First records of Pectinatella magnifica (Leidy, 1851) (Bryozoa: Plumatellida: Pectinatellidae) in the Bulgarian shoreline zone of the Danube River.
The magnificent bryozoan Pectinatella magnifica is a freshwater invertebrate species, which forms large gelatinous colonies that grow attached to submerged surfaces such as rocks or branches. This species is native to eastern North America; in the 19th century, it was introduced to Europe, although for about 100 years its distribution was limited mainly to Central Europe. In the 2000s, the findings of high number of colonies were reported in the Middle and Lower Danube River and the Danube Delta. During Joint Danube Survey 3 (JDS3) in 2013, P. magnifica was recorded at nine sites from Hungary to Romania, the only record in the Bulgarian - Romanian sector was downstream of the town of Kozloduy (685 rkm), at about 30 m from the border on the Romanian side. We report the first findings of P. magnifica in the Bulgarian shoreline zone of the Danube River and the first findings for Bulgaria. The sampling was conducted in July - October 2019, along the Danube and adjacent water bodies in Bulgaria, in the frame of JDS4. Pectinatella magnifica was recorded at two sites. In August, a big colony was found flowing in an open canal near the town of Vidin (790 rkm). In October, numerous colonies were found at the same site. They had smaller size and were attached to the branches of fallen trees. The species was also caught with fishing nets upstream of the village of Archar (771 rkm). Regular monitoring of the population status and spread of the species are needed in order to take appropriate measures to prevent the range extension and the negative impact of P. magnifica in Bulgaria.