Eutrophication and some European waters of restricted exchange

Abstract

Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002) concerns 'Oceanographic Applications to Eutrophication in Regions of Restricted Exchange'. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfjärden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q. It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex 'research' model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socio-economic issues that need to be taken into account in managing the trophic status of RREs

Sediment and waternutrients and microalgae in a coastal shallow lagoon, Ria Formosa (Portugal): Implications for the Water Framework Directive

“…5 They have natural conditions for the accumulation of nutrients and therefore for the occurrence of eutrophication.…”

The importance of habitat-type for defining the reference conditions and the ecological quality status based on benthic invertebrates: The Ria Formosa coastal lagoon (Southern Portugal) case study

“…Consequently, the water residence time is short, with an estimated average time of 1.5 days (Saraiva et al, 2007). However, upstream locations present higher residence times due to irregular tidal flushing throughout the lagoon (Tett et al, 2003). In these locations, residence time can reach an average of 2.4 days (Mudge et al, 2008).…”

“…However, in the upstream locations the residence time is higher (Newton and Mudge, 2003;Tett et al 2003) as well as in some of the water reservoirs studied by Gamito (2006). For this study the residence time in each station was not determined but an ordinal scale, varying from 0 to 4, based on previous knowledge on water dynamics in the lagoon was elaborated to stand as a proxy of water renewal.…”

Mussels and Yachts in Loch Fyne, Scotland: a Case Study of the Science-Policy Interface

“…4 gives key details of the physical-biological model. This model was assembled from existing mathematical models, including a simple box model of sea-loch exchange and microplankton growth (Tett et al 2003, Laurent et al 2006) and a dynamic energy balance model of individual mussel growth (Grant and Bacher 1998). The microplankton model parameterizes the coupled dynamics of pelagic microalgae (phytoplankton) as a single entity that includes pelagic protozoa and bacteria (Tett and Wilson 2000).…”