Nocturnal Acoustic Activity in the Shallow Waters of the WWF-Miramare Natural Marine Reserve (Trieste, Italy)

Abstract

A growing body of scientific evidence shows that the increasing noise pollution in coastal environments due to human activities has detrimental effects on marine animals, including many endangered species. As a consequence, research studies and subsequent conservational actions are needed to mitigate the effects of noise pollution. One important step is to safeguard sensitive areas known as marine protected areas (MPAs) from anthropogenic noise; these ecologically rich areas, critical habitats for key species, are often located in highly populated coastal zones. This is the case of the WWF-Miramare Natural Marine Reserve, a UNESCO-Man and Biosphere Programme (MAB) Biosphere Reserve located in the Gulf of Trieste (Italy) and considered an important seasonal nursery area in the North Adriatic Sea (Guidetti et al. 2005). Although a recent study (Codarin et al. 2008), based on daytime acoustic monitoring, shows that the Miramare fish population is living in a heavily noisy underwater environment year-round, relatively little is known about the features and anthropogenic factors of nocturnal sea ambient noise (SAN) in the Reserve. This information is particularly relevant considering that intraspecific communication of many marine species (i.e., the brown meager, Sciaena umbra, during spawning season; Bonacito et al. 2001) occurs after sunset and during night. As a consequence, the present study aims 1) to quantify the nocturnal ambient noise levels at the Reserve, 2) to distinguish and quantify the biological versus anthropogenic components of the noise, and 3) to discuss their possible interaction.