Project description:

Project: Shelf Basin Interactions (SBI) Phase I

Data: Abundance and measurements of copepods in historical zooplankton
 samples.  This readme file refers to two companion text formatted data
 files named "BSE_copepod_abundance.txt" and "BSE_copepod_lengths.txt".

PI: Dr. Sharon L. Smith, RSMAS/MBF, 4600 Rickenbacker Causeway, Miami, FL,
 33149.  Tel. No. 305-361-4819.  Email:ssmith@rsmas.miami.edu
Alternate contact: Peter Lane, RSMAS/MBF, 4600 Rickenbacker Causeway, Miami,
 FL, 33149.  Tel. No. 305-361-4818.  Email:plane@rsmas.miami.edu
NSF Award No. OPP-9815682 (Advection and Food Webs in the Western Arctic:
 Retrospective Sample and Data Analysis and Modelling), 06/23/1998

Primary purpose of study was to determine historic distribution, abundance,
 and size of large bodied copepods of the Chukchi and Beaufort Sea shelves
 and slope regions.  The samples analyzed were collected in 1950 and 1951,
 representing years of contrasting temperature environments in that region
 (see Johnson, M., 1956, The Plankton of the Beaufort and Chukchi Sea Areas
 of the Arctic and its relation to the Hydrography, Arctic Institute of
 North America, Technical Paper No. 1, 32 pp).  Our work expanded on
 Johnson's analyses by estimating abundance of various life history stages
 of large-bodied copepods and making measurements on specimens from selected
 samples.  Additional measurements were made on selected species in an
 effort to clarify taxonomic identification.  The data generated were useful
 in planning proposed field work in Phase 2 of SBI.  Further description of
 this work is given at the following WWW URL:  
http://www.rsmas.miami.edu/groups/zoopec/SBI1_Dec2001/SBI1.html

Data Set Description: The samples analyzed for the present description were
 collected in 1950 and 1951 from aboard the U.S.S. BURTON ISLAND in the
 Beaufort and Chukchi Seas.  Collection methods are given in: Johnson, M.,
 1956, The Plankton of the Beaufort and Chukchi Sea Areas of the Arctic and
 its relation to the Hydrography, Arctic Institute of North America,
 Technical Paper No. 1, 32 pp.  The samples are archived in the Planktonic
 Invertebrates Collection of Scripps Institute of Oceanography under the
 supervision of Dr. Mark Ohman. (http://www-sioadm.ucsd.edu/plankton/)  Dr.
 Ohman and A. Townsend are gratefully acknowledged for their assistance in
 accessing the samples.  Our analyses were conducted during two visits to
 Dr. Ohman's lab, in January and Sept/Oct 2000.  A total of nineteen samples
 from 1950 and 1951 were selected for analysis based on their distribution
 near the Pt Barrow area on the Beaufort and Chukchi shelves.  Each of the
 selected samples listed in the accompanying data set were sorted in their
 entirety for late stage copepodites and adults of large bodied copepod
 species (Calanus spp. and Neocalanus spp.).  Abundance estimates were made
 by first calculating the approximate volume filtered (m^3) based on the net
 mouth area (m^2) and wire out (m), and then dividing by the total number of
 specimens counted in the sample by the volume filtered.  Size measurements
 of individuals were made using a Wild M-5 microscope with ocular
 micrometer.  Our data are being made available to allow other investigators
 interested in zooplankton dynamics in the region to utilize these
 measurements for historical or proposed future studies.

Data Structure:
File "BSE_copepod_abundance.txt" is a text file containing the abundance
 data.  Comments at the beginning of the file are denoted with a # sign. 
 There are 15 columns, which represent date (local), time (local), latitude,
 longitude, station number, sonic depth (m), sample number, sample depth
 (m), genus, species, growth stage (copepodite 1 through adult), sex (adults
 only), number of specimens per sample, estimated volume filtered (m^3),
 abundance (no/m^3).  There are 258 data records following the comments and
 headers.  Local time was used because previous references to this data set
 are in local time, and because it is usually more applicable to biological
 measurements.  Variables for which there are no=20data are denoted as "nd".
  In most cased these refer to cases such as sex of juveniles, which was not
 determined.

File "BSE_copepod_lengths.txt" contains copepod length measurement data. 
 The format of the file is similar to the abundance data file. There are 15
 columns, which represent date (local), time (local), latitude, longitude,
 station number, sonic depth (m), sample number, sample depth (m), genus,
 species, growth stage (copepodite 1 through adult), sex (adults only),
 state of egg internal egg development in females (state =3D 1-5), prosome
 length (mm), total length (mm).  The state of egg development is a proxy
 variable for potential egg production of copepods, also referred to as
 female reproductive state.  This index is defined in detail in Smith, S,
 1990, Egg production and feeding by copepods prior to the spring bloom of
 phytoplankton in Fram Strait, Greenland Sea, Marine Biology, 106: 59-69. 
 Briefly, reproductive potential increases with egg state from 1 to 4, with
 state 5 representing "spent" females, or those that have finished their
 reproductive cycle.