ИСТИНА

The species composition, diversity and abundance of the native Caspian fauna are presently under severe pressure from invasive species and anthropogenic impact. However, the magnitude and rate of diversity decline and abundance loss can only be estimated based on comparison with communities that lived before the onset of the crisis. An in-situ mollusc fauna retrieved from late Khazarian (early Late Pleistocene) deposits at Selitrennoye (Astrakhan province, Russia) provides a snapshot of a natural Caspian assemblage that lived under similar circumstances as during the current interglacial. The fauna is almost entirely composed of endemic species. In total, 24 gastropod and 17 bivalve species were found. The fauna represents an anomalohaline lake community that lived on a sandy floor at a water depth of approximately 10 m. The richness of the fauna is in great contrast with the largely depleted and invasives-dominated Caspian fauna of today. The Selitrennoye assemblage serves as a natural baseline fauna of pre-invasive influence and underlines the huge magnitude of the current biodiversity crisis.