Abstract:Arctic marine ecosystems are undergoing rapid correction in response to multiple expressions of climate change, but the consequences of altered biodiversity for the sequestration, transformation and storage of nutrients are poorly constrained. Here, we determine the bioturbation activity of sediment-dwelling invertebrate communities over two consecutive summers that contrasted in sea-ice extent along a transect intersecting the polar front. We find a clear separation in community composition at the polar front… Show more
“…S4 ). Moreover, the stable redox interface also indicates only minor disturbance of the sediment column through bioturbation, which is in accordance with a recently reported very shallow mean bioturbation depth (<1 cm) at all investigated stations 40 . Fig.…”
Burial of organic material in marine sediments represents a dominant natural mechanism of long-term carbon sequestration globally, but critical aspects of this carbon sink remain unresolved. Investigation of surface sediments led to the proposition that on average 10-20% of sedimentary organic carbon is stabilised and physically protected against microbial degradation through binding to reactive metal (e.g. iron and manganese) oxides. Here we examine the long-term efficiency of this rusty carbon sink by analysing the chemical composition of sediments and pore waters from four locations in the Barents Sea. Our findings show that the carbon-iron coupling persists below the uppermost, oxygenated sediment layer over thousands of years. We further propose that authigenic coprecipitation is not the dominant factor of the carbon-iron bounding in these Arctic shelf sediments and that a substantial fraction of the organic carbon is already bound to reactive iron prior deposition on the seafloor.
“…S4 ). Moreover, the stable redox interface also indicates only minor disturbance of the sediment column through bioturbation, which is in accordance with a recently reported very shallow mean bioturbation depth (<1 cm) at all investigated stations 40 . Fig.…”
Burial of organic material in marine sediments represents a dominant natural mechanism of long-term carbon sequestration globally, but critical aspects of this carbon sink remain unresolved. Investigation of surface sediments led to the proposition that on average 10-20% of sedimentary organic carbon is stabilised and physically protected against microbial degradation through binding to reactive metal (e.g. iron and manganese) oxides. Here we examine the long-term efficiency of this rusty carbon sink by analysing the chemical composition of sediments and pore waters from four locations in the Barents Sea. Our findings show that the carbon-iron coupling persists below the uppermost, oxygenated sediment layer over thousands of years. We further propose that authigenic coprecipitation is not the dominant factor of the carbon-iron bounding in these Arctic shelf sediments and that a substantial fraction of the organic carbon is already bound to reactive iron prior deposition on the seafloor.
“…Although our analyses confirm a positive relationship between sea temperatures and decreasing latitude, it is important to emphasize that sea temperature is also influenced by local environmental cycles and other phenomena (e.g., depth, upwelling, El Niño) that can affect regional physiological responses. In this respect, it is noteworthy that the large degree of overlap of the Arctic and temperate latitudinal zones reflects the boreal origins of many benthic species (Piepenburg, 2005), and that the large degree of overlap in high POC in the Arctic and temperate regions reflects food availability to the benthos and species distribution (Solan et al., 2020). A key characteristic of the Arctic is the Atlantic influence and overlap of species distributions and physiological responses over the polar front (Piepenburg, 2005; Richard et al., 2012), which contrasts with the Antarctic, which is effectively isolated by the Antarctic Circumpolar Current from the southern temperate zone (Clarke & Crame, 2010) resulting in a relatively long evolutionary isolation of the Southern Ocean (Chown et al., 2015; Clarke et al., 2005; Crame et al., 2014).…”
Aim
Growth rates of organisms are routinely used to summarize physiological performance, but the consequences of local evolutionary history and ecology are largely missed by analyses on wide biogeographical scales. This broad approach has been commonly applied to other physiological parameters across terrestrial and aquatic environments. Here, we examine growth rates of marine bivalves across all biogeographical realms, latitude, and temperature, with analyses to determine regional effects on growth on global scales.
Location
Global: marine ecosystems.
Time period
1930–2018.
Major taxa
Bivalves.
Methods
We use a comprehensive data set of bivalve growth parameters (n = 966, 243 species) representing all biogeographical realms to calculate overall growth performances. We use these data with environmental temperature to analyse global patterns in growth, accounting for regional primary productivity and phylogeny using general additive mixed and linear models. The Arrhenius relationship and corresponding activation energies are used to quantify the sensitivity to temperature in each biogeographical realm and province.
Results
Our analyses show that bivalve growth demonstrates latitudinal asymmetry and exhibits nonlinear relationships with latitude. We find that overall growth performance is affected by temperature and particulate organic carbon, but the form of these relationships differs with phylogeny. Growth is slower and more sensitive to increasing temperature in the Antarctic than it is in the Arctic, and decreases with increasing temperature in some tropical realms, a previously unidentified and fundamental difference in growth and physiological sensitivity.
Main conclusions
Our findings provide compelling evidence that the widely used curvilinear relationship between temperature and growth rates in marine ectotherms is an inappropriate descriptor of thermal sensitivity, because it normalizes regional variations in physiological performance. Without a more detailed assessment of global physiological patterns, the responses of species to local variations associated with climate change will be under‐appreciated in global assessments of climate risk, minimizing the effectiveness of management and conservation.
“…The fate of fixed carbon is tightly linked to climate feedback mechanisms via sedimentary processes, such as bioturbation. Solan et al [34] examine how invertebrate faunal activity and associated ecosystem functioning is influenced by seasonal ice cover that affects food supply to the seafloor, and by mesoscale oceanographic features that influence benthic community structure. Their experiments, conducted over two consecutive summers along a transect intersecting the Barents Sea Polar Front, reveal that while faunal composition reflects proximity to Arctic versus boreal conditions, faunal activity is moderated by seasonal variations in sea ice extent that influence food supply to the benthos.…”
One contribution of 18 to a theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
