Unravelling diversity and abundance of freshwater fish in Svalbard through molecular-based monitoring

All living organisms are shedding DNA and RNA traces in their environment, for example through pieces of skin, hair, egg, blood or mucus. In aquatic habitats, it is possible to detect these traces by collecting water samples to identify all species living there. Also called environmental DNA (eDNA) and RNA (eRNA) based monitoring, this powerful and non invasive method allow to reliably inventory species in extreme and remote environments without needing to catch them. In this project, researchers from the Netherlands and from Norway will team up to sample two freshwater lakes in Svalbard in Spring, Summer, Autumn and Winter to monitoring the changes in the freshwater fish community across seasons in these fragile habitats, and to identify the invertebrate species that they prey on. In addition, using Arctic Charr fish as a model organism, we will assess whether the amount of eDNA and eRNA detected in the water can be link to the fish abundance obtained through fishing. This study aim to pave the way for the implementation of routine monitoring of Arctic lakes through eDNA and eRNA detection and quantification to assess fish presence and their abundance across seasons, and to identify newly migrating invasive species spreading as a result of global warming.

Within the scope of this international research network project between researchers from WUR (The Netherlands) and NHM-UiO, UNIS, NINA and Akvaplan-niva (Norway), we aim to conduct seasonal eDNA and eRNA samples in two freshwater lakes near Longyearbyen and Ny-Ålesund to detect and quantify anadromous fish species. We aim to pave the way for the implementation of routine monitoring of Arctic lakes through eDNA and eRNA detection and quantification to assess fish presence and relative abundance across seasons. We will collect eDNA and eRNA samples in Lake Søre Dieset and Lake Linné in Summer, Autumn and Winter 2024, as well as Spring 2025, alongside an ongoing monitoring program led by Akvaplan-niva to estimate Arctic Charr densities of these systems through traditional monitoring. Approx 300 samples (including negative controls) will be collected and analyzed through metabarcoding using 12S primers (targeting fish) and COI primers (targeting invertebrates) to recover DNA and RNA from fish and invertebrates. Following sequencing and bioinformatics processes and analysis, this will allow to identify the diversity of these lakes through seasons, identify the presence of potential new invasive species, and reconstruct food webs interactions. Then, these eDNA and eRNA samples will be analyzed using ddPCR and species specific primers targeting Arctic Char to quantify the levels of DNA and RNA in the sampled lakes across seasons. We will then investigate of these levels can be use as a proxy to estimate the abundance of Arctic Charr through seasons using the abundance data collected by Akvaplan-niva. This funding application seeks funding to cover travel and accommodation from mainland to Longyearbyen and in Ny-Ålesund for each sampling event (i.e. two researchers from the different collaborating institutions will team up for each sampling event to ensure fair distribution of workload amongst participants), and additional costs of metabarcoding and ddPCR analysis.