Sediment Thickness

Status of Environmental Work Carried out by India

Dr. S.K.Das Ministry of Earth Sciences Government of India

9th November, 2010 Kingston, Jamaica Objectives

• To establish baseline conditions of deep-sea environment in the proposed mining area

 To assess the potential impact of nodule mining on marine ecosystem

 To understand the processes of restoration and recolonisation of benthic environment

 To provide environmental inputs for designing and undertaking a deep-sea mining operation. Activities and milestones achieved Activity Period Status • Baseline data collection 1996 - 1997 Completed • Selection of T & R sites 1997 Completed • Benthic Disturbance and 1997-2001 Completed impact assessment • First monitoring studies 2001-2002 Completed • Second monitoring studies 2002-2003 Completed • Third monitoring 2003-2004 Completed

• Fourth monitoring 2005 Completed • Environmental variability study 2003-2007 Completed • Evaluation of nodule associated 2008 onwards Continuing micro-environ. Creation of environmental database 2011 onwards Continuing Environmental studies for marine mining in Central Indian Basin

Phase 1: Baseline data collection

Phase 2: Benthic Disturbance & Impact Assessment

Phase 3: Monitoring of restoration modeling of plume creation of environmental database

4 PARAMETERS ANALYSED

Geology Biology Chemistry •Seafloor features •Surface productivity • Metals •Microbiology •Sediment thickness • Nutrients •Biochemistry •Topography • Meiofauna • DOC • Macrofauna •Sediment sizes • POC •Megafauna •Porewater and sediment chemistry Physics •Geotechnical • Currents props. • Temperature • Conductivity •Stratigraphy • Meteorology 5 Benthic Disturbance (1997)

* 200 x 3000 m * 5400 m depth *Central Indian Basin * 26 tows * 9 days

* 47 hrs * 88 km

* 3737 t (wet) / 580 t (dry) sediment re-suspended

6 Results of different parameters in diff. Phases (4cm from top in disturbance zone)

Parameter Pre-dist. Post-dist. Mon-I Mon-II Mon-III (1997) (1997) (2001) (2002) (2003) Sediment sizes Clay content (%) 35 40 62 62 56

Geotech.prop. Water cont (%) 544 563 463 567 616 Sh.Str. (Kpa) 2.08 0.75 3.47 3.35 2.47

Geochem. Prop. Org.carbon (%) 0.35 0.46 0.28 0.35 0.37 Nitrogen (%) 0.084 0.093 0.085 -- -- Phosphorus (%) 0.008 0.008 0.013 0.013 0.01

------7 (continued…………) Parameter Pre-dist. Post-dist. Mon.-I Mon-II Mon-III (1997) (1997) (2001) (2002) (2003)

Microbial ATP.ug g-1 22.5 3.47 1.44 0.00 9.45 adenosine triphosphate (ATP) Total Count.g-1 109 106 107 106 106

Biochemical (mg.g-1) Chlorophyll 0.16 0.18 0.10 0.07 0.10 Proteins 0.42 0.08 0.52 0.55 0.87 Lipids 0.29 0.21 0.02 0.01 -- LOM 0.88 0.42 0.66 0.83 -- (Labile Organic Matter) Meiofauna (no.10 cm-2) Abundance 46 23 11 6 11 No. of groups 11 4 9 6 10

Macrofauna (no.m-2) 8 Abundance 244 80 266 -- 100

------Monitoring of restoration of benthic environment

Pre disturbance – 1997 Post disturbance – 1997 Monitoring I -- 2001 Monitoring II -- 2002 Monitoring III -- 2003 Monitoring IV -- 2005

Test area Reference area Concentration of clays at test and reference locations

80 80 Av. clay % of different phases for 0 to 4 cm depth DZ Av. clay % of different phases for 0 to 4 cm depth 70 70 A1/A 60 60 50 50 EDZ A1/B

40 40 Clay % Clay 30 % Clay 30 20 NDZ 20 A1 10 10 0 0 Pre. D. Post. D. M-1 M-2 M-3 M-4 SDZ Baseline M-1 M-2 M-3 M-4 T1/B Phases Phases 0-4 cm 0-4 cm

