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

GUTIÉRREZ, JORGE L.; BAGUR, M.; ARRIBAS, L. P.; PALOMO, M.G.

HELGOLAND MARINE RESEARCH

SPRINGER

Lugar: Berlin; Año: 2018

1438-387X

Mussel attachment strength variesin space and time, frequently in association with variations in wave exposure. Yet,it remains uninvestigated whether different rock types can contribute tovariation in mussel attachment. Here we compared the attachment strength of themussel Brachidontes rodriguezii between soft and hard intertidal rocksubstrates that are typical of coastal Buenos Aires Province, Argentina:Pampean loess cemented by calcium carbonate and orthoquartzite, respectively. Overallcomparisons of mussel attachment across natural platforms of either rock type (10loess sites and 4 orthoquartzite sites) indicated stronger mussel attachment toorthoquartzite. However, mussel attachment strength did not differ whencompared across natural loess platforms and introduced orthoquartzite blocks(i.e., groins and revetments) occurring within the same site. Mussels attachingto loess showed more byssal threads than those attaching to orthoquartzite atthe same site. These findings suggest, first, that rock type does not influencemussel attachment strength in our study system, secondly, that overalldifferences in mussel attachment strength with rock type across naturalplatforms in our study range are due to confounding influences of co-varyingfactors (e.g., wave exposure) and, finally, that mussels can increase byssus productionto counteract potential substrate failure when attaching to soft, friable rock.The latter likely explains the ability of mussels to maintain relatively stablecover across rocks of contrasting hardness.