Abstract
Segmentina nitida Müller 1774 is a freshwater snail which was
formerly widespread throughout England and south Wales. Since the 1840s
it has seen a rapid decline in its range which has been attributed to
deteriorating water quality due to nutrient enrichment, lowering of
water tables and over-management of the ditches in which it resides.Segmentina nitida has therefore been identified as a UK
Biodiversity Action Plan (UKBAP) priority species which recommends
further research for its conservation. Here we have developed a Taqman
based qPCR eDNA assay for the detection of S. nitida at the
Stodmarsh National Nature Reserve and compared the results with a manual
survey of the ditches at this location. Our eDNA analysis exhibited an
observed percentage agreement of 84% with a kappa coefficient of
agreement between manual and eDNA surveys of 0.56. Three ditches
determined to be negative for Segmentina nitida by eDNA analysis
were manual survey positive, and a further two ditches that were
negative by manual survey were positive by eDNA analysis revealing the
potential for improved overall detection rates using a combination of
manual and eDNA methodologies. eDNA analysis could therefore augment
manual survey techniques for Segmentina nitida as a relatively
quick and inexpensive tool for collecting presence and distribution data
that could be used to inform manual surveys and management of ditches.