Test area Reference area

Avg. Pre Post Mon.I Mon.II Mon.III Mon.IV

Conc. (June 97) (Aug 97) (Apr 01) (June 02) (Apr 03) (Apr 04)

Clay (%) 35 40 62 62 56 68 Geotechnical properties in different phases

Average Pre Post Mon.I Mon.II Mon.III Mon.IV

Values (Jun 97) (Aug 97) (Apr 01) (Jun 02) (Apr 03) (Apr. 05)

Water Content (%) 544 563 463 567 616 503

Shear strength (Kpa) 2.08 0.75 3.47 3.35 2.47 3.00 Organic carbon and nitrate concentrations in different phases

Average Pre-dist. Post-dist. Mon.-I Mon.-II Mon.-III Mon.-IV

(%) (Jun. 97) (Aug. 97) (Apr. 01) (Jun. 02) (Apr. 03) (Apr.05)

OC 0.35 0.46 0.28 0.35 0.37 0.31 Macrofauna distribution in different phases

12 250 10 ) 200 -2 229 8 150 179 177 100 6 4 Density (no.m 50 66 64 No. groups of 0 2

dist

Post- Mon-I

Mon-III Pre-dist Post-dist Mon-I Mon-III Mon-IV

Mon-IV Pre-dist Test area (average density) Test area (cumulative groups)

250 600 Station 2 Station 3 Station 5 A1/a 225 A1/b

) 500 -2

) 200 T1/b -2 400 175 150 300 125

200 100 Density (no.m

100 (no.m Density 75 50 0 25

Mon-I

Mon-III Mon-IV Mon-IV

Pre-dist Mon-I Mon-III Mon-IV Post-dist Test area (station wise) Reference area (station wise)

Average Pre-dist. Post-dist. Mon.-I Mon.-II Mon.-III Mon.-IV abundance (Jun. 97) (Aug. 97) (Apr. 01) (Jun. 02) (Apr. 03) (Apr.05)

No. m-2 229 179 177 -- 66 64 Meiofauna distribution in different phases

50 30 Disturbance area 45 Disturbance track

40 25

)

) -2

35 -2

30 20 25 15 20

15 Density(no.10cm 10 10 Density(no.10cm 5 5 0

0 Mon-I

Mon-II Mon-I Mon-II Mon-III Mon-IV

Mon-III

Mon-IV

Pre-dist Post-dist Test area (mean density) Reference area (mean density)

12 11 10 10 9 Avg. Pre- Post Mon-I Mon-II Mon-III Mon-IV

8 Values dist. dist. 6 6 (Jun 97) (Aug 97) (Apr 01) (Jun 02)(Apr 03)(Apr05) 4 4 No. of groups No. of 4

2 Abund. 46 23 17 6 11 6 0

Groups 11 4 9 6 10 4

Mon-I

Mon-II

Mon-III

Mon-IV

Pre-dist Post-dist Test area (cumulative groups) Microbial distribution in different phases

1.00E+10

1.00E+07

1.00E+04

Cells.g-1sedimentdry pre- po Moni Moni Moni Moni st- 1 2 3 4 Sampling stage

Test area (total count) Reference area (total count)

10000

100

ATP ng.g-1dry ATP sediment pre post Moni 1Moni 2 Moni 3Moni 4 Sampling stages

Test area (ATP) Reference area (ATP) Salient findings of benthic impact experiment

Immediate impact

• Lateral migration of sediment • Vertical mixing of sediment • Changes in physicochemical conditions • Overall reduction in biomass

BC9

Longterm restoration 75.99 76.00 76.01 76.02 76.03 -10.02 -10.02

BC12

MC02a BC4 BC13

MC01 BC10

• Restoration started initially BC5 BC8 -10.03 -10.03 LEGEND

BC17 ) BC14 Coring Stations -

S BC3

° BC11 Pre Disturbance

(

e Coring Stations -

u t

i Post Disturbance

• High sediment influx t a

L Coring Stations - BC7 BC2 Monitoring Disturbance Zone BC15 -10.04 -10.04

• Conditions fluctuating annually BC16 BC6

• Large local variations BC1 -10.05 -10.05 75.99 76.00 76.01 76.02 76.03 Longitude (°E)

