Awareness about the potential deleterious impacts on marine ecosystems that the generation of underwater noise can exert has only recently started to emerge.
Low frequencies emitted by ships, ranging between 10 Hz and 150 Hz, have in fact been identified as those most disruptive to fish and marine mammals. So much so that this field of research is fledgling one, with a lack of long-term monitoring data on continuous underwater noise which even makes it impossible to describe the baseline soundscape of Maltese waters.
Such a paucity in data does not only have an impact of the effective management of marine ecosystems and of maritime activities but also blunts Malta’s efforts at fulfilling its reporting obligations within a number of European and regional agreements it is party to.
For instance, Descriptor 11 of the Marine Strategy Framework Directive (MSFD) includes a number of indicators on continuous underwater noise, for which Malta is currently not able to acquire any monitoring data.
In order to address this glaring lacuna, resident academics from the Oceanography Malta Research Group (OMRG) of the Department of Geosciences within the Faculty of Science (ocean.mt), including Prof. Alan Deidun and Dr Adam Gauci, as well as Ms Julia Micallef Filletti, a former student of the Institute of Earth Systems, teamed up with underwater noise experts based at the INFN (Istituto Nazionale di Fisica Nucleare) – Dr Giorgio Riccobene and Dr Salvatore Viola – to assess the contribution of shipping traffic to continuous underwater noise generation in selected spots within Maltese waters.
The study involved the installation, for a number of weeks, of an underwater noise logger at two different depths within two different locations within Maltese waters – off the entrance to the Grand Harbour and within the Cirkewwa marine reserve.
These two locations were selected by virtue of their proximity to busy commercial shipping or ferry lines. In addition, shipping traffic data was tapped into through the extraction of AIS (Automatic Identification System) data for Maltese waters, given that the OMRG operates its own AIS monitoring system, installed in 2014 through the Biodivalue project.
Data analysis was conducted via a novel software, dBWav by Marshall Day Acoustics, which is specifically designed for efficiently conducting Fast Fourier Transform and power spectral density analyses.
The results obtained concluded that the Maltese marine acoustic environment is in a sub-optimal condition and aspire to encourage the national competent authorities to appropriately allocate resources in order to stay on track in achieving ‘Good Ecological Status’ as stipulated by the MSFD.
These and other findings have been published in a recent paper featured within the Journal of Marine Sciences and Engineering, which was financed through a number of Interreg Italia-Malta projects the OMRG was involved in, including CORALLO, SENHAR and CAPSENHAR.
The underwater noise logger deployed in the current study was financed through a previous grant of the University of Malta’s Research Committee. The full publication can be accessed through Prof. Deidun’s ResearchGate profile or .
