Atlantic CPR survey pulled a Hardy plankton recorder (Fig. 16.16) from commercial
vessels on standard routes, collecting plankton in serial fashion on rolls of gauze.
These rolls have been analyzed on a regular basis in a standard way for over 50 years.
The program is kept going currently by the private Sir Alister Hardy Foundation for
Ocean Science (SAHFOS) located at Plymouth, England. CalCOFI sampled offshore
from California on onshore–offshore lines of stations spaced every 40 nautical miles
using research vessels and standard ring or bongo nets. Time intervals between
CalCOFI surveys have varied from monthly in some early years to quarterly in recent
decades, with some longer gaps. The Japanese collections were 150–0 m vertical
hauls with 0.45 m ring-nets with 333 μm mesh, made all around Japan and east to the
date line in huge numbers from about 1950 to present. Initially, they were only
examined for biomass, a project of Kazuko Odate. Recent re-evaluations have been
called “the Odate Project”. All three series show long-term changes in stocks of
plankton, and consistently the changes follow multi-year sequences of changing wind
patterns, ocean temperatures and variations of circulation. The changes are generally
termed “oscillations” and characterized by indices, the North Atlantic Oscillation
(NAO), and the Pacific Decadal Oscillation (PDO). There are other named
“oscillations”.
Fig. 16.16 Sketch of a Hardy continuous plankton recorder (CPR).
(^) (After Hardy 1970.)