---

3. PHOTOGRAPHS OF PHYTOPLANKTON OF THE ARCTIC SEAS

Identification of the phytoplankton taxonomic composition of a sample is the most critical stage of the data processing. As a result high level specialists are usually involved in this type of work. Ultimately, the quality of plankton data depend on the accuracy of species identification.

In practice, for the identification of the various species in biological communities, systematic specialists widely use taxonomic keys containing drowings and/or photographs of organisms. The accuracy of the species identification depends on accuarcy of the representation in a photograph or drowing. The majority of the modern illustrative materials do not present the detail structure of microalgae cells. This disadvantage brings up the problem of getting more realistic images of phytoplankton cells, closest to the natural appearance.

Information on the Barents Sea and the Kara Sea phytoplankton is presented as an interactive collection of photographs of 50 phytoplankton color images in JPEG format with a resolution of 75 dpi.

Click on a photo shows a zoomed picture of live cells of microalgae, a drawing from the taxonomic keys, and a classification table. The table has scientific names and synonyms. Each taxon is provided with its biomass value, its ecological and phytogeographical characteristics, as well as its corresponding ITIS (Integrated Taxonomic Information System) TSN (Taxonomic Serial Number) and NODC (National Oceanographic Data Center) code. Biomass (cell weight) was calculated through the method of geometrical shape similarity for each species (Koltsova, 1970; Kozhova et al., 1978; Plinski et al., 1984).

Phytoplankton filming

Algae samples were collected throughout the Barents Sea using standard methods ( Manual, 1980). The samples were concentrated by the usual method of reverse filtering (Dodon and Thomas, 1964; Sukhanova, 1983) through specialized nuclepore filters (produced in the Integrated Institute of Nuclear Research, Dubna) with a pore size of 1.0-2.0 µm. It was necessary to avoid deformation and breakage of phytoplankton cells resulting from preserving or storing live samples. The samples were preserved in a weak solution (Lougol, 1% formaldehyde) or were placed and stored in a thermos. In May-June, water samples with live materials were collected from points located in the Kola Bay. In August they were collected in the fjord Dalnezelenskaya (area of biological station of the MMBI in the settlement Dalnie Zelentsy, 69^o07'08"N, 36^o05'08"E). Slightly preserved algological material were collected from the southern Barents Sea during July cruise of the Viktor Kingisepp. Only phytoplankton collected in 1998 have been used for photography.

The experiment targeted natural microalgae images, which rejected the use of color shading, outline tracing, or emphasizing any cell segment. Shading was applied only as a background in case of thick mud/severe dirt or the presence of other cells within the exposure. Due to object size, the filming was performed at magnifications from 80^x to 800^x.