Environmental monitoring at St George’s Bay (Malta) in connection with beach replenishment works

Abstract

Adverse impacts of coastal beach replenishment projects on the marine environment are well documented. As a result, coastal managers have been seeking ways and techniques with which to implement beach replenishment projects without causing adverse changes to marine ecosystems. In May 2004, the Malta Tourism Authority undertook beach replenishment at St George’s Bay (St Julians, Malta) in which coarse sediment of terrestrial origin, having a mean grain size of 2 mm, was deposited at the head of the bay to create an artificial beach. An extensive 2-year (January 2004 to December 2005) environmental monitoring programme was commissioned by the MTA to monitor the potential impacts of the replenishment works on the marine environment. The programme included surveys of physico-chemical attributes (beach and seabed profile surveys, granulometric analysis and microscopic examination of sublittoral sediments, and water quality studies), and use of seagrass as a bioindicator of environmental quality. For most of the attributes surveyed, data was collected from stations located within the putatively ‘impacted’ inlet, and from control stations before initiation of the works and following the beach replenishment works. Data for mean sediment grain size, water quality attributes (salinity, dissolved oxygen, total suspended solids and nutrients) and seagrass morphometric parameters (shoot density, length and biomass of adult leaves, and shoot epiphyte biomass) were analysed using analysis of variance (ANOVA). Overall, the results of the various monitoring components indicated that (i) no major transport of sediment from the beach to the sublittoral had occurred, and (ii) the beach replenishment works did not result in any adverse impacts on the marine environment. Good project planning and management, the relatively sheltered location of the replenished beach, together with appropriate choice of grain size of the sand used for replenishment appear to have contributed to the success of the project.