Coral reefs serve as a highly effective natural barrier against incoming ocean waves. However, climate change and human-induced degradations are threatening reefs, reducing their capacity to protect coastal populations by diminishing the frictional processes that dissipate wave energy. The most common approach to represent wave energy dissipation through bottom friction relies on the estimation of a representative roughness length, whose definition on coral environments remains to be elucidated. As a consequence, a generic parametrization for friction processes on coral reef systems is still lacking. In this study, high-resolution hydrodynamical and topographical data collected at the South-West barrier reef of Mayotte, Indian Ocean, were used to perform an estimation of wave friction. The hydraulic roughness estimated across the reef varies spatially, and attempts are made to connect this information with the diverse bed morphologies observed in the field.
The increase in nautical leisure activities within French marine protected areas (MPAs) presents complex challenges for managers. While these activities bring economic benefits and cultural value, they also intensify pressures on marine ecosystems. In response, managers and public authorities are seeking legal solutions to regulate both individual activities and overall visitation. This article examines the legal constraints and opportunities for regulating recreational uses in MPAs through an interdisciplinary design combining (i) legal analysis of the relevant regulatory framework and competent authorities and (ii) empirical fieldwork in two case studies-Port-Cros National Park and the Iroise Marine Park-based on semi-structured interviews with key stakeholders and visitor questionnaires (n = 228). The results show that social acceptability of rules varies by activity, stakeholder profile, and distance from decision-making centres. They also highlight persistent misunderstandings regarding regulatory competence, with many users attributing greater authority and legitimacy to MPA managers than to maritime prefects, despite the latter holding key administrative police powers at sea. The article concludes that improving communication and strengthening participatory procedures are necessary conditions to enhance the perceived legitimacy and effectiveness of leisure-activity regulation in French MPAs.
The Surface Water and Ocean Topography (SWOT) mission provides two-dimensional observations of sea surface height (SSH) at unprecedented spatial resolution, enabling exploration of ocean variability down to scales of O(10 km). At these scales, however, interpreting SSH variability is challenging because ocean dynamical signals overlap with measurement noise, and their respective spectral signatures are not yet fully understood. Recent analyses of SWOT 2-km posting observations have shown that along-track spectra are red, with a power-law-like behavior at small scales and spectral slopes around or steeper than -1, with their magnitudes and slopes correlated with SWOT measurement noise. Here, we investigate the hypothesis that the red along-track spectra can arise from two-dimensional filtering and aliasing of spatially uncorrelated (white) noise. Using synthetic experiments, we show that the resulting one-dimensional along-track spectra exhibit red, power-law-like behavior at small scales, consistent with observations. The apparent spectral slope depends on the noise level, its cross-track variability, and the background ocean signal. This finding highlights the importance of carefully accounting for measurement noise and processing effects when interpreting SWOT spectra, and suggests that such a noise model should serve as a baseline null hypothesis for small-scale spectral analyses.
Carbon (C) and nitrogen (N) are essential nutrients for coral–Symbiodiniaceae associations, yet global change can disrupt C and N acquisition by corals, affecting their resilience under stress. We investigated how two octocorals (Sarcophyton glaucum, Lobophytum sp.) and two hexacorals (Stylophora pistillata, Turbinaria reniformis) assimilate nitrogen from three 15N-labelled sources—dissolved free amino acids (DFAAs), Synechococcus (picoplankton), and Artemia salina nauplii (microplankton)—supplied at 1 µM N, under control (26 °C) and heat stress (30 °C) conditions. Corals were also incubated with natural pico-nanoplankton assemblages, with concentrations measured via flow cytometry. In addition, we measured the rates of photosynthesis and respiration, to estimate the relative contribution of autotrophy to the corals’ respiratory needs. Across all species, Synechococcus was the most efficiently assimilated N source, with uptake increasing under heat stress. Estimates of heterotrophic carbon assimilation (using C:N ratio) coupled with respiratory measurements showed that Synechococcus can provide 30–70
In his comment on our paper, Morley (2026) criticizes various aspects of our scenario of evolution of South-East Asia. We agree with some of the issues raised regarding the precise location of faults or the correspondence between faults in the model and geological features. We have adapted the model accordingly. We consider, however, that many of the remarks refer to details in fault mapping that do not jeopardise our simplified reconstructions. In this reply we address all the points raised, and include additional references. Alongside this response, we provide a new version of the model as supplementary material. We show that even though many details are omitted in this simplified model, the concept of extrusion tectonics enables us to understand most of the geological history of Southeast Asia over the past 50 million years.
