Vol49_2_2006 729 ANNALS OF GEOPHYSICS, VOL. 49, N. 2/3, April/June 2006 challenging goals posed by the scientific com- munity involved in the various disciplines relat- ed to the deep-sea environment (such as geo- physics, geochemistry, biology, oceanography). Availability of suitable infrastructures, like re- search vessels, deep-sea ROVs, manned sub- mersibles and seafloor observatories represents another major limitation. In this scenario, projects built around clear and challenging scientific objectives, as well as sound technological background and innovation perspective, stand for a potential source of spin- offs and exploitation opportunities of the utmost importance. To make this potential become a re- ality is neither easy nor frequent. In the last decade, in the field of marine research, the EU- sponsored project GEOSTAR (GEophysical and Oceanographic STation for Abyssal Research, The exploration of Eastern Mediterranean deep hypersaline anoxic basins with MODUS: a significant example of technology spin-off from the GEOSTAR program Elisa Malinverno (1), Francesco Gasparoni (2), Hans W. Gerber (3) and Cesare Corselli (1) (1) CoNISMa LRU, Dipartimento di Scienze Geologiche e Geotecnologiche, Università di Milano «Bicocca», Milano, Italy (2) Tecnomare-ENI SpA, Venezia, Italy (3) TFH Berlin – University of Applied Sciences, Berlin, Germany Abstract A significant example of technological spin-off from the GEOSTAR project is the special-purpose instrument- ed module, based on the deep-sea ROV MODUS, developed in the framework of the EU-sponsored project BIODEEP. The goal to be achieved has been defined as the exploration of the deep hypersaline anoxic basins of the Eastern Mediterranean Sea through real-time video images, measurements and accurate video-guided sam- pling at water depths well exceeding 3000 m. Due to their peculiar characteristics, these basins are one of the most extreme environments on Earth and represent a site of utmost interest for their geochemical and microbial resources. The paper presents the strategies and the main results achieved during the two cruises carried out with- in the BIODEEP project. Mailing address: Dr. Elisa Malinverno, CoNISMa LRU, Dipartimento di Scienze Geologiche e Geotecnologi- che, Università di Milano «Bicocca», Piazza della Scienza 4, 20126 Milano, Italy: e-mail: elisa.malinverno@unimib.it Key words deep-sea – anoxic basins – ROV – ma- rine technology – exploration 1. Introduction Exploration and long-term observation of the deep-sea environment is one of the last frontiers of marine science and technology. This technol- ogy, including marine engineering and underwa- ter acoustics, plays a primary role in the develop- ment of equipment which can make possible, and economically feasible, the fulfilment of the 730 Elisa Malinverno, Francesco Gasparoni, Hans W. Gerber and Cesare Corselli 1996-2001) represented one of the very few cas- es where successful results were followed by re- al exploitation. Besides making the first Euro- pean seafloor observatory available, GEOSTAR developed the special deep-sea ROV, MODUS (Mobile Docker for Underwater Sciences), whose exploitation for the purposes of the EU- sponsored project BIODEEP (BIOtechnologies for the DEEP, 2001-2004) is the object of the present paper. Together with a brief description of MO- DUS, this paper will report about its adaptation and successful use for the exploration of a high- ly peculiar environment in the deep Mediter- ranean Sea, the Deep Hypersaline Anoxic Basins (DHABs). 2. MODUS: general description MODUS is a deep-sea Remotely Operated Vehicle (ROV) originally designed for the pur- pose of GEOSTAR seafloor observatory de- ployment and recovery (fig. 1, Gerber et al., 2002). Suspended from an electro-mechanical umbilical cable, it is equipped with electrical thrusters ensuring mobility on the horizontal plane, while the dedicated winch onboard the support vessel regulates its ascent/descent. Ca- ble and winch are the infrastructure property of INGV that allow MODUS operation from ves- sels of opportunity. MODUS configuration (Clauss et al., 2002) fills the gap between full 6D-space operation and simple hook deployment systems. This means there are no free-swimming capabilities typical for ROVs (especially those equipped with tether management system). However this does not represent a disadvantage, since MO-DUS is not required to carry out close inspection or manipu- lation tasks like typical ROVs. On the contrary, MODUS can handle heavy loads (up to 30 kN; for comparison, typical payload of a commercial ROVs is less than 1.5 kN), overcoming one of the basic limitations of the existing ROVs. This peculiar characteristic of MODUS is essential for the GEOSTAR concept; its modular design concept opens a wide range of interesting oppor- tunities for its utilisation in different contexts. Some of these opportunities have already been explored: among these, the possibility to carry out visual and instrumental surveys in Fig. 1. MODUS and GEOSTAR-stations onboard R/V Urania. 