Assessing net primary production in the northwestern Barents Sea using in situ, remote sensing and modelling approaches
Date
2023
Authors
de la Guardia, Laura Castro
Fariñas, Tania Hernández
Marchese, Christian
Amargant-Arumí, Martí
Myers, Paul G.
Bélanger, Simon
Assmy, Philipp
Gradinger, Rolf
Duarte, Pedro
Journal Title
Journal ISSN
Volume Title
Publisher
Progress in Oceanography
Abstract
The northwestern Barents Sea (NW-BS) is a highly productive region within the transitional zones of an Atlantic to Arctic-dominated marine ecosystem. The steep latitudinal gradients in sea ice concentration, Atlantic and Arctic Water, offer an opportunity to test hypotheses on physical drivers of spatial and temporal variability of net primary production (NPP). However, quantifying NPP in such a large ocean region can be challenged by the lack of in situ measurements with high spatial and temporal resolution, and gaps in remote sensing estimates due to the presence of clouds and sea ice, and assumptions regarding the depth distribution of alga biomass. Without reliable data to evaluate models, filling these gaps with numerical models is limited by the model representation of the physical environment and its assumptions about the relationships between NPP and its main limiting factors. Hence, within the framework of the Nansen Legacy Project, we combined in situ measurements, remote sensing, and model simulations to constrain the estimates of phytoplankton NPP in the NW-BS. The region was subdivided into Atlantic, Subarctic, and Arctic subregions on the basis of different phytoplankton phenology. In 2004 there was a significant regime change in the Atlantic subregion that resulted in a step-increase in NPP in tandem with a step-decrease in sea ice concentration. Contrary to results from other Arctic seas, this study does not find any long term trends in NPP despite changes in the physical environment. Mixing was the main driver of simulated annual NPP in the Atlantic subregion, while light and nutrients drove annual NPP in the Subarctic and Arctic subregions. The multi-source estimate of annual NPP ranged 79–118gCm−2yr−1 in the Atlantic, 74–82gCm−2yr−1 in the Subarctic, and 19–47gCm−2yr−1 in the Arctic. The total NPP in the NW-BS region was estimated between 15 and 48TgCyr−1, which is 15–50% of the total NPP needed to sustain three of the most harvested fish species north of 62°N (roughly 90TgCyr−1). This research shows the importance of continuing to strive for better regional estimates of NPP.
Description
We acknowledge the excellent support received by the crew of RV Kronprins Haakon and the participating scientists of the Nansen Legacy field expeditions. The authors are grateful to the NEMO development team and the Drakkar project for providing the model and continuous guidance, the efforts of NASA Goddard Space Flight Center, Ocean Ecology Laboratory, the Ocean Biology Processing Group for maintaining Chl-A and SIC data sets, the Takuvik Research Laboratory based at the University of Laval for making available and maintaining the Takuvik NPP data, the Digital Research Alliance of Canada, Westgrid and Compute Canada (https://alliancecan.ca/en) and the Norwegian Research Infrastructure Services (NRIS) and Sigma2 (https://www.sigma2.no/) for computational resources to perform our analysis, simulations, and archival of model experiments. Special thanks to Tobias Vonnahme for conducting the 2018 NPP assessments onboard RV Kronprins Haakon, and to colleagues Melissa Chierici and Elizabeth Jones at the Institute of Marine Research, Norway and Agneta Fransson at the Norwegian Polar Institute, Tromsø for their support with the laboratory analysis. All authors approved the version of the manuscript to be published.
Keywords
Net primary production, Northwestern Barents Sea, Bioregionalization, Nansen Legacy
Citation
de la Guardia, L. C., Fariñas, T. H., Marchese, C., Amargant-Arumí, M., Myers, P. G., Bélanger, S., ... Duarte, P. (2023). Assessing net primary production in the northwestern Barents Sea using in situ, remote sensing and modelling approaches. Progress in Oceanography, 219, 103160. https://doi.org/10.1016/j.pocean.2023.103160