Changes in phytoplankton concentration now drive increased Arctic Ocean primary production

Abstract

<jats:p>Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.</jats:p>

Atlantic walrus signal latitudinal differences in the long-term decline of sea ice-derived carbon to benthic fauna in the Canadian Arctic

“…The decadal declines of δ 13 C Phe in Atlantic walrus from both study areas is six to eight times higher than the decrease of δ 13 C of dissolved inorganic carbon in Arctic marine waters (−0.11‰ per decade) attributed to increasing concentrations of anthropogenic CO 2 in the atmosphere known as the Suess effect [47]. Additionally, our decadal declines in δ 13 C Phe parallel estimates from [47] where the entire pool of δ 13 C of particulate organic carbon in the Arctic Ocean decreased by 0.6‰ per decade with declining sea ice in combination with increased phytoplankton primary productivity [5]. It is unlikely that bacterial and meiofaunal processes in the benthic substrate contributed to higher δ 13 C Phe values over time [48] since temporal decreases in δ 13 C Phe corresponded to that of temporal declines in H-Print values.…”

“…It is unlikely that bacterial and meiofaunal processes in the benthic substrate contributed to higher δ 13 C Phe values over time [48] since temporal decreases in δ 13 C Phe corresponded to that of temporal declines in H-Print values. From 1998 to 2018, both Jones Sound and Foxe Basin have undergone an increase in phytoplankton biomass [5] which in turn, sinks as phytodetritus to then be exploited by benthic consumers. Net primary productivity across the Arctic has increased by 57% from 1998 to 2018 due to increased phytoplankton biomass supported by an influx of new nutrient availability [5], however, it is unknown whether this ever-increasing phytoplankton production can subsidize the continual loss of sea ice algae for benthic consumers.…”

“…Second, the sea ice algal bloom is subsequently followed by a pronounced summer phytoplankton bloom that provides the majority of primary productivity to the Arctic marine environment [3]. Climate warming is increasing the intensity of phytoplankton blooms in relation to thinning sea ice, a longer growing season, an influx of new nutrients, and warmer ocean temperatures which has also facilitated a poleward shift of more temperate-associated species leading to a reorganization of the food web [4][5][6][7][8][9]. Moreover, the structure of rocky-bottom Arctic communities are undergoing ecological regime shifts with prominent increases in both macroalgal cover and abundance of benthic invertebrates [10].…”

Nitrate assimilation and regeneration in the Barents Sea: insights from nitrogen isotopes

“…It is an enclosed basin filled with waters from the Atlantic and Pacific Oceans, which provide varying concentrations of nutrients (Torres-Valdes et al, 2013). In turn, these nutrient supply pathways influence the distribution and extent of primary production throughout the Arctic Ocean (Lewis et al, 2020).…”

“…As the Arctic continues to warm and more sea ice is lost, phytoplankton growth will become less limited by light availability. Instead, nutrient availability, principally nitrate (Codispoti et al, 2013), may become the primary control on phytoplankton growth (Arrigo and van Dijken, 2015;Lewis et al, 2020). A greater understanding of how nitrate is supplied to the Arctic inflow shelves and on shelf nutrient dynamics is therefore imperative in order to predict changes to Arctic primary production and food web dynamics.…”