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A simple and low-cost method of monitoring and collecting particulate matter detaching from (or interacting with) aquatic animals is described using a novel device based on an airlift pump principle applied to floating cages. The efficiency of the technique in particle collection is demonstrated using polyethylene microspheres interacting with a cyprinid fish (Carassius carassius) and a temporarily parasitic stage (glochidia) of an endangered freshwater mussel (Margaritifera margaritifera) dropping from experimentally infested host fish (Salmo trutta). The technique enables the monitoring of temporal dynamics of particle detachment and their continuous collection both in the laboratory and in situ, allowing the experimental animals to be kept under natural water quality regimes and reducing the need for handling and transport. The technique can improve the representativeness of current experimental methods used in the fields of environmental parasitology, animal feeding ecology and microplastic pathway studies in aquatic environments. In particular, it makes it accessible to study the physiological compatibility of glochidia and their hosts, which is an essential but understudied autecological feature in mussel conservation programs worldwide. Field placement of the technique can also aid in outreach programs with pay-offs in the increase of scientific literacy of citizens concerning neglected issues such as the importance of fish hosts for the conservation of freshwater mussels.

Glycogen is a primary metabolic reserve in bivalves and can be suitable for the evaluation of bivalve condition and health status, but the use of glycogen as a diagnostic tool in aquaculture and biomonitoring is still relatively rare. A tissue biopsy combined with a simplified phenol-sulfuric acid method was used in this study to evaluate the inter-and intraindividual variation in the glycogen concentrations among several tissues (foot, mantle, gills, adductor muscle) of the unionid bivalve, the duck mussel Anodonta anatina. This short report documents that individual bivalves differ in the spatial distribution of glycogen among tissues. Sampling of different types of tissues can cause distinct results in the evaluation of energetic reserves at the individual level. At the same time, spatial variability in glycogen content has the potential to provide a more detailed evaluation of physiological conditions based on tissue-specific glycogen storage. The results obtained and the simplified methodology provide a new opportunity for researching the energetic reserves and health status of freshwater mussels in various applications.

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In vitro culture has great potential for the propagation of freshwater mussels in both commercial and conservation aquaculture. The use of in vitro techniques precludes the need for host fish, thus decreasing costs and increasing efficiency. However, protocols are still lacking for many species that grow substantially during the parasitic stage. In this study, we tested the effects of taurine addition, serum type and source of lipids on the survival rate and increase in length of Margaritifera margaritifera larvae during the initial stage of culture (first 11 days of exposure to media). Our results show that taurine has no significant effect on the early survival rate of glochidia; however, the possible importance of this amino acid in subsequent stages is discussed. The use of an emulsified lipid mixture instead of traditional fish oil showed significantly higher rates of survival. Finally, the addition of serum showed variable effects, with both horse serum and newborn calf serum having higher survival in trials using mussel populations from different sources. These findings can contribute to the invention or improvement of in vitro protocols for species growing during infection and at the same time show the potential that early survival assessments could have for the development of in vitro methods in species with long parasitic stages.