R/V URANIA

Catania, August 10 – Catania, August 23, 2005

CHIEF SCIENTIST

Leonardo Langone

Istituto Scienze Marine - CNR

Sede di Bologna - Geologia Marina

Via Gobetti, 101- 40129 Bologna, Italy

Tel. +39 051 6398870- Fax. +39 051 6398940

E-mail: leonardo.langone@ismar.cnr.it

http://www.bo.ismar.cnr.it/

http://www.eu-hermes.net/

LIST OF PARTECIPANTS

Bergami Caterina ISMAR-BO Foraminifera, pore water, alkalinity

Cargini Daniele CoNISMa-ULR Ancona Sediment sub-sampling

Covazzi Anabella CoNISMa-ULR Ancona Sediment sub-sampling

D’Amico Davide UNI-MI Sediment sampling

Foglini Federica ISMAR-BO GIS, seismic, navigation

Gallerani Andrea ISMAR-BO Foraminifera, pore water, alkalinity

Gambi Cristina CoNISMa-ULR Ancona Sediment sub-sampling

Gitto Daniele So.Pro.Mar. Multi-beam, seismic, hydrology

Langone Leonardo ISMAR-BO Chief scientist, sediment sampling

Maselli Vittorio UNI-TS Seismic, navigation

Minisini Daniel UNI-BO Seismic,navigation, sediment sampling

Miserocchi Stefano ISMAR-BO O₂ profiles, pore water

Molari Massimiliano CoNISMa-ULR Ancona Sediment sampling

Occhiena Fabrizio So.Pro.Mar. Multi-beam, seismic, hydrology

Remia Alessandro ISMAR-BO Navigation, seismic, hydrology

Santambrogio Daniela UNI-MI Hydrology, navigation

Scopa Maria Spina CoNISMa-ULR Ancona Sediment sub-sampling

Turchetto Margherita ISMAR-VE Hydrology, alkalinity, O₂

Veneruso Mariacira ISMAR-BO Sediment sampling, hydrology

Verdicchio Giuseppe UNI-BO Seismic,navigation, sediment sampling

Zeppilli Daniela CoNISMa-ULR Ancona Sediment subsampling

The scientific staff of the cruise GELA-05

INDEX

1. INTRODUCTION……………….……………………………………………….…….….……..4

2. NAVIGATION AND DATA ACQUISITION………………………………………..….…..8

3. HYDROLOGICAL AND BIOCHEMICAL PARAMETERS………………………….….….13

4. SEISMIC PROFILES, SWATH BATHYMETRY AND SEDIMENT SAMPLES….…20

5. BIODIVERSITY AND ECOSYSTEM FUNCTIONING AND EFFICIENCY………..26

6. BENTHIC RESPONSE AND EARLY DIAGENESIS CHARACTERISATION……..30

ANNEX 1: CRUISE SUMMARY REPORT – ROSCOP REPORT………………………..34

ANNEX 2: SAMPLING EVENT LOG FILE OF THE CRUISE GELA-05….…………...38

R/V URANIA

1. INTRODUCTION

Leonardo Langone

Istituto Scienze Marine, ISMAR-CNR, Sede di Bologna - Italy

leonardo.langone@ismar.cnr.it

The objective of the GELA-05 oceanographic cruise was to investigate a set of very recent slides showing markedly distinct morphology on the slope of Gela basin, Strait of Sicily. Box-cores stations formed downslope parallel transects, both within and outside the mass-transport complexes, in order to gather information about the variability of sedimentological parameters (such as grain size and composition) and the benthic ecosystems. Furthermore, a peculiar slope transect of box cores was performed cross-cutting the Malta Escarpment (Ionian Sea), in order to analyse the fauna variability at distinct water depths from the shelf edge to 3000 m water depth.

The cruise involved two main teams: CNR-ISMAR Bologna and Venezia, and the Department of Marine Sciences, Polytechnic University of Marche (ConISMA).

