Fine-Scale Cartography of Human Impacts along French Mediterranean Coasts: A Relevant Map for the Management of Marine Ecosystems

Abstract

Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant scale for biodiversity conservation.

Dramatic loss of seagrass habitat under projected climate change in the Mediterranean Sea

“…Mediterranean warming, together with other stressors, could produce an irreversible regression of Posidonia oceanica (Jordà et al, ) . In fact, the meadows of P. oceanica are already suffering a widespread decline as a consequence of the effects of a range of anthropogenic pressures including coastal development, dredging, pollution, fish farming, moorings, and invasive species (e.g., Boudouresque et al, ; Burgos et al, ; Holon et al, ; Marbà et al, , ; Oprandi et al, ; Telesca et al, ). Indeed, the joint effect of anthropogenic stresses and Mediterranean warming could lead to an earlier decline than predicted by our models, as predicted by Jordà et al ().…”

“…In addition to various national legislations, P. oceanica is also protected by the Barcelona convention (Annex II) and the Annex 1 of the European Union's Habitats Directive, while C. nodosa is listed by the OSPAR convention. Despite their ecological value as important foundation species, their meadows are experiencing a well‐documented regression in the Mediterranean due to anthropogenic pressure and invasive species (e.g., Boudouresque, Bernard, Pergent, Shili, & Verlaque, ; Burgos et al, ; Holon et al, ; Marbà et al, ; Marbà, Díaz‐Almela, & Duarte, ; Oprandi et al, ; Telesca et al, ), which will probably be aggravated by the effect of climate change. Documented seagrass mortality, mesocosms experiments on thermal limits, and projections of the increase in SST under climate change scenarios have pointed to the possible disappearance of P. oceanica meadows with future Mediterranean warming (Jordà et al, ; Marbà & Duarte, ; Marbà et al, ; Olsen, Sánchez‐Camacho, Marbà, & Duarte, ).…”

Multi-objective spatial tools to inform maritime spatial planning in the Adriatic Sea

“…Since then, its application has become a widespread modelling technique for cumulative impact assessment on global (Halpern et al, 2008), seabasin (Andersen and Stock, 2013) and regional (e.g. Holon et al, 2015) scale. The CI algorithm applied in this research is provided by Andersen and Stock (2013).…”

A modelling framework for MSP-oriented cumulative effects assessment

“…Their application has been exemplified in many different geographical domains ranging 5 from global (Halpern et al, 2015) or sea basin (Korpinen et al, 2012;Micheli et al, 2013) level to regional level Holon et al, 2015;Murray et al, 2015) assessments. Moreover, the need to address anthropogenic impacts on marine ecosystems is widely expressed through environmental legislations (MSFD), requiring coordinated management programs to reach the good 10 environmental status (GES) and the marine spatial planning (MSP) directive, requiring an ecosystem-based approach aiming at ensuring that collective pressures from human activities are kept at levels compatible with the GES and contribute to the sustainable use of marine goods and services and their preservation for future generation.…”