Sea Slugs of Southern Norway: An example of citizens contributing to science

Sea slugs are a group of marine gastropod molluscs that are known by their various colours and shapes. They occur in all waters around the world and are a key target for underwater photographers due to their bonny appearance. In February 2018, the Norwegian Biodiversity Information Centre gave funding to projects that focus on biodiversity research in little-known or lesser studied animal groups. Since no dedicated research had been undertaken on sea slugs in southern Norway for nearly 80 years, the project received funding for a two-year period of research on sea slugs by help of citizen scientists.

The project aims to catalogue the diversity, geographical distribution, and ecology of sea slug species along Norway’s southern coastline, from Bergen to the border with Sweden, with a special focus on alien species and cryptic species complexes. The work is accomplished by actively involving locals from the various places in southern Norway to sample sea slugs, record ecological data, photograph specimens, and finally send them to the department of Natural History at the University Museum of Bergen. The entire project is run by the project leader Manuel A. E. Malaquias and the project coordinator Cessa Rauch, a contrasting structure compared to the previous introduced large-scale projects. The team uses social media to find and reach out to enthusiastic divers and invite them to become a part of the citizen science community which currently counts around 135 active members. To ensure appropriate data collection, the citizen scientists receive each their sampling kit with an instruction sheet, jars, fixative, other accessories and a flash drive with a spreadsheet for data entry and space to upload pictures that have been taken from alive specimens. This way the team makes sure to obtain sampled material that is connected to both the pictures and the spreadsheet data. In addition, the project gives sea slug courses and furthers regular discussions on social media platforms to establish to an educative collaborative environment.

Since the beginning of the project in February last year, material stored in the museum collections has been revised and newly collected specimens have been added. Prior to the project, the museum collection consisted of roughly 800 records, one record being one or several specimens assigned to a catalog number related to the University Museum of Bergen. Due to the high sampling effort by the team, the number of records has increased to more than 1200, whereof more than half are contributions by citizen scientists. By date, a total of 91 sea slug species are registered in the database. In addition to recordings on external morphology by photographs, nearly 600 specimens have been DNA barcoded and implemented in the Norwegian Barcode of Life database (NorBOL). The project’s progress is documented on the blog from the invertebrate collections at the University Museum of Bergen and has recently been published as an article in the journal The Malacologist (Rauch and Malaquias, 2019).

As part of the project, two cases of potential cryptic species complexes are recently studied, conducting additional genetic and anatomical studies using scanning electron microscopy. These studies are undertaken as master theses on Polycera quadrilineata (O. F. Müller, 1776), accomplished November 2019, and Jorunna tomentosa (Cuvier, 1804), accomplished by June 2020. Both projects were presented as posters on the World Congress of Malacology 2019 in Monterey Bay, California, whereof the latter was presented by me. In addition to a visualization of ongoing research by means of the posters, Cessa Rauch presented the Sea Slugs of Southern Norway project as part of a session on citizen science, demonstrating how effective data collection with eager citizen scientists can be accomplished in a short period of time.

Further reading:
Norwegian Barcode of Life
Norwegian Biodiversity Information Centre
Blog of the Invertebrate Collections

Rauch, C. and Malaquias, M. A. E. (2019) ‘Sea slugs of southern Norway - An example of citizens contributing to science’, The Malacologist, 73, pp. 23–27.

The photographs are taken by two of the project's most active members, Bjørnar Nygård and Anders Schouw.