These observations suggest that the background changes mask the experimental changes over a period of time Temporal and spatial variability of environment

April-May 2003 April-May 2005 72.0 72.5 73.0 73.5 74.0 74.5 75.0 75.5 76.0 76.5 77.0 -10.0 -10.0 BC-26 BC-1R

-10.5 -10.5

-11.0 -11.0 BC-23 BC-24 BC-25 BC-2RR

-11.5 -11.5 Rel. Area - Phase I

-12.0 -12.0 Rel. Area - Phase II BC-22 BC-21 BC-20 BC-3R Rel. Area - Phase III -12.5 -12.5

Retained Area

) S

° -13.0 -13.0 Coring stations (

e BC-17 BC-18 BC-19 BC-4

i t

a -13.5 -13.5 L

-14.0 -14.0 BC-16 BC-15 BC-14 BC-5

-14.5 -14.5

-15.0 -15.0 BC-11 BC-12R BC-13 BC-6

-15.5 -15.5

-16.0 -16.0 BC-10 BC-9 BC-8 BC-7

-16.5 -16.5 72.0 72.5 73.0 73.5 74.0 74.5 75.0 75.5 76.0 76.5 77.0 Longitude (°E) Multi-beam and parasound data in PMN area

Evaluation of depth variation and sediment thickness • N-S transect • E-W transect Depths and sediment thickness data along N-S transect (75o 30’E, 10o - 16o)

Sl.No Station Depth (m) Sediment thickness . Number (m) Depths between 10 - 12º 1. TVBC 26 5338 70

S are relatively higher 2. TVBC 25 5292 50

(5250-5340 m) with 3. BC 28 5266 30

respect to south i.e.12- 4. TVBC 20 5239 50

16º S (4900-5230 m). 5. BC 30 5180 - Sediment thickness 6. TVBC 19 5096 - generally higher in the 7. BC 34 5225 10 north (30-70 m) as 8. TVBC 14 5189 15 compared to the south 9. BC 35 5237 10 (10-15 m). 10. TVBC 13 4899 15 11. TVBC 8 5201 10 Depth and sediment thickness along E-W transect (13o S, 74o 30’-76o 30’)

•The eastern section is deeper than the western section of the transect

•The deepest point on west is 5150 m, while center is 5250 m and in the east is 5650m

•Sediment thickness varies with the seafloor topography, i.e. less thickness on peaks and higher thickness on slopes and valleys. Depth and sediment thickness in First Gen. Mine-site

General depth varies between 5000 – 5400 m, which include bathymetric highs (hills), slopes and valleys.

Sediment thickness varies with the seafloor topography, i.e. less thickness on peaks and higher thickness on slopes and valleys. Relation of sediment thickness with seafloor topography Seafloor depth Sed. thickness Hilltop (n=4) Hilltop (n=4)

60 30 50 • Most hill tops are located 25 40 20 30 15 20

at depths of 5000-5150 m 10 Hill tops 10 Frequency%

5 0 Frequency% 0

5-9.99 • All the valleys are between 10-14.99Thickness15-19.9920-24.99 (m)25-29.9930-34.99 5000-50495050-50995100-51495150-51995200-5249 5150 – 5400 m. Depth (m) slope (n=9)

• Sediment thickness at most 25 20 of the hill tops is the lowest 15 10

(< 10 m) 5 Frequency% Slopes 0

0-4.999 • Sediment thickness on the 10-14.99 20-24.99 30-34.99 40-44.99 50-54.99 slopes is intermediate (10- Thickness (m)

20 m) valley (n=7) Valley (n=7)

50 30 25 40 20 • Sediment thickness in the 30 15 20 10

valleys is the maximum 10 5 Frequency% Frequency% 0 (35-60 m). 0 Valleys 0-4.99910-14.9920-24.9930-34.9940-44.9950-54.99 5000-50495050-50995100-51495150-51995200-52495250-5300 Thickness (m) Depth (m) Concentrations of sand-silt-clay in sediment samples

