Secretion of byssal threads and attachment strength ofMytilus galloprovincialis: the influence of size and food availability

Abstract

Secretion of byssal threads and attachment strength of Mytilus galloprovincialis: the influence of size and food availability jose m.f. babarro, mar ia jos e fern andez reiriz and ux io labarta Instituto de Investigaciones Marinas CSIC, Eduardo Cabello 6, 36208 Vigo, Spain Byssogenesis rate and attachment strength of the mussel Mytilus galloprovincialis were investigated in the laboratory considering different body sizes and feeding conditions. Byssal thread secretion was significantly higher in juveniles as compared to larger mussels of approximately 87 mm shell length. Asymptotic number of threads attached was obtained from approximately 72 hours onwards within a range of 42 -46 and 27-31 for juveniles and larger experimental mussels, respectively (P , 0.05 ANOVA). Absorption efficiency values of control fed individuals dropped significantly from 0.78 in juveniles to 0.70 in larger mussels (P , 0.001 ANOVA) which pointed out energetic constraints of mussels with regard to their size and its probable effect on byssus secretion rates. Attachment force was 2.8 times higher in larger mussels than in juveniles (2.21 versus 0.78 N for both sizes, respectively; P , 0.001 ANOVA) which in turn followed the same order of magnitude than differences in the thread's thickness values of both experimental mussel sizes. Tenacity followed a reverse pattern with juveniles presenting two-fold higher values than larger mussels (P , 0.001 ANOVA) based on a lower increment of attachment force (x2.8) as compared to shell area (x6) for the comparison larger versus juvenile mussel size, which in turn might suggest that larger specimens secreted weaker threads. When animals were maintained unfed for a week, a significant drop in both byssus secretion and attachment force were observed in juveniles but was not the case for larger mussels most likely as a consequence of a relatively short period of maintenance under food availability stress for the latter individuals that showed significantly higher initial condition and/or energetic store values. Accordingly, the use of energetic reserves in juveniles kept unfed for a week together with a significant drop in byssus secretion and attachment force might suggest a link, i.e. transfer of energy between soft tissues and byssus under stress. Quantitative values of byssal threads, based on the significance of the byssus versus attachment force relationship, together with its morphometric value, i.e. thread's thickness, represented a primary mechanism to explain variability in attachment strength of M. galloprovincialis of the different body sizes studied here.

Predicting the Effects of Ocean Acidification on Predator-Prey Interactions: A Conceptual Framework Based on Coastal Molluscs

“…OA has been shown to weaken the byssus of mytilid mussels, which could increase susceptibility to predation. In addition, byssus secretion has an energetic cost (Babarro et al, 2008), and OA could hypothetically cause a trade-off between calcification, growth, reproduction, and byssus secretion that would also affect predator-prey interactions.…”

Byssus secretion of Mytilus galloprovincialis: effect of site at macro- and micro-geographical scales within Ría de Vigo (NW Spain)

“…Consequently, the influence of the latter factors may establish temporal and spatial variability in byssus secretion. Variability in attachment strength of individuals has been proposed to be based not only on the number of byssal threads secreted by the animals, but also on thread thickness (Bell & Gosline 1997, Zardi et al 2007, Babarro et al 2008, Babarro & Fernández Reiriz 2010. reported that seasonal variations in attachment strength do not always reflect variability in thread number, which suggests that other factors might play a significant role, such as thread mechanical properties, decay rates and other endogenous parameters such as reproductive condition.…”

Aggregation and attachment responses of blue mussels, Mytilus edulis—impact of substrate composition, time scale and source of mussel seed

“…In the present experiment suspended mussels were significantly smaller than bottom mussels (t-test p < 0.001). However, the mean size difference between suspended and bottom mussels was 4.1 mm, and the mussels in this study were considered as being in the same size class (Babarro et al 2008;Lee et al 1990). The difference in mussel size is therefore not expected to interfere with our results.…”

“…From the literature it is unclear how the secretion of byssal threads changes with mussel size (Babarro et al 2008;Clarke and McMahon 1996;Lee et al 1990). In the present experiment suspended mussels were significantly smaller than bottom mussels (t-test p < 0.001).…”