Spatio-temporal distribution of the Caprellidae (Crustacea: Amphipoda) associated with the invasive seaweed Asparagopsis armata Harvey in the Southern Iberian Peninsula

Resum

The caprellid fauna associated to Asparagopsis armata was studied in a spatiotemporal scale at the Southern coast of the Iberian Peninsula. Fourteen stations were selected for the spatial study along the axis Mediterranean-Atlantic and five stations were studied bimonthly (Feb08-Feb09). A gradient of decreasing oxygen and increasing salinity from the Atlantic to the Mediterranean was measured. Eight caprellid species were found: Caprella acanthifera, C. danilevskii, C. equilibra, C. grandimana, C. hirsuta, C. liparotensis, C. penantis and Pseudoprotella phasma. Caprella penantis and C. liparotensis were the dominant species, and Caprella hirsuta was the most discriminating species between Mediterranean and Atlantic stations, reaching high abundances only in the strictly Mediterranean localities. The seaweed biomass showed higher values in April-June while water temperature was higher in August-October. Maximum caprellid densities were found in April-June (Mediterranean stations) and August-October (Atlantic stations) showing a gradient along the spatial axis. Therefore, optimal seasonal environmental conditions for caprellid cycles are reached sooner in the Mediterranean than in the Atlantic. The number of associated caprellid species in the non-native A.armata is very high when compared with data of other native seaweeds of the Iberian Peninsula and Northern Africa, so the toxic and unpalatable substances of this seaweed do not seem to affect negatively to the caprellid community.