Variability of taurine concentrations in Mytilus galloprovincialis as a function of body size and specific tissue

Metabolic dysfunctions in pearl oysters following recurrent marine heatwaves

Marine heatwaves (MHWs) have become more frequent, intense and extreme in oceanic systems in the past decade, resulting in mass mortality events of marine invertebrates and devastating coastal marine ecosystems. While metabolic homeostasis is a fundamental requirement in stress tolerance, little is known about its role under intensifying MHWs conditions. Here, we investigated impacts of MHWs on the metabolism in pearl oysters (Pinctada maxima) - an ecologically and economically significant bivalve species in tropical ecosystems. Activities of digestive enzymes (gastric proteases, lipases, and amylases) did not significantly respond to various scenario of recurrent MHWs varying from 24 °C to 28 °C (moderate) and 32 °C (severe). The metabolomics analysis revealed nine and five key metabolism pathways under both MHWs scenarios. Specifically, pathways associated with energy metabolism were impaired by moderate MHWs, manifesting in downregulation of differential metabolite (The nicotinic acid and N-acetyl-glutamic acid). The content of CDP-ethanolamine was significantly decrease, and the perturbations of oxidative stress caused by the decreased of content of D-glutamine. Metabolites related to a suite of body functions (e.g., the lipid metabolism, biomineralization, and antioxidant defenses) showed significantly negative responses by severe MHWs. These findings reveal the metabolic impairments of marine bivalves when subjected to MHWs varying in intensity and frequency, implying cascading consequences which deserve further investigation.

Integrated transcriptomic and functional immunological approach for assessing the invasiveness of bivalve alien species

Biological invasions started when humans moved species beyond their normal geographic limits. Bivalves are the most notoriously invasive species in subtidal aquatic environments. Next-generation sequencing technologies are applied to understand the molecular mechanisms involved in the invasion. The ecological immunology focuses on the role of immunity in invasion, and its magnitude could help to predict the invasiveness of alien species. A remarkable case of invasion has been reported in the Ría de Vigo (Spain) by the black pygmy mussel Xenostrobus securis. In Galicia, the Mediterranean mussel Mytilus galloprovincialis is the predominant cultured bivalve species. Can we predict the invasiveness of alien bivalve species by analyzing their immune response? Can X. securis represent a risk for the autochthonous mussel? We evaluated the suitability of the immune-related hypotheses in our model by using an integrated transcriptomic and functional immunological approach. Our analysis suggests lower immune capabilities in X. securis compared to M. galloprovincialis, probably due to the relocation of energetic resources from the immune response to vital physiological processes to cope with salinity stress. This multidisciplinary approach will help us understand how the immune response can be influenced by the adaptive process and how this immune response can influence the invasion process.

Influence of size and density on filtration rate modeling and nutrient uptake by green mussel (Perna viridis)

This study investigates green mussel filtration rates based on variation of the mussel size and density, and attempts to correlate these with the amount of Chaetoceros calcitrans consumed by kinetic modeling. The filtration rates were found to be more effective in small mussels and with greater volumes of seawater/mussel which represent low mussel densities in the mussel farms. Under field condition, the first order kinetic model is useful for evaluation of mussel filtration rate. However, the composite exponential kinetic model was determined to better describe filtration rates in a close system. Higher ratios of seawater volume L/g DW mussel tissue, resulted in an increasing filtration rate until a maximum plateau was reached at 10.37 L/h/g DW tissue as determined by first order kinetics. Based on the filtration rate, carbon, nitrogen, and phosphorus uptake by green mussels were found to be 2128.72, 265.41, and 66.67 mg/year/indv, respectively.