14 TVBC-26 16 BC-27 R ABP-04, FGM 12 TVBC-25R3 14 BC-28 BC-29 10 BC-28 12 TVBC-20 BC-30 8 10 BC-31 BC-30 8 6

Sand% Sand BC-32 TVBC-19 Sand% 6 4 BC-33 BC-34 4 2 TVBC-03 TVBC-14 (<8%) 2 0 TVBC-04 BC-35 0

TVBC-18

0-2 4-6

8-10 TVBC-13

0-2 2-4 4-6 6-8

15-20 25-30 35-40

8-10 TVBC-19

15-20 20-25 25-30 30-35 35-40 40-45 Depth (cm) TVBC-08 R 10-15 Depth (cm) TVBC-20 60 TVBC-26 BC-27 R 70 TVBC-25R3 ABP-04, FGM BC-28 50 60 BC-28 BC-29 40 50 TVBC-20 BC-30 40

30 BC-30 BC-31 Silt % Silt BC-32 20 TVBC-19 % Silt 30 BC-33 BC-34 Silt 20 10 TVBC-03 TVBC-14 10 0 TVBC-04 BC-35 0

(20-50%) TVBC-18

0-2 4-6

8-10

2-4 4-6 6-8

TVBC-13 0-2

15-20 25-30 35-40

8-10 TVBC-19

10-15 15-20 20-25 25-30 30-35 35-40 40-44 Depth (cm) TVBC-08 R Depth (cm) TVBC-20 90 TVBC-26 90 BC-27 R 80 TVBC-25R3 80 BC-28 70 BC-29 70 BC-28 60 60 BC-30 TVBC-20 50 50 BC-31 BC-30

40 % Clay 40

Clay % Clay BC-32 TVBC-19 30 Clay 30 BC-33 20 BC-34 20 TVBC-03 10 10 TVBC-14 ABP-04, FGM TVBC-04 0 0

BC-35 (40-80%) TVBC-18

0-2 4-6

0-2 2-4 4-6 6-8 8-10

TVBC-13 8-10 TVBC-19

15-20 25-30 35-40

10-15 15-20 20-25 25-30 30-35 35-40 40-45 Depth (cm) TVBC-08 R Depth (cm) TVBC-20 N-S profile FGM Average sand-silt-clay content (N to S) along 75.5o E profile

Sr. No. Lat. Sample No. Average (oS) Sand % Silt % Clay %

1 10 TVBC-26 2.08 35.94 62.04

2 11 TVBC-25R3 2.44 34.21 63.36

3 11.5 BC-28 1.40 30.48 68.12

4 12 TVBC-20 2.97 37.70 59.34

5 12.5 BC-30 2.37 35.37 61.84

6 13 TVBC-19 3.70 32.72 63.58

7 13.5 BC-34 3.76 36.46 59.77

8 14 TVBC-14 1.67 31.05 67.28

9 14.5 BC-35 6.52 44.27 49.22

10 15 TVBC-13 1.93 29.07 69.00

11 16 TVBC-08 R 0.47 22.21 77.32

Silt decreases, clay increases from N-S (BC-35 shows exceptional values) Temporal variation of sediment particles

Sr. Latitude EVD-I (April 2003) EVD-II (April 2005) no. (o S) Station no. Clay % Station no. Clay %

1 10 BC-26 62.05-79.25 TVBC-26 49.20-74.10

2 11 BC-25 41.71-74.12 TVBC-25 R3 51.55-70.95

3 12 BC-03 RR 60.77-74.02 TVBC-03 51.11-78.33

4 12 BC-20 45.41-66.36 TVBC-20 52.69-69.69

5 13 BC-04 35.46-55.19 TVBC-04 33.45-64.24

6 13 BC-18 47.28-72.29 TVBC-18 47.70-71.97

7 13 BC-19 49.66-81.04 TVBC-19 38.93-79.10

8 14 BC-14 51.20-71.34 TVBC-14 57.87-78.58

9 15 BC-13 41.79-62.32 TVBC-13 52.69-78.26

10 16 BC-08 55.48-77.56 TVBC-08 R 72.18-82.84 Figs. in orange show the range in different phases Sediment texture is ‘silty clay’ in both phases

