Abstract
Abstract. The effects of climate change on Arctic marine ecosystems and their biogeochemical cycles are difficult to predict given the complex physical, biological and chemical interactions among the ecosystem components. We studied benthic biogeochemical fluxes in the Arctic and the influence of short-term (seasonal to annual), long-term (annual to decadal) and other environmental variability on their spatial distribution to provide a baseline for estimates of the impact of future changes. In summer 2009, we measured fluxes of dissolved oxygen, nitrate, nitrite, ammonia, soluble reactive phosphate and silicic acid at the sediment–water interface at eight sites in the southeastern Beaufort Sea at water depths from 45 to 580 m. The spatial pattern of the measured benthic boundary fluxes was heterogeneous. Multivariate analysis of flux data showed that no single or reduced combination of fluxes could explain the majority of spatial variation, indicating that oxygen flux is not representative of other nutrient sink–source dynamics. We tested the influence of eight environmental parameters on single benthic fluxes. Short-term environmental parameters (sinking flux of particulate organic carbon above the bottom, sediment surface Chl a) were most important for explaining oxygen, ammonium and nitrate fluxes. Long-term parameters (porosity, surface manganese and iron concentration, bottom water oxygen concentrations) together with δ13Corg signature explained most of the spatial variation in phosphate, nitrate and nitrite fluxes. Variation in pigments at the sediment surface was most important to explain variation in fluxes of silicic acid. In a model including all fluxes synchronously, the overall spatial distribution could be best explained (57%) by the combination of sediment Chl a, phaeopigments, δ13Corg, surficial manganese and bottom water oxygen concentration. We conclude that it is necessary to consider long-term environmental variability along with rapidly ongoing environmental changes to predict the flux of oxygen and nutrients across Arctic sediments even at short timescales. Our results contribute to improve ecological models predicting the impact of climate change on the functioning of marine ecosystems.
Highlights
The CryosphereIncreased effort is put into estimating climate change effects in Arctic ecosystems (ACIA, 2004; Barber et al, 2012; Wassmann et al, 2011)
Link et al.: Multivariate benthic ecosystem functioning in the Arctic play a pivotal role in the remineralisation of the organic matter settling to the seafloor, what we define as the benthic remineralisation function
We discuss their spatial pattern and influences of the environment at different timescales with the aim to estimate dynamics of benthic ecosystem functioning related to variation in the quality and quantity of organic matter export
Summary
The CryosphereIncreased effort is put into estimating climate change effects in Arctic ecosystems (ACIA, 2004; Barber et al, 2012; Wassmann et al, 2011). H. Link et al.: Multivariate benthic ecosystem functioning in the Arctic play a pivotal role in the remineralisation of the organic matter settling to the seafloor, what we define as the benthic remineralisation function. Link et al.: Multivariate benthic ecosystem functioning in the Arctic play a pivotal role in the remineralisation of the organic matter settling to the seafloor, what we define as the benthic remineralisation function Sediments can be both a major source of nutrients and carbon to the overlying water column or/and a significant sink (Schulz, 2006). Evidence is increasing that benthic nutrient remineralisation is not directly correlated with oxygen uptake, in coastal and shelf environments (Braeckman et al, 2010; Davenport et al, 2012; Holstein and Hensen, 2010; Michaud et al, 2009; Robert et al, 2013). An evaluation of benthic remineralisation function and its relation with oxygen uptake in the Arctic is needed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
