Growth and shell morphology of three mytilidae (Bivalvia) species from the Sea of Japan

The growth and shell morphology of bivalve mollusks Crenomytilus grayanus, Mytilus coruscus, and Modiolus modiolus from the Sea of Japan are examined. The changes in body proportions and shell form in the ontogenesis of C. grayanus, M. coruscus, and M. modiolus are different even in the cases when the mussels develop in similar environmental conditions. Rapid growth shapes a well-streamlined and flat form of shell; slow growth leads to the formation of a massive and convex form. The parameters of the Bertalanffy growth curve for each species are calculated. The differences are discussed from the standpoint of functional morphology and spatial distribution patterns of mytilids in the coastal areas of the sea.     

Modulation of Mytilus trossulus (Bivalvia: Mollusca) larval survival and growth in culture. Short communication

Commercial importance and ability to live in a wide range of salinities have made the common mussel, Mytilus trossulus, a relevant model to study modulation of larval growth and development. We investigated the effects of various salinities combined with neomycin and ampicillin application on Mytilus larvae survival and growth. Both neomycin and ampicillin enhanced trochophore and veliger survival under condition of low salinity. The average veliger size was increasing in accordance with the increase of salinity. In case of neomycin treatment 3.6% of the larvae reached the pediveliger stage. No abnormalities of larval morphology of the FMRFamide and 5-HT systems occurred after 7 days of culturing with both antibiotics.     

Morphological Adaptations of the Mussel Crenomitilus grayanus (Bivalvia) to Attached Life

The morphology of the mussel Crenomytilus grayanus from different biotopes manifesting the adaptation of this mollusk to attached life on the bottom surface was studied. It was established that colonization of rocky coastal areas with active hydrodynamics by mussels is related to retardation of linear growth rates, the formation of convex shells, and vigorous development of retractor muscles of the foot and byssus. An environment protected from the effect of surfs on silted bottoms facilitated the fast growth of mussels, which resulted in the formation of an elegant flat shell. In that biotope mussels are specified by a rather poor development of the muscles responsible for its attachment to the substrate.     

Effects of Environmental Factors on Byssal Thread Formation in Some Members of the Family Mytilidae from the Sea of Japan

The ability to attach repeatedly to a substrate (glass, boulders, sand) in three common mussel species of the upper sublittoral zone of the Sea of Japan, Grayan's mussel Crenomytilus grayanus, the Korean mussel Mytilus coruscus, and northern horse mussel Modiolus modiolus, was studied under experimental conditions. It was found that during 120 h of the experiment C. grayanus and M. modiolus produced more byssal threads than M. coruscus. A decrease in the water temperature from 20 to 0°C slowed the rate of production of byssal threads down to full passivity in some experimental mollusks. This was more typical of M. coruscus and less typical of C. grayanus. Renewed threads differed in their length, thick, size of the adhesive plate, and strength. M. coruscus formed the shortest, thickest, and strongest threads with rather a large adhesive disk. The observed differences are discussed from the position of morphophysiological adaptations of species for colonization of different natural substrata under contrasting conditions of the upper sublittoral zone.     

Dynamics of byssal thread production in <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> and <Emphasis Type="Italic">Modiolus modiolus</Emphasis> (Bivalvia) upon reattachment to substrate

It was established that the process of repeated attachment to a substrate in bivalve mollusks Crenomytilus grayanus (Grays mussel) and Modiolus modiolus (the northern horse mussel) involved several successive stages which took in vitro about one month at a water temperature of 19 ± 2°C. Comparison with Grays mussel revealed that the northern horse mussel had a higher rate of byssal thread production and a greater thread number by the end of the complete formation of the byssus complex. The observed differences are explained by the adaptation of mollusks to habitation in different biotopes.Original Russian Text Copyright © 2004 by Biologiya Morya, Selin, Vekhova.     

Variation of sperm morphology in Pacific oyster precludes its use as a species marker but enables intraspecific geo-authentification and aquatic monitoring

According to recent reports, shell morphology is unreliable for the identification of oysters because of the high phenotypic plasticity of these bivalves. Using COI DNA barcoding and sperm morphology, we reinvestigated the species validity of wild Pacific oyster Crassostrea gigas habituating the Peter the Great Bay (Sea of Japan). DNA barcoding confirmed the species validity of samples collected. Application of the single sperm pattern was not possible for species identification due to pronounced sperm plasticity being found. Six sperm morphs were discovered in the testes of each oyster collected. The amount of abundant sperm morphs and the type of the most dominant sperm pattern are particular to geographical localities that are individual depending on the environmental factors. Ecological monitoring of marine areas and commercially assigned intraspecific geo-authentification of the Pacific oyster seems possible based on the analysis of this species’ heterogenic sperm. Further work will be needed to test if sperm heterogeneity exists in other Ostreidae species and if heterogenic sperms could be used for interspecific analysis.     

Morphology of the Bivalve Mollusks Crenomytilus grayanus and Mytilus coruscus in Relation to Their Spatial Distribution in the Upper Subtidal Zone

The morphology of the shell and byssus threads was studied in two closely related mussel species Crenomytilus grayanus and Mytilus coruscus. The two species differ significantly from each other in the shell shape and in the degrees of development and deformation of byssus threads. These differences, in turn, determine (either directly or indirectly) the differences in strength of the byssal attachment and are discussed in terms of their functional morphology with respect to the spatial distribution of the mussels in marine coastal zones.     

The Byssal Apparatus in the Pacific Mussel,Mytilus trossulus (Bivalvia,Mytilidae), from the Sea of Japan

Biology Bulletin - In the commercial Pacific mussel species, Mytilus trossulus, from the Sea of Japan, features of the morphological structure of the byssal apparatus, byssal threads, and pedal...     

Reattachment of certain species of mytilid bivalves to various substrates

Reattachment to various substrates (concrete, wood, and iron) was studied in three species of Mytilidae in the laboratory. Each of the investigated species exhibited substrate selectivity. The most successful substrate colonization occurred on concrete, which, owing to its physicochemical properties, proved to be more appropriate for rapid and firm anchorage of the mollusks. Mytilid response to any specific substrate, judged from the reattachment rate and substrate preference, may indirectly indicate the possibile existence of natural communities of organisms associated with a corresponding biotope.