Soundscape of green turtle foraging habitats in Fiji, South Pacific

Assessing the potential acoustic impact of floating offshore wind farms in the Central Mediterranean Sea

The Strait of Sicily, a vital marine passage with diverse fauna, is seeing a steep rise in the planning of offshore wind farm projects. This study assesses the acoustic impact of these wind farms on local marine species. Underwater propagation was modeled for three proposed floating wind farms using JASCO's Marine Operations Noise Model (MONM), which integrates a parabolic equation method for frequencies from 10 to 800 Hz and a beam-tracing model for 1 to 25 kHz. Propagation losses were calculated in one-third octave bands for ten source locations selected to represent the variability in bathymetry, and considering sound speed profiles for February and August. Sound levels from floating turbines were used to estimate exceedance ranges to known acoustic thresholds for marine species. Modeling indicated that sound levels could exceed temporary threshold shift and, for some species, permanent threshold shift criteria within a few tens of meters, but only if animals were to remain for 24 h at such small distances from a turbine. Behavioral disturbance thresholds for marine mammals were exceeded up to 68 km from the wind farms' boundaries. The study emphasizes considering species-specific sensitivities and ecological contexts in environmental impact assessments, recommending mitigation measures, such as the strategic placement of the turbines and continuous monitoring, to minimize adverse effects on local marine fauna, including marine mammals and turtles.

Chatting behind the reef: Fish bioacoustic diversity of tropical back-reefs in Fiji, South Pacific

Back-reef habitats are important and fragile transition zones acting as nurseries for many coral reef fishes. In this framework, Passive Acoustic Monitoring (PAM) can be an important tool to evaluate the diversity and dynamics of sonic fish community. Here, we investigated the diversity, spatial and diel dynamics of fish sounds in back-reef habitats at Makogai Island in Fiji, South Pacific. Synchronized underwater recorders were deployed in 4 bays collecting data for about 4 days. The abundance of 12 different sub-categories of fish sounds were quantified. Signals were acoustically characterized and the level of discrimination between the sub-categories was evaluated by Discrimination Function Analysis. Generalized Additive Models showed that the abundance of signals was related to the bay and the hour. Moreover, the Shannon Diversity and Equitability Indices were calculated using acoustic and visual census data to describe fish biodiversity of each bay. The two bays with greater biodiversity based on visual census also showed a greater acoustic diversity at dawn and night. Our results highlight the importance of PAM to reveal the diversity of fish community in back-reef habitats, providing a baseline to understand future changes in these crucial environments.

Anthropogenic noise predicts sea turtle behavioural responses

Anthropogenic noise is a pollutant of global concern. While the effects of underwater noise pollution have been frequently studied in fish and mammals, our understanding of how this anthropogenic stressor affects marine reptiles is scant. Using a multichannel data logger equipped with a camera and hydrophone, we quantified behavioural responses of a free-ranging green turtle (Chelonia mydas) to vessel noise in the Galapagos Archipelago, an important nesting site in the eastern Pacific. We found that while travelling the turtle increased its vigilance with increasing vessel noise. However, when on the seabed the turtle did not increase its vigilance with increasing noise levels. Our findings illustrate that noise pollution has the potential to alter overall time budgets of animals. Identifying real-time responses of wild animals illustrate how in situ approaches allow to assess the effects of human activities on marine systems.

Conservation status and cultural values of sea turtles leading to (un)written parallel management systems in Fiji

Globally and locally, conservationists and scientists work to inform policy makers to help recovery of endangered sea turtle populations. In Fiji, in the South Pacific, sea turtles are protected by the national legislation because of their conservation status, and are also a customary iTaukei resource. Centered on our interview-based study at Qoma and Denimanu villages, parallel management systems coexist, where both the (written) national legislation and the (unwritten) customary iTaukei rules determine the time and the quantity of sea turtle harvest. In addition, non-governmental organizations and academic institutions may influence local sea turtle management by providing scientific awareness and helping divert the economic values from the meat to the living animal. We suggest that the government and non-governmental organizations emphasize community management of sea turtles, and work alongside the customary chiefs and their fishing clans to understand the real harvest (eventually by allowing quotas) and to monitor the recovery of South Pacific sea turtles in Fijian waters.

"Draw the sea…": Children's representations of ocean connectivity in Fiji and New Caledonia

In the South Pacific region, marine territories and resources play a crucial role for local communities. Children engage with these territories and resources from an early age onwards. As the next ocean stewards, they are a stakeholder group whose understandings of ocean connectivity and fisheries should be given serious consideration in decision-making processes towards the sustainable use and management of coastal seas. This paper analyses 290 children's drawings from Fiji and New Caledonia, created in 2019 in spontaneous response to the instruction: "Draw the sea and what you and others do in the sea". Exploring the webs of connections with and within the sea revealed by these children's drawings and their own interpretations leads us to discuss children's representations of the sea: (1) beyond a land-sea compartmentation, (2) as a locus of both exploitation and conservation of marine life, and (3) as a 'place-full' space connecting human and more-than-human realms.