Published online by Cambridge University Press: 22 September 2009
The distribution and abundance patterns of the caprellids (Crustacea: Amphipoda) associated with the alga Stypocaulon scoparium (L.) Kützing were studied on a spatial scale along the Iberian Peninsula. Fourteen stations and five environmental factors were considered (seawater temperature, conductivity, dissolved oxygen, turbidity and pH). The Atlantic coast was characterized by lower temperature and conductivity as well as higher values of oxygen and turbidity than the Mediterranean coast, probably associated with a higher swell. Cover of S. scoparium was higher in the Strait of Gibraltar than in the remaining stations, coinciding with maximum values of number of caprellid species and Shannon diversity, while abundances were higher in the Mediterranean. Caprella acanthifera and C. liparotensis were dominant at the stations of the Strait of Gibraltar, C. penantis and C. danilevskii were restricted to Atlantic stations, while C. grandimana and C. hirsuta were very abundant in all the Mediterranean stations; Deutella schieckei, C. acanthifera discrepans, Phtisica marina and Pseudoprotella phasma, were only found at some Mediterranean sites. Multivariate analysis showed that some species, such as C. penantis, significantly correlated with oxygen concentrations, while other species, such as P. phasma, D. schieckei and Phtisica marina were associated with stations with higher values of conductivity, temperature and turbidity. Number of caprellids associated with S. scoparium was significantly higher than in other dominant algae from the Mediterranean and the Atlantic, probably due to the optimal morphological structure of this seaweed for caprellids to cling.