Continued glacial retreat linked to changing macronutrient supply along the West Antarctic Peninsula

Spatiotemporal variability of dissolved inorganic macronutrients along the northern Antarctic Peninsula (1996–2019)

“…High sea surface concentrations of nitrate (12–24 μ mol kg −1 ) and phosphate (1.0–1.6 μ mol kg −1 ) are observed offshore south of the northern Antarctic Peninsula (Hauri et al 2015), under strong influence of the Antarctic Circumpolar Current that carries Circumpolar Deep Water. Furthermore, high sea surface concentrations of DIN and phosphate (greater than 11.0 and 0.9 μ mol kg −1 , respectively) were found during summer at Marian Cove in the central basin of Bransfield Strait, which was associated with the strong influence of modified Circumpolar Deep Water intrusions (Jones et al 2023).…”

“…Local sources of nutrients are known to be important along the northern Antarctic Peninsula. Terrestrial input of iron (De Jong et al 2012; Ferreira et al 2020) and silicic acid (Hawkings et al 2017; Jones et al 2023) is well known over the Antarctic continental shelf. However, remineralized macronutrients after intense phytoplankton blooms in fjords that flow into the northern Antarctic Peninsula (Forsch et al 2021) can be injected into downstream regions, increasing DIN and phosphate concentrations (Jones et al 2023).…”

“…Terrestrial input of iron (De Jong et al 2012; Ferreira et al 2020) and silicic acid (Hawkings et al 2017; Jones et al 2023) is well known over the Antarctic continental shelf. However, remineralized macronutrients after intense phytoplankton blooms in fjords that flow into the northern Antarctic Peninsula (Forsch et al 2021) can be injected into downstream regions, increasing DIN and phosphate concentrations (Jones et al 2023). Moreover, the abrupt freshwater outflow from fjords increases the upper ocean stability and fertilizes the region with iron (Forsch et al 2021), triggering intense phytoplankton blooms downstream.…”

“…Moreover, the abrupt freshwater outflow from fjords increases the upper ocean stability and fertilizes the region with iron (Forsch et al 2021), triggering intense phytoplankton blooms downstream. Likewise, such favorable conditions for intense phytoplankton growth, mainly diatoms, are also triggered by glacial meltwater (Meredith et al 2022; Jones et al 2023) and sea ice melting (Mendes et al 2018; Costa et al 2020). Such high primary productivity sustains a high zooplankton density (Henley et al 2019; Plum et al 2020), which can increase the concentration of remineralized macronutrients locally and downstream via sloppy feeding (Ratnarajah and Bowie 2016), as well as intensifying the recycling of organic matter (Avelina et al 2020) at their resting depths by respiration and throughout their depth habitat range by fecal pellet production (Whitehouse et al 2011; Henley et al 2020).…”

“…The importance of nutrients to fuel the primary production that underpins the food web has been emphasized in some studies throughout the northern Antarctic Peninsula (Anadón and Estrada 2002; Henley et al 2019), as well as the impact of mesoscale processes on nutrient supply (Forsch et al 2021; Meredith et al 2022). Furthermore, some studies have shown that macronutrient concentrations south of the northern Antarctic Peninsula, at Marguerite and Ryder Bays, are mainly regulated by Circumpolar Deep Water intrusions (Henley et al 2017, 2018; Jones et al 2023), nutrient regeneration and local features such as deep glacially scoured canyons (Henley et al 2019 and references therein). Nevertheless, little is known about what regulates the spatial and temporal variability of macronutrient distributions due to the high complexity and heterogeneity biogeochemical provinces along the northern Antarctic Peninsula.…”