Eutrophication and environmental policy in the Mediterranean Sea: a review

Abstract

The Mediterranean Sea is a semienclosed basin connected with the open sea mainly through the Strait of Gibraltar. Due to the circulation pattern and the long residence time ranging between 80 and 100 years, the Mediterranean Sea is a sensitive environment to eutrophication pressures. The main body of water of the Mediterranean is characterized by very low nutrient concentrations, and therefore, the Mediterranean is classified among the most oligotrophic (very poor waters in nutrients) seas of the world's oceans. However, some coastal areas, mainly in the northern part of the basin, receive excessive loads of nutrients from sewage effluents, river fluxes, aquaculture farms, fertilizers, and industrial facilities, showing intense eutrophic phenomena with many adverse effects for the marine ecosystem and humans. Various national and international authorities, in addition to monitoring, have taken legal and administrative measures to mitigate eutrophication trends in the area. The Mediterranean environment is a good paradigm of integration of extensive legal framework, scientific knowledge, and administrative practices. The Barcelona Convention, the Mediterranean Action Plan, and European Union Directives on water quality and coastal management, together with scientific information derived from international research programs in the Mediterranean, provide a sound background for practical actions in eutrophication problems. In the present work, the problem of coastal eutrophication in the Mediterranean is reviewed in connection with public policies of the Mediterranean States based on national and international legislation and scientific knowledge on Mediterranean oceanography-ecology and actions coordinated by international bodies. These common actions and practices on coastal management are also discussed in relation to the need for sustainable development and protection of the coastal zone in the Mediterranean Sea.

Challenges and difficulties in assessing the environmental status under the requirements of the Ecosystem Approach in North African countries, illustrated by eutrophication assessment

“…As reported by other authors (Ignatiades et al 2009;Karydis and Kitsiou 2012), chlorophyll-a concentrations were in general low among all the OWBs (Fig. 3a).…”

“…To our knowledge, few methods have been proposed under the requirements of the MSFD in the Mediterranean Sea (e.g., Ferreira et al 2011;Karydis and Kitsiou 2012). However, a broad background exists in relation to the WFD (Birk et al 2012).…”

Marine cage culture and the environment: effects on water quality and primary production

“…The trend of increasing nitrogen levels in coastal waters due to anthropogenic sources is a concern worldwide, especially because it may cause algal blooms and contribute to nutrient enrichment or eutrophication (Cloern 2001, Galloway et al 2004, Anderson et al 2008, Tett 2008, Karydis & Kitsiou 2012. Marine cage aquaculture operations are a recognized source of nitrogenous discharge released both in the form of particulate matter (uneaten food and feces containing undigested food that passes through fish digestive tracts) and dissolved metabolic wastes including ammonia and urea (Cole 2002, Nash et al 2005, Huntington et al 2006, IUCN 2007, Pittenger et al 2007).…”

Benthic fluxes of oxygen and nutrients in sublittoral fine sands in a north-western Mediterranean coastal area

“…A large fraction of this pelagic primary production, as well as organic inputs from continent, can reach the sediment surface due to the shallow depth in the inner shelves (Huettel et al, 2014). At surface sediments, an excess of organic material can promote benthic primary production (Karydis and Kitsiou, 2012), organic matter accumulation and even can turn the seafloor anoxic (Morata et al, 2012). Organic matter present in the sediment is the main driving force of mineralization in inner shelve bottoms, which organic and nutrient production can be transported to water column by advective and diffusive transport or fixed by benthic photosynthesizers.…”