A multidisciplinary approach in the analysis of the low frequency hydrophone aboard the NEMO-SN1 observatory of EMSO: first results on shipping noise and bioacoustics.

The NEMO-SN1 observatory was deployed and connected in June 2012 using the Cabled termination of the Catania cabled infrastructure, part of the Western Ionian Sea node of the EMSO Research Infrastructure. The observatory was equipped with several probes and sensors acquired on-line from shore. A SMID DT405D hydrophone was installed aboard the NEMO-SN1 observatory in the aim of searching foracoustic signals in the frequency range 0.001:1000 Hz. Hydrophone’s signals, are sent to two different read-out channels with +30dB and +60 dB gain respectively, thus digitised by a 12 bit ADC at 2000 Hz sampling rate frequency. The low-gain channel data is primarily used to search for seismicevents, the high-gain channel data is used for acoustic monitoring of sea noise and search for biological noise. All data are continuously recorded on-shore and saved in files for off-line analysis. Data has been analysed in collaboration between the EMSO Italia and SMO teams. Thanks to the use of an AIS (Automatic Identification System) antenna installed at the Catania infrastructure, acoustic data were analysed in correlation with ship-traffic information. Preliminary results show correlation between sea-noise increase and shipping activities. Clear evidence of the presence of fin whales in the area has been also found.