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 strengthvaries in space and time, frequently in association with variations in waveexposure. Yet, it remains uninvestigated whether diferent rock types cancontribute to variation in mussel attachment. Here we compared the attachmentstrength of the mussel Brachidontesrodriguezii between softand hard intertidal rock substrates that are typical of coastal Buenos AiresProvince, Argentina: Pampean loess cemented by calcium carbonate and orthoquartzite,respectively. Overall comparisons of mussel attachment across natural platformsof either rock type (10 loess sites and 4 orthoquartzite sites) indicatedstronger mussel attachment to orthoquartzite. However, mussel attachmentstrength did not difer when compared across natural loess platforms and introducedorthoquartzite blocks (i.e., groins and revetments) occurring within the samesite. Mussels attaching to loess showed more byssal threads than thoseattaching to orthoquartzite at the same site. These fndings suggest, frst, thatrock type does not infuence mussel attachment strength in our study system,secondly, that overall diferences in mussel attachment strength with rock typeacross natural platforms in our study range are due to confounding infuences ofco-varying factors (e.g., wave exposure) and, fnally, that mussels can increasebyssus production to counteract potential substrate failure when attaching tosoft, friable rock. The latter likely explains the ability of mussels tomaintain relatively stable cover across rocks of contrasting hardness.