Presented are (a) physical and biological data collected during 158 scientific cruises carried out in the period 1913-1999 and (b) data on phytoplankton collected in 1994-1999 during cruises of nuclear icebreakers in the region extending from the Barents Sea to the Kara Sea. Listed are phytoplankton and zooplankton species of the Arctic Seas. Ecological and geographic characteristics are given to each individual species. Pictures of live cells illustrate the dominant species. Based on the pattern of the annual cycle of the plankton variability, proposed criteria are presented for the quality control of phytoplankton and zooplankton data. The methods of objective analysis are used for mapping the distribution of physical and biological characteristics of the Barents and Kara Seas. Changes in the plankton community structure between the 1930's, 1950's, and 1990's are discussed. It is demonstrated that observed differences substantially exceed the error resulting from the use of various methods for plankton sampling.

1. INTRODUCTION

Plankton is a biological component of the World Ocean and a major food source for a variety of marine life. This fact makes the problem of plankton investigation an important part of the study of the Ocean and its biological resources.

Hydrobiological investigations of the Barents Sea and the Kara Sea were launched in the second half of the 19th century. Peak studies occured between 1960 and 1990 when dozens of scientific research vessels were carrying out monthly collections of physical and hydrobiological data in this region. These data are potentially useful for a variety of oceanological, biological, and fishery problems. In practice, utilizing these data has been problematic because they have not been compiled systematically into a single database accessible to the broad scientific community. Compiling the data is a challenging project for several reasons. The data collected in the 1920's-1950's are available only as manuscripts, many of which are written in Russian. Additionally, the methods of collection and sample processing have changed over time. Unless the methods were extremely well documented, it is very difficult to evaluate the comparability of the data collected, and to obtain a coherent dataset.

The goal of this work was to implement the information of the plankton communities of the Arctic Seas into the study of the ocean climatic system. To reach this goal we needed to solve the following problems:
a) develop an electronic plankton database for the Barents and Kara Seas;
b) document the variation in the plankton communities over periods of time.

As an information data source we used the observations of MMBI performed during 1953-1999, and data presented in Russian and U.S. publications during the period 1913-1964. These publications are available in the NOAA Central Library (Silver Spring, MD, USA.), the Slavic Library (Helsinki, Finland), the New York Public Library (New York, USA), and the Dartmouth College Library (Hanover, NH, USA).

The section Photographs of Phytoplankton Living Cells was prepared by P. Makarevich, Ph.D., based on materials collected in 1998-1999. The section Methods of continuous observations was prepared by A. Shavykin, Ph.D., based on the information acquired during cruise 72 of R/V Dalnie Zelentsy.