Impact of Environmental Factors on the Formation of Soil-Mite (Acari) Assemblages on Coastal Marshes of Shokalsky Island, Kara Sea

摘要

At least 35 species of soil mites inhabit seashore biotopes of Shokalsky Island (73 degrees N) in the Kara Sea, Arctic Ocean. Twenty-six Acari species, including seven dominants, have been registered on a model marine marsh profile near the Pereprava River, and their distribution in soil samples collected at three hypsometric levels was analyzed. The following parameters of the soil samples were determined: salinity, granulometric composition, carbon and nitrogen content, and condition of the plant cover. Overall, the species diversity and total abundance of mites increase from lower to higher marsh levels. CCA ordination made it possible to identify a significant correlation between the abundance of Ameronothrus nigrofemoratus, a typical mycetophagous littoral dweller, and the concentration of chlorides in the soil specimens. The distribution of Svalbardia paludicola, Scutacarus offaliensis, Steneotarsonemus arcticus, and two Arctoseius species is primarily determined by drainage properties of the substrate (these mites prefer sandy grounds). Mites abundant at the upper littoral level primarily depend either on the phytomass content (the majority of species) or on concentrations of the main biogenic elements (Nanorchestes cf. gilli,Eustigmaeus cf. tjumeniensis, and Cheilostigmaeuslongisetosus) in the soil samples. The CCA ordination model explains 80.5% of the data dispersion. A comparative analysis of the species structure in mite communities shows that the assemblage inhabiting a high marsh level featuring a well-developed moss layer is the most diverse and distinct. Two acarocoenoses formed under plant associations occupying different marsh levels (ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae) but on similar clayey grounds have the most similarity to each other. Apparently, this is due to the similar duration of seawater inundation periods determined by the drainage conditions.