Baseline survey (University la Sapienza)
Bionomic cartography of the sea bottom
This is one of the key elements of the project, with the aim of protecting the priority habitats in the area represented by the Posidonia meadows and coral formations. Characterisation involves the acquisition of geo-referenced information used to produce detailed cartography of the benthonic population in 1:1000 scale. 1:5000 cartography will provide information about the wider area bordering on the project area. Multibeam and Side Scan surveys will be used to characterise the morphology of the sea bottom by means of sonograms interpreted by sector experts and supplemented with the data gathered by video control surveys performed by ROVs and divers in the areas identified. Data on sandy bottom benthonic components will be acquired by direct bucket sampling to identify the characteristic elements of the biocoenoses present. A particle size analysis will complete the study of the characteristics of the sea bottom. The survey by Multibeam RESON Seabat 7125, performed from 30 June to 7 July, produced detailed bathymetric data both in the specific area and around the entire east coast of the island. Data is already available for the specific area and processing is underway for the wider area. The survey by EDGETECH 4125P Sonar Side Scan was performed from 8 to 12 July and the data is now being processed. Surveys using an ENNE Elettronica underwater video camera began on 7 July and are still underway. Of the total 27 crossings planned for the specific area (30 meters apart), 23 have been completed.
Study of Posidonia oceanica
Surveys undertaken by divers to gather detailed information about the condition of the Posidonia meadows were performed on 3 July and have so far covered the area of the sea bottom between the wreck and the coast. To date 15 dives have been made which, together with the surveys mentioned previously, have provided lots of detailed information about the meadows (Posidonia coverage and density) in the area between the wreck and the port to the south, and between the wreck and Cala Cupa to the north. In the area close to the wreck, two balise control stations have been positioned near the lower edge. Six more stations will be completed in the coming days. Also in the coming days, samples will be taken and control balises positioned in accordance with the Water Framework Directive (WDF 2000/60 CE) for the calculation of the PREI (Posidonia oceanica Rapid Easy Index) in 3 pre-established stations. In the wider area, measurement stations will be positioned and further dives performed in locations based on the results of the SSS and MultiBean survey. In various points of the wider area, control dives have already been performed to check on the condition of the meadows compared with the situation observed near the wreck. The biological material needed to perform lepidochronological studies on the Posidonia will be gathered over the coming days and analysis will begin immediately afterwards.
Characterisation of sensitive habitats: Coral
The sites studied to characterise the coral in the specific area have been identified because of their precise location in relation to the position of the Concordia. The surveys were performed along the two rocky ridges that drop down steeply from the point in which the ship is now resting. The surveys were performed by a professional diver/operator equipped with a rebreather and HD video camera, from 10 to 14 July, along 5 pre-established routes (Fig. 1). The video recordings made it possible to record the characteristics or each site (depth, species present, etc.) and to take photographs inside a standard-sized area (50 x 37 cm) to define the species present and estimate the percentage coverage. Video recordings were made to a depth of 80 m. Inside the wider area, the recordings will document the actual state of populations at increasingly distant sites from the Concordia, based on the results of the morpho-bathymetric surveys currently being processed.
Benthonic sampling of sandy bottoms for fauna characterisation and biocoenotic identification
The samples used to characterise the sandy bottom were taken from 3 to 7 July in 30 stations at depths of between 10 and 90 m. The results, expected in mid-August, will provide additional information to map the sandy bottom populations present.
Surveys to define macroalgal populations in the intertidal zone
Surveys to characterise macroalgal populations in the intertidal zone around the island will be performed on 17 and 18 July.
Particle size characterisation of sandy bottoms
Samples to characterise the sediments were taken concurrently with sandy bottom benthonic population samples, in 30 stations, from 3 to 7 July.
Study of currents and suspended sediments
Preliminary investigations of the currents and the dynamics of suspended sediments were performed from 28 June to 1 July in a measurement campaign using a vertical acoustic current profiler with Doppler V-ADXCP effect.
In parallel, the waters were characterised by a CTD probe to measure parameters including T, salinity, dissolved oxygen and alpha chlorophyll.
In the same period 6 sediment traps were positioned on the sea bottom around the Concordia to measure the sedimentation rate before the start of work.
This data will be used to create a mathematical model of the water circulation to determine possible preferential sediment re-suspension paths.
1:1,000 mapping of the information gathered so far about the two priority habitats (Posidonia and coral) and the other biocoenoses identified in the specific area is nearing completion and will be concluded on schedule by the end of July.
The general framework of the geographical software (ArcGis 9.3) has been developed and implementation work will continue with the addition of new information as it becomes available.
The plankton population was sampled in 6 stations at 2 different depths from 3 to 7 July as planned.
Surveys to characterise fish populations using a visual census performed by divers will begin on 16 July.
So far as commercial fish are concerned, surveys began on 10 July on the fleet of small fishing boats based in Giglio Port. The information gathered includes species caught, yield and operating method used by the island’s trawling and small-scale fishing operations.
Characterisation of the marine mammal species present and identification of the background sound level
Background noise measurements were performed by means of a survey using underwater hydrophones over a period of 24 hours, with measurements taken at an increasing distance from the coast, from 27 to 30 June.
Processing this data will make it possible to develop a noise dissipation model that will be used to define the size of a safety area and the noise threshold above which behavioural disturbances may be caused in marine mammals.
At the present time the study of marine mammals in the area is being conducted on a bibliographic basis, for the description of available knowledge about the populations present.
Study of Pinna nobilis
This phase focuses on the presence of specimens of Pinna Nobilis on the sea bottom around the wreck of the Concordia, particularly inside the Posidonia meadow. A first examination of the data reveals a high density of these molluscs throughout the wreck area.
Study of alien species
Sightings of alien species, and Caulerpa genus seaweed in particular (Caulerpa taxifolia e C. racemosa), are recorded during all activities involving divers and ROV surveys.