Clay (<4 micron) is the major component (~40-80%), silt (4-64 micron) is intermediate (20-50%), sand (>64 micron) is the least (< 10%) Shows minor temporal variations (maximum and minimum are same) Geotechnical properties of sediments in CIB (including FGM)

Water Wet bulk Shear Specific Porosity content density strengt gravity (%) (%) (g/cm3) h (kPa)

Minimum 121 1.59 1.09 75.5 1.44 (bottom) Maximum 729 2.58 1.42 90.3 11.5 (top)

Average 453 2.21 1.15 75.5 4.37 Temporal variability of geotechnical properties of sediments

Water content Shear strength (Pink: EVD-I, Blue: EVD-II) Spatial variability of water content of sediments

10-11.30 o

12-13 o

13-14 o

14-15 o

15-16 o

Alternate bands of high and low values, also for shear strength Temporal variation of meiofauna

Density of meiofauna ABP-04 AAS-61

• variable at different locations ) • less in 2003 than 2005 -2 15 • may be due to surface

productivity 10 • and organic carbon supply

5 Meiobenthic density (no.10cm density Meiobenthic

TVBC-04 TVBC-08 TVBC-18 TV BC-03 TV BC-13 TV BC-14 TV BC-19 TV BC-20 TVBC - 25 TV BC 26 Stations Vertical distribution of meiofauna N-S profile FGM

Meiobenthic density (%) Meiobenthic density (%) 0 5 10 15 0 2 4 6 8 10 12 14 0 -0.5

0 -0.5 0.5-1.0

1.0-1.5

1.0-1.5 1.5-2.0

2.0-4.0

2.0-4.0 4.0-6.0 Nematoda 6.0-8.0 Nematoda Harpacticoida 6.0-8.0 Harpacticoida 8.0-10 Polycheata Polycheata 10.0-12.0 Turbellaria Halacarida 10.0-12.0 Halacarida 12.0-14.0 Nemertina Nemertina Sediment depth (cm) 14-16 Nauplii Crustacea 14-16 Nauplii 16-18 Sediment depth (cm) depth Sediment Tardigrada Crustacea 18-20 Ostracoda 18-20 Tardigrada 20-25

Ostracoda 25-30

25-30 30-35

35-40 9-10 common groups, Nematoda most abundant group at all depths, ~75% fauna in top 10 cm of sediment column Distribution of major macrofaunal groups Spatial variability Temporal variability

Spatial variability of macrofauna (75.5 degrees) Abundance of macrofauna (%) during the March 03 cruise Tanaidacea Harpacticoida 7% H alacarid 15% 7% Bivalvia P o lychaete 5% 60% T anaid 11% Other 9% Isopoda P olychaete 2% Iso po d 34% 4% Unidentified Gastro po d 7% 2% Larvae Nematodes (unidentified) 7% 35% N emato de 4% Fig 7.13: Macrofaunal anbundance in the first N-Sgeneration profile mine site April ‘03

Abundance of macrofauna (%) during April 05 cruise Polychaeta Tanaidacea 24% 8% Nematode 48% Harpacticoida 15% Bivalvia 5%

Isopod Bivalvia 2% 3%

Tanaid Nematodes Isopoda Polychaete 49% 2% 10% 34%

FGM April ‘05 Vertical distribution of macrofauna in sediment cores

Abundance (%) 0 20 40 60 80

0-2 Apr-05 Mar-03 2--5

5--10 Depth (cm) Depth 10--15

25--30 Fig 7.4: Temporal variation in the vertical distribution of macrofauna Macrofauna Temporal Abundance (%) Abundance (%) 0 10 20 30 40 50 0 10 20 30 40 50

0-2 0--2

2--5 2--5 Nematoda 5--10 Polychaeta 5--10

Depth (cm) Depth Nematoda

Depth (cm) Harpacticoida 10--15 Harpacticoida Isopoda Tanaidacea 10--15 15--20 Polychaeta Isopoda 25--30 Oligochaeta 15--20 Fig 7.14: Vertical distribution of macrofauna (%) Fig 7.8: Vertical distribution of macrobenthos along the 75.5 degree longitude in the First generation mine site N-S profile FGM Temporal and spatial variability is evident, > 75% of macrofauna in top 10 cm Phases of observations and parameters analysed

