Phaeocystis colony distribution in the North Atlantic Ocean since 1948, and interpretation of long-term changes in the Phaeocystis hotspot in the North Sea

W. W.C. Gieskes, S. C. Leterme, H. Peletier, M. Edwards, P. C. Reid

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

1 Citation (Scopus)

Abstract

Monitoring of Phaeocystis since 1948 during the Continuous Plankton Recorder survey indicates that over the last 5.5 decades the distribution of its colonies in the North Atlantic Ocean was not restricted to neritic waters: occurrence was also recorded in the open Atlantic regions sampled, most frequently in the spring. Apparently, environmental conditions in open ocean waters, also those far offshore, are suitable for complete lifecycle development of colonies (the only stage recorded in the survey). In the North Sea the frequency of occurrence was also highest in spring. Its southeastern part was the Phaeocystis abundance hotspot of the whole area covered by the survey. Frequency was especially high before the 1960s and after the 1980s, i.e., in the periods when anthropogenic nutrient enrichment was relatively low. Changes in eutrophication have obviously not been a major cause of long-term Phaeocystis variation in the southeastern North Sea, where total phytoplankton biomass was related significantly to river discharge. Evidence is presented for the suggestion that Phaeocystis abundance in the southern North Sea is to a large extent determined by the amount of Atlantic Ocean water flushed in through the Dover Strait. Since Phaeocystis plays a key role in element fluxes relevant to climate the results presented here have implications for biogeochemical models of cycling of carbon and sulphur. Sea-to-air exchange of CO2 and dimethyl sulphide (DMS) has been calculated on the basis of measurements during single-year cruises. The considerable annual variation in phytoplankton and in its Phaeocystis component reported here does not warrant extrapolation of such figures.

Original languageEnglish
Title of host publicationPhaeocystis, Major Link in the Biogeochemical Cycling of Climate-Relevant Elements
EditorsM A van Leeuwe, J Stefels, S Belviso, C Lancelot, P G Verity, W W C Gieskes
Place of PublicationThe Netherlands
PublisherSpringer Netherlands
Pages49-60
Number of pages12
ISBN (Electronic)9781402062148
ISBN (Print)9781402062131
DOIs
Publication statusPublished - 1 Dec 2007
Externally publishedYes

Keywords

  • Annual variation
  • North Atlantic-wide
  • North Sea hotspot
  • Phaeocystis

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