Missing and misidentified museum specimens hinder long-term monitoring: a case study of shell-bearing gastropods from the Kola Meridian transect, Barents Sea

The consequences of global change cannot be estimated without long-term monitoring programmes. The Kola Meridian transect, along 33°30’E, in the Barents Sea is the longest term monitoring area in the Arctic. Regular (usually annual) hydrobiological benthic surveys along that transect have been performed since 1899. Materials stored in museum collections remain the main source of the faunistic information obtained during the surveys, while only a minor part of these data was published. We reexamined all samples of shell-bearing gastropods from the Kola Meridian stored at the Zoological Institute of the Russian Academy of Sciences and at Saint Petersburg State University. We found only 159 museum lots from 73 samples, which constitute a very small portion of the total material collected along the transect. Approximately one-third of them (54 lots) was misidentified or includes individuals that cannot be identified at species level. The species composition revealed by museum materials differs substantially from published checklists. Majority of the studied samples (40) were collected during 1899–1920. However, the extant collections do not provide a reliable baseline for the Kola Meridian. We propose that the storage of zoological material in public collections should be considered as an essential part of long-term monitoring programmes.