Norwegian nudibranchs – about the project

Norwegian nudibranchs is the title of a research project Jussi Evertsen and I have been running on and off since 1997. The main aim has been to study the diversity of nudibranchs in Norwegian waters. Number of species, their distribution and abundance was the aims from the start. After several years with this scope the project was expanded to encompass DNA barcoding of the entire Norwegian nudibranch fauna, as well as taxonomy of selected species. In the years to come taxonomy of species, species groups, and phylogeny will be the main aims of the project.

Jussi Evertsen and Torkild Bakken after a successful dive looking for nudibranchs. Photo: Petter F. Schmedling

We are about to finis analyses of results from the DNA barcoding studies. Results from the DNA barcoding demonstrate several taxonomic challenges and hidden diversity. Cryptic species is almost certainly present, but this must await further analyses, beyond what we do by the help of barcoding. That we had taxonomic challenges was not a surprise. Having worked on species found in Norwegian waters since 1997 this has been evident. Reports and hints in the literature clearly demonstrate that. What was more surprising was the number of additional species we seem to have in Norwegian waters. This has been revealed by DNA barcoding and further studies on each of the species or species groups are needed to reach conclusions.

We believe that results from molecular studies should be coupled with morphological characteristics, which we intend to do. The challenge in most cases is that taxonomic challenges require examination of type specimens. In many cases these may be difficult to obtain as many species were described as early as 1776. But there is hope as many museums have type specimens from the early 1800s.

How it all started

Flabellina pedata photographed at Sør-Gjæslingan in 1997. Photo: Torkild Bakken

The history how the nudibranch project started can be summarised as follows. As in many research projects it started by coincidence, in September 1997. In August that year I took part in a diving trip to the Sør-Gjæslingan archipelago in the Nord-Trøndelag County. There I found and identified Flabellina pedata based on the newly acquired book on British nudibranchs by Bernard Picton and Christine Morrow. According to a newly published account of marine benthic invertebrates in Norway this species had never been found as far north as this. At the same time Jussi started his work on a master thesis on ecology and reproduction biology of nudibranchs in the Trondheimsfjord and Svalbard. We found that no one had done anything on nudibranchs in Norway since the 1940s. It was obvious from the literature that the knowledge was poor in general, and especially in some geographical areas concerning nudibranchs. As we had the opportunity to dive, photograph in situ and to keep live specimens in aquaria with running sea water, we realised we easily could obtain a lot of new information on this group being so hard to identify from preserved specimens. From the start we have worked on the project on and off since then.

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