Responsible: Olli Hyvärinen
Researchers: Alexander Eiler, Bente Edvardsen, Simon Hasselø Kline, Eivind Stensrud, Halvor Knutsen, Sissel Jentoft, Ketil Hylland.
Background
Sustainable management of marine resources necessitates robust long-term monitoring of biodiversity. Traditional monitoring methods such as fisheries catch-data
and acoustic surveys have been essential for informing management. However, these
methods are generally costly, time-consuming and patchy. Furthermore, these methods do not yield the detailed information on whole food webs that are needed to predict how entire ecosystems respond to changing oceans. In this project, we aim to develop and evaluate two methods to characterize the food web in Oslofjord. These
methods are (1) identifying the short and long-term diets and trophic position of top
predatory fish and copepod zooplankton through dietary DNA and tissue stable isotope analyses and (2) seawater sampling, filtration and environmental DNA metabarcoding. Developing improved cost-effective methods to monitor food web responses to changing oceans is crucial for informing evidence-based policy and management for the conservation and sustainable use of marine resources.
Methods
1. Dietary studies
Dietary DNA (dDNA) and tissue isotope analyses of three
model fish species and one common copepod species. We selected the
species below because of their contrasting ecological role and different
microbiomes.
A) We sample the gut from individuals of the different species covering all size classes. We will extract the guts for dietary DNA and perform DNA metabarcoding. This will yield information on the immediate diet of the organism and allow us to track the seasonal patterns in the diets of different species and size classes.
B) We sample the tissue of the different species covering all size classes. We will look at the bulk tissue carbon and nitrogen isotopic signatures, which will inform us about the long-term trophic position of the organism. We will also investigate the carbon and nitrogen isotopic signatures in preselected essential and non-essential amino acids. Because essential amino acids are produced by primary producers, and they must be obtained by the fish through their diet, this will inform us about the source of the primary production in the food web.
2. Environmental DNA (eDNA)
We aim to perform environmental DNA metabarcoding from seawater samples filtered through different sized filters (0.22 m and 0.8 m). We will deploy a suite of primers targetting the whole tree of life from bacteria and acrhae to eucaryotic protists, metazoa, fish, sea birds and marine mammals.
Study system
Our focal study area is the Oslofjord in southern Norway. Because of the large human
impact on the fjord system, it makes Oslo fjord a convenient model system to study the impact of environmental change on marine food webs.