731 The exploration of Eastern Mediterranean deep hypersaline anoxic basins with MODUS deep waters, and to serve as a carrier of special instrumented packages, ensuring the scientist a virtual presence and operational capabilities in the area of interest. In the short, but already sig- nificant, history of GEOSTAR spin-offs, the ex- ploration of the Deep Hypersaline Anoxic Basins in the Eastern Mediterranean Sea is the first of these opportunities. 3. The deep hypersaline anoxic basins of the Eastern Mediterranean and BIODEEP project The anoxic basins of the Eastern Mediter- ranean represent a peculiar deep-sea environ- ment having extreme physical and chemical con- ditions. They are in fact characterised by the presence of hypersaline brines, separated from normal deep-sea water by a sharp physical and chemical interface. They have a variable pH and ionic composition, no oxygen and at some places high sulfide concentration, high temperature, and methane seepage (Corselli et al., 1998). Several DHABs, having diverse morpholo- gies and dimensions, are present in the Eastern Mediterranean in different tectonic settings and at variable depths (3300-3700 m) along the Mediterranean ridge (Jongsma et al., 1983; Sci- entific Staff of Cruise Bannock 1984-1912, 1985; Medriff Consortium, 1995); their origin is due to the interaction among tectonic processes, fluid migration and dissolution of Messinian evaporitic rocks present in the subsurface at shallow depth (Westbrook and Reston, 2002). The peculiar physical and chemical charac- teristics of the DHABs and their location in the deep-sea make such basins an especially inter- esting site for different fields of research and a new frontier for exploration. In particular, the EU-funded Project BIODEEP was targeted to the investigation of microbial life in such ex- treme conditions. The challenging goal was to characterise, in four selected DHABs, the phys- iology and ecology of the extremophiles micro- bial communities, their cellular components or products and to identify how their features can translate into new biotechnological applications. Although driven by biotechnological goals, the BIODEEP approach is multidisciplinary, in- volving geological, geochemical and hydrolog- ical tasks besides micro- and macro-biological studies. A fundamental requirement to fulfil the scientific purposes of the project is the execu- tion of accurate sampling at the seawater-brine interface and visual surveys at the surface of the DHABs and at their margins. In particular the latter is intended to obtain a direct, although re- motely driven, description of this peculiar envi- ronment. In fact the seawater-brine interface has only been detected by geophysical methods (Jongsma et al., 1983; Medriff Consortium, 1985) and directly investigated through CTD measurement and sampling (De Lange et al., 1990): no investigation proved that this transition is visually detectable. Therefore, be- sides the sampling task, the main questions ad- dressed are related to how the brine interface appears at a visual inspection, which features can be visually detected on it and in particular which features and structures are present at the beach, i.e. the line where the brine surface im- pinges the bottom. 4. MODUS adaptations for BIODEEP To perform the challenging tasks described above, conventional off-the-shelf equipment is not available. ROVs and manned submersibles have never approached the DHABs close enough to obtain samples at the interface or to make accurate visual surveys, because of the peculiar characteristics of the brines, which can cause damage to the systems. Until recently, sampling in the DHABs has been carried out using tools like CTD/rosettes deployed from the ship. This approach has three basic draw- backs: a) It is intrinsically inaccurate: the sensors and the sampling devices hang at the end of a very long cable (in the order of 3500 m), so that an accurate regulation of their position for sam- pling at the brine interface is unlikely. b) The scientific payload is limited to the es- sential, and the electro-mechanical cable serv- ing the CTD/rosette has normally no provision for additional telemetry channels (especially high capacity channels imposed by TV cam- eras). 