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- Boat noise impacts Lusitanian toadfish breeding males and reproductive outcomePublication . Amorim, M. Clara P.; Vieira, Manuel; Meireles, Gabriela; Novais, Sara C.; Lemos, Marco F.L.; Modesto, Teresa; Alves, Daniel; Zuazu, Ana; Lopes, Ana F.; Matos, André B.; Fonseca, Paulo J.Anthropogenic noise is a growing threat to marine organisms, including fish. Yet very few studies have addressed the impact of anthropogenic noise on fish reproduction, especially in situ. In this study, we investigated the impacts of boat noise exposure in the reproductive success of wild Lusitanian toadfish (Halobatrachus didactylus), a species that relies on advertisement calls for mate attraction, using behavioural, physiological and reproductive endpoints. Two sets of artificial nests were deployed in the Tagus estuary and exposed to either ambient sound or boat noise during their breeding season. Toadfish males spontaneously used these nests to breed. We inspected nests for occupation and the presence of eggs in six spring low tides (in two years) and assessed male vocal activity and stress responses. Boat noise did not affect nest occupation bymales but impacted reproductive success by decreasing the likelihood of receiving eggs, decreasing the number of live eggs and increasing the number of dead eggs, compared to control males. Treatment males also showed depressed vocal activity and slightly higher cortisol levels. The assessment of oxidative stress and energymetabolism-related biomarkers revealed no oxidative damage in noise exposed males despite having lower antioxidant responses and pointed towards a decrease in the activity levels of energy metabolism-related biomarkers. These results suggest that males exposed to boat noise depressed their metabolism and their activity (such as parental care and mate attraction) to cope with an acoustic stressor, consistent with a freezing defensive response/behaviour. Together, our study demonstrates that boat noise has severe impacts on reproductive fitness in Lusitanian toadfish. We argue that, at least fishes that cannot easily avoid noise sources due to their dependence on specific spawning sites, may incur in significant direct fitness costs due to chronic noise exposure.
- Impact of anthropogenic noise on the survival and development of meagre (Argyrosomus regius) early life stagesPublication . Trabulo, Rita; Amorim, M. Clara P.; Fonseca, Paulo J.; Vieira, Manuel; Matos, Manuel J. B.; Marin-Cudraz, Thibaut; Lemos, Marco F.L.; Novais, Sara C.; Pousão-Ferreira, Pedro; Candeias-Mendes, Ana; Faria, Ana M.The growth of human populations has been driving an unprecedent and widespread increase in marine traffic, posing a real threat to marine biodiversity. Even though we are now aware of the negative effects of shipping noise exposure on fish, information about the impact on their early life stages continues to lack. Meagre (Argyrosomus regius) is a vocal fish that uses estuaries with high levels of anthropogenic noise pollution as both breeding areas and nurseries. Here, the effects of boat noise exposure on the development and survival of meagre larvae were studied. Embryos and larvae were exposed to either noise (boat noise playback) or control treatments (coils producing a similar electric field to the speakers) and hatching rate, survival rate, morphometric traits and stress-related biomarkers, at hatching and at 2 days-post-hatching (dph) were analyzed. Results showed no conclusive effects of the impact of boat noise playback, even though there was an increased lipid droplet consumption and a decrease in body depth at 2dph larvae under this stressor. The assessment of oxidative stress and energy metabolism-related biomarkers at hatching showed a marginal decrease in superoxide dismutase (SOD) activity and no changes in DNA damage or electron transport system activity (ETS), although it cannot be disregarded that those effects could only be visible at later stages of larval development. Whether these morphological and developmental results have implications in later stages remains to be investigated. Further studies with longer exposure and wild meagre could help deepen this knowledge and provide a better understanding of how anthropogenic noise can impact meagre early stages.