This dataset contains results from Continuous Plankton Recorder (CPR) surveys in the Southern Ocean. When the opportunity arises, zooplankton species, numbers and abundance data are recorded on a continuous basis as vessels steam through the area between Australia and Antarctica, including Heard and Macquarie Islands. Observations have been made since June 1990 and are ongoing. Obviously the observations are not continuous over the region with time.
Many of the original SO-CPR logbooks from the various voyages have also been scanned, and are available via the Australian Antarctic Data Centre's Reports Register.
Zooplankton have been identified to lowest possible taxon, usually species, and counted for each segment. For copepods, copepodites and for some species nauplii (e.g. Rhincalanus gigas) have been counted separately, and for euphausiids, naupliar, calyptopis and furcilia developmental stages are identified.
The fields in this dataset are:
Tow_number - the CPR tow number
Ship_name - the name of the ship on which the tow was conducted
Season - two-year Antarctic season based around the austral summer, e.g. '2000-01' runs from July 2000 to June 2001
Latitude - the decimal latitude of the segment sample
Longitude - the decimal longitude of the segment sample
Observation_date - UTC date and time of the segment sample in ISO8601 format (yyyy-mm-ddTHH:MMZ)
Observation_date_year - the observation date year
Observation_date_month - the observation date month
Observation_date_day - the observation date day
Observation_date_hour - the observation date hour
Observation_date_minute - the observation date minute
Observation_date_time_zone - the observation date time zone (0=UTC)
Segment_number - the individual segment number within each tow
Segment_length - the distance travelled by the CPR during this segment (nautical miles). This is the true segment length as used in the Geocoding program used to cut the silk, and to calculate positions and average environmental data for each segment. In theory, all segments are 5 nautical miles long. However, this wasn't always the case with early Aurora Australis tows, where it was assumed that each marked segment was 5 nautical miles whereas each tow had subtle variations in silk advancement, depending on the wear of the cassette or travel with or against a current. True segment length has since been recalculated. At other times, some silks have been incorrectly cut and the true length has again been recalculated. The last segment of each tow may be less than 5 nautical miles. This field can be used to standardise species counts to say 5 nautical miles or to a theoretical volume filtered by multiplying the distance travelled by aperture area (12.7 x 12.7 mm): Volume Filtered = Distance (n miles) x 1852 metres x 0.0127^2. A 5 nautical mile segment theoretically represents 1.49 m^3.
Total_abundance - total count of all zooplankton in a segment
Phytoplankton_colour_index - visual estimation of the green colour of the silk mesh. Values are 'No Colour', 'Very Pale Green', 'Pale Green', or 'Green'. This colouration is due to the green chlorophyll pigments derived from chloroplasts of intact and broken cells and small unarmoured flagellates. It may provide an indicator of phytoplankton standing stock, although in the Southern Ocean there are some diatoms that are quite common on the silks but as they have very low amounts of chlorophyll the colour doesn't register in the PCI analysis.
Fluorescence - water fluoresence measured by the vessel, averaged for the segment (arbitrary units). See Quality notes for more information.
Salinity - water salinity measured by the vessel, averaged for the segment (psu). See Quality notes for more information.
Water_temperature - water temperature measured by the vessel (degrees Celsius). See Quality notes for more information.
Photosynthetically_active_radiation - photosynthetically active radiation measured by the vessel (micro-Einsteins m-2 s-1). This is not available on some vessels but has been included as a useful parameter to help differentiate data from night and day.
The remaining fields ('Abylidae' through to 'Vibilia_sp') are zooplankton taxon names. The entries in these columns are the counts of each taxon in the segment.
