NONINDIGENOUS AND CRYPTOGENIC SPECIES ON PIERS AND PILINGS IN THE MAR DEL PLATA HARBOUR, ARGENTINA.

ALBANO MARIANO J.; OBENAT SANDRA

Mar del Plata

Congreso; biolief 2011; 2011

Historically harbours have been emisor-receptors, trough vessels (ballast water and fouling), of exotic marine fauna. Studies in estuaries showed that different structures may increase the abundance, diversity and species richness of invasive species. However, little is known in marine environments and harbours. In this study we assess if invasive and cryptogenic species are present seasonally in different structures in the strictly marine Mar del Plata harbour (Argentina) (38° 02´S, 57° 31´W). Epibenthic subtidal fauna were sampled in concrete pier and wood piling from autumn 2007 until summer 2008 by SCUBA. Six quadrats (0.0625 m2) were scraped at each surface and then we identified the “status” (exotic or cryptogenic) of the species, quantified the number of species and the percentage of each taxa. Multivariate analyses were done, to test similarities trough seasons and each surface. In concrete pier were found a total of 21 exotic species and 8 cryptogenic meanwhile on wood pilings we recorded 23 and 6 species respectively. At each surface the crustaceans represented the highest percentage for each status with, 38% in concrete piers (both status) and 43.5% and 50% on wood pilings for exotic and cryptogenic respectively. Differences trough seasons were registered only for exotic species assemblages on wood pilings (ANOSIM, Global R=0.22; p=0.01). SIMPER showed that the invasive amphipod, Monocorophium acherusicum was the species that most contribute (> 20%) in all seasons on concrete pier. In marine harbour areas exotic and cryptogenic species could be present all year long on concrete piers and wood pilings.