Epicontinental oceans and seas cover 71% of the Earth’s surface and constitute a great diversity of ecosystems, some of the most productive of which are found in coastal seas, coastal zones and interface areas between the marine and terrestrial environments: estuaries, bays and lagoons. These areas are strongly impacted by climate change and more broadly since the beginning of the last century by many anthropogenic factors linked on natural ecosystems.
The latest IPCC report ( IPCC_AR6_WGI_SPM_final.pdf ) unequivocally confirms the influence of human activities on climate change. Global surface temperatures have risen faster since 1970 than in any other 50-year period in the past 2,000 years. Globally, average sea level has risen faster since 1900 than in any other century for at least 3,000 years. The temperature of the world’s ocean has risen faster in the last century than in the last glacial transition, 18,000 years ago. Human action has increased the risk of extreme events: heat waves and droughts with large-scale fires in many parts of the world, and frequent and severe flooding. These changes affect not only terrestrial but also aquatic ecosystems. The threshold of 1.5°C warming could be reached as early as 2030. The impact of this very rapid climate change on the rise in sea level, on the increase in the temperature of the oceans and coastal seas, on the acidification of marine waters, on the deeper intrusion of marine waters into the transition areas between marine and terrestrial ecosystems, on the inflow of fresh water into coastal areas, has a major role to play in the evolution of coastal ecosystems, which are essential for the development of many marine species.

At the same time, the latest IPBES report (IPBES 2019 – Global Assessment Report on Biodiversity and Ecosystem Services | IPBES secretariat) shows that climate change constitutes an additional pressure to the fragmentation of natural populations, local disappearances of species and marine habitats. The way in which terrestrial and marine resources are exploited, the direct exploitation of organisms, pollution and the introduction and invasion of non-native species are all pressure factors that greatly reduce the resilience of ecosystems to factors of change.
Epicontinental or semi-enclosed seas such as the English Channel-North Sea, the Mediterranean or the Seto Inland Sea in Japan are areas of intense and diverse human activity. Among the human activities common to all coastal areas: traditional activities such as fishing and shellfish farming, maritime transport, industrial port installations leading to dredging and dredging deposits, industrial pollution and contamination of sea products, more recent activities have developed in coastal areas of all the world’s seas: communication networks (submarine cables), aggregate extraction, tourism and yachting, marine renewable energies (wind and tidal power).
In response to the constant increase in anthropogenic pressures to which estuarine, coastal and marine areas have been subjected in recent years, it seems essential to develop an ecosystem approach that takes into account the cumulative effects of human activities at sea. The implementation of such a strategy can be justified both by the specific nature of these marine areas and by the important economic, ecological and heritage issues that link the interface territories to the coastal areas. Its implementation ranges from local to regional, within countries and between countries bordering a common sea.
Given our current production and consumption patterns, the negative evolution of biodiversity and the degradation of ecosystem functions can only continue and get worse. Only scenarios that include more sustainable and responsible modes of exploitation and consumption with a minimisation of the ecological footprint of the various activities, and not just fishing, will make it possible to maintain the good ecological status of marine ecosystems. Thus, in this context of global change, the adaptation of human and non-human communities to the rapid modifications of their environments is one of the major challenges of the 21st century.
Another challenge is that of resolving conflicts of use and occupation of space in epicontinental seas: the English Channel, the North Sea or semi-enclosed seas such as the Mediterranean or the Seto Inland Sea in Japan, for example. Among other activities, the development of marine renewable energies to reduce the amount of fossil fuels in our energy mix in some maritime areas that are already highly coveted, alongside traditional artisanal fishing areas, which are already affected by the decrease in productivity in coastal areas, is one of the major challenges in terms of strategic planning of maritime areas. According to the term now adopted, the ‘blue economy‘ can only be developed through consultation between all the players, particularly between traditional and emerging activities, on the basis of multidisciplinary knowledge in order to be a source of innovation in a fluid, totally interconnected, three-dimensional space.

Key-words: Global change, anthropogenic cumulative pressure, coastal and interface areas, biodiversity, habitat and ecosystem connectivity modifications, coastline modifications, social and economical impacts of traditional activities, minimization of ecological footprints, conflicting uses and coexistence between traditional and new activities (such as MRE for example).