Addressing the aquatic vertebrate community of Vågsfjorden 2019 with the use of Environmental DNA

Abstract

In order to estimate biodiversity or do species counts, detramental techniques such as trawling or longlining have been used. Lately techniques used to monitor, such as baited remote underwater video systems and environmental DNA have been tested as possible methods to investigate species richness and abundance, the latter which will be used in this thesis. Using eDNA methodology, a northern Norwegian fjord was investigated in order to detect the species richness throughout a year at two depths. In addition, an attempt was made to explain the variation of eDNA reads by correlating it to biotic and abiotic factors. The fjord showed presence of 40 different taxonomical units (MOTUs). The fish community were unevenly distributed, where a few MOTUs (Pollachius virens, Hippoglossus sp., Gadus morhua, Salmo salar, and Molva molva) were present most dates in both depths throughout the year. On contrast 19 MOTUs were present one to three times throughout the year, where 12 MOTUs were detected only once. The spring season contained more species and higher numbers of eDNA than the rest of the year. This might have been as animals gathered in order to predate upon either spawning Gadus morhua, their eggs, or to graze on the increased primary production during this period. The 20m samples and 350m samples were more similar during the spring turnover period, but it is hard to say if this is a factor of turnover, as high numbers of reads were also associated with this period indicating a higher amount of biomass in total. The use of eDNA succeeded in providing a picture of the Vågsfjorden biodiversity. For very numerous animals the method was applicable to associate with biological traits, but not for rarer animals.