The invasive Asparagopsis armata versus the native Corallina elongata: Differences in associated peracarid assemblages

A comparison between peracarid assemblages inhabiting the invasive Asparagopsis armata and the native Corallina elongata was conducted along the Atlantic coast of the Iberian Peninsula. A total of 76 peracarid species were recorded during the present study, 59 of the 76 species were present in C. elongata, while 47 were found in A. armata. The most abundant species in C. elongata were the gammarids Hyale stebbingi, Jassa falcata, Parajassa pelagica, Stenothoe monoculoides and the isopod Ischyromene lacazei, whereas the gammarids Aora spinicornis, Apherusa bispinosa, Dexamine spiniventris and the isopod Dynamene magnitorata were dominant in A. armata. The amphipods Hyale schmidti and Caprella penantis reached very high densities in both substrates. SIMPER analysis showed a dissimilarity of 80.5% between the species composition of C. elongata and A. armata. The most relevant differences in species composition were found for isopod assemblages, where species richness, Shannon diversity and total abundance were significantly higher in C. elongata. The two-dimensional MDS plot showed segregation of sampling stations mainly by substrates and PERMANOVA showed significant differences in peracarid assemblages among the two algae. These results should be taken into consideration in management and monitoring programmes to control this invasive seaweed, which is now totally established and became naturalized in European ecosystems.