732 Elisa Malinverno, Francesco Gasparoni, Hans W. Gerber and Cesare Corselli c) The interaction of the scientists with the phenomena under observation is minimal; there is no possibility to see where the instrumented package is and in which conditions the measur- ing and sampling operations are performed. The task the BIODEEP team had to fulfill has therefore been to find a new approach, meet- ing the challenging scientific requirements and at the same time compatible with the constraints imposed by the project (cost-effectiveness, re- duced risks and short development time). The solution developed by Technische Uni- versität Berlin, TFH Berlin and Tecnomare (the technological partners of BIODEEP project) was based on the adaptation of MODUS to serve as the carrier of a specially developed module (SCIPACK – SCIentific PACKage), the instrumented unit intended to enter the DHABs. In this concept, illustrated in fig. 2, MODUS becomes a powerful and stable platform, capa- ble of being actively positioned and «flown» a few meters over the DHABs surface, moreover providing plenty of telemetry capabilities for the transmission of video images, data and con- trol signals. To manage SCIPACK, the original idea was to equip MODUS with an underwater deep-sea winch (like those of the ROVs tether manage- ment systems). In this way SCIPACK could re- main sheltered inside MODUS during the launch/transfer/recovery phases and subsequent- ly lowered into the brines like a «tethered satel- lite» when MODUS had reached the desired po- sition over the DHAB. This idea was then substi- tuted by the simple low-cost solution where SCI- PACK is suspended under MODUS using a fixed length of cable. Although this solution has some impact on the operability of the system (in par- ticular the launch and retrieval procedures are more complicated), it maintains the basic func- tionalities of the innovative concept. MODUS has been adapted for BIODEEP purposes as indicated in fig. 2. The docking cone (visible in the foreground of fig. 2) – not necessary for this operation as no seafloor ob- servatory is involved – has been disassembled and replaced by a frame (SCISKID) housing mechanical and electronic equipment for the SCIPACK operation, an easy procedure be- cause of the modularity of the MODUS design concept. The fully assembled MODUS and the scientific module SCIPACK (equipped with water samplers, CTD, echosounder, a TV cam- era with light) are shown in fig. 3. The operational sampling procedure is schematically shown in fig. 4: SCIPACK is de- ployed from the vessel in a first step; it is fol- lowed by MODUS which is constantly commu- nicating with it, allowing control of the proce- dures to be executed during surveying and sam- pling. As mentioned above, the deployment and control of the vertical position is performed with the deep-sea winch of the R/V. Horizontal posi- tion is controlled by the MODUS pilot. By adopting umbilical cables of different lengths, it is possible to keep SCIPACK more or less close to MODUS, according to the task to be undertak- en: for exploration well inside the body of the brines, cables up to 200 m can be used, while for sampling at the interface shorter cables (10-20 m) are preferred, so that MODUS can more ac- curately manage SCIPACK operations. During these operations it is possible, through the down- ward-looking TV cameras installed on MODUS, to get visual control of the position of SCIPACK; this was an important innovation in the critical phase of sampling at the seawater-brine interface, Fig. 2. MODUS with SCISKID (background) and docking cone (foreground). 733 The exploration of Eastern Mediterranean deep hypersaline anoxic basins with MODUS providing for the first time the possibility to have a «virtual presence» in this unique environment. For the execution of visual surveys, the sys- tem configuration is modified: SCIPACK and its umbilical cable are removed; all TV cameras are placed onboard MODUS/SCISKID, that can now be flown over the surface of the DHABs. Fig. 3. MODUS with SCISKID (left) and SCIPACK (right) onboard R/V Urania. Fig. 4. Operational concept of BIODEEP mission for sampling and surveying: A – deployment of SCIPACK from the ship; B – operation of the MODUS-SCIPACK system at the interface of the DHAB. 734 Elisa Malinverno, Francesco Gasparoni, Hans W. Gerber and Cesare Corselli Two missions were carried within the BIODEEP project using this new technology. During these missions, four DHABs were ex- plored (Urania, Bannock, Discovery, L’Ata- lante); in all of them sampling tasks were car- ried out, while three were visually investigated both at the brine surface and at their margins. 