Application of a G.I.S. to the Management of Marine Protected Areas: Cartography of Infralittoral Fringe Communities as Environmental Health Indicators

L. Mangialajo (1), R. Cattaneo-Vietti (1), M. Chiantore (1), A. Meinesz (2), J. De Vaugelas (2)

(1) Dipartimento per lo Studio del Territorio e delle sue Risorse, Università di Genova (IT)
(2) Laboratoire Environnement Marin Littoral, Université de Nice-Sophia Antipolis (FR)

The absence of tides in the Mediterranean Sea forces upper infralittoral communities to be in a very narrow fringe and always in contact with the superficial waters, whose quality is affected by the presence of floating pollutants (mostly tensioactives and hydrocarbons), often abundant in highly anthropised zones. The brown algae Cystoseira spp., characterising some of the most productive communities in the Mediterranean Sea, are very sensitive to this kind of pollution. In particular, the two species typical of this very shallow habitat, C. amentacea and C. mediterranea, are recognized as species of Community Interest in the Annex V of the council directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora.
The cartography, supported by a G.I.S, of the distribution of superficial communities is a useful tool in the coastal management: their distribution is related to environmental factors such as light and hydrodynamism, but is also a good indicator of environmental health. Furthermore, the census of the most productive and sensitive communities is necessary, especially in areas where severe accidental pollution may occur, to operate when and where protective actions are needed.
In this study, two rocky areas on the Portofino Promontory Marine Protected Area have been investigated in 2000. The coastline was divided into over 200 sectors (20 m in length each). Sectors were classified according to various factors, such as slope and nature of substratum, geographical orientation and hydrodynamism. The exact location of the borders of each sector was recorded on the digitalized magnifications of the coastline, elaborated from UTM regional ortophotomaps. The quantification of conspicuous species was expressed by meters of linear covering; both the presence of anthropic wastes and hydrocarbon residues have been carefully monitored. Data processing and thematic maps were realised with the aid of a Geographical Information System (Mapinfo). The abundance of C. amentacea var. stricta (present in 98% of the sectors characterised by high hydrodynamism and good light exposure), forming a well structured belt on the southern front of the Promontory, suggested good environmental conditions of this area. Lower percentage cover of Cystoseira spp. was found in more sheltered coastlines (inner part of the San Fruttuoso Bay and Golfo Paradiso). Herein, the presence of nitrophilic species of the Ulvales order (Enteromorpha spp., Ulva spp.), as well as the distribution of anthropic wastes (hydrocarbon residues were absent from this area), evidenced a very localised disturb associated to urban settlings. In order to evaluate any temporal evolution of these zones, specially after 5 years of protection (institution of the M.P.A. in 1998), the same sectors are presently under study.