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Lyonsia hyalina Conrad possesses “radial mantle glands” of a complex structure located deep within the periostracal groove. They occur along the mantle edge in alignment with slightly raised striations of the periostracum, are deeply staining and are composed of three cell types. Secretory and supportive cells, which are flask-shaped, alternate throughout the gland, while a third cell type is ovoid and borders the gland. A sulfated mucopolysaccharide is secreted over the periostracum by the glands and functions in adhesion of sand grains to the shell.
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Human activities have generated large quantities of microplastics that can be consumed by filter-feeding organisms as potential food sources. As a result, organisms may experience marked reductions in growth and/or health. To date there has been no investigations connecting microplastics (MPs) with the critically important ribbed mussel Geukensia demissa. Here we examined MP abundances within a bed of G. demissa in New Jersey. Results indicate that MP densities ranged between 11,000-50,000pieces/m2. The abundance of larger MPs (5mm>=1mm) did not vary among sampling sites while the smaller MPs (<1mm) abundances did vary between sampling sites. These smaller MPs also accounted for 79% of MPs recovered from these sites. Based on the higher abundance of smaller MPs, we also investigated MP ingestion/rejection in a laboratory setting. These results confirmed that ribbed mussels can ingest MPs with negative consequences for the buoyancy of plastics rejected in feces and pseudofeces. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Aqueous-phased xenobiotic contaminant exposure can biochemically modify newly generated periostracum of the Asian freshwater bivalve,Corbicula fluminea. Laser-induced desorption of partially polymerized periostracum produces spectra distinguishable from mass spectral images generated from uncontaminated periostracum. Organic xenobiotic contamination putatively impedes full polymerization of the periostracin protein. The detection of the effects of pollution on periostracum by the laser microprobe mass analyzer constitutes a novel bioprobe for the definitive but qualified detection of xenobiotic contamination.
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Temperature is a determinant environmental variable in metabolic rates of organisms ultimately influencing important physiological and behavioural features. Stressful conditions such as increasing temperature, particularly within high ranges occurring in the summer, have been suggested to induce flotation behaviour in Corbicula fluminea which may be important in dispersal of this invasive species. However, there has been no experimental evidence supporting this hypothesis. It was already proven that C. fluminea drift is supported by a mucilaginous drogue line produced by mucocytes present in the ctenidia. Detailed microscopic examination of changes in these cells and quantification of clam flotation following one, two and three weeks of exposure to 22, 25 and 30°C was carried out so that the effects of increasing water temperatures in dispersal patterns could be discussed. Results show that changes in temperature triggered an acceleration of the mucocytes production and stimulated flotation behaviour, especially following one week of exposure. Dilution of these effects occurred following longer exposure periods. It is possible that these bivalves perceive changing temperature as a stress and respond accordingly in the short-term, and then acclimate to the new environmental conditions. The response patterns suggest that increasing water temperatures could stimulate C. fluminea population expansion.
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