5. The missions The two cruises were performed with the Italian R/V Urania (August 17-September 4, 2001 and November 7-27, 2003) within the framework of the BIODEEP project. The posi- tioning during the cruise was done using dedicat- ed navigation software (NavPro version DOS 5.5 of the Communication Technology), interfaced with a DGPS system. The reference cartograph- ic system used during the Cruise was the ED 50 Ellipsoid, with UTM (Universal Transverse of Mercatore) projection. A detailed bathymetric survey was per- formed with two Atlas DESO-25 echosounders – 12 and 33 kHz – at the margins of the basins, based on previous bathymetric maps of the area (Medriff Consortium, 1995), to identify the best sites to lower the MODUS system for the visu- al survey, i.e. areas with gentle slopes and ab- sence of rough topography. Configuration of the MODUS system for the sampling tasks (sampling at the seawater- brine interface and sampling inside the body of the brines) followed two basic modes, one char- acterised by a short cable (10 m) and one by a long cable (200 m) connecting MODUS with SCIPACK (fig. 5). Configuration 1 is character- ized by a 200 m secondary umbilical with dou- ble sided Y connection, connecting the SCI- PACK during operations in deep zones of the brines. After major difficulties with the teleme- try system and a short circuit in a cable, it was decided to leave the deep sampling task out and to shorten the umbilical to 10 m. This yields a detailed view of the sampling activities with cameras. Due to the high number of revolutions of the SCIPACK during descent and ascent, the umbilical situation was changed again to a twin cable configuration: this further prevented the payload from uncontrolled vertical turns (Con- figuration 2). The final dive configuration was found after placing the DAQ-box from the SCI- Fig. 5. Summary of the operations during cruise I and II of BIODEEP in the four DHABs (D – Discovery; A – L’Atalante; U – Urania; B – Bannock): type of operation and configuration (colour code and number code in the legenda), operation depth and duration (length of the blocks and white squares). 735 The exploration of Eastern Mediterranean deep hypersaline anoxic basins with MODUS PACK to the SCISKID frame at MODUS (Con- figuration 2). The latter allowed us to work with a single secondary umbilical, which significant- ly improved the quality of data transmission. Configuration for the visual surveys (Con- figuration 3, fig. 5) did not include SCIPACK. In this case a simple white-painted iron ball with a white flag was hung at the end of a 7/10 m rope, to create a clear reference and dimen- sion scale during the approach of MODUS to the interface and seabed. The strategy has been to lower the system in an area characterized by regular topography, as near to the beach as pos- sible, thanks to the accurate bathymetric con- trol, and then to move the ship toward the se- lected target, dragging MODUS along and keeping it straight by using its thrusters. Two different approaches were followed, depending on the morphology of the selected area and on the wind and sea direction, as the ship had al- ways to be directed with the bow against the wind, in order to maintain an accurate position- ing at the low speed (1-1.5 knots) needed for the survey. The first approach is to move from the brine pool toward the normal bottom, i.e. upward. This kind of operation is more dangerous, as the bot- tom can rise quite rapidly, possibly causing MODUS to touch the bottom: the winch operator must be ready at any time to recover the cable. Nevertheless this method allows a better depth control using the sonar and the altimeters. In fact the sonar can «see» the slope while approaching it, while the altimeters, ad hoc developed, can de- tect the bottom under the brines when these are shallow enough (around 10 m) and therefore dis- close in advance when the beach is reached. The second approach is to move from the normal bottom toward the beach, i.e. downward, and then to proceed inside the basin. This opera- tion allows safety conditions for MODUS, but the control on the bottom is less clear: the sonar as well as the altimeters can just see the normal bottom, which is also seen with the TV camera. Therefore the difficulty in this case is that the moment at which the brines are reached remains unknown. In total seventeen dives were carried out for sampling and surveying during cruise I and three during cruise II; fig. 5 illustrates the diving Fig. 6a,b. Images of the interface as seen by MO- DUS: a) view from MODUS to the suspended SCI- PACK (10 m mechanical cable) right before entering the Urania Basin; b) sequence of the survey at the interface of L’Atalante (10 m cable): iron ball and flag approach- ing the interface (I-III), entering the brines (IV), laying below the interface (V-VII) and coming out (VIII). a b 736 Elisa Malinverno, Francesco Gasparoni, Hans W. Gerber and Cesare Corselli depth, the duration of each dive and the dive con- figuration at the four different anoxic basins. The operational performance of the system was successful, with up to three dives per day. Only four dives were interrupted for technical reasons during cruise I (all related to failures of single components and not to design faults). The capabilities were confirmed during the re- cent cruise II where, thanks to the adoption of more sophisticated tools (as a high resolution zoom camera), more accurate sampling within the DHABs and visual observations along the beaches were carried out. Several samples, dedicated to geochemical and microbiological