DOI: 10.14466/cefasdatahub.18
title: Cefas 1976 Phytoplankton Cruise Series

description: This dataset has been extracted as part of an exercise to assemble "all" Cefas Temperature Data and publish it in a Data paper. It is one of 17 Cefas data sources assembled.

A series of 12 cruises was carried out in 1976 by DFR staff to investigate the distribution, abundance, mortality and main predators of planktonic fish eggs and larvae of important commercial fish species (e.g. plaice, cod). The cruises secondary aims included the investigation of phytoplankton standing stock (via measurements of chlorophyll concentration, phytoplankton size and abundance) and of zooplankton biomass.

Plankton samples were collected at each site on a planned survey grid. These data consist of numbers of macroplankton from 8 of the samples collected from an area off the North East coast of England, along with associated positional data and volumes filtered

Measurements of surface water temperature and salinity, and bottom temperature, were carried out at each sampling station on a planned survey grid (see below). Samples for the analysis of dissolved inorganic nutrient and chlorophyll concentration were also collected at the surface at each sampling station.

All the hydrographic observations were made from the vessels (RV Corella and Clione). Surface water temperature was monitored through a stainless–steel ship–board pumping system. The pump had an intake 4 m below the water surface and delivered sea water to sensors set up in the ship’s laboratory. The temperature sensor (as well as the salinity, pH, dissolved oxygen and transparency sensors) was mounted in a Perspex box though which the pumped water flowed continuously.

The measurement of temperature at the “bottom” at each sampling station was obtained from the chart records of the electronic depth gauge and thermistor sensors mounted on the plankton sampler.

The data collected during these cruises was presented in the ‘Fisheries Research Technical Report’ n. 86 by Harding and Nichols in 1987. Steve Milligan has the original log books from these cruises; some of these log books (e.g. containing plankton and icthyoplankton data) were not digitised (because not relevant for the project).

Sampling was carried out along the survey on twelve cruises between the end of January and the beginning of November; each survey lasted approximately twelve days. Seven cruises were planned for the first four months to sample cod and plaice spawning, while the remainder, at approximately monthly intervals, were to sample summer– and autumn–spawning fish. All surveys were carried out on board the RV Corella, except the final survey which was carried out on board the RV Clione.

The temperature sensor in the Perspex box was calibrated at regular interval during each survey against known standards. Calibration of the thermistor used for measuring temperature at the “bottom” was carried out against a secondary standard thermometer; the chart records were corrected accordingly to the calibration.

Temperature data extracted from cruise datasets as part of Cefas Seedcorn Project DP302 which looked at historical light and chlorophyll measurements; some chlorophyll measurements were recorded during the series of cruises carried out off the north-east coast of England in 1976 on board the vessel Corella.

Records of these cruises were only on paper and during DP302 they were digitised. Measurements of temperature at the surface and bottom were recorded together with the various details of each sampling stations.

The multiple sources are described in 17 separate metadata entries under the same Title, e.g. Seawater temperature records for the UK Shelf - 15 - RV Cefas Endeavour FerryBox Monitoring System. These data have been described in detail via the following publication. Morris, D. J., Pinnegar, J. K., Maxwell, D. L., Dye, S. R., Fernand, L. J., Flatman, S., Williams, O. J., and Rogers, S. I.: Over 10 million seawater temperature records for the United Kingdom Continental Shelf between 1880 and 2014 from 17 Cefas (United Kingdom government) marine data systems, Earth Syst. Sci. Data, 10, 27–51, https://doi.org/10.5194/essd-10-27-2018, 2018.