The main operations carried out on the cruise were:

• sediment box coring on 26 stations. On each station, at least 3 replicas were retrieved. On 7 of the sampling stations additional box cores were collected in order to extract pore waters for benthic response and early diagenesis characterization. In total we collected 86 box cores;

• once onboard, each box core was subsampled for macrobenthos, meiofauna, foraminifera, bacteria/viruses, organic matter, enzymes, dissolved oxygen profiles and grain size;

• long piston cores were collected in four sites using ISMAR CP20 piston corer (armed, in this case, with a 10 or 15 m barrel and a maximum core recovery of 11.61 m), and three gravity cores for a total of ca 42 m of sediment section;

• Three benthic traps were deployed in the search for megabenthos and were recoverd after 24-48 hours;

• two stations were made for epibenthic dredging to recover megabenthos;

• a hydrological survey was performed along 6 transects normal to shore for a total of 27 stations. Water sampling was performed on 19 stations for physical and bio-geochemical characterisation of particulate suspended matter; in total, 85 water samples were collected;

• ca. 880 nautical miles of morphobathymetric profiles were collected using a hull-mounted Reson Seabat 8160 multi-beam system simultaneously with high-resolution CHIRP-sonar profiles;

• navigation data were processed onboard on a daily basis and plotted through the new HERMES GIS system against the pre-cruise data and thematic layers. The multi-beam bathymetry data were also pre-processed on board creating grids of variable resolution to allow the best definition of sampling targets.

All the operations were carried out successfully. The geologists and biologists on board worked together on several different activities during the cruise. This co-operation turned out to be really exciting because of an effective exchange of knowledge. Furthermore, apart from the science, the life on board was pleasant and the friendly atmosphere. For the most part of the cruise, the weather was good and the sea smooth.

We are grateful to the Captain of R/V URANIA, Com.te Nicolangelo Lembo, to the officers, to the on board technical staff and to the crew for their assistance in the on board operations.

The chief scientist has assembled this cruise report from individual contributions of the participants.

Fig. 1-1. Map showing the two study areas - Gela Basin and Malta Escarpment - of the Gela-05 cruise located SW and SE of the Sicily island, respectively.

Fig. 1-2. Map of sampled stations and track lines.

2. NAVIGATION AND DATA ACQUISITION

F. Foglini, A. Remia

ISMAR-CNR (Bologna-Italy)

The research vessel Urania was set-up for data acquisition and navigation with RESON PDS-2000 and Communication Technology NAVPRO softwares.

The Positioning system NAVPRO V5.5 provided by Communication Technology (Cesena, Italy) was used. The integrated system used a Microtecnica Gyrocompass and a Trimble 4000 Differential Locator, with a DGPS Satellite link by FUGRO. Instruments were interfaced by a Digiboard Multi Serial I/O.

The datum WGS84 and the UTM projection Zone 33N were chosen for navigation and display purposes. Timing was set to UTC, whereas the acquisition rate was set to 10 s. The SBP-CHIRP workstation received the 'VESSEL(0,0)' positions by the NAVPRO serial output. The speed of sound for echosounder ATLAS-KRUPP DESO 25 (33 kHz) was set at 1535 m s^-1, with a transducer immersion of 3.8 m.

The navigation system PDS-2000 V2.3.4.35 by RESON was used for multi-beam data acquisition. The system interfaced the RESON 8160 Operator's console, an OCTANS gyrocompass and MRU, and the Trimble 4000 DGPS receiver.

The RESON 8160 MBES sonar head was positioned by a sub on the ship's keel using a V-shaped steel frame, and the cable's dry end passed trough a pipe after water-proofness.

The instrumental offsets are presented in Table 2-1.

Table 2-1. Instrumental offsets (in m) on R/V Urania. Point (VESSEL(0,0)) is located on the axis of the mast, just behind the Command Bridge. The main GPS antenna (primary positioning system) is located on point POS1.

GIS AND DATA PRE-PROCESSING

Track Line charts

Navigation data were processed onboard on a daily basis and plotted through the new HERMES GIS system (ArcInfo 9.1) against the pre-cruise data and thematic layers Figs. 2-1, 2-2.

Fig. 2-1. Chart of Track Lines of Gela Basin.

Fig. 2-2. Chart of Track Lines of Malta Escarpment.

The Urania position was displayed and reported by a GPS device in ArcMap using ArcMap GPS Support (Fig. 2-3). The GPS device was connected by an input/output (I/O) interface and by a GPS compatible cable. The GPS connection was extremely useful to make an effective cruise plan in real time and to be aware about the pre-cruise data position.

Fig. 2-3. The GPS device in ArcMap. The small red boat represents the actual navigation position.

Multi-beam Bathymetry

About 880 nautical miles of morpho-bathymetric profiles were collected using a hull-mounted multi-beam echosounder  (Reson Seabat 8160) covering an area of about 1400 km². Deployments of a CTD probe were performed in each subarea in order to calculate sound velocity profiles to calibrate the echosounder.

