TITLE:  SBI Mesozooplankton abundance

PIs:
Drs. Carin Ashjian and Robert Campbell
Phone:  508-289-3457 (Ashjian) and 401-874-6692 (Campbell)
e-mail:  cashjian@whoi.edu, campbell@gso.uri.edu

NSF GRANT: OPP-0124766

DATE SET OVERVIEW:
This data set contains mesozooplankton abundance from net tows conducted during
the SBI process cruises.  Each data set presents abundances of all taxa,
including copepodite stages for the copepods, as # per m-3.  Station number,
station name, date, position (latitude, longitude), depth intervals for each
tow, and bottom depth are presented. 

METHODS:
Vertically discrete sampling of the water column zooplankton was conducted every
10-14 days by vertical hauls using a 1-m2 mouth area, 6-m length ring net
equipped with 150 īm mesh nets, a flow meter, and a Sea-Gear Inc. double release
mechanism to permit sampling at selected depths.  The net was deployed on the
down cast open with the mouth upwards, and hence not collecting plankton.  The
flow meter was prevented from incrementing on the down cast by a pin that
immobilized the tail; the tail was freed just prior to starting the up cast by
tripping the first release of the double trip and pulling the pin away from the
tail.  The net was closed using the second release of the double trip mechanism
at the upper depth of the desired depth interval.  Either the upper 100 m of the
water column or, when the water depth was shallower than 100 m, from the surface
to 10 m off the bottom was sampled.  Samples were preserved in 4% buffered
formaldehyde in sea water immediately following collection. 

      Zooplankton were enumerated at the Atlantic Reference Center, Huntsman
Marine Science Center, St. Andrews, New Brunswick under the direction of Dr.
Gerhard Pohle.  Large animals (e.g., Cnidarians, ctenophores, fish larvae, all
jellies, amphipods, chaetognaths, appendicularians, decapods, ostracods,
pteropods, and other) first were removed from the sample and counted. 
Subsamples then were obtained using the beaker splitting technique (Van Guelpen
et al., 1982) to obtain approximately 300 organisms.  All copepods were
identified to species and copepodite stages.  Other taxa were identified to the
lowest taxonomic level possible. Five target copepod taxa were selected: 
Calanus glacialis, C. hyperboreus, Metridia longa, M. lucens, and Pseudocalanus
spp.  For the first four species, successive aliquots were enumerated until at
least 150 of the target copepod species were encountered or until the entire
sample had been examined. For Pseudocalanus spp., successive aliquots were
enumerated until at least 50 of the target copepod species were encountered or
until the entire sample had been examined.

References
Van Guelpen, L., D.F. Markle, and D.J. Duggan.  1982. An evaluation of accuracy,
precision, and speed of several zooplankton subsampling techniques. J. Cons.
Int. Explor. Mer, 40: 226-236