Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer

Sian Henley, Elizabeth M. Jones, Hugh J. Venables, Michael P. Meredith, Yvonne L. Firing, Ribanna Dittrich, Sabrina Heiser, Jacqueline Stefels, Julie Dougans

Research output: Contribution to journalArticlepeer-review

Abstract

The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density. We use nutrient stoichiometric and isotopic approaches to invoke remineralization of organic matter, including nitrification below the euphotic surface layer, and dissolution of biogenic silica in deeper waters and potentially shelf sediment porewaters, as the primary drivers of cross-shelf enrichments. Regenerated nitrate and phosphate account for a significant proportion of the total pools of these nutrients in the upper ocean, with implications for the seasonal carbon sink. Understanding nutrient and carbon dynamics in this region now will inform predictions of future biogeochemical changes in the context of substantial variability and ongoing changes in the physical environment.
Original languageEnglish
JournalPhilosophical Transactions A: Mathematical, Physical and Engineering Sciences
Volume376
Issue number2122
Early online date14 May 2018
DOIs
Publication statusPublished - 28 Jun 2018

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