Nudibranchia of the central coast of Norway

Research on the nudibranchiate fauna of the central coast of Norway has been conducted since 1997. The aim of the research is to register the diversity of nudibranchs within sectors 12-15 as described in Research Report 1997-1 for the Directorate of Nature Management (Brattegard & Holthe eds.). The central coast of Norway is chosen as study area because it will be naturally covered by NTNU, concerning both research and management. Many works on the nudibranchiate fauna of the Norwegian coast, both on taxonomy and individual species, have been published. In Norway there are recorded about 85 species of nudibranchs constituting all four suborders. Much of the work is mostly older literature (see Brøgger 1872; Friele & Hansen 1876; G. O. Sars 1878), which still must be given great importance when recent investigations are lacking. In the Trondheim fjord nudibranchs appear in great numbers, both in diversity and abundance, and about 50 species are recorded from this area. But exact information on abundance, nutrition and ecology is greatly needed. Løyning (1922), Larsen (1925) and Odhner (1907; 1922; 1926 and 1939) have described the appearance of different species along the coast of Norway. These studies are mainly based on preserved material. An important factor to this can be the difficulty of studying nudibranchs from seagoing vessels. Dons (1942a,b,c) has given a certain description of the nudibranchiate fauna of the littoral zone in the Trondheim fjord and Møre and Trøndelag. There has not been any research on the nudibranchiate fauna of Norway since then, but a few recent revisionary compilations based on earlier litterature (see Just & Edmunds 1985; Høisæther 1986). The distribution of different nudibranchiate species therefore show a great discontinuity in distribution, and recordings are widely scattered along the whole coast. The study of living individuals in situ gives a more accurate angle of reasearch on the ecology, and covers the more difficult sub-littoral zone hardly reached by seagoing vessels in middle Norway. Individuals are photographically recorded in situ, and are after identification preserved for furhter studies. The soft and frail body is an important factor concerning the difficulty of identifying preserved specimens. The use of living individuals gives a more accurate identification. The main aim of the research, constituting both a master degree and separate projects, is therefore to publish a distributional review on the nudibranchiate fauna of central Norway, and to reveal the ecology concerning these species. The research is based upon own material collected and upon material deposited at the Museum of Natural History, NTNU. There is also an aim of publishing a field-guide of the species represented in the area.