Dataset: zooplankton abund and stages_nbp
Deployment: NBP0204

Zooplankton abundance, vertical and horizontal distribution, and population structure were assessed using a 1 m^2 Multiple Opening and Closing Nets and Environmental Sampling System (MOCNESS) with nine nets having 333 um mesh and environmental sensors of temperature, salinity and depth. The entire water column was sampled on the downcast using net # 0, which was not analyzed here. The water column was typically sampled from close to the bottom at stations on the shelf where depths were less than 1000 m, or to 1000m at stations off the shelf where depths were often from 3000 to 4000 m. Nets 1 through 8 sampled from various depth intervals to the surface with smaller strata near the surface. Several tows targeted krill swarms by towing in a single strata. Approximate locations of broadscale study stations are shown in Figs. 1-4, below.

Zooplankton samples were immediately preserved in 5% buffered formalin solution. In 2006, the samples were sent to the Atlantic Reference Centre, Huntsman Marine Science Centre, St. Andrews, New Brunswick, Canada to be sorted. All the large organisms (>15 mm) in the sample were removed and identified to taxa. The sample was then split to about 100 individuals of euphausiids. All euphausiids in the split were identified to species and life history stage. Next, the sample was split to about 100 individuals of copepods. Copepods were identified to species and life history stage (female, male, copepodite V, or other copepodite). All other zooplankton in the split were identified to taxa and counted. For the Euchaetidae, we followed the designation of Park (1994) who ascribed the Antarctic species to the genus Paraeuchaeta. This data object ('zooabund_nbp') reports the counts of zooplankton per subsample/split by taxa and life stage or size class. The companion data object 'zooabund_lmg' reports similar for the MOCNESS samples collected on the L.M. Gould cruises and data object 'krill' reports the abundance of each euphausiid species by life stage and size class, also on the L. M. Gould.

Displacement volume measurement:
Entire sample plus liquid was measured in a large graduated cylinder then poured through a sieve into a second cylinder. The difference in volume is the displacement volume.

Greenwich Mean Time was local time + 4 hours.

Fig. 1. NBP-0103: Locations for the oblique MOCNESS tows taken in austral fall 2001 as part of the broad-scale survey (solid dots) and the horizontal tows taken in krill patches in Marguerite Bay (asterisks).

Fig. 2. NBP-0104: Locations for the oblique MOCNESS tows taken in austral winter 2001 as part of the broad-scale survey.

Fig. 3. NBP-0202: Locations for the oblique MOCNESS tows taken in austral fall 2002 as part of the broad-scale survey.

Fig. 4. NBP-0204: Locations for the oblique MOCNESS tows taken in austral winter 2002 as part of the broad-scale survey.