Around one third of current Arctic Ocean primary production sustained by rivers and coastal erosion

Abstract

Net primary production (NPP) is the foundation of the oceans’ ecosystems and the fisheries they support. In the Arctic Ocean, NPP is controlled by a complex interplay of light and nutrients supplied by upwelling as well as lateral inflows from adjacent oceans and land. But so far, the role of the input from land by rivers and coastal erosion has not been given much attention. Here, by upscaling observations from the six largest rivers and using measured coastal erosion rates, we construct a pan-Arctic, spatio-temporally resolved estimate of the land input of carbon and nutrients to the Arctic Ocean. Using an ocean-biogeochemical model, we estimate that this input fuels 28–51% of the current annual Arctic Ocean NPP. This strong enhancement of NPP is a consequence of efficient recycling of the land-derived nutrients on the vast Arctic shelves. Our results thus suggest that nutrient input from the land is a key process that will affect the future evolution of Arctic Ocean NPP.

Evaluation of ocean dimethylsulfide concentration and emission in CMIP6 models

“…1 and S1 of Lana et al, 2011), and many regions remain poorly documented. Thus, as pointed out by Tesdal et al (2016), small-scale features are transformed into large-scale ones by the interpolation procedure, and anomalous values observed at local scale could induce bias when extrapolated across data-sparse regions. This is illustrated by Hayashida et al (2020), who show that the entire Arctic region in L11 is based on extremely limited data (0 %-4 % areal coverage north of 60 • N).…”

“…Conversely, recent studies report on high DMS concentrations measured in the North Atlantic (Bell et al, 2021) and in a coastal station of the West Antarctic Peninsula or in the Ross Sea (Webb et al, 2019;del Valle et al, 2009), which are not represented in L11. To conclude, although L11 presents some weaknesses that are inherent to the original data and the interpolation methodology, it has been considered so far as a reference (Tesdal et al, 2016), and it is the only DMS climatology solely based on in situ measurements. It has also been widely used to calibrate or validate other DMS estimation techniques (see, for instance, Galí et al, 2019).…”

Rain-fed streams dilute inorganic nutrients but subsidise organic-matter-associated nutrients in coastal waters of the northeast Pacific Ocean

“…The Calvert and Hecate islands are characterised by bog forests and extensive wetlands and are located within the hypermaritime zone (i.e., rainfall-dominated outer coast) of the perhumid NPCTR (Meidinger and Pojar, 1991;Thompson et al, 2016). Mean annual 1981-2010 air temperature and precipitation near sea level on the islands were 8.93 ± 0.20 • C and 2800 ± 49 mm, respectively (http://www.…”

Projected increase of Arctic coastal erosion and its sensitivity to warming in the 21st Century

“…3). Hotspots of extreme erosion are also observed in the Beaufort Sea Coastal erosion is estimated to sustain about one fifth of the total Arctic marine primary production at present-climate conditions [25]. Therefore, the projected additional OC loss could have a substantial impact on the Arctic marine biogeochemistry.…”

“…The thawing of permafrost globally releases organic carbon (OC) and increases atmospheric and oceanic greenhouse gas concentrations, feeding back to further warming [20][21][22][23]. Arctic coastal erosion alone releases about as much OC as all the Arctic rivers combined [23,24], fueling about one-fifth of Arctic marine primary production [25]. Despite consistent improvements in the representation of permafrost dynamics [26,27], the current generation of Earth system models (ESMs) does not account for abrupt permafrost thaw, which may cause projections of OC losses to be largely underestimated [28,29].…”