Coherent Sign Switching in Multiyear Trends of Microbial Plankton
William K. W. Li,*
W. Glen Harrison,
Erica J. H. Head
Since the 1990s, phytoplankton biomass on the continental shelf of Nova Scotia and in the Labrador Sea has undergone sustained changes in the spring and fall, which are accompanied by changes in bacterioplankton that are dampened in amplitude but coherent in the direction of change. A reversal of trend in biomass change, so-called sign switching, occurs both in time and in space. Thus, whenever (spring or fall) and wherever (Scotian Shelf or Labrador Sea) phytoplankton increase or decrease, so also does bacterioplankton. This tandem sign switch indicates coupling of the trophic levels at a multiyear time scale and contributes to an ecological fingerprint of systemwide forcing.
Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada.
* To whom correspondence should be addressed. E-mail: LiB{at}mar.dfo-mpo.gc.ca