Phases of observations Parameters analysed

•Nodule size and morphology Env. Variability-1 (April 2003) •Sediment size classes

Env. Variability-2 (April 2005) • Geochemistry of sediments and porewaters

Env. Variability-3 (Decem. 2006) • Geotechnical properties

• Nodule associated fauna Env. Variability-4 (Sept 2009) • Meiofaunal diversity

• Microbiology and biochemistry

• Fungal diversity Sediment texture – silty clay Sand(63µ-2mm) Silt (4-63µ) Clay (<4µ)

BC 18

Range* 0.2-13.9% 18-50% 47-72% Average** 2.4- 3.0 % 34-44 % 59-63%

BC 20

Range* 0.38-5.5% 27-52% 45-69% Average** 1.70-2.6% 36-41 % 52-61%

* For ~10 subsections each of 4 cores taken during different seasons/years ** For 4 cores taken during different seasons/years Geotechnical properties

Parameter/ Stn.no. BC 18 BC20 Water content -Range 355-720 325-729 (%) - Avg. 489 506 Shear strength-Range 2.15-7.54 1.46-6.82 (kPa) - Avg. 4.275 3.533 Sp. Gravity - Range 1.88-2.49 2.02-2.51 - Avg. 2.22 2.2 Porosity - Range 88.9-94.4 88-93.9 (%) - Avg. 91.3 91.6 Wet density - Range 1.11-1-17 1.11-1.18 (g/cc) - Avg. 1.14 1.3 Geochemical properties

Parameter EVD-I,II,III EVD-IV Remarks OC - Surface (0-10 cm) 0.20 - 0.4 % 0.02 - 0.2 % lower - Subsurface (>10 cm) 0.02 - 0.2 % --do-- same pH - BC 18 7.4 - 7.6 7.5 - 7.7 higher - BC 20 7.2 - 7.4 7.4 - 7.45 higher

Indicate removal of top layers of sediments (similar to mining experiment) due to some natural events or variation in supply of fluxes from water column

Nutrients Range in different seasons / years (µM) Silicates 300-600 Nitrites 0.1 - 0.8 Phosphates 1.0 - 3.0

Vary over a wide range in different time scales Have a symbiotic relation with benthic fauna Microbial and biochemical properties

no. g-1 dryw t mg/g dryw t mg/g dryw t mg/g dryw t 1.00E+04 1.00E+06 1.00E+08 1.00E+10 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E-03 1.00E-02 1.00E-01 1.00E+00 0 0 0 0 5 EVDC I IVBC 18C Proteins 10 IVBC 18C Carbohydrates 2 IVBC 20A LOM EVDC II 2 2 15 EVDC III 20 4 4 EVDC IV 4 25 EVDC I EVDC I EVDC I

30 6 6 EVDC II depth(cm) depth(cm) 6 depth(cm) EVDC II depth(cm) EVDC II 35 EVDC III EVDC III EVDC III 8 40 8 8 EVDC IV EVDC IV 45 EVDC IV

IVBC 18C TC 10 10 50 10

no. g-1 dryw t mg/g dryw t mg/g dryw t mg/g dryw t 1.00E+04 1.00E+06 1.00E+08 1.00E+10 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E-03 1.00E-02 1.00E-01 1.00E+00 0 1.00E-03 1.00E-02 1.00E-01 1.00E+00 0 0 0 5 EVDC I IVBC 20A Proteins 10 2 EVDC II 2 2 IVBC 18A LOM 15 EVDC III 20 4 EVDC IV 4 4 25 EVDC I EVDC I EVDC I 30 6 6 depth(cm) EVDC II

depth(cm) 6 depth(cm) depth(cm) EVDC II EVDC II 35 EVDC III EVDC III EVDC III 40 8 8 8 EVDC IV 45 EVDC IV EVDC IV

