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Year No. Year Phase
0 1989 Baseline study
0 1989 Disturbance
0 1989 1st post-impact study
0.5 1989 2nd post-impact study
3 1992 3rd post-impact study
7 1996 4th post-impact study
Table 1
DISCOL/ATESEPP study phases.
Seasonal and interannual production and sedimentation cycles may
be of significance in scheduling such long-term ecological studies. Only the
second post-impact study is out of seasonal phase (September) with the
three other cruises that occurred from January to March, with the main
sampling periods during February.
However, the DEA, situated on the outskirts of a German mining
claim, may be influenced by interannual variation in organic matter supply
due to upwelling intensities off the coast of Peru and Chile, although it is
600 nautical miles from the coast. It is known today that fast-sinking
aggregates of organic matter reach the deep seafloor within about six
weeks, and they can create seasonal cycles even in high-oceanic regions 18 .
An experiment like DISCOL should probably have been conducted in an
oceanic polymetallic nodule region with relatively high predictability of
production cycles.
1.5. Equipment used during DISCOL/ECOBENT
The benthos was sampled with the standard equipment previously
used in other deep-sea studies in the Atlantic Ocean 19 .
1.5.1. Megafauna
For the collection of megafauna an epibenthic trawl was employed twice.
The trawl was equipped with 0.3-m wide skids alongside the 2.3-m broad
opening of the net. The sediment in the DEA has a high water content and
the skids sank into it, possibly gliding on the large manganese nodules. The
trawl collected many of the large nodules (up to 13 cm in diameter).
332 INTERNATIONAL SEABED AUTHORITY