Impact of freshwater runoff from the southwest Greenland Ice Sheet on fjord productivity since the late 19th century
Open Access
- 24 June 2022
- journal article
- research article
- Published by Copernicus GmbH in The Cryosphere
- Vol. 16 (6), 2471-2491
- https://doi.org/10.5194/tc-16-2471-2022
Abstract
Climate warming and the resulting acceleration of freshwater discharge from the Greenland Ice Sheet are impacting Arctic marine coastal ecosystems, with implications for their biological productivity. To accurately project the future of coastal ecosystems and place recent trends into perspective, palaeo-records are essential. Here, we show runoff estimates from the late 19th century to the present day for a large sub-Arctic fjord system (Nuup Kangerlua, southwest Greenland) influenced by both marine- and land-terminating glaciers. We followed a multiproxy approach to reconstruct spatial and temporal trends in primary production from four sediment core records, including diatom fluxes and assemblage composition changes and biogeochemical and sedimentological proxies (total organic carbon, nitrogen, ratio, biogenic silica, δ13C, δ15N, and grain-size distribution). We show that an abrupt increase in freshwater runoff in the mid-1990s was reflected by a 3-fold increase in biogenic silica fluxes in the glacier-proximal area of the fjord. In addition to increased productivity, freshwater runoff modulates the diatom assemblages and drives the dynamics and magnitude of the diatom spring bloom. Our records indicate that marine productivity is higher today than it has been at any point since the late 19th century and suggest that increased mass loss of the Greenland Ice Sheet may continue promoting high productivity levels at sites proximal to marine-terminating glaciers. We highlight the importance of palaeo-records in offering a unique temporal perspective on ice–ocean–ecosystem responses to climate forcing beyond existing remote sensing or monitoring time series.
Keywords
Funding Information
- Danmarks Frie Forskningsfond (9064-00039B)
- Geocenter Danmark (2018-5)
- European Commission
- Arctic Research Centre (n/a)
This publication has 74 references indexed in Scilit:
- Measuring Biogenic Silica in Marine Sediments and Suspended MatterPublished by Wiley ,2013
- Are phytoplankton blooms occurring earlier in the Arctic?Global Change Biology, 2010
- Habitat use of humpback whales in Godthaabsfjord, West Greenland, with implications for commercial exploitationJournal of the Marine Biological Association of the United Kingdom, 2010
- Comparing past and present climate – a tool to distinguish between natural and human-induced climate changeIOP Conference Series: Earth and Environmental Science, 2009
- Production of giant marine diatoms and their export at oceanic frontal zones: Implications for Si and C flux from stratified oceansGlobal Biogeochemical Cycles, 2006
- Physical and chemical predictors of diatom dissolution in freshwater and saline lake sediments in North America and West GreenlandLimnology and Oceanography, 2006
- Benthic diatoms of a high Arctic fjord (Young Sound, NE Greenland): importance for ecosystem primary productionMarine Ecology Progress Series, 2002
- Common Diatom Species in Arctic Spring Blooms: Their Distribution and AbundanceBotanica Marina, 2000
- The net phytoplankton in Kongsfjorden, Svalbard, July 1988, with general remarks on species composition of arctic phytoplanktonPolar Research, 1998
- The colorimetric determination of silicate with special reference to sea and natural watersAnalytica Chimica Acta, 1955