standardization of environmental data and information - International ...

There was an increasing appreciation that productivity regimes in the open
ocean varied on seasonal, interannual (e.g., El Niño) and decadal scales,
including specific decadal oscillation, and they were likely to vary with global
warming. A recent study showed that changes in temperature of the
surface ocean altered the amount of carbon exported from it, so that even
on global warming time scales there would be changes. The major
challenge was to understand natural patterns of variability in time and
space in these systems in order to be able to remove natural variability from
any anthropogenic influences due to mining.
SUMMARY OF DISCUSSION
CCFZ variability
A participant observed that the CCFZ seemed to be a transition zone
between the equatorial region and the central gyres, with characteristics of
both. Oceanic productivity was generally much lower than in coastal
regions but there seemed to be a gradient from exceptionally low
productivity in the central gyre to areas of intermediate character.
Smith agreed that the CCFZ was an enormous zone with longitudinal
and especially latitudinal gradients in POC flux and many other parameters.
As one moved from east to west and from south to north, there were
dramatic reductions in the rain rate of organic matter and in productivity.
The latitudinal gradients were probably quite a bit steeper that the
longitudinal ones, although the flux measured in the JGOFS study was
similar to that measured north of Hawaii, which was supposed to be an
oligotrophic site.
Recolonisation rates
Questions were raised about the idea of studying recolonisation
rates by placing trays of azoic sediments onto the seabed in a patch where
the native sediment had been removed. One participant thought that might
work for the larger animals but might be misleading for smaller ones such
as the meiofauna, because they probably came up from underneath rather
than from outside, even if the trays were placed in the middle of a large
patch.
Smith responded that an experiment in which the top few
millimetres of sediment were removed along with all the fauna over a large
area of perhaps one kilometre in diameter should give a good idea of
79 INTERNATIONAL SEABED AUTHORITY