30-50 miles off capes of Kaliakra, Galata and Emine, Varna and Burgas bays and Varna and Beloslav lakes

Zooplankton taxonomy-related abundance per unit volume of the water column; Zooplankton taxonomy-related biomass expressed as carbon per unit volume of the water column; Phytoplankton generic biomass in water bodies; Phytoplankton taxonomic abundance in water bodies

Plankton nets

This data set is divided into 6 sub-groups including - investigations on marine bacteria (since 1970), phytoplankton (since 1960), mesozooplankton (since 1956) and macrozooplankton (since 1991), benthos (since 1956), and ichthyoplankton (since 1960). Bacterioplankton - measurements on total bacterial abundance and biomass, as data about the two main groups constituting bacterial community - heterotrophic and autotrophic bacteria are separated by their proportions in the total abundance Phytoplankton - the algal data are collected within the regular sampling program on monthly or seasonal basis in the 30-miles zone offshore. In the period 1994 – 2000, the phytoplankton was collected on weekly basis in the Bay of Varna. In summers, during phytoplankton blooms, the daily samples were collected. Mesozooplankton - mesozooplankton was collected by vertical hauls of "Jedy" plankton net, with 36 cm. opening diameter and mesh size 150 μ. Samples were seasonally/monthly collected at standard depths: 5-0, 10-5, 25-10, 50-25, 100-50, 150-100 m. at four monitoring transects: Galata, Emine, Kaliakra, Maslen nos; and from different strata in the Varna Bay, and Varna Lake, and in the Bay of Bourgas. Zooplankton was identified to species level, except of the meroplankton, which was divided to 5 main groups: Polychaeta larvae, Cirripedia naupii and cypris, Lamellibrancia veliger, Gastropoda veliger, and Decapoda mysis, and zoea. Species abundance (ind.m-3) and wet biomass (mg.m-3) of all mesozooplankton species (200μm - 20mm) were estimated. Macrozooplankton: Macrozooplankton samples are seasonally/monthly collected at three monitoring transects: Galata, Emine, and Kaliakra. The macrozooplankton is sampled by “Bongo” net, with opening diameters d=2x0.60m and mesh size of 300 μ and 500 μ. The net is provided with flow-meter to register the volume of filtered water and with depth-meter to identify the maximal depth of sampling. The abundance, linear size and bio-volume of different gelatinous species are defined onboard ships. In laboratory the abundance and biomass of gelatinous plankton per unit area (ind.m-2, g.m-2) are calculated Benthos: The main purposes during the benthos investigations are to monitor the species composition, abundance and biomass of benthic species off the Bulgarian coast; to establish temporal trends in species composition, abundance and biomass (at a timescale of months and years). The sampling is carried out during ship cruises, using grab “Van-Veen” with an opening of the mouth 1/10 m2. Samples were seasonally/monthly collected at four transects: Galata, Emine, Kaliakra, Maslen nos, and in the Varna Bay, Varna Lake, and the Bay of Bourgas. Density and biomass are estimated for surface 1 m2. Ichthyoplankton: samples were seasonally/monthly collected at three monitoring transects: Galata, Emine, and Kaliakra. The ichthyoplankton is sampled by “Bongo” net, with opening diameters d=2x0.60m and mesh sizes of 300 μ, and 500 μ.

Institute of Fishery Resources
4 Primorski Blvd P.O. Box 72
Varna

9000
Bulgaria