The multi-beam bathymetry data were pre-processed on board, creating grids of variable resolution to allow the best definition of sampling targets. Swath bathymetry maps were produced on board processing the DTM extracted, on daily basis, from PDS-2000. The DTM was filtered by ISMAR's routine filter_bat, and gridded by ISMAR's nearneighbor routine. The latter grids were converted to raster by ArcInfo Coversion tools.

The ArcInfo Surface analysis tool was used to derive contours, angle of slope and shaded relief (hillshade) maps used for navigation and structural analysis (Figs. 2-4, 2-5, 2-6).

Fig. 2-4. Example of a contour map. Fig. 2-5. Example of a hillshade map.

Fig. 2-6. Example of a slope map.

3. HYDROLOGICAL AND BIOCHEMICAL PARAMETERS

M. Turchetto¹, A. Remia², G. Verdicchio², F. Foglini²

¹ISMAR-CNR (Venice-Italy) – ²ISMAR-CNR (Bologna-Italy)

During the GELA_05 cruise on board the R/V “Urania”, a grid of 22 stations placed along 5 transects in the Gela basin and 6 stations over the Malta Escarpment, were sampled by a rosette with Niskin bottles (10 l), coupled with a SeaBird CTD probe, equipped with a SeaTech fluorometer and a Wetlab 25 cm path length transmissometer. Before the beginning of the multi-beam surveys, additional CTD stations were performed to calculate the sound velocity for multi-beam calibration. At each station vertical continuous profiles of temperature, salinity, dissolved oxygen, fluorescence and light transmittance were performed.

CTD data have been checked, filtered and averaged to 1 m depth; dissolved oxygen data were calibrated with O₂ data determined from water samples by the Winkler method.

At selected stations, water samples were collected at different depths in relation to the hydrological structure, turbidity and fluorescence profiles. Water samples were collected to determine total suspended matter (TSM), particulate organic carbon (POC), particulate nitrogen (PN), organic carbon stable isotopes (¹³C_POC).

Samples for TSM, POC, PN and ¹³C_POC analyses were filtered onto GF/F Whatman, 25 mm diameter, glass fibre filters. Filters for TSM were pre-weighed and those for POC, PN and ¹³C_POC analyses were pre-combusted at 450°C for 4 h to eliminate the organic contaminants.

TSM will be determined gravimetrically. POC and PN will be determined by FISONS NA2000 Elemental Analyser (EA), after removal of inorganic carbon with HCl. Stable isotopic analyses of organic carbon will be carried out using a FINNIGAN Delta Plus mass spectrophotometer directly coupled to the FISONS NA2000 EA by means of a CONFLO interface.

Details of the sampled stations and of the depths sampled for each parameter are reported in Table 3-1 and 3-2, respectively.

Conductivity temperature depth CTD. Hydrological laboratory  on board.

Table 3-1. List of the hydrological stations.

Table 3-2. Details of hydrological stations sampled for particulate matter analyses.

In the Gela basin, temperature at the surface layer ranged from 23.7 to 25.4 °C (Fig. 3-1a), with a mean of 24.7 °C, showing a slight north-south gradient, whereas at depth it dropped to values < 14°C (Fig. 3-2).

Salinity had an average value of 37.73 at surface (Fig. 3-1), increasing with depth, maximum values (> 38.8) typical of the Levantine Intermediate Water (LIW) were observed from 150 to 300 m depth (Fig. 3-2); the bottom layer showed a mean value of 38.79.

A typical Deep Chlorophyll Maximum was recorded at 60-90 m depth, where the highest fluorescence values were measured (Fig. 3-2).

Fig. 3-1a. Surface distribution of potential temperature and salinity in the Gela basin.

Fig. 3-1b. Bottom distribution of potential temperature and salinity in the Gela basin.

Fig. 3-2. Vertical sections of temperature, salinity and fluorescence in the Gela basin.

Fig. 3-3. Scatter plots of temperature and fluorescence in the Gela basin.

In the area over the Malta Escarpment the surface temperature ranged from 25.6 to 26.3 °C, whereas the bottom layer showed values < 14°C (Figs. 3-4 and 3-5).

Surface salinity showed a wider range from 37.48 to 38.75. Maxima were measured around 150-250 m depth with values > 38.8 (LIW). At the bottom, salinity varied from 38.8 in the shallower more coastal stations to 38.76 in the deeper (1000-2000 m depth) stations.

A Deep Chlorophyll Maximum (DCM) was found at 60-80 m depth although less pronounced with slightly lower maximum fluorescence values (Fig. 3-4 and 3-5).

