1 Scientific RepoRts | 6:34230 | DOI: 10.1038/srep34230 www.nature.com/scientificreports temporal patterns in the soundscape of the shallow waters of a Mediterranean marine protected area Giuseppa Buscaino 1 , Maria Ceraulo 1,2 , Nadia pieretti 2 , Valentina Corrias 1 , Almo Farina 2 , Francesco Filiciotto 1 , Vincenzo Maccarrone 1 , Rosario Grammauta 1 , Francesco Caruso 1 , Alonge Giuseppe 3 & salvatore Mazzola 1 The study of marine soundscapes is an emerging ield of research that contributes important information about biological compositions and environmental conditions. The seasonal and circadian soundscape trends of a marine protected area (MPA) in the Mediterranean Sea have been studied for one year using an autonomous acoustic recorder. Frequencies less than 1 kHz are dominated by noise generated by waves and are louder during the winter; conversely, higher frequencies (4–96 kHz) are dominated by snapping shrimp, which increase their acoustic activity at night during the summer. Fish choruses, below 2 kHz, characterize the soundscape at sunset during the summer. Because there are 13 vessel passages per hour on average, causing acoustic interference with ish choruses 46% of the time, this MPA cannot be considered to be protected from noise. On the basis of the high seasonal variability of the soundscape components, this study proposes a one-year acoustic monitoring protocol using the soundscape methodology approach and discusses the concept of MPA size. Soundscape analysis is an emerging ield of ecological research 1 that contributes information about biological compositions and environmental conditions. In marine ecosystems, studies have underlined the importance of the acoustic environment to provide information about the quality and types of species habitats 2–5 . he acoustic environment of a given habitat, or “soundscape”, includes the sounds produced by biotic, abi- otic and anthropogenic activity 6 . hese three components, deined as biophony, geophony and anthropophony, interact with each other and determine the peculiar and distinct underwater sound signatures 5,7,8 , which show a recognizable temporal pattern on daily and seasonal time scales 6,9 . In marine shallow waters, biophonies are produced by ish, invertebrates and marine mammals. Marine ani- mals emit sounds mainly for communication, and environmental recognition. In some cases, animals generate sounds involuntary during other activities (e.g., during swimming, grazing or shell movement). All these sounds contribute to the biophonic component of a particular soundscape 10–12 . Vocal ishes produce impulsive or frequency-modulated sounds at low frequencies and low amplitudes, with diferences in the duration and number of pulse trains for each species 13 . Invertebrates, such as shrimp, lobsters and bivalves, emit voluntary or involuntary impulsive and cracking broadband signals 10,14,15 . In coral reefs, snapping shrimp produce the dominant acoustic energy and exhibit clear daily acoustic trends 16 . hese benthic-dwelling shrimp produce wideband pulses from 3 to 100 kHz, with an irregular pulse repetition rate 14 , which results from the rapid closing of their enlarged claws and the consequent collapsing cavitation bubble 17 . Marine mammals in Mediterranean coastal habitats, such as bottlenose dolphins, use two types of sound: broad- band impulsive signals (clicks/burst), ranging from a few kHz up to 120 kHz 18 , and modulated narrowband whis- tles 19,20 . Biological sources included in a characteristic soundscape can be either transient 21,22 , show seasonal patterns 11 or be resident 21 . Moreover, the occurrence of acoustic signals can be related to diferent ecological 1 national Research council – institute for coastal Marine environment – Bioacousticslab capo Granitola, Via del Mare, 6 – 91021 Torretta Granitola, Campobello di Mazara (TP), Italy. 2 Department of Pure and Applied Sciences (DiSPeA) – University of Urbino– Campus Scientiico “Enrico Mattei”– 61029 Urbino, Italy. 3 ENEA – Observations and Analyses of Earth and Climate – Via Principe di Granatelli, 24 – 90139 Palermo, Italy. Correspondence and requests for materials should be addressed to G.B. (email: giuseppa.buscaino@cnr.it) Received: 18 May 2016 Accepted: 30 August 2016 Published: 28 September 2016 OPEN