Petryashov et at.: Macrobenthos Distribution in the Laptev Sea
175
~ Delrlloleeders
~ Saslonofaede,s
Figure 5: Distribution of macrozoobenthic trophic zones in the Laptev Sea.
grounds, i.e. only from sites off the islands Stolbovoi, Kotelnyi and Belkovskii (Golikov et
aI., 1990). There, sedentary organisms, such as the algae Phyllophora truncata, the sponge
Suberites domuncula, the hydroid Laphoeina maxima, the barnacle Balanus crenatus and the
bivalve Musculus corrugatus, predominated the communities at depths of 3 to 22 m. On
sediment grounds (sand and silt, without stones) in adjoining areas at the same depths, where
burrowing organisms, such as the bivalve molluscs Portlandia aestuariorum, P. arctica,
Tridonta borealis and Nicania montagui predominated, species numbers were 1.2 to 6 times
higher. In the southern and central Laptev Sea, the maximum numbers of species (50 to 100)
were noted mainly in sandy sediments (weight proportion of sand 45 to 70% and that of silt 9
to 31 %). Beside~' faunal composition, macrobenthic biomass is also strongly affected by seabed
granulometric characteristics, albeit in the opposite direction: biomass values were found to be 2
to 6.5 times higher on rocky and stony grounds than those (100 g m- 2 at maximum) reported
from adjacent sandy and silty sediment in the same depths.
Near-bottom water salinity
The strong salinity gradients caused by the strong riverine inflow into the Laptev Sea apparently
have the most important effect on macrobenthic distribution patterns. It is evident that the
indicator species of the major biocenoses, as outlined above (Figure 5) and also presented by
Sirenko et al. (1995), are confined to certain salinity ranges. This implies that the distribution of
the communities primarily reflects the extent of the spreading of brackish near-bottom waters
during summer.
The bivalve Portlandia aestuariorum, for instance, as well as the isopod Saduria entomon
glacialis and the mysid Mysis relicta, occur in the estuaries of the large rivers and are closely
175
~ Delrlloleeders
~ Saslonofaede,s
Figure 5: Distribution of macrozoobenthic trophic zones in the Laptev Sea.
grounds, i.e. only from sites off the islands Stolbovoi, Kotelnyi and Belkovskii (Golikov et
aI., 1990). There, sedentary organisms, such as the algae Phyllophora truncata, the sponge
Suberites domuncula, the hydroid Laphoeina maxima, the barnacle Balanus crenatus and the
bivalve Musculus corrugatus, predominated the communities at depths of 3 to 22 m. On
sediment grounds (sand and silt, without stones) in adjoining areas at the same depths, where
burrowing organisms, such as the bivalve molluscs Portlandia aestuariorum, P. arctica,
Tridonta borealis and Nicania montagui predominated, species numbers were 1.2 to 6 times
higher. In the southern and central Laptev Sea, the maximum numbers of species (50 to 100)
were noted mainly in sandy sediments (weight proportion of sand 45 to 70% and that of silt 9
to 31 %). Beside~' faunal composition, macrobenthic biomass is also strongly affected by seabed
granulometric characteristics, albeit in the opposite direction: biomass values were found to be 2
to 6.5 times higher on rocky and stony grounds than those (100 g m- 2 at maximum) reported
from adjacent sandy and silty sediment in the same depths.
Near-bottom water salinity
The strong salinity gradients caused by the strong riverine inflow into the Laptev Sea apparently
have the most important effect on macrobenthic distribution patterns. It is evident that the
indicator species of the major biocenoses, as outlined above (Figure 5) and also presented by
Sirenko et al. (1995), are confined to certain salinity ranges. This implies that the distribution of
the communities primarily reflects the extent of the spreading of brackish near-bottom waters
during summer.
The bivalve Portlandia aestuariorum, for instance, as well as the isopod Saduria entomon
glacialis and the mysid Mysis relicta, occur in the estuaries of the large rivers and are closely