Selective byssus attachment behavior of mytilid mussels from hard- and soft-bottom coastal systems

Abstract

A B S T R A C TIn both sedimentary and rocky coastal habitats, epibenthic mytilid mussels use byssal threads for attachment to the substratum and to form beds with high densities of individuals. Number and attachment strength of byssal threads can be adjusted according to external factors such as hydrodynamic forces or predators, but it is unknown whether mytilid mussels distinguish between substrata of different quality for byssus attachment in different habitat types. In field studies, we examined the attachment strength of the mussel Perumytilus purpuratus growing on Pacific hard-and soft-bottom shores in Chile and of the blue mussel Mytilus edulis from an Atlantic rocky shore in France and a sedimentary shore in the North Sea (Germany), respectively. In additional laboratory experiments, we studied mussel substratum selectivity of both bivalve species from soft and hard bottoms by offering living versus dead, barnacle-fouled vs. unfouled, and firmly attached vs. loose conspecifics. In the field, attachment strength of P. purpuratus on hard bottoms was substantially higher than on soft bottoms even though mussels produced more byssus in the latter habitat. In contrast, blue mussels M. edulis showed only a slightly reduced attachment strength on soft compared to hard bottoms. In the soft-bottom habitat, fouled individuals from the edge of a blue mussel bed were especially strongly attached. In the byssus attachment behavior experiments, P. purpuratus from both habitats showed a significant preference for living conspecifics and those from soft bottoms preferred firmly attached conspecifics. Blue mussels had no preference for particular conspecifics except those from soft-bottom habitats, which preferred fouled over clean mussels. In general, in the choice experiments hard-bottom M. edulis produced more byssus. Our results confirmed that mytilid mussels may show active substratum choice for byssus attachment, which depends on mussel species and habitat type. The results suggest that mussels are adapted to a particular habitat type, with P. purpuratus showing lower adaptation to soft-bottom areas while M. edulis shows successful strategies for both environments.

Epibiosis in sedimentary coastal environments: Effects of an introduced barnacle on a native mussel

“…Mussels with epibionts were more strongly attached to the substrate than clean mussels. While the strength of byssal attachment may be altered by the water flow conditions, temperature, and the substrate types (Aguilera et al., 2017; Garner & Litvaitis, 2013), our controlled laboratory experiment, even if limited in terms of representing the natural complexity of the study site, allowed us to specifically assess the effect of the epibiosis. Our results agree with those of Witman and Suchanek (1984) who found that, in laboratory conditions, attachment strength of mussels with epibiosis was 6.7 higher than clean mussels.…”

“…However, the later were obtained in the field, where mussels are anchored to many particles of loose sediment and even conspecifics (Commito et al., 2014; Salas et al., 2016), which may explain the discrepancy between results. While dislodgment force varies between different substrates (Ackerman et al., 1996) and seems to be site‐specific (Gutiérrez et al.,l., 2018), no further valid comparisons can be performed, since most studies on mussels’ attachment strength come from hard bottoms, where they reach higher strength than in soft bottoms (see Aguilera et al., 2017). Epibiosis can increase the friction strength in environments with great current velocity, thus causing the basibiont to detach (Thieltges & Buschbaum, 2007; Wahl, 1989).…”

“…The mussels were then individually incubated for 15 days in aquaria without water flow on sandstone tiles. Since experiments assessing the byssogenesis and attachment strength in laboratory are usually performed a few hours after mussels’ manipulation (Aguilera et al., 2017; Babarro & Carrington, 2013; Garner & Litvaitis, 2017), the 15‐day acclimation period was considered long enough to ensure the full development of byssus threads. Water was daily renewed to provide natural feeding.…”

Byssus production ability and degree of byssal‐gland development in the infaunal clam Ruditapes philippinarum

“…shell size (Allen, Cook, Jackson, Preston, & Worth, ; Babarro, Reiriz, & Labarta, ; Van Winkle, ), somatic condition (Babarro & Reiriz, ; Babarro et al, ; Clarke, ), spawning stress (Babarro & Reiriz, )] and exogenous factors [e.g. water temperature (Allen et al, ; Masilamoni et al, ; Selin & Vekhova, ; Young, ), salinity (Allen et al, ; Young, ), water current (or agitation) (Moeser, Leba, & Carrington, ; Van Winkle, ; Young, ), substrate type (Aguilera, Thiel, Ullrich, Luna‐Jorquera, & Buschbaum, ; Selin & Vekhova, ), exposure to air (Van Winkle, ), presence of predators (Caro, Escobar, Bozinovic, Navarrete, & Castilla, ; Cheung, Luk, & Shin, ; Reimer & Tedengren, )] and thus shows spatial and temporal variations (Babarro & Carrington, ; Carrington, ; Lachance, Myrand, Tremblay, Koutitonsky, & Carrington, ; Nicastro, Zardi, & McQuaid, ; Salas, Defeo, & Narvarte, ; Zardi, McQuaid, & Nicastro, ).…”