Restoration of Deep-Sea Macrofauna after Simulated Benthic Disturbance in the Central Indian Basin |
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| Authors: | B S Ingole S Pavithran Z A Ansari |
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| Institution: |
a National Institute of Oceanography, Dona Paula, Goa, India |
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| Abstract: | Macrofaunal communities of the Central Indian Basin (CIB) were sampled with a spade before (June 1997), and immediately after (August 1997), and 44 months (April 2001) after a simulated benthic disturbance for polymetallic nodule mining. The average density recorded down to a sediment depth of 40 cm ranged from 89 to 799 ind·m-2 (mean: 373 ± 221 SD; n = 12) and 178-1066 ind·m-2 (mean: 507 ± 489 SD; n = 3) in the test and reference area, respectively. Most of the macrobenthic animals (64%) were concentrated in the upper 0 to 2 cm sediment layers, whereas, sizeable fauna (6%) inhabited the 20-40 cm sediment section and the deepest 5 cm section from 35-40 cm contributed only about 2% to the total population density. The fauna, comprised of 12 groups, were dominated by the nematodes, which constituted 54% of the total population. The macrofaunal density in the test site showed a significant increase (x:400 ind·m-2) in the 44 months postdisturbance sampling (x:320 ind·m-2). The population of nematodes and oligochaetes was nearly restored after 44 months, but the polychaetes and crustaceans did not reach the baseline populations measured in June 1997. The top 0-2 cm sediment layer was severely affected by the disturber, and the study suggests that physically disturbed deep-sea macrofauna may require a longer period for restoration and resettlement than normally believed. |
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| Keywords: | deep-sea macrofauna environmental disturbance restoration Central Indian Ocean |
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