There has been a decline in the total biomass of benthos from 1924-1935 to 1968-1970 (Antipova, 1975b). This happened almost throughout the Barents Sea, and has been attributed to climate change by many investigators. The mechanism behind this biomass reduction is not clear, however. Some studies suggest that it is due to a change in faunal distribution during the cold period between the 1960s and 1980s (Figure 2.4.7; Bryazgin, 1973, Antipova, 1975b, Bochkov and Kudlo, 1973), while others invoke declining biomass of resident boreal-arctic species during the 1930s-1960 warm period (Galkin, 1987; Kiyko and Pogrebov, 1997a; Kiyko and Pogrebov, 1998).
Boreal-arctic species dominate the biomass of benthos in the Barents Sea (as well as throughout the arctic shelf), and have an optimum temperature range lying within the long-term temperature mean of the region. According to this latter theory, any deviation from the long-term mean has a negative impact on boreal-arctic species reproduction, abundance, and biomass.
The surveys done in 1924-1935 and 1991-1994 followed long-lasting cold periods with predominance of negative temperature anomalies, and the total biomass of benthos did not significantly differ between these two surveys. On the other hand it exceeded the biomass recorded after a warm period in 1968-1970 (Kiyko and Pogrebov, 1997a). Identification of these types of patterns highlight the importance of these investigations for the basic knowledge and understanding of the dynamics of the Barents Sea fauna.