Efeitos do tráfego náutico no comportamento do peixe-donzela Stegastes fuscus (CUVIER, 1930) em ambiente natural

Abstract

Nautical tourism has increased over the years in coastal and marine environments worldwide. Impacts derived from this activity, such as chemical, physical and noise pollution, may affect ecosystems and species, leading to shifts in community diversity and structure. Fishes comprise excellent models to assess the effects of boat noise activities on reef ecosystems, particularly considering key-species, such as damselfishes (family Pomacentridae). These fish are recognized by their role in structuring benthic communities in reefs, presenting ecologically relevant behaviours, which include sound production. This work assessed the effects of boat traffic on the behaviour and sound production of a Brazilian damselfish, Stegastes fusucus, which, due to its behavioural and ecological characteristics, is a potential model to studies involving bioacoustics and anthropogenic impacts. Samplings were carried out at Tamandaré coastal reefs (state of Pernambuco, Brazil) through simultaneous video and audio recordings in two areas under different boat traffic intensities (an open and a closed area to boat traffic). Four types of sounds were produced by S. fuscus, which were associated with agonistic and reproductive behaviours. Moreover, S. fuscus presented a behavioural repertoire composed of 15 behaviours, from which swimming was the most frequent (open area – 48.05%; closed area – 42.38%), followed by feeding (open area – 30.77%; closed area – 35.52%) and aggressive behaviours (open area – 81%; closed area – 88%). Damselfish showed higher behaviour diversity at the open area. In relation to boat traffic effects, S. fuscus in the high season at the open area showed higher frequency of swimming and agonistic behaviours, and lower dominant frequency and pulse duration of sounds produced. Boat noise mean dominant frequency (400 Hz) potentially overlaps S. fuscus sounds’ mean dominant frequency at the open area. We conclude that nautical traffic represents an additional pressure on damselfish populations in Tamandaré reefs, and propose measures related to boat traffic zoning and instruction of tourists and owners about boating activities in the area.