50 IVBC 20A TC 10 10 10 IVBC 20A Carbohydrates Total counts Proteins Carbohydrates LOM (in all seasons/yrs) (mg/g) (mg/g) (mg/g) BC 18 4.98x107-1.10x108 0.03-0.09 0.011-0.029 0.39-0.52 BC 20 5.43x106-1.43x108 0.2-0.6 0.005-0.024 0.04-0.35

Lowest values in EVD-IV out of all 4 observations (EVD I-IV, 2003-2009) All parameters vary significantly between seasons / years Isolate Fungi Core Section(cm) Method Medium Fungal diversity F51 Nigrospora sp. BC-18C 8-10 PI MEA

F52 Cladosporium sp. BC-18C 10-15 PI CDA

• 19 cultures, 14 species isolated F53 Trametes sp. BC-18C 0-2 PI MEA

F54 Chaetomium sp. BC-18C 8-10 PI PDA • Growth under high pressure conditions confirms presence in F55 Aspergillus sp. BC-18C 4-6 PI CDA deep-sea F56 Ascotricha sp. BC-18C 10-15 PI MEA F57 Pleospora sp. BC-18C 20-25 PI PDA • Different media used for F58 Cladosporium sp. BC-18C 2-4 PI PDA culturing deep-sea fungi F59 Eurotium sp. BC-18C 0-2 PI MEA

• Potential for production of useful F60 Cerrena sp. BC-18C 30-35 PI PDA enzymes and drugs F61 Cerrena sp. BC-18C 20-25 PI SDA

F62 Penicillium sp. BC-20A 20-25 PP CMA

F63 Penicillium sp. BC-18C 35-40 PP PDA

F64 Aspergillus sp. BC-18C 4-6 PP CDA

F65 Sagenomella sp. BC-18C 6-8 PP MEA

F66 Cerrena sp. BC-20A 4-6 PI MEA

F67 Cerrena sp. BC-20A 15-20 PI SDA

F68 Hortaea sp. BC-20A 15-20 PP CMA

Y14 Hortaea sp. BC-20A 6-8 PP PDA Top: Cerrena sp., Trametes sp. (Mangroves) Bottom: Cerrena sp., D. Trametes sp. (Deep-sea) Nodule associated fauna

• 109 nodules analysed from 6 samples (2 stns.)

• 30-80% nodules (avg. 40%) have associated fauna

• 10 groups of meiofauna identified

• Nematoda (30%), herpacticoida (20%), Nematode associated with nodule from CIB polychaetes (15%) dominate Nodule associated meiofauna at stn 18C Tanaidacean Nematoda P olychaeta 10% Nematoda 27% 15% C nidaria 30% • 1-14 individuals per nodule 10% B ivalves Is opoda 15% 10%

Oribatida • 2-8 groups of meiofauna per nodule 10% Harpacticoida 12% F oraminifera K inorhyncha 11% Orbitadea Harpacticoida 10% 15% 25% • Nodule morphology plays a major role in Nodule associated fauna at 19D hosting sediments with faunal groups Faunal diversity associated with nodules

6 16 y = 0.0238x + 2.017 R2 = 0.112 y = 0.0176x

14 5 R 2 = -0.349 ) • Nodule surface area and faunal abundance have -1 12 4 weak correlation 10 -1) 8 3 6 y = 0.042x 2 4 2 y = 0.0032x + 1.5997

R = 0.0246 (Nodule Taxa R 2 = 0.0132

2 1 Individual (nodule Individual 0 0 50 100 150 200 0 0 50 100 150 200 -2 Nodule surface area (cm ) Nodule surface area (cm-2)

Faunal abundance with nodule surface area Macrofaunal community

• 30 taxa belonging to 11 groups from 6 samples (2 stns.)

