balance science time with travel time in order to get as far north as possible since we cannot conduct net tows or CTD casts while the ship is underway.
Using the water samples that we collect, we will analyze the water for:
Underway stations will be conducted using the uncontaminated seawater supply system. Water samples for biogeochemical measurements will be collected at each UW station.
Upon arrival on station, a Manta trawl (see section 2.1) will be deployed. After the manta trawl operation is complete, a CTD cast to 75m for water column measurements will occur (see section 2.2).
Ship loading starting at 1000 hrs
Depart from Snug harbor at 0700 hrs. Science personnel on-board by 0600
26 Aug – 4 Sept
Station 1-12 operations
Pack, clean labs
Arrive Port Hueneme, CA at 1500 hrs. Offload ship.
CTD (0-150m) / Manta Traw l/ Optics Operations
Underway Stations 1–12
Various biogeochemical parameter sampling from uncontaminated seawater system
ADCP, Thermosalinograph, fluorometry, pCO2
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