tasks, were obtained from the four selected DHABs along with data from the sensors mounted on SCIPACK and with an accurate visual control (fig. 6a). Sampling strate- gies and details are described, among others, in Borin et al. (2002). Three DHABs (Urania, L’Atalante, Discov- ery) were investigated through visual survey dur- ing which their beaches were detected and ex- plored. The brine interface, observed both during the sampling operations and during the dedicated surveys, appears in all basins as a sharp surface, acting as a «black hole». In fact objects hung un- der MODUS disappear when crossing the brine surface (fig. 6b). This mechanism can be due to the high light adsorption within the brines or at the boundary itself, due to the high density and optical contrast between the two media. 6. Conclusions The MODUS system has shown good suit- ability for deep-sea operations not only for the deployment of stations, as foreseen in the origi- nal concept, but also as a surveying and support- ing carrier for other scientific packages. The adaptation of this technology, developed during the GEOSTAR project, to the new aims pro- posed by the BIODEEP project, allowed the ex- ecution of sampling and surveying tasks which were up to now not feasible with other conven- tional equipment, even more sophisticated and expensive, like deep-sea ROVs and manned sub- mersibles. The BIODEEP project started April 2001, and the cruise where MODUS was used for the first time in the DHABs started mid August of the same year. This means that in four months a new concept for the exploration of the DHABs was developed, fully tested in the laboratory and final- ly made available fully operative for the first ap- plication. This would not have been possible without the availability of a carrier like MODUS. The application of MODUS technology to the study of the anoxic basins of the Eastern Mediterranean allowed for the first time: – to observe the seawater/brine interface, which is optically detectable as a light-absorb- ing surface, as demonstrated by the disappear- ance of objects when entering the brines; – to observe the beaches of the selected anoxic basins; – to accurately sample the brine interface with real-time visual control Acknowledgements Authors wish to dedicate this paper to the memory of Giuseppe Smriglio, coordinator of GEOSTAR project, who prematurely died in September 2001. BIODEEP Project is carried out under the VFP of the European Community (contract EVK3-CT-2000-00042). Captain and crew of R/V Urania and the scientific team on board dur- ing the two cruises are warmly acknowledged. GEOSTAR project was carried out under EU contracts MAS3-CT95-0007 (GEOSTAR-1) and MAS3-CT98-0183 (GEOSTAR-2). REFERENCES BORIN, S., D. DAFFONCHIO, T. BRUSA, F. GASPARONI, D. CALORE, C. CORSELLI and BIODEEP SCIENTIFIC TEAM (2002): Bacterial communities in the seawater-brine chemocline in deep anoxic hypersaline basins in the Eastern Mediterranean Sea, in Proceedings of the 8th Symposium on Aquatic Microbial Ecology, SAME8, October 25-31, 2002, Taormina (ME), Italy. CLAUSS, G.F., S. HOOG, M. VANNAHME, H.W. GERBER, F. GASPARONI and D. CALORE (2002): MODUS: space shuttle for deepwater intervention, in Off-shore Tech- nology 2002 Conference Proceedings, Paper 14051 (CD-ROM). CORSELLI, C., B. DELLA VEDOVA, A. CAMERLENGHI, G.J. DE 737 The exploration of Eastern Mediterranean deep hypersaline anoxic basins with MODUS LANGE and G.K. WESTBROOK (1998): Emission of warm fluids and high temperature in the Urania Basin: observations from 1993 to 1998, in Proceedings of the EU-Workshop on Extreme Marine Environments, No- vember 19-22, 1998, Kiel. DE LANGE, G.J., J.J. MIDDELBURG, C.H. VAN DER WEIJDEN, G. CATALANO, G.W.I. LUTHER, D.J. HYDES, J.R.W. WOITTIEZ and G.P. KLINKHAMMER (1990): Composition of anoxic hypersaline brines in the Tyro and Bannock basins, Eastern Mediterranean, Mar. Chem., 31, 63-88. GERBER, H.W., G. CLAUSS and S. HOOG (2002): MODUS – Remotely operated carrier for abyssal research – Experi- ences in the Mediterranean Sea, in Proceedings of the ISOPE 2002 (International Symposium for Ocean and Polar Engineering), May 2002, KitaKyushu, Japan. JONGSMA, D., A.R. FORTUIN, W. HUSON, S.R. TROELSTRA, G.T. KLAVER, J.M. PETERS, D. VAN HARTEN, G.J. DE LANGE and L. TEN HAVEN (1983): Discovery of an anox- ic basin within the Strabo Trench, Eastern Mediter- ranean, Nature, 305, 795-797. MEDRIFF CONSORTIUM (1995): Three brine lakes discovered in the seafloor of the Eastern Mediterranean, Eos, Trans. Am. Geophys. Un., 76 (33), 313-318. SCIENTIFIC STAFF OF CRUISE BANNOCK 1984-12 (1985): Gyp- sum precipitation from cold brines in an anoxic basin in the Eastern Mediterranean, Nature, 314, 152-154. WESTBROOK, G.K. and T.J. RESTON (2002): The accretionary complex of the Mediterranean ridge: tectonics, fluid flow and the formation of brine lakes, Mar. Geol., 186, 1-8.