| Fieldname |
Description |
Units |
| cruiseid |
Cruise identifier (LMG0104, LMG0203) |
|
| year |
Year of cruise |
|
| station |
Station number |
|
| cast |
Net tow number |
|
| lat |
Latitude at beginning of tow, negative = South |
decimal degrees |
| lon |
Longitude at beginning of tow, negative = West |
decimal degrees |
| depth_w |
Depth of the water at specified station |
|
| month_local |
month of year, local time |
|
| day_local |
day of month, local time |
|
| time_local |
Time net tow began, local time, GMT = local time + 4 hrs |
HHmm |
| month_gmt |
month of year, GMT time |
|
| day_gmt |
day of month, GMT time |
|
| time_gmt |
Time net tow began, GMT time |
HHmm |
| net |
Net number (1-8) |
|
| vol_filt |
Volume of water filtered by net |
meter3 |
| depth_open |
Depth each net was opened |
meters |
| depth_close |
Depth each net was closed |
meters |
| taxon |
Scientific name of organism or common name of group |
|
| stage |
Life history stage e.g.:
CV = copepodite stage V,
C2 = calyptopis
stage 2,
F2 = furcilia stage 2 |
|
| samp_fraction_denom |
The sample size represented as a fraction, only the denomator is reported as all samples have been reduced to 1/denominator |
|
| lenbin_min |
Minimum of length bin range, generally bin ranges are 1/2 mm under 16 mm and 1 mm bin over 16 mm. |
mm |
| lenbin_max |
Maximum of length bin range |
mm |
| length_min |
Minimum length of individual euphausiid. For some casts, actual lengths were measured while most were measured to within a 0.25 mm range |
mm |
| length_max |
Maximum length of individual euphausiid |
mm |
| count_per_lenbin |
Number of euphausiids within a length bin for the species, stage and sample fraction (split) listed. Only the final entry for each bin has the count for that bin. Preceeding entries show a count of zero (0). |
# |
| abund_per_lenbin |
Abundance of euphausiids of a size range described by the length bin min and max. Only the final entry for each bin has the abundance for that bin. Preceeding entries show an abundance of zero (0). |
#/m3 |
| count_per_stage |
Number of euphausiids within a stage for the species and sample fraction (split) noted. Only the final entry for each stage has the count for that stage. Preceeding entries show a count of zero (0). |
# |
| abund_per_stage |
Abundance of euphausiids within a stage and species. Only the final entry for each stagge has the abundance for that stage. Preceeding entries show an abundance of zero (0). |
#/m3 |
| count_species |
Number of euphausiids within a species for the sample fraction (split) noted |
# |
| abundance_species |
Abundance of euphausiids for the species |
#/m3 |
| epibionts |
relative presence or absence of epibionts on the euphausiid carapaces |
|
| comments |
comments regarding the sample or individual |
|
Data Contributed By:
Kendra L. Daly
College of Marine Science
University of South Florida
140 Seventh Ave. S.
St. Petersburg, FL 33701
Phone: 727-553-1041
E-Mail: kdaly@marine.usf.edu
Net sample collections: Meng Zhou, Yiwu Zhu, Ryan
Dorland, Dan Mertes, and Joe Smith
Sample Analyses: Jason Zimmerman, Alexander Timonin, Tatjana
Semenova
Cruises:
Laurence M. Gould, 23 April - 6 June 2001 (LMG0104 cruise report), 18 net tows
Laurence M Gould, 7 April - 21 May 2002 (LMG0203 cruise report), 16 net tows
Methods
Zooplankton abundance, vertical and horizontal distribution, and population structure were assessed using a 1 m2 Multiple Opening and Closing Nets and Environmental Sampling System (MOCNESS) with nine nets having 333 µm 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. The upper water column was
typically sampled using nets 1 and 2 from 500 m to 200 m at 150 m depth intervals, nets 3 and 4 from 200 m to 100 m at 50 m depth intervals, and nets 5
to 8 from 100 m to the surface at 25 m depth intervals. Some tows were deployed down to 1000 m, and some tows were towed targeting krill swarms at irregular depths. Approximate locations of process study stations are shown in Fig. 1. More precise locations of the casts in Fig. 2.
Zooplankton samples were immediately preserved in 10% buffered formalin solution. 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 and measured for length to the nearest 0.5 mm for larvae and to the nearest 1.0 mm for juvenile and adults. 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 ("krill") reports the
abundance of each euphausiid species by life stage and size class. The companion data object "zooabund" reports the counts of zooplankton per
subsample/split by taxa and life stage or size class.
Greenwich Mean Time was local time + 4 hours.
Reference:
Park, T. 1994. Taxonomy and distribution of the marine
calanoid copepod family Euchaetidae. Bulletin of the Scripps Institution of
Oceanography University of California, San Diego v. 29, University of
California Press, Berkeley, CA, 203 pp.
Fig. 1. Approximate locations of process cruise stations
in Marguerite Bay during austral autumn 2001 and 2002.
Fig. 2. Locations of MOCNESS stations for LMGould-0104 (2001) and LMGould-0203 (2002) cruises. Numbers correspond to the cast number.
Notes on Volume Filtered values:
The 1 m2 MOCNESS net volume filtered data were corrected for the following net tows:
The flowmeter used to calculate the volume of water
filtered did not work for the tows shown below; the data shown in the
listings for those tows are therefore derived, not measured.
Using the net distance and the average angle
of the net, the volume filtered was estimated. These estimates
have about a 10% error or higher when currents were present.
LMG0104: St. 4, Cast 9, event #98
2001: No further corrections. MOC-1 net volume filtered values were used to calculate abundance/m3 for all net tows. No Optical Plankton Counter (OPC) volume filtered values were available for 2001.
2002: The flowmeter data was not accurate for some net tows in 2002. Optical Plankton Counter (OPC) volume filtered was used to calculate abundance/m3 for all MOC-1 net tows, except casts 11 and 16 which used the MOC-1 volume filtered values. The decision to use OPC values was determined by plotting all OPC volume filtered numbers versus MOC-1 flow meter data (see below). MOC-1 flow meter data were consistently lower and had a lower R2 regression for volume filtered versus length of tow (time). Meng Zhou and Yiwi Zhu, who conducted the MOC-1 net tows, noted on the haul sheets that there were problems with the MOC-1 flow meters and that they often were not responsive or worked intermittently. Thus, it was decided that the OPC flow meter data provided a more consistent measure of net flow volume for 2002 net tows. The OPC mouth opening for flow meter data was corrected to the MOC-1 net mouth opening by multiplying the OPC flow data by 200. The two casts that used MOC-1 flow meter data were cases where the OPC flow meter data appeared to underestimate the flow.
Fig. 3. Volume filtered over time for both MOCNESS and Optical Plankton Counter showing consistently lower flow rates for the MOCNESS.
Revised data received Jan. 2008. Reformatted for this data system from Excel spreadsheets, joined with event log metadata (date, lat, lon, depth_w) using 8200 server and restructured using rs 2.0 before serving here. --njc 7/7/08