The maximum and mean biomasses and http://www.selleckchem.com/products/nutlin-3a.html abundance of G. m. margaritacea in the study area exceeded that of G. v. vulgaris only by a factor of 1.3–2.4. This means that one third of the total sipunculan biomass in the study area consists of G. v. vulgaris. A similar situation was observed

in the other area of the Barents Sea with a high density of sipunculan populations off the Novaya Zemlya archipelago coast ( Garbul 2009). According to the data of 1996, the mean biomass of G. m. margaritacea in the area was 30.8 ± 10.0 g m− 2 and that of G. v. vulgaris was 7.2 ± 7.1 g m− 2. Moreover, according to these same data, the mean biomasses of G. v. vulgaris and G. m. margaritacea in the central Barents Sea, given the equal frequency of occurrence, were 13.0 ± 5.5 g m− 2 and 6.4 ± 3.6 g m− 2 respectively ( Garbul 2010). This example illustrates the point that both Golfinia species are typical of the benthic fauna of the Barents Sea and form quantitatively comparable populations. As in the case of Nephasoma species, there are methodological reasons for the underestimation of the role of G. v. vulgaris in the biocoenotic structure of the Barents Sea bottom fauna. Both Golfingia species (G. v. vulgaris and G. m. margaritacea) are morphologically highly variable. At the same time, there are only a few size and

morphological differences between them. As a rule, therefore, field identification without special skills is difficult. Large individuals in particular are hard to identify because their STA-9090 in vitro basic external taxonomic

characteristics differ only marginally: the presence of hooks on the introvert and the skin texture. Furthermore, in the field key for marine benthic organisms ( Gayevskaya 1948) commonly used on Russian scientific cruises, G. v. vulgaris is absent from the identification key of the Sipuncula of the Russian Arctic. As a result, the fact that G. v. vulgaris was present in the sipunculan fauna of this region was ignored in most benthic investigations in the Barents Sea, and all large sipunculan individuals of the Golfingia genus were automatically recorded as G. m. margaritacea, presumed to be a single species, widely distributed in this area. As Denisenko (2007) pointed out, very the biomass and distribution pattern of sipunculans in the Barents Sea (in common with other species and groups of benthic organisms) evolved to a remarkable extent during the course of the past century. In particular, Denisenko found that the Gephyrea biomass had decreased significantly in the northern and central parts of the Barents Sea over the period from 1968–1970 to 2003. According to his data (Denisenko 2007), the mean Gephyrea biomass declined almost five fold in this period, from 12.9 ± 3.0 to 2.6 ± 0.6 g m− 2.