(^) It has been argued (e.g. Mackas & Beaugrand 2010) that mesozooplankton
abundance and species composition are among the more accessible indices of climate
response of marine ecosystems. Life cycles are mostly less than a year, hence stocks
will be quite responsive to interannual climate changes. Yet they are long enough that
modest sampling frequency (say, monthly) can indicate shifts. Some short time-series,
like the approximately monthly HOTS zooplankton samplings, show substantial
abundance changes. In that subtropical area (Sheridan & Landry 2004) net
zooplankton doubled in the eight years from 1994 to 2002 (Fig. 11.32), an increase
among small animals remaining near the surface day and night and affecting about
equally the summer peaks and winter lows. There was no increase in night samples of
diel migrators. Whether that change is part of a longer cycle or a really long-term
change is always an issue with short time-series (and all time-series of direct
biological observations are too short).
(^) There are some time-series of population estimates in the sea that extend to decades.
Three for zooplankton are the continuous plankton recorder (CPR) survey out of the
United Kingdom, which was established about 1952 and fully operational by about
1958, the California Cooperative Oceanic Fisheries Investigations (CalCOFI) survey,
which started in 1950, and more than 50 years of collections by Japanese Fishery
Agency scientists, the “Odate collection”, that are being reanalyzed. The North
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