Seasonal Dynamics of Oribatid Mites (Acari, Oribatida) in a Bog in Poland

TLDR: Two species, Liacarus acutus and Dissorhina ornata peloponnesiaca are reported for the first time for the Polish fauna; both were found only in one season showing that sampling throughout the year is important to determine biodiversity.

Abstract: The Oribatida is the most abundant and diverse group of mites and one of the most abundant groups of invertebrates in bogs, important for the decomposition of organic matter. These mites are relatively poorly studied in bogs and their seasonal dynamics have never been investigated in detail throughout the year. The study was performed on the periphery of a bog pond located in north-eastern Poland during four seasons. The analyses were based on 25,128 mites comprising 24,393 Oribatida from 66 species. The second most abundant group was Prostigmata, followed by Mesostigmata. The density of mites and of Oribatida reached a maximum in autumn (ca. 90,000 individuals/m2), and was nearly two-fold greater than in other seasons. In autumn, spring and summer the oribatid communities were dominated by the aquatic genus Limnozetes, while in winter these mites were replaced by species with lower water demands (e.g. Liochthonius alpestris, Mainothrus badius, Scheloribates laevigatus) or eurytopic ones (e.g. Oppiella nova). Oribatida reproduced in all seasons with the greatest proportion of juveniles (25%) observed in winter. Two species, Liacarus acutus and Dissorhina ornata peloponnesiaca are reported for the first time for the Polish fauna; both were found only in one season showing that sampling throughout the year is important to determine biodiversity.