Preliminary Cruise Report

C-MORE science and volunteer crew reported to Snug Harbor at 0630 on Monday, 25 August, 2008. After fueling the ship, the R/V Kilo Moana departed from Honolulu, HI at approximately 1630. Starting at 2200 on this first day and for the duration of the cruise, daily and nightly underway samples were collected from the ship's flow-through system. Water collected from this system was processed for particulates, nutrients, ATP, chlorophyll, and a suite of other analyses for contextual data.

The cruise track began with a northeasterly course from Oahu to 34° N, 151° W. The first station consisted of a single CTD cast at 1300 on Tuesday, 26 August to collect water for a mixing experiment (mixing deep water with surface water to change nutrient concentrations). From Wednesday, 27 August to Monday, 1 September, two to three stations were visited per day, during which the manta trawl was deployed for 1.5 hours, the CTD rosette was cast to the deep chlorophyll maximum, and the HyperPro profiler and LISST particle analyzer were deployed to approximately 125m depth.

Upon recovery of the manta trawl, the net was rinsed with sea water, and the cod end was detached and placed in a bucket on deck. The cod end was then taken to Lab 2, where the contents were sieved through three filters of the following mesh sizes: 5mm, 2mm, and 0.2mm. Large pieces that were not kept for later use were measured and photographed (the upper size limit for whether a sample was retained was determined by the size of the largest storage containers). The presence and abundance of fauna collected in the net were recorded. The metazoan community consisted primarily of Valella valella, Porpita porpita, Halobates, Janthina, isopods, copepods, amphipods, and small crabs.

In the following summary of sample allocations, the "large" size class refers to plastic pieces >5mm; "medium" refers to 2-5mm sized pieces, and "small" refers to 0.2-2mm sized pieces. For each sample, 30-100 pieces of plastic were collected from the large and medium size classes for DNA and RNA analyses. For chlorophyll extractions, 3 large, 6 medium, and 30 small pieces were placed in acetone and refrigerated (each size class was divided into 3 tubes, for a total of 9 chlorophyll samples per station). For ATP, 5 large, 15 medium, and 50 small pieces were boiled in TRIS buffer and then frozen (each size class was divided into 5 tubes, yielding a total of 15 ATP tubes per station). From 6 of the 14 trawl collections,between 14-19 large and medium pieces were used for incubation experiments. The remaining plastic pieces were sorted by size class and stored in 5% formalin. All of the 2-5mm and >5mm sized pieces were counted, and as many of the 0.2-2mm sized pieces were counted as time allowed. In addition to these collections, an incubation experiment was conducted in which microbial processes were examined in treatments without plastic particles, with sterilized plastic particles, and with "in situ" (non-sterilized) plastic particles.

The combined density of plastic particles in the 2-5mm and >5mm size classes ranged from 0.35-3.71 pieces m-3 across all sampling stations (Figure 1). Integrated over the top 0.5m of the ocean, the particle concentrations along the transect ranged from 174,000 to 1.85 million plastic fragments km-2.

Plastic particle concentrations
Figure 1. Combined particle concentrations of marine debris in the 2-5mm and >5mm size classes across the SUPER cruise sampling transect. Sea surface temperatures are based on integrated August-September temperature data from 2002-2008. (Courtesy of A. White)

Six stations were visited before heading east, approximately tracing 35° N latitude, along which 10 additional stations were taken (Figure 1). This track took us 27 hours off of the great circle path between Honolulu and Port Hueneme. The total distance of the sample transect was 2115 km.

In addition to the science activities, Lucy Marcus maintained a daily web log documenting her shipboard experience. Curriculum development meetings were held with Barbara Mayer, who will be assisting with the development of a C-MORE science kit based on marine debris.


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