Minerals Report - International Seabed Authority
Minerals Report - International Seabed Authority Minerals Report - International Seabed Authority
egions, one study pointed out that taxonomic similarities reflect distance along the ridge system rather than shortest oceanic distance, implying a primarily along-ridge flow of genetic information 10 . These authors also showed that some present day relationships between vent faunas separated by major discontinuities in the global ridge system can be explained on the basis of past connections between ridges such as the northern EPR and the northeast Pacific ridges, and between the northeast Pacific ridges and the back-arc basins of the western Pacific 10 . At the scale of individual ridge systems, studies of the influence of distance and discontinuities on gene flow are indicating that high levels of long distance gene flow may be a pre-requisite for success of vent species. However, molecular work is also showing that the ability of species to move along and between segments can vary considerably. Eastern Pacific tubeworms are very good at dispersing their genes along ridge axes although neighbouring populations are more similar than more distant ones, producing a quantifiable effect of along-axis geographic distance on gene flow 20, 21 . Discontinuities between ridge axes can also have a measurable effect on gene flow, as has been shown by comparison of populations of the same species on either side of transform faults of different length. For the northeast Pacific tubeworm, Ridgeia piscesae, no detectable genetic differentiation was found across the 160km offset between the Juan de Fuca and Explorer Ridges, while populations on either side of the 360km offset between the Juan de Fuca and Gorda Ridges had significant genetic differences 21 . Depth discontinuities may also act as a barrier to gene dispersal and confound interpretation of genetic differences between sites. Vertical mixing is limited in the deep sea so that water mass and larval transport tend to be horizontal. Mussel populations at the Snake Pit and Lucky Strike sites on the MAR show distinct genetic differences that may reflect their separation by transform faults but may also be influenced by depth differences between the two sites (3489m vs. 1650m) 22 . A clearer example of a likely depth effect is that of the amphipod crustacean Ventiella sulfuris in the eastern Pacific. The species shows low divergence along the EPR, even across the 240km Rivera Fracture Zone, while the 5000m deep, 50km wide Hess Deep between the Galapagos spreading center and the EPR separates populations with major genetic differences 23 . INTERNATIONAL SEABED AUTHORITY 286
5. Response to Perturbations Recent observations of the biological consequences of seafloor volcanic eruptions and the growth of hydrothermal sulphide chimneys and larger multi-chimney edifices provide new insight into the ability of vent communities to colonise newly-created habitat, to recover from major perturbations and to adapt to local-scale changes in habitat conditions. 5.1 Seafloor eruptions Information on the effects of eruptions on vent fauna comes from time series observations at 9° 45' - 9° 52' N on the East Pacific Rise that followed the serendipitous discovery of a very new lava flow, and from similar studies on the Juan de Fuca and Gorda Ridges in the northeast Pacific. While the characteristics of the eruptions and the suites of observations made vary between sites, the post-eruptive periods have a number of consistent features that reveal the interconnection of magmatic, hydrothermal and biological processes. Seafloor eruptions provoke rapid and significant changes in the location and style of venting. Widespread diffuse venting is usually observed soon after the event, with new vents being created in areas where there was no previous venting24 . The biological consequences of this perturbation of the hydrothermal system are considerable. Existing vent communities can be destroyed by lava flows or as a result of the re-organization of hydrothermal venting. Both the 9° N and CoAxial eruptions initiated intense bursts of biological activity as organisms colonized new vents. Most immediate were blooms of free-living microorganisms. The ubiquity of microorganisms of most metabolic types in seawater and their ability to grow rapidly under favourable conditions result in their being the first life forms to exploit the new energy source. In the first few weeks after the eruptions, observers24, 25 reported the outpouring of particulate microbial material from the subsurface through "snow blower" vents and the massive accumulation of filamentous bacterial mats and flocculent microbial waste on the seafloor in areas of diffuse flow. The discharge of biogenic particulates from snow blower vents can be sustained for several months24, 25 , suggesting continuous microbial production in the subsurface. Post-eruptive diffuse venting can initially be INTERNATIONAL SEABED AUTHORITY 287
- Page 244 and 245: 3. J.R. Hein and C.L. Morgan (1999)
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- Page 250 and 251: Angeles, CA, International Society
- Page 252 and 253: geochemistry of Central Pacific fer
- Page 254 and 255: 73. J.W. Moffett (1990), Microbiall
- Page 256 and 257: 86. D. Puteanus and P. Halbach (54)
- Page 258 and 259: 110. A Koschinsky and P Halbach (46
- Page 260 and 261: 132. J.R. Hein et al. (1) 133. H.H.
