Characterisation of the 'bare sand' macrobenthic assemblages of the infralittoral to circalittoral transition zone off the northeastern coast of Malta

Abstract

A so called 'bare sand' habitat normally occurs at a depth of around 50m off the gently sloping northeastern coast of Malta between lower infralittoral meadows of marine phanerograms and upper circalittoral maerl grounds. Given the general lack of data on the benthic ecosystems of the Eastern Mediterranean basin, the main aim of this study was to characterise the macrobenthic assemblages of the 'bare sand' habitat and to determine if there is any spatial or temporal (seasonal) variation in these assemblages, between, and within two locations off the northeastern coast of Malta. Another objective was to relate variation in the macrofaunal assemblage structure to edaphic factors, namely sediment granulometry and % organic carbon. Samples were collected by means of a Van Veen grab (0.1m2) Faunal samples were · collected in July 2001 and January 2003, representing the summer and water seasons respectively Additional samples were collected in winter for sediment analyses. Spatio-temporal variation in the distribution of the macrofauna and spatial variation in sediment parameters were studied using a fully nested hierarchical sampling design. Triplicate grab samples were collected from each of eight 'Plots' (A-H). Two Plots (1 km apart) were nested within each of four 'Sites': Off Ghallis, Off Sliema, Off Marsascala and Off Delimara. Two Sites (5 km apart), were in tum nested within each of two 'Locations' (Location 1 and Location 2) which were 16 km apart. Data were analysed using nested ANOV A and post-hoc SNK tests, as well as with multivariate (classification and ordination) techniques.