O30- Does noise matter ? Passive Acoustic Monitoring reveals the co-occurring presence of two threatened sympatric vocal species (Sciaena umbra and Umbrina cirrosa; Sciaenidae) in highly anthropized Venice inlets
Marta Picciulin1*, Chiara Facca1, Marta Bolgan2, Matteo Zucchetta3, Riccardo Fiorin4, Federico Riccato4 and Stefano Malavasi1
1Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari; University of Venice, Venice, Italy
2Laboratoire de Morphologie Fonctionnelle et Evolutive, Institut de Chimie, Université de Liège, Belgium
3Institute of Polar Sciences, ISP-CNR, Venice-Mestre, Italy;
4Laguna Project S.N.C., Venice, Italy
Human impacts on marine ecosystems are accelerating, and the number of fish species listed in the Red List is growing. In the Mediterranean Sea, seven of the 10 bony fishes defined as Threatened by the IUCN are known to be vocal, including the shi drum (Umbrina cirrosa) and the brown meagre (Sciaena umbra). As a result, non-invasive Passive Acoustic Monitoring (PAM) can be used to pinpoint their distribution at sea. This is of particular interest since these species are closely related, elusive, sympatric, vocal sciaenids.
During summer 2019, three PAM surveys were conducted on a total of 40 listening points along the three tidal inlets of the Venice lagoon (Italy), which connect the open sea to one of the principal ports of the Northern Adriatic Sea. Here, the calls of both species have been recognized according to their temporal features: shi drum sounds were made up of a lower number of longer pulses with a different envelope, repeated at a lower rate than those of the brown magre. Call discrimination highlighted a partially overlapping distribution of the two species, inhabiting these highly anthropized inlets. Furthermore, S. umbra was found to emit longer sounds, with a higher number of faster repeated pulses during the chorus; these sound features are related to spawning activities in captive Sciaenids and were therefore used as proxy of spawning events in the study area. A cluster analysis based on S. umbra vocalizations separated the listening points in three areas; the areas in which vocal activity was highest were also characterized by the highest noise levels and number of vessel passages. This indicates that S. umbra spawning grounds are located in the noisier areas of the inlets, despite vessel noise is known to affect the efficiency of fitness-related behaviors. Results are discussed in a conservation perspective.