Shell allometry and length-mass-density relationship for Mytilus edulis in an experimental food-regulated situation

Abstract

We examined the influence of food availability and population density on the morphometry and shell length body mass relationship of Mytilus edulis. Mussels were reared in the laboratory for 22 mo at 8 different density levels in 1 l chambers supplied with natural seston at 2 different concentrations. This allowed us to assess separately the effects of food availability and mussel density. The shell length/width and shell height/width ratios were affected by food, density and time. Mussels tended to be narrower (flatter) at high density and at low food level. Therefore, narrow shells could result from reduced food concentration in high density situations without implying physical interference. Shell mass was also influenced by both food and density levels, but to a lesser extent than tissue dry mass. In contrast with soft tissue mass, shell mass increased significantly for all food and density levels between October 1995 and October 1996. The elevation of the shell length-body mass-population density relationship was lower at low food availability. The slope of the tridimensional relationship, however, increased with decreasing food level, indicating apparent asymmetric competition for all food-density treatments pooled together. This pattern, however, is misleading because mussels obviously cannot interact among chambers. Since the slopes of length mass relationships are used in predicting self-thinning exponents in space-regulated situations, it follows that self-thinning exponents in mussels should be sensitive to background food level, thus limiting the use of self-thinning relationships for resolving factors regulating growth.KEY WORDS: Mussels · Shell allometry · Food regulation · Length-mass-density relationship · m-N curve Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 219: [177][178][179][180][181][182][183][184][185][186][187][188] 2001 one of the most important roles in Mytilus edulis (Seed 1968, 1973, Brown et al. 1976). High population density has generally been reported to lead to elongated shells in mussels (Coe 1946, Lent 1967, Brown et al. 1976, Richardson & Seed 1990, although extreme deformation may be observed in some cases (Bertness & Grosholz 1985). Individual shape is also affected by population density in oysters (Tanita & Kikuchi 1957, Chinzei et al. 1982, clams (Ohba 1956, Cigarria & Fernandez 1998 and tunicates (Paine & Suchanek 1983), for instance. Perhaps the most spectacular effect of high population density on individual shape in benthic suspension feeders is found in conspicuous hummocks formed by high-density barnacle populations (Bertness et al. 1998). Crowding is usually understood as implying physical interference. Manipulations of population density in some infaunal bivalves, however, have shown no evidence of physical interference (Peterson 1982). This is consistent with food depletion in dense bivalve beds and with individual growth being food regulated (Wildish & Kristmanson 1984, Fréchette & Bourget 1985a. The...

Feeding physiology of the Argentine mussel Mytilus edulis platensis (d’Orbigny, 1846): does it feed faster in suspended culture systems?

“…Food availability and mussel density exert a large effect on the morphometry and L-DW relationship of Mytilus edulis (Alunno-Bruscia et al 2001). A higher DW, lower W relative to L and decreased shape variability in cultivated mussels compared to wild mussels probably result from the availability of three-dimensional space for growth in the water column experienced by the former as compared to the bottom two-dimensional space availability experienced by wild specimens.…”

Morphology and density of mussels on natural and aquaculture structure habitats: implications for sea duck predators

“…Intertidal mussels likely produce a thicker shell in response to exposures stresses and wave activity (Seed 1968, Beadman et al 2003, while the fast-growing subtidal mussels (Seed 1968) and mussels at high densities (Alumno-Bruscia et al 2001) tend to have less massive shells. Shell morphology is also considered to be an inducible plastic defense.…”

Evaluation of self‐thinning models and estimation methods in multilayered sessile animal populations

“…This dependence has not been considered in current models and can cause bias in the estimation of the ST parameters. The alternative procedure of analyzing data obtained at a single sampling time (Alunno-Bruscia et al 2000, Alunno-Bruscia et al 2001 do not allow a proper dynamic interpretation of the self-thinning process. Therefore, we suggest that the temporal effect should be included in the ST models in future studies.…”