ECSA - Workshop on Intertidal Seagrass Beds and Algal Mats: Organisms and Fluxes at the Ecosystem Level

Abstract

Volume 54, 2–3 of Helgoland Marine Research contains papers presented during the ECSA – Workshop on Intertidal Seagrass Beds and Algal Mats held at the Wadden Sea Station Sylt of the Alfred Wegener Institute Foundation for Polar and Marine Research at List on the island of Sylt, Germany, on 7–13 August 1998. Over the past few decades there have been catastrophic losses of seagrass beds amounting to thousands of hectares, and this decline is still continuing all over the world. During the workshop, the causes and consequences of seagrass decline were outlined. In particular, the role of eutrophication and its consequences for seagrasses, other primary producers, and also for benthic invertebrates were shown. The effect of pesticides on seagrass plants was also found to be an important cause of decline, especially in southern England and the German estuaries. Examining long-term changes in seagrass beds and seagrass modelling indicated the problems and difficulties of predicting the development of seagrass beds, especially in the North Sea region. It is well known that seagrass beds, with their high productivity and biodiversity, have a significant ecological and economic value. Interactions of seagrasses with the hydrodynamic environment were demonstrated in detail. At the ecosystem level, seagrass beds have an important role to play in material exchanges and the food web. However, it depends on the ambient environment or on the density of seagrass beds whether they act as particle traps, as could be shown for the Wadden Sea. Negative and positive factors were listed as well as being ranked as key factors with regard to seagrass systems (see Table 1). Coastal managers and nature protection agencies urgently need an effective management tool in order to quantify the impact and consequences of various environmental changes on seagrass beds. Assessing the ecological role of seagrass beds is still in progress and is subject to many difficulties because of major gaps in our knowledge. However, the ecological value of this special Helgol Mar Res (2000) 54:53–54 © Springer-Verlag and AWI 2000