It Is Not Just a Matter of Noise: Sciaena umbra Vocalizes More in the Busiest Areas of the Venice Tidal Inlets

Marta Picciulin,Matteo Zucchetta,Stefano Malavasi,Riccardo Fiorin,Chiara Facca,Federico Riccato

doi:10.3390/jmse9020237

Abstract

Boat noise is known to have a detrimental effect on a vulnerable Mediterranean sciaenid, the brown meagre Sciaena umbra. During summer 2019, two acoustic surveys were conducted at 40 listening points distributed within the inlet areas of Venice (northern Adriatic Sea). Two five-minute recordings were collected per each point during both the boat traffic hours and the peak of the species’ vocal activity with the aims of (1) characterizing the local noise levels and (2) evaluating the fish spatial distribution by means of its sounds. High underwater broadband noise levels were found (sound pressure levels (SPLs)50–20kHz 107–137 dB re 1 μPa). Interestingly, a significantly higher background noise within the species’ hearing sensibility (100–3150 Hz) was highlighted in the afternoon (113 ± 5 dB re 1 μPa) compared to the night (103 ± 7 dB re 1 μPa) recordings due to a high vessel traffic. A cluster analysis based on Sciaena umbra vocalizations separated the listening points in three groups: highly vocal groups experienced higher vessel presence and higher afternoon noise levels compared to the lower ones. Since the species’ sounds are a proxy of spawning events, this suggests that the reproductive activity was placed in the noisier part of the inlets.

Highlights

Many human activities generate sounds in the aquatic environment that are very different from those arising from natural sources both at the intensity and frequency levels; as a result, man-made noise has changed the acoustic underwater landscape of many areas, and it has become a pollutant of international concern, given its potential to harm marine fish [1].Living in a very noisy environmental condition represents a constraint for aquatic species
This is expected to be the case of the inlets that allow for shipping traffic in and out of the Venice Lagoon; Venice is one of the principal ports of the northern Adriatic Sea, with a number of about 3500 port calls for commercial vessels and cruise ships
The present study could not fully define a continuous and extremely variable phenomenon such as marine background noise by using a non-continuous monitoring approach; the acquired data are indicative of an environment saturated by the anthropic presence at the lower frequencies (

Summary

Introduction

Many human activities generate sounds in the aquatic environment that are very different from those arising from natural sources both at the intensity and frequency levels; as a result, man-made noise has changed the acoustic underwater landscape of many areas, and it has become a pollutant of international concern, given its potential to harm marine fish [1].Living in a very noisy environmental condition represents a constraint for aquatic species. Many human activities generate sounds in the aquatic environment that are very different from those arising from natural sources both at the intensity and frequency levels; as a result, man-made noise has changed the acoustic underwater landscape of many areas, and it has become a pollutant of international concern, given its potential to harm marine fish [1]. Continuous and chronic disturbance from boat noise is typically associated with marinas, boat channels, and harbor entrances. This is expected to be the case of the inlets that allow for shipping traffic in and out of the Venice Lagoon; Venice is one of the principal ports of the northern Adriatic Sea, with a number of about 3500 port calls for commercial vessels and cruise ships. The large number of fishing boats and motorand speed-boats operating along the inlets gives a large contribution to the local anthropogenic noise levels, during the summer period [7]

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