ZnO Nanoparticles Alter Redox Metabolism of Limnoperna Fortunei

Nanoparticles incorporated in consumer and industrial products cause concerns about their potential ecological impacts. Zinc oxide nanoparticles (ZnO-NP) have several