Hypoxia effects on fish in west Norwegian fjords: harnessing the power of multidisciplinary studies

Informations

Funding country

Norway

Acronym

-

URL

-

Start date

1/1/2020

End date

12/31/2024

Budget

1,476,000 EUR

Fundings

Abstract

Loss of oxygen linked to ocean warming has become a large concern worldwide. Oxygen is a key element in metabolic processes in animals, and oxygen loss can lead to changed vertical migration behaviors and reduce habitat volumes, affect fish physiology, challenge the immune system, increase the fish’s susceptibility to pathogens, change trophic interactions and growth, and have consequences for recruitment, population dynamics and communities in deep sea ecosystems. This project (HypOnFjordFish) uses deep West Norwegian fjords as natural infrastructures to generate new knowledge on effects of oxygen loss on mesopelagic and demersal fish communities. Such information is needed for sustainable management of marine resources, and for determining optimal coastal and fjord sites for fish farming, representing one of Norway’s largest, most successful industries. The open ocean as well as coastal waters, along continental margins, enclosed seas and fjords have lost oxygen over the past 50 years. This includes many west Norwegian fjords, such as Masfjorden where warming of the Atlantic waters has led to increased time between basin water renewals. Little is known on how oxygen loss affects marine ecosystems. Studies are difficult in open oceanic ecosystems but is more readily conducted in enclosed systems. The semi-enclosed West Norwegian fjords are unique in this respect. Own data from an annual field course at BIO UiB (BIO325) and this project show that the basin water in Masfjorden lost >60% of its oxygen in less than 8 years, a change that is more pronounced than reported from marine ecosystems elsewhere in the world. This suggests that west Norwegian fjords can be mor vulnerable to climate change than previously thought. Since the project started in 2020, we have been on six field campaigns (3 annual field courses for BIO325 & 3 project campaigns) where we have tracked distribution patterns of mesopelagic fish using acoustics, collected biological materials, water samples and measured light, temperature, oxygen and salinity in Masfjorden and 3 additional fjords. For Masfjorden these collections cover a time period prior to and during hypoxic conditions, but also just after basin water renewal which occurred late spring/early summer of 2021. All samples for all HypOnFjordFish work packages have been collected and data are synthesized into master files to allow for analyses of the changes in the communities and populations with time and response to oxygen status. Most biological materials have been or are under processing and are being explored by two PhD-students, one Postdoc and many MSci students (3 completed, 3+ starting) and Bachelor students research projects (BIO299). We do not yet know how the populations respond to oxygen loss. Responses can be marginal in populations with prior experience from hypoxia and that are adapted to low oxygen, but in fish populations experiencing acute hypoxia for the first time, life history challenges are likely. Project participants have been active on scientific meetings, and preliminary data were presented at the 53rd International Colloquium on Ocean Dynamics in Belgium. The two PhD-students Martine R Solås and Francesco Saltalamacchia wrote event report for SOLAS (https://www.solas-int.org/publications/publicatios-reader/issue-24-53rd-liege-colloquium-and-3rd-go2ne-open-conference-on-ocean-deoxygenation.html) after this meeting. Participants also presented at the annual meetings of the Fisheries Society of the British Isles and Ocean Scientists in Norway (Havforskermøtet). In addition, the project Postdoc Natalya Gallo gave an oral presentation at the British Ecological Society and MET Office meeting on Climate Science for Ecological Forecasting, and at the PICES and ICES conferences. Gallo was Event organiser and panel participant in UN Ocean Decade Virtual Laboratory Satellite Event titled, "The science we need for the healthy fjords we want: Challenges and opportunities for sustainable management of productive fjord ecosystems" in June 2022. Full recording of the event is available on Youtube: https://www.youtube.com/watch?v=WG3I5UoQQc0&feature=youtu.be Gallo was also Invited panel participant in UNFCCC COP26 event titled “Ocean Acidification in the NE Atlantic, Arctic, and Baltic Waters” organized by the Plymouth Marine Laboratory.