In:
Biogeosciences, Copernicus GmbH, Vol. 15, No. 13 ( 2018-07-06), p. 4131-4145
Abstract:
Abstract. Future deep-sea mining for polymetallic nodules in abyssal plains will
negatively impact the benthic ecosystem, but it is largely unclear whether
this ecosystem will be able to recover from mining disturbance and if so, to
what extent and at what timescale. During the “DISturbance and
reCOLonization” (DISCOL) experiment, a total of 22 % of the seafloor
within a 10.8 km2 circular area of the nodule-rich seafloor in the Peru
Basin (SE Pacific) was ploughed in 1989 to bury nodules and mix the surface
sediment. This area was revisited 0.1, 0.5, 3, 7, and 26 years after the
disturbance to assess macrofauna, invertebrate megafauna and fish density and
diversity. We used this unique abyssal faunal time series to develop
carbon-based food web models for each point in the time series using the
linear inverse modeling approach for sediments subjected to two disturbance
levels: (1) outside the plough tracks; not directly disturbed by plough, but
probably suffered from additional sedimentation; and (2) inside the plough
tracks. Total faunal carbon stock was always higher outside plough tracks
compared with inside plough tracks. After 26 years, the carbon stock inside
the plough tracks was 54 % of the carbon stock outside plough tracks.
Deposit feeders were least affected by the disturbance, with modeled
respiration, external predation, and excretion rates being reduced by only
2.6 % inside plough tracks compared with outside plough tracks after
26 years. In contrast, the respiration rate of filter and suspension feeders
was 79.5 % lower in the plough tracks after 26 years. The “total system
throughput” (T..), i.e., the total sum of modeled carbon flows in the food web,
was higher throughout the time series outside plough tracks compared with
the corresponding inside plough tracks area and was lowest inside plough tracks
directly after the disturbance (8.63 × 10−3 ± 1.58 × 10−5 mmol C m−2 d−1). Even 26 years after the DISCOL
disturbance, the discrepancy of T.. between outside and inside plough
tracks was still 56 %. Hence, C cycling within the faunal compartments of
an abyssal plain ecosystem remains reduced 26 years after physical
disturbance, and a longer period is required for the system to recover from
such a small-scale sediment disturbance experiment.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-15-4131-2018
DOI:
10.5194/bg-15-4131-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2158181-2
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