Response of meiofauna to immediate benthic disturbance in the Central Indian Ocean Basin

Twenty-four stations (12 each, during pre- and postdisturbance studies) 530 0 to 5330 m deep between 10 degrees 01' and 10 degrees 03'S lalialde and be tween 75 degrees 59' and 76 degrees 02'E longitude were sampled to study th e effect of benthic disturbance oil the distribution of meiofauna in the Ce ntral Indian Ocean. Bottom-sampling was conducted with a box corer: Total,m eiofauna density ranged from 35 to 45 organisms per 10 cm(2) of bottom area during rite predisturbance period and 21 to 32 organisms per 10 cm(2) duri ng the postdisturbance period in the rest and reference sites. Differences between pre- and postdisturbance study results were statistically significa nt (P < 0.05). Nematoda was the most abundant metazoan group, on an average representing >55% of the meiofaunal population. The abundance of nematodes and harpacticoid copepods as well as total meiofauna showed marked decreas es during postdisturbance sampling. Vertical distribution of meiofauna in t he sediment cores revealed that 75% to 90% of the metazoan population was c onfined to the top 2-cm layer of the sediment. Recolonization experiments s uggest that harpacticoid copepods may take more time for recolonization tha n the nematodes and ar-e more sensitive to the physical disturbance. These findings suggest that nematodes and harpacticoid copepods can be used as in dicator organisms in recolonization experiments.