This data set is derived from displacement volume measurements and dry weight conversion calculations. The MOCNESS-1 plankton sampler has nine rectangular nets (1m x 1.4 m) with a mesh size of 0.333 mm, which are opened and closed sequentially by commands through conducting cable from the surface (Wiebe et al., 1976).
\nMethods:
\nDisplacement volume measurement: The 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.
\nDetailed instructions:
Measuring Displacement Volume
\nSupplies: rubber gloves, safety goggles, 2 1-liter graduated cylinders, 2 smaller graduated cylinders (25 to 100 ml), 2 funnels: 1 wide-necked open funnel and 1 small-necked one with mesh attached to the inside or a sieve that fits inside the small-necked funnel, squeeze bottles (water and formalin or other preservative), sieve of mesh size equal to or smaller than that on sampling net.
\nPut on rubber gloves
\nRemove jars for 1 net from sample box (may be from one to many jars for a single net sample)
\nFill in the data sheet with MOC tow#, date, and net#. jar#
\nTake first sample to hood. Put on safety goggles.
\nRemove lid and internal label with long forceps. Get most of zooplankton off by dipping into jar and place label inside lid after checking that internal label agrees with lid label.
\nRemove large (>5cc) animals (medusae, some fish or shrimp) and measure their displacement volume in the small graduated cylinders:
\n-Put animal and enough liquid to cover in one small graduated cylinder.-Note this volume on
\ndata sheet.
\n-Place small sieve in small funnel and set them on top of second empty small grad graduated cylinder.
\n-Pour animal plus liquid into sieve and let drain.
\n-Note this volume on data sheet as well as the type of animal.
\n-Return the specimen to the main sample.
\nPour the large sample into the 1-liter graduated cylinder using the open funnel on top (no mesh in funnel). Rinse sparingly the jar, funnel and sides of the graduated cylinder. Diluting the sample with water could cause it to rot. Add a little water with the squeeze bottle to bring the level up to an even line on the graduated cylinder.
\nNote this volume on the data sheet (sample + liquid)
\nPlace the large funnel containing the sieve or mesh on top of the second, empty graduated cylinder.
\nPour the sample into the empty grad. Don't worry about animals stuck to the sides of the first grad. Do not add any liquid to wash sample into the second grad.
\nSwirl the funnel to remove excess liquid until most of liquid is done dripping (about 1 minute, but varies sample to sample). Carefully drawing the samples toward the center with large forceps is sometimes helpful.
\nNote this volume on data sheet (liquid vol.)
\nRinse the graduated cylinder and the mesh-funnel into the sieve with the hose and return most of the dry sample to the jar using the open funnel.
\nUse water from faucet with hose to wash the sample on sieve to one side and then use squirt bottle of water (sparingly) or the preservative filled one to rinse the sample from sieve to jar.
\nAdd enough of the filtered formalin to fill the jar, dispose of remainder in appropriate waste container.
\n- Check the sample's pH and add buffer (sodium borate or borax) if = 8.0.
\n- Replace cap, swirl if buffer of formalin was added, and rinse outside of jar.
\n- Rinse everything well after each net sample.
Dry weight calculations:
\ndry weight = (dvol/(100.139))(1/1.003); [mg/m3]
\nintegrated dry weight = depth interval * dry weight; [mg/m2]
\ntotal dry weight for the entire sampled water column = sum of integrated dry weights for all nets for one tow; [mg/m2]
This data set is derived from displacement volume measurements and dry weight conversion calculations\u00a0(see Methods below). The MOCNESS-1 plankton sampler has nine rectangular nets (1m x 1.4 m) with a mesh size of 0.333 mm, which are opened and closed sequentially by commands through conducting cable from the surface (Wiebe et al., 1976).
\nCruises:
\nNathaniel B. Palmer, April-June 2001 (NBP01-03), 24 tows
\nNathaniel B. Palmer, July-Sept. 2001 (NBP01-04), 17 tows
\nNathaniel B. Palmer, April-May 2002 (NBP02-02), 24 tows
\nNathaniel B. Palmer, July-Sept. 2002 (NBP02-04), 19 tows
Related\u00a0Datasets:
\n- Zooplankton Biomass and Abundance from MOCNESS tows using silhouette analysis: NB Palmer, austral fall & winter of 2001 & 2002. Biomass (wet weight) and abundance were determined principally by silhouette digitization of taxa lengths and conversion to equivalent wet weights according to the equations and methods adapted from Davis and Wiebe (1985) and Wiebe et al. (2004). https://www.bco-dmo.org/dataset/2389
- Zooplankton Abundance Based on Taxa and Life Stages or Size Collected during the Broadscale Cruises, Austral Autumn 2001 and 2002, NB Palmer. These abundance values on the same tows were derived by counting and identifying a subset of the zooplankton to the species and life stage for euphausiids and dominant copepods and to taxonomic group with broad size categories for other zooplankton (pteropod, chaetognath, polychaete, etc.).\u00a0https://www.bco-dmo.org/dataset/2387
Displacement volume measurement:
\nEntire 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.
Dry weight calculations:
\ndry weight = (dvol/(100.139))(1/1.003); [mg/m3]
\nintegrated dry weight = depth interval * dry weight; [mg/m2]
\ntotal dry weight for the entire sampled water column = sum of integrated dry weights for all nets for one tow; [mg/m2]
This displacement volume data comes from nets with a mesh size of 333 mm.