C. Raghukumar et al., Bacterial standing stock, meiofauna and sediment-nutrient characteristics:indicators of benthic disturbance in the Central Indian Basin, DEEP-SEA II, 48(16), 2001, pp. 3381-3399
Citations number
35
Categorie Soggetti
Aquatic Sciences","Earth Sciences
Journal title
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
As part of the environmental impact assessment studies for polymetallic nod
ule mining, the effect of simulated "benthic disturbance" caused by a benth
ic hydraulic disturber was studied in the Central Indian Basin (CIB). We ha
ve compared the abundance and distribution of meiofauna, macrofauna, total
counts of bacteria (TC) and cultivable bacteria in the sediments, retrieved
from depths of 5000-5300m, using box corer, before and after disturbance.
Nine box core samples each in pre- and post-disturbance stages, were analyz
ed for labile organic matter (LOM constituted by carbohydrates, protein and
lipids), total organic carbon (TOC), ATP and sediment enzymes, phosphatase
and lipase. Immediately after the benthic disturbance, (within 10 days), w
e observed a decrease in meiofauna, macrofauna and bacterial numbers, accom
panied by a decrease in LOM, ATP and lipase activity, indicating importance
of quality food for the deep-sea benthos. On the other hand, there was an
increase in TOC, phosphatase activity and cultivable bacteria, suggesting b
eneficial effect of disturbance. The results show that a benthic disturbanc
e caused by a hydraulic device may have mixed effects, such as bringing up
nutrients from the subsurface layers on one hand and blanketing the bottom
by the discharged sediment plume resulting in a decrease in the number of b
enthos on the other hand. The distinct change in nutrient characteristics o
f the bottom sediments caused by the disturbance which is probably comparab
le to a magnified bioturbation process, can be used as an indicator of bent
hic disturbance. (C) 2001 Elsevier Science Ltd. All rights reserved.