Does rock type account for variation in mussel attachment strength? A test with Brachidontes rodriguezii in the southwestern Atlantic

GUTIÉRREZ, JORGE L.; BAGUR, MARÍA; ARRIBAS, LORENA P.; PALOMO, M. GABRIELA

HELGOLAND MARINE RESEARCH

SPRINGER

Año: 2018 vol. 72

1438-387X

Mussel attachment strength varies in space and time, frequently in association with variations in wave exposure. Yet, itremains uninvestigated whether different rock types can contribute to variation in mussel attachment. Here we comparedthe attachment strength of the mussel Brachidontes rodriguezii between soft and hard intertidal rock substratesthat are typical of coastal Buenos Aires Province, Argentina: Pampean loess cemented by calcium carbonate andorthoquartzite, respectively. Overall comparisons of mussel attachment across natural platforms of either rock type(10 loess sites and 4 orthoquartzite sites) indicated stronger mussel attachment to orthoquartzite. However, musselattachment strength did not differ when compared across natural loess platforms and introduced orthoquartziteblocks (i.e., groins and revetments) occurring within the same site. Mussels attaching to loess showed more byssalthreads than those attaching to orthoquartzite at the same site. These findings suggest, first, that rock type does notinfluence mussel attachment strength in our study system, secondly, that overall differences in mussel attachmentstrength with rock type across natural platforms in our study range are due to confounding influences of co-varyingfactors (e.g., wave exposure) and, finally, that mussels can increase byssus production to counteract potential substratefailure when attaching to soft, friable rock. The latter likely explains the ability of mussels to maintain relativelystable cover across rocks of contrasting hardness.