Variations in Rates of Biological Production in the Beaufort Gyre as the Arctic Changes: Rates From 2011 to 2016

Abstract

The Arctic Ocean is experiencing profound environmental changes as the climate warms. Understanding how these changes will affect Arctic biological productivity is key for predicting future Arctic ecosystems and the global CO2 balance. Here we use in situ gas measurements to quantify rates of gross oxygen production (GOP, total photosynthesis) and net community production (NCP, net CO2 drawdown by the biological pump) in the mixed layer in summer or fall from 2011 to 2016 in the Beaufort Gyre. NCP and GOP show spatial and temporal variations with higher values linked with lower concentrations of sea ice and increased upper ocean stratification. Mean rates of GOP range from 8 ± 1 to 54 ± 9 mmol O2·m−2·d−1 with the highest mean rates occurring in summer of 2012. Mean rates of NCP ranged from 1.3 ± 0.2 to 2.9 ± 0.5 mmol O2·m−2·d−1. The mean ratio of NCP/GOP, a measure of how efficiently the ecosystem is recycling its nutrients, ranged from 0.04 to 0.17, similar to ratios observed at lower latitudes. Additionally, a large increase in total photosynthesis that occurred in 2012, a year of historically low sea ice coverage, persisted for many years. Taken together, these data provide one of the most complete characterizations of interannual variations of biological productivity in this climatically important region, can serve as a baseline for future changes in rates of production, and give an intriguing glimpse of how this region of the Arctic may respond to future lack of sea ice.

Summertime Evolution of Net Community Production and CO2 Flux in the Western Arctic Ocean

“…When the ship crossed over the shelf break from the Chukchi Shelf into the basin, NCP decreased dramatically, by one to two orders of magnitudes to 0–2.5 mmol C m −2 d −1 . Our estimates of NCP in the basin agree well with observations (0.9–2.1 mmol C m −2 d −1 ) from discrete O 2 /Ar samples collected in this region in 2011–2016 (Ji et al., 2019) and with modeled NCP (0–3.5 mmol C m −2 d −1 ) (Islam et al., 2016). Similarly, the CO 2 flux results (‐1.6 to ‐2.2 mmol C m −2 d −1 ) are consistent with other observations in the Canada Basin (Evans et al., 2015; Islam et al., 2016).…”

Two Decades of Ocean Acidification in the Surface Waters of the Beaufort Gyre, Arctic Ocean: Effects of Sea Ice Melt and Retreat From 1997–2016

“…Stronger stratification inhibits nutrients resupply from below and constrain primary production (Carmack et al, ) and causes a deepening in subsurface chlorophyll maximum in the Canada Basin (McLaughlin & Carmack, ). At the surface, however, increased biological production was observed with retreat of sea ice and increased stratification in the Canada Basin, especially in 2012, within observation period of 2011 and 2016 (Ji et al, ). This may be the reason of increased ΔDIC diseq after 2007.…”

Inorganic Carbon and pCO2 Variability During Ice Formation in the Beaufort Gyre of the Canada Basin

“…There are almost no reports of NCP that overlap this region during winter and spring. NCP was 2–4 mmol• m −2 • day −1 in late summer 2015 when the mooring was recovered (Ji et al, ). The low salinity surface waters in the Canada Basin are generally without measurable nitrate during the summer (Brown et al, ).…”