standardization of environmental data and information - International ...

in 1992 compared to 1989. Seven years after the disturbance, the
rarefaction curves indicated that there were still differences in the
polychaete community between the undisturbed reference area and the
disturbed area.
The meiofauna had reacted immediately after the impact as well.
The number of nematodes within the impacted area had declined along
with harpacticoid copepods and foraminiferans, and a further decrease in
the abundance of nematodes and harpacticoid copepods had occurred half
a year later. This second decrease might have been a follow-up to the
disturbance of the food chain, or else the higher number counted directly
after the impact might have included healthy animals that subsequently
died. However, the populations had recovered within three years. The
foraminiferans had increased slightly, which might be an indication that
protozoans reacted faster than metazoan meiofauna. The numbers of
nematodes had increased tremendously by 1992 and the harpacticoids
slightly, for reasons that were unexplained. Seven years after the start, the
abundance of these two groups had returned to pre-impact levels, although
in the case of the harpacticoid copepods there were still differences in
diversity at the genus level when compared to the baseline study.
The researchers had learned during all their expeditions that it was
important, especially for macrofauna sampling, to use a box corer. They
had used a 2500-cm² corer with several modifications. They had changed
the top plates, which were opened when the gear was lowered to permit a
better flow of water and to reduce the bow wave. Additionally, they had
installed special seals on the top plates and the spade so that the box
would close properly after taking the sample and so that the sample could
not escape during hoisting. Without the seal, a sample might be lost,
especially in the nodule area, if there was a nodule between the spade and
the edge of the box.
Procedures for future research
As Borowski had stated in the paper for the Workshop (section 4
above), no method should be altered during sampling, even over the course
of years when better methods became available, because the data would
no longer be comparable. To meet statistical standards, it was also
advisable to avoid what Borowski had done in his initial sampling when he
had used only 500 cm² instead of the total 2500 cm² of the box corer.
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