The distribution of Cystoseira species was studied at 103 coves in the island of Menorca (Balearic Islands, NW Mediterranean). Both geomorphological parameters and anthropogenicpressures were considered in order to investigate which were the main environmentalfactors explaining their distribution. Several factors contributed to explain the composition of Cystoseiraassemblages in the sampled coves being coastal morphology, bottom nature, nutrient concentration in seawater and urbanization level of the coast the most important. The relatively high number of Cystoseira species found in Menorca suggested a general high quality of the environment. However, in southern coves the number and abundance of Cystoseira spp. was reduced compared to the northern ones. This pattern seems to be related both to a higher anthropogenic pressure and to a less favourable geomorphology at southern coves. When strong anthropogenic disturbances were present (proximity to harbour areas), coves were completely devoid of Cystoseira specimens. As historical data is available for some of these sites, we can document the disappearance of some Cystoseira species at these coves, which seems to be related to increased pollution levels. However, as the absence of Cystoseiraassemblages can also respond to a lack of a suitable geomorphology, their use as bioindicators of water quality needs of a definition of proper reference sites.

Marta Sales was supported by an I3P grant from CSIC and FI grant from Generalitat de Catalunya both co-funded by European Social Fund. Financial support was provided by Institut Menorquí d'Estudis and Agència Catalana de l'Aigua.

7 páginas, 4 figuras, 3 tablas.

Peer reviewed