Influence of seabed topography on the distribution of manganese nodules and associated features in the Central Indian Basin: A study based on photographic observations

Understanding Mn-nodule distribution and related deep-sea mining impacts using AUV-based hydroacoustic sensing and optical observations

“…Within sub-area A2 a smaller variability of Mn-nodule coverage can be 25 observed in correlation with the 'Slope A2E' towards the East. This is in agreement with observations by Sharma and Kodagali (1993) who also observed more uniform nodule abundances in sloping areas. The authors point out that this could be a result of a larger exposure of the Mn-nodules rather than absolute difference, since they discovered discrepancies between direct sampling and results of photo analyses.…”

“…Several studies correlate bathymetry and nodule abundance, revealing a complex/non-coherent interrelation which mainly depends on the con-10 sidered spatial scale. Most studies have focused on nodule abundance variability between very different terrain settings such as seamounts, valleys, plains and undulating terrain Halbach (1988); Pattan and Kodagali (1988); Skornyakova and Murdmaa (1992); Sharma and Kodagali (1993); Park et al (1997); Jung et al (2001); Kim et al (2012). The detected Mn-nodule variability has been associated with sediment deposition properties, e.g.…”

Rise of the Dormant: Simulated Disturbance Improves Culturable Abundance, Diversity, and Functions of Deep-Sea Bacteria of Central Indian Ocean Basin

“…The deep-sea sediments of the Central Indian Basin (CIB) have been studied extensively since the 1980s (Parulekar et al 1982;Nath and Mudholkar 1989;Sharma and Rao 1991;Sharma and Kodagali 1993). In our earlier work, we have tried to relate bacterial abundance to the biochemical characteristic of the sediments (Sheelu et al 1999;Raghukumar et al 2001).…”

Quantitative estimation of seafloor features from photographs and their application to nodule mining

“…Distribution of nodules (coverage) from seabed photographs (after Sharma and Kodagali, 1993). *Excluding locations with only Fe-Mn encrustations and no nodules, as follows: (a) two locations with 100% and one with 60% coverage, on the crests; (b) one location with 60% coverage on the slopes; and (c) one location with 50% coverage in the valleys.…”

“…The map shows that the comparatively higher nodule concentrations (20-40, 40-60, and >60%) occur in the southern and south western parts of the survey area, whereas the lower nodule coverages (< 20%) are in the remaining areas. A detailed study of the nodule concentrations in different topographic settings (Sharma & Kodagali, 1993) shows that the nodule concentrations are the highest along the slopes (average = 15.32% coverage, 3.96 kg/m 2 abundance in the photographs and 6.65 kg/m 2 in the grabs), followed by the crests of the seamounts (average = 12.34% coverage, 3.48 kg/m 2 abundance in the photographs and 5.53 kg/m 2 in the grabs), the abyssal plains (1.36%, 0.83 kg/m 2 and 3.56 kg/m 2 ), and are lowest in the valleys (0.25%, 0.20 kg/m 2 and 2.03 kg/m 2 ). However, due to the patchy nature of distribution of nodules, areas with no nodule occur in all the domains ( Table 1).…”