Background: Several different classifications to characterize estuarine systems have been proposed. In this present paper, one of the most important estuaries in North Africa, the Oued Loukkos (Morocco), forms a case-study for proposing a systematic classification of this particular tidal estuary according to the vertical salinity gradient. Findings: This study, conducted using a CTD, shows that the spatial-temporal distribution of salinity depends on the stage of the tide and the upstream distance from the mouth of the river. In this case, it is also evident that the morphology of the bottom was capable of impacting the distribution of salinity by locally changing the water circulation. Conclusions: Based on the vertical salinity gradient measurement, the Oued Loukkos represents an estuarine environment with one section near its mouth that can be characterized as a mixed mesotidal estuary and another section upstream which can be characterized as a stratified mesotidal estuary. Between, there is an intermediate zone with a low vertical gradient of salinity, classified as a partially mixed mesotidal estuary. When the effect of terrestrial inputs is low compared to marine inputs, the river bed topography plays a role in the stratification of salinity by either disrupting the vertical stratification of the water or by changing the lateral distribution of salinity. The proposed classification deepens our hydrological knowledge and provides descriptive labels to the Oued Loukkos estuary. It provides a valid starting point for predicting the environmental impact of future recreational, agricultural and commercial activities on the estuary.

Maritime and underwater cultural heritage (MUCH) is concerned with the relationship between people and the marine and coastal environment over time. Rooted in the past, MUCH is a resource that can help us understand and appreciate our current situation. But MUCH is also a medium through which we address the future to develop resilience and motivate adaptation. MUCH is both a source of inspiration and of evidence: to study and understand it requires and develops interdisciplinary skills across the social sciences, STEM, and SHAPE subjects.The UN Decade of Ocean Science for Sustainable Development 2021‐2030, in promoting a common framework for supporting stakeholders in studying the world's oceans, presents a vital opportunity to improve the integration of MUCH within the marine sciences. The Ocean Decade Heritage Network's Decade Action, the Cultural Heritage Framework Programme, focuses on ensuring that MUCH specialists—archaeologists and cultural heritage managers—can engage constructively with the marine sciences under the auspices of the Ocean Decade, and make the best of the opportunity that the Ocean Decade presents in addressing present and future challenges facing the world's oceans.

This paper considers the importance of including Marine Cultural Heritage (MCH) in the UN Decade of Ocean Science for Sustainable Development (2021–2030) in order to fully address the challenges facing the health of our oceans. It outlines the aims and objectives of the Cultural Heritage Framework Programme (CHFP), an official action of the UN Decade of Ocean Science and the only one that specifically deals with cultural heritage. The role of MCH in the Decade is discussed, and its under-appreciation in the UNESCO Cultural Conventions is outlined. The paper then presents the activities of the CHFP, discussing the main themes identified to date, and finishes by outlining the initiative’s next steps.

Human activity along the Amalfi coastline in Italy has been tied to the sea for millennia – for sustenance, migration, trade, warfare, and leisure. As a result, this region has an equally rich and extensive maritime cultural landscape composed of tangible and intangible elements. In 2016, a multi-disciplinary project began efforts to model and to understand changes within this landscape, and this essay presents the preliminary results of our first three seasons of work. Some efforts, such as the documentation of maritime cultural heritage in local museums, archival work, and geomorphological research proceeded smoothly. Unexpectedly, however, little material from the pre-modern era was found under water, adding questions to this study that future work in the Marine Protected Area west of Positano may answer.