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Fig. 3-5. Scatter plots of temperature and fluorescence over the Malta escarpment.

Fig. 3-4. Vertical sections of temperature, salinity and fluorescence over the Malta escarpment.

4. SEISMIC PROFILES, SWATH BATHYMETRY AND SEDIMENT SAMPLES

D. Minisini, G. Verdicchio, M. Veneruso, D. Santambrogio, V. Maselli, D. D’Amico, L. Langone

ISMAR-CNR (Bologna-Italy)

A dense network of Chirp-sonar seismic profiles and swath bathymetric data collected during the cruise meant to be useful for the characterisation of geomorphology and stratigraphy of the Gela basin and a sector of the Malta Escarpment.

Chirp-sonar profiles use a 2-7 kHz sweep-modulated band width, equivalent to a 3.5 kHz profiler fired from 16 transducers, and have a 500-2000 ms recording length, depending on water depth. High-resolution swath-bathymetric data were gathered using a 50-kHz EM-300 multi-beam, minor sectors were covered by conventional bathymetric data that were anyhow sufficient to identify the morphologic expression of the seafloor.

Fig. 4-1. Swath bathymetry and track-lines of seismic profiles of a surveyed area in the Gela basin, Strait of Sicily.

Stratigraphic and geomorphological goals of cruise GELA-05 concerned 3 main themes:

• activity/inactivity of the margins, particularly along the slope of Gela basin;

• location and variability of mass-transport products;

• chronology and time constrain of main mass-transport events.

Seismic profiles

Chirp-sonar profiles collected on the shelf offshore Gela document a regional shallowly-buried erosion unconformity, overlaid by onlapping or draping sediment units that, as in other areas of the Mediterranean, indicates a region affected by the sea-level low stand of the last glacial cycle. Most of the slope and base-of-slope area record stacked deposits with acoustically transparent facies, separated by laterally continuous high-amplitude reflectors, that are interpreted as multiple mass-transport events documenting the recurrence of failures in the area along a stretch of more than 65 km (Fig 2). Seismic profiles show evidence of several exposed, partially overlapping, mass-transport deposits, which emanated from slide scars that are clearly detectable on the slopes of Gela basin. The exposed slide deposits correspond to transparent-chaotic seismo-facies with erosional base and local hyperbolic returns at the seafloor that suggest the presence of sharp reliefs. Slide scars are particularly evident along the northern flank of the Gela basin.

Fig. 4-2. Multiple mass-transport events. Deep penetration of acoustic-signal into the subbottom suggests that these stratigraphic units are dominantly fine-grained sediment, both within and outside mass-transport deposits.

The surveyed sector of the Malta Escarpment documents an extremely high steepness (up to 75°) and irregular geomorphology. A dense network of gullies and minor incisions dissect the walls of the main Escarpament whose high stiffness and coherence do not allow acoustic signal to penetrate. Along less steep slopes, located in the shallowest part of the area, a thin layered sediment unit drapes the basement that crops out in the Malta Escarpment. At the base of the Escarpment several sediment lobes overlap, generating a complex stratigraphy and seafloor morphology.

Swath bathymetry

Two main slide scars appear in water depths deeper than 200 m and reach the base of the slope in 860 m (Fig. 1); the headscarps of these slides are more than 6 km wide, are rounded in plain view, and appear composed of several internal smaller-scale scarps. The slope gradients below the shelf edge are around 16° and become on average 4.5-1.5° at the base of the slope. Within the slide scarps slope gradients are as steep as 27°.

Moving toward south-east, the slope presents smaller headscarps, dense occurrence of gullies and several minor incisions. Proceeding in the same direction, the continental slope reveal evidence of widespread failure products either clearly exposed at the seafloor, or mantled by a sediment drape thin enough to leave morphologic expression at the seafloor (Fig. 3).

Swath bathymetry detected also a field of pockmarks that occurs atop of a distal mass-transport deposit, more precisely, along a pre-existing local bulge that increases the slope from 0.8° to 2.2°. The field of pockmarks is subrounded, 2.5 km large and present 37 pockmarks (in the order of 100 m apart from each other). Chirp-sonar profiles document craters more than 10 meters deep and few hundred meters in diameter without any sediment drape. Fluid escapes at the toe of northern slide may be responsible for this pockmark field.

Fig. 4-3. Swath bathymetry showing evidence of widespread failure products along the south-east continental slope of Gela basin.

