Decrease in water clarity of the southern and central North Sea during the 20th century

Capuzzo, Elisa, Stephens, David, Silva, Tiago, Barry, Jon and Forster, Rodney M. (2015) Decrease in water clarity of the southern and central North Sea during the 20th century. Global Change Biology, 21 (6). pp. 2206-2214. ISSN 1354-1013

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Abstract

Light in the marine environment is a key environmental variable coupling physics to marine biogeochemistry and ecology. Weak light penetration reduces light available for photosynthesis, changing energy fluxes through the marine food web. Based on published and unpublished data, this study shows that the central and southern North Sea has become significantly less clear over the second half of the 20th century. In particular, in the different regions and seasons investigated, the average Secchi depth pre-1950 decreased between 25% and 75% compared to the average Secchi depth post-1950. Consequently, in summer pre-1950, most (74%) of the sea floor in the permanently mixed area off East Anglia was within the photic zone. For the last 25+ years, changes in water clarity were more likely driven by an increase in the concentration of suspended sediments, rather than phytoplankton. We suggest that a combination of causes have contributed to this increase in suspended sediments such as changes in sea-bed communities and in weather patterns, decreased sink of sediments in estuaries, and increased coastal erosion. A predicted future increase in storminess (Beniston et al., 2007; Kovats et al., 2014) could enhance the concentration of suspended sediments in the water column and consequently lead to a further decrease in clarity, with potential impacts on phytoplankton production, CO2 fluxes, and fishery production.

Item Type:	Article
Additional Information:	Publisher Copyright: © 2015 John Wiley & Sons Ltd.
Uncontrolled Keywords:	chlorophyll,coastal seas,long-term changes,north sea,secchi disk,suspended particulate materials,water clarity,global and planetary change,environmental chemistry,ecology,environmental science(all),sdg 14 - life below water ,/dk/atira/pure/subjectarea/asjc/2300/2306
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Collaborative Centre for Sustainable Use of the Seas
Related URLs:	http://www.scopus.com/inward/record.url?...
Depositing User:	LivePure Connector
Date Deposited:	16 Feb 2026 14:31
Last Modified:	23 Feb 2026 01:06
URI:	https://ueaeprints.uea.ac.uk/id/eprint/101948
DOI:	10.1111/gcb.12854

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