German Exploration License in the Indian Ocean (INDEX) - Environmental Studies by BGR
Report of the project:
The application and grant of the exploration license for polymetallic sulfides in the Indian Ocean obligate BGR to detailed and enhanced environmental base line studies in the license area and the surrounding region. The environmental studies, established through regulations from the International Seabed Authority, include the research of the biodiversity, sedimentation and water column studies as well as oceanographic measurements, among others. Since the beginning of BGR’s prospecting program for the preparation of the license application, base line studies for the biodiversity in the 300 000 km² area in the western Indian Ocean are established and represent an important and integral part of the activities. Since 2011 the studies are conducted by biologists from the German Center for Marine Biodiversity Research at the Senckenberg Institute in Wilhelmshaven. Apart from the biodiversity at active hydrothermal vents, so-called chimneys or black smokers which have to be excluded from potential future marine mining activities according to ISA regulations, the entire region and all seafloor areas are studied. This also includes distal areas apart from inactive sulfide deposits.
Figure: Example for the study of the biodiversity along the northern Southeast Indian Ridge during cruise INDEX 2012. The number of species and their taxionomic order are shown for different video sled tracks. Unidentified species are subject of subsequent laboratory studies and detection
Source: German Center for Marine Biodiversity Research at the Senckenberg Institute in Wilhelmshaven
Detailed imaging by the swath bathymetry system allows for the documentation of the distribution of plankton in the water column. Its detection and recording provide insights into density, daily and seasonal movements and the amount and distribution of nutrients for higher species (e.g., fish swarms, marine mammals).
Figure: Example for the distribution of zooplankton in the water column of the Southeast Indian Ridge, recorded by swath bathymetry water column imaging. With decreasing daylight, the zooplankton is migrating upwards in the water column and forms high density layers close to the seawater surface
Source: BGR
Oceanographic studies include the identification of the different water masses in the western Indian Ocean by swath bathymetry. Different water mass layers can be identified by their respective distinctive physicochemical characteristics. The variability in the water column has important consequences for the marine life, but also for the regional study of global oceanographic currents.
Figure: Example of layered water masses in the area of the southern Central Indian Ridge. Seafloor (green) has a depth of about 3500 m. The upper limit of the Indian Central Water (ICW) layer occurs at a depth of about 350 m. The upper limit of the Antarctic Intermediate Water (AAIW) is determined at a water depth of about 800 m. The transition to the Indian Deep Water (IDW) cannot be clearly identified at this particular site
Source: BGR