Mass occurrence of Salpa fusiformis and records of the rare salps Cyclosalpa bakerii and Thetys vagina from northern Scotland

Gelatinous zooplankton including salps are an important but often overlooked component of marine ecosystems. This study documents a bloom of Salpa fusiformis at five locations to the north of mainland Scotland. The bloom was observed at Sula Stack, Sula Sgeir, North Rona and at two other locations to the west coast of the Orkney Islands. Salp blooms have the potential to deplete phytoplankton biomass, impacting on other zooplankton, including copepods and fish larvae. New records of two rare salps Cyclosalpa bakerii and Thetys vagina are also documented from North Rona and Skirza Head, Caithness. These specimens were observed in the aggregate (sexual) form. These observations represent the second record in the UK of C. bakerii and the third and fourth records of T. vagina.