• Avg. abundance 316 no./m2 (stn. 18) and 148 no./m2 (stn. 19)

• Tanaids (35%), polychaetes (22%), amphipods (20%) dominate

• Fauna belonging to 10 groups (stn. 18) and 4 groups (stn. 19)

Mean macrobenthic abundance (no. m-2) at Stn. IVBC-18

Group Mean±sd % Polychaeta 103.5 ± 106.5 32.8 Nemertinia 5.3±13 1.7

Oligochaeta 7.1±17.3 2.2 Macrobenthic abundance (no. m-2) at station IVBC-19 Amphipoda 72.5±33.1 23.0 Group Mean abundance Composition (%) Harpacticoida 12.4±19.5 3.9 ±sd Isopoda 15.9±26.6 5.0 Minor phyla 21.2±30 14.3 Tanaidacea 81.3±51.4 25.8 Amphipoda 21.2±30 14.3 Pycnogonida 5.3±13 1.7 Isopoda 21.2±30 14.3 Prawn 7.1±17.3 2.2 Bivalvia 5.3±13 1.7 Tanaidacea 84.8±2.3 57.1 Water column characteristics

CTD-18A CTD-19A XBT 1-20

Temperature varied from 26o (surface) to1.5o (3000m) Steep temperature decline upto ~400 m Salinity remained constant except at ~ 400 m Surface temperature is 24-29o C from 12o N to 12o S TC-M3

Overall conclusions 1.00E+09

1.00E+06 dry sediment These studies have shown that environmental conditions -1 no. no. g 1.00E+03 pre- post- Moni 1 Moni 2 Moni 3 Moni 4

• vary over different time scales (seasonal and annual) LOM-M3 5.000

4.000

• on a wide range, but always follow a particular trend 3.000

dry sediment 2.000 -1

1.000 mg g mg

0.000 pre- post- Moni 1 Moni 2 Moni 3 TC and LOM during monitoring phases at BC-3 Implications

These variations could probably well encompass the changes in conditions created by other activities such as deep seabed mining.

Org C during EVD-I,II,III,IV Org C during pre, pot-dist, monitoring at BC-2,3,5 Environmental variability - conclusions

1. Bathymetry and sediment thickness • Seafloor deeper in N (5250-5340 m) than S (4900-5230 m) • Sediment thickness higher in N (30-70 m) than S (10-15 m) • Most hilltops between 5000-5100 m, valleys 5150-5400 m • Sediment thickness least on hilltops (<10 m), intermediate on slopes (10-20 m), maximum in valleys (35-60 m) 2. Sediment texture • Silty clay in entire area • Sand (<8%), silt (20-50%), clay (40-80%) • Silt content decreases, clay increases from N-S • Minor temporal variations locally Environmental variability - conclusions

3. Geotechnical properties • High water content (500-700%) on top, low (300-400%) at bottom • Low shear strength (2-3 kPa) on top, high (5-8 kPa) at bottom • High-low bands in WC and SS from N-S • Localised temporal variability 4. Faunal distribution • >75% fauna in top 10 cm • 9-10 groups common at all locations and in all observations • Similar distribution of groups, but concentrations may vary • Different temporal variations between locations Modeling of sediment plume dispersion

Model capabilities

• sediment dispersion of plume and settling

• takes into account processes including advection, dispersion After 1 hour

 •· predicts suspended and bed load sediment movement

• specialized features for graphics and post-processing

After 20 hours Concluding Remarks • Studies carried out over one decade indicates that the nodule area of CIOB is comprised of highly heterogeneous environmental conditions in terms of spatial variations. •The Sea floor as well sediments have undergone relatively more intense impact within the disturber track and little or no impact in the north of disturbance zone. • The monitoring of environmental conditions after the benthic disturbance experiment indicates that the benthic conditions are steadily moving towards restoration and the effect of disturbance is waning off. •These studies have shown that environmental conditions vary over different time scales (seasonal and annual) on a wide range, but always follow a particular trend. •Plume dispersion model developed. Platforms used

• RV Akademic Alexander Sidorenko • RV Yuzhmorgeologiya • RV Boris Petrov •THANK YOU Benthic Impact Experiments (BIEs)

------Expt. Tows Duration Distance Discharge ------DISCOL* 78 ~12days 10.8 sqkm -- (German) NOAA 49 5290 mins 141 km 6951 cu.m. (USA) JET 19 1227 mins 33 km 2495 cu.m. (Japan) IOM 14 1130 mins 35 km 2693 cu.m. (Inter Ocean Metal) INDEX 26 2534 mins 88 km 6015 cu.m. (India) DISCOL was conducted with plow harrow and other expts. * 49 were. conducted with hydraulic suction device