Evaluation of the effects produced by the construction and expansion of marinas on Posidonia oceanica (L.) Delile meadows

Abstract

New legislation in the Valencian Community (Decree 36/2002, 5th of March) has allowed the expansion of the existent marinas in this region of the SE of Spain, affecting in a significant way the Alicante province that possesses over thirty nautical facilities of this type. Of particular importance are the effects that expansion of these ports would have on marine ecosystems, especially on Posidonia oceanica beds. This species is of a great ecological and biological importance, and is very sensitive to human activities along the coastline. The present study focuses on the current impacts and potential impacts of port extension of the Port of Altea and the Marina Luis Campomanes (NE Alicante) on the existing P. oceanica meadows near them. Density, cover, morphology and phenology of P. oceanica growing close to the ports were compared with adjacent control sites. The present ports have caused the destruction of at least 11 Ha of Posidonia meadow and the degradation of another 14 Ha where it has been detected an important reduction of its cover and density, and an increase in rhizome growth, the herbivore rate and the load of epiphytes of its leaves. Furthermore the analysis of all these data have also allowed to determine that the outer expansion of both ports would cause the disappearance of 64 Ha and the regression of 18 Ha of P. oceanica meadows.