- Page 262 and 263: B. 14°30'N 14°20'N 14°10'N 160°
- Page 264 and 265: Appendix 4. 1-m-diameter circular c
- Page 266 and 267: economic potential in hydrogenetic
- Page 268 and 269: Zealand Oceanographic Institute, th
- Page 270 and 271: depths. Up welling increases primar
- Page 272 and 273: een recovered is 25 cm. He also sai
- Page 274 and 275: shallower than 1500 metres, a shall
- Page 276 and 277: In relation to mining technology, o
- Page 278 and 279: On the most promising sites for cru
- Page 280 and 281: In addition to the International Se
- Page 282 and 283: 1. Introduction Plant life is impos
- Page 284 and 285: Table 1 Potential microbial metabol
- Page 286 and 287: Figure 2 Simplified representation
- Page 288 and 289: Figure 3 Major components of a gene
- Page 290 and 291: the mussel's nutrition. When experi
- Page 292 and 293: Reasons for this do not appear to b
- Page 296 and 297: very widespread, supporting microbi
- Page 298 and 299: Studies of the rapid colonisation o
- Page 300 and 301: y mining, which is expected to be v
- Page 302 and 303: 2. J. B. Corliss, J. Dymond, L. Gor
- Page 304 and 305: 19. V. Tunnicliffe, A.G. McArthur a
- Page 306 and 307: SUMMARY OF THE PRESENTATION AND DIS
- Page 308 and 309: together with mucus that is secrete
- Page 310 and 311: close to neutral ph conditions, it
- Page 312 and 313: France, Germany, the United Kingdom
- Page 314 and 315: of the sedimentary column, whereas
- Page 316 and 317: Table 2: Research Submersibles and
- Page 318 and 319: 4. Technical Requirements For resea
- Page 320 and 321: 5. Processing Technologies The phys
- Page 322 and 323: grow on substrate rocks because of
- Page 324 and 325: 5. M.D. Hannington, A.G. Galley, P.
- Page 326 and 327: Dr. Herzig informed participants th
- Page 328 and 329: search for sites of hydrothermal ve
- Page 330 and 331: with such a grab. In addition to th
- Page 332 and 333: Remotely operated vehicles (ROVs) D
- Page 334 and 335: equired to make sure that the ship
- Page 336 and 337: Dr. Herzig summarized the technical
- Page 338 and 339: commercial. Since confidentiality o
- Page 340 and 341: CHAPTER 8 FACTORS IN FINANCING EXPL
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5. Response to Perturbations<br />
Recent observations of the biological consequences of seafloor volcanic<br />
eruptions and the growth of hydrothermal sulphide chimneys and larger<br />
multi-chimney edifices provide new insight into the ability of vent<br />
communities to colonise newly-created habitat, to recover from major<br />
perturbations and to adapt to local-scale changes in habitat conditions.<br />
5.1 Seafloor eruptions<br />
Information on the effects of eruptions on vent fauna comes from time<br />
series observations at 9° 45' - 9° 52' N on the East Pacific Rise that followed the<br />
serendipitous discovery of a very new lava flow, and from similar studies on<br />
the Juan de Fuca and Gorda Ridges in the northeast Pacific. While the<br />
characteristics of the eruptions and the suites of observations made vary<br />
between sites, the post-eruptive periods have a number of consistent features<br />
that reveal the interconnection of magmatic, hydrothermal and biological<br />
processes.<br />
Seafloor eruptions provoke rapid and significant changes in the<br />
location and style of venting. Widespread diffuse venting is usually observed<br />
soon after the event, with new vents being created in areas where there was<br />
no previous venting24 . The biological consequences of this perturbation of the<br />
hydrothermal system are considerable. Existing vent communities can be<br />
destroyed by lava flows or as a result of the re-organization of hydrothermal<br />
venting. Both the 9° N and CoAxial eruptions initiated intense bursts of<br />
biological activity as organisms colonized new vents. Most immediate were<br />
blooms of free-living microorganisms. The ubiquity of microorganisms of<br />
most metabolic types in seawater and their ability to grow rapidly under<br />
favourable conditions result in their being the first life forms to exploit the<br />
new energy source. In the first few weeks after the eruptions, observers24, 25<br />
reported the outpouring of particulate microbial material from the subsurface<br />
through "snow blower" vents and the massive accumulation of filamentous<br />
bacterial mats and flocculent microbial waste on the seafloor in areas of<br />
diffuse flow. The discharge of biogenic particulates from snow blower vents<br />
can be sustained for several months24, 25 , suggesting continuous microbial<br />
production in the subsurface. Post-eruptive diffuse venting can initially be<br />
INTERNATIONAL SEABED AUTHORITY 287
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