Pontocaspian habitat polygon shapefiles from: Decline of unique Pontocaspian biodiversity in the Black Sea Basin: a review

The unique aquatic Pontocaspian (PC) biota of the Black Sea Basin (BSB) is
in decline. The lack of detailed knowledge on the status and trends of
species, populations and communities hampers a thorough risk assessment
and precludes effective conservation. This paper  reviews PC
biodiversity trends in the BSB ( Bulgaria, Romania, Moldova, Ukraine and
Russia) using endemic molluscs as a model group. We aim to assess changes
in PC habitats, community structure and species distribution over the past
century and to identify direct anthropogenic
threats. Presence/absence data of target mollusc species was
assembled from literature, reports and personal observations. Pontocaspian
biodiversity trends in the north-western BSB coastal regions were
established by comparing 20th and 21st century occurrences. Direct drivers
of habitat and biodiversity change were identified and documented. A
pronounced decline of PC species and communities is driven by a) damming
of rivers, b) habitat modifications that disturbed previous natural
salinity gradients and settings in the studied area c) pollution and
eutrophication, d) invasive alien species and e) climate change. Four out
of the 10 studied regions, namely, the Danube Delta – Razim Lake system,
Dniester Liman, Dnieper-Bug Estuary and Taganrog Bay-Don Delta contain the
entire spectrum of ecological conditions to support PC communities and
still host threatened endemic PC mollusc species. Distribution data is
incomplete, but the scale of deterioration of PC species and communities
is evident from the assembled data, as are major direct threats.
Pontocaspian biodiversity in the BSB is profoundly affected by human
activities. Standardised observation and collection data as well as
precise definition of PC biota and habitats are necessary for targeted
conservation actions. This study will help to set the research and policy
agenda required to improve data collection to accommodate effective
conservation of the unique PC biota.