Swath bathymetry in the Malta Escarpment area reveals 3 main geomorphological features: 1) a suite of valleys and gullies forming a drainage-like pattern, 2) a horseshoe-shaped 500 m-high escarpment, 3) a complex of overlapping sediment lobes at the toe of the escarpment. All together this area ranges between 500 and 2600 m of water depth and includes slopes from 1° to 75°.

Sediment samples

Seabed sampling location meant to be useful for the dating and the characterisation of sediment features recognized on Chirp-sonar profiles and swath bathymetric data. Two types of samples have been collected: long sediment cores and box-cores.

Six long sediment cores were collected using gravity and piston corers with variable barrel lengths (5-15 m), for a maximum core recovery of 88% and 11.61 m. Long cores in the Gela basin were recovered in key spots decided on the base of seismic profiles, to reconstruct the stratigraphy of the basin through analyses and correlations of biostratigraphic determinations, sediment facies and magnetic susceptibility. In particular, direct stratigraphic information has been acquire to: 1) establish stratigraphic correlations among slope areas not affected by sediment failure; 2) determine the age of the most recent slide events; 3) reconstruct the stages of failure and the downslope evolution of the mass-transport processes.

Piston corer onboard Coring operation

In addition, a box-corer was employed to collect 86 large-diameter undisturbed core tops; box-corer was deployed 3-4 times per station in order to recover large amount of sediment for biological, geochemical and radiochemical analyses (see the specific reports).

Box core and recovery of undisturbed top to analyse fauna and sediment.

Table 2. List of box core stations

Table 3. List of gravity and piston cores

5. BIODIVERSITY AND ECOSYSTEM FUNCTIONING AND EFFICIENCY

C. Gambi, A. Covazzi, M.S. Scopa, D. Zeppilli, D. Cargini, M. Molari

CoNISMa-ULR (Ancona-Italy)

The primary objectives of the seabed sampling were to study and compare the biodiversity of benthic communities and sediment characteristics along two landslides and the adjacent open slopes (which were used as control stations) in the Strait of Sicily and a transect along the Malta Escarpment. Sediment cores were collected for biological and biochemical analyses to understand the relationship between ecosystem functioning and efficiency, and biodiversity in two different systems (landslides and open slopes). Biological analyses included the biochemical composition of organic matter, prokaryotic secondary production, enzymatic activities, bacterial, meio- and macro-faunal abundance, biomass and diversity.

Sediment Cores

^{Sediment samples were collected using a box corer (box size I.D. 32.4 cm cross-section, 52 cm height) along the axes of two landslides, along three across-shelf transects in the open slope of Gela basin and along one across-shelf transect in the Malta escarpment. The depth of sampling stations ranged between 183 and 807 m for the Gela basin and between 607 and 2325 m for the Malta Escarpment. All stations were successfully sampled and were surveyed prior to collect sample using the URANIA seabeam depth sounder, to identify sample locations within the landslides axis and the open slopes. For macro-megafauna samples were deployed benthic traps at stations 5, 10 and 12, respectively, but no organisms were collected. Also a dredge was deployed at stations 9 and 23, without success.}

^{Recovery of the box corer. Sediment subsamples from a box core.}

Processing of cores

^{Each box core was sub-sampled using thin PVC liners of different internal diameters (10 cm, 5.5 cm and 3.6 cm, respectively). For biological analyses, sediment cores were sliced into different layers: 0-1, 1-3, 3-5, 5-10 and 10-15 cm. For macrofauna analyses an entire box core for each station was sieved using a 500 µm mesh.}

^{Sediment samples will be analyzed for biological analyses (biochemical composition of organic matter, prokaryotic secondary production, enzymatic activities, bacterial, meio- and macro-faunal abundance, biomass and diversity).}

^{Some analyses such as prokaryotic secondary production and enzymatic activities (for the top 1 cm) were immediately performed on board after the samples collection; for all the other analyses sediment samples were processed on board and stored until the analyses in the laboratory.}

For living forams, the uppermost 5 cm of the box cores were subsampled by C. Bergami (ISMAR-BO) with short liners and extruded to obtain sediment samples 0.5/1 cm thick. Sediment samples were treated with Bengal Rose to detect the living (=stained) assemblage, then results will be presented as living and total (living + dead foraminifera) assemblage.

Deployment of the benthic trap buoys. Benthic traps.

Table 5-1. Subsampling of box cores for biological analyses in the Gela Basin (Strait of Sicily) and Malta Escarpment. BC_ID, label of the box core, where the first digit marks the station number, while the second one shows the deployment number; OM, organic matter; EA, enzymatic activity.