Abundance and distribution of meiofauna in the Chukchi Sea

The metazoan meiofauna in the Chukchi Sea were collected from seven shallow water stations (depths ranging 46 to 52 m) and five deep sea stations (depths ranging between 393 and 2 300 m) during the 4th Chinese National Arctic Research Expedition in 2010. The results showed that abundance of meiofauna was higher in shallow water sediments (average of 2 445 ind./(10 cm2)) than in deep sea sediments (407.06 ind./(10 cm2)). A UNIANOVA test for difference between the two different regions was highly significant (F=101.15, p<0.01). Nematodes were numerically dominant, representing (96.6±4.6)% of the total meiofaunal abundance at the shallow water stations and (98.90±1.42)% at deep sea stations. The number of higher taxonomic groups and abundance of meiofauna were higher at Stas CC1, CC4, and R06 near the Bering Strait and the continent, than at the rest of the shallow water and deep sea stations. The primary factors causing the differences were concentrations of nutrients P and Si of bottom seawater (R=0.831, p<0.003), followed by depth (R=-0.655, p<0.05) and sand fractions of sediments (R=0.632, p <0.05). The numbers of meiofauna on the 65 μm and 32 μm sieves were significantly higher than those on the rest of the screens. Differences in numbers of meiofauna retained on screens with different mesh openings were highly significant among all sampling stations (F=31.60, p<0.01). The highest numbers of individuals on screens with 32 μm mesh openings were found at deep sea stations. The number of meiofauna in the top 0-1, 1-2, and 2-4 cm segments constituted 84.4% of the total and was significantly higher than those in the bottom 4-6 and 6-10 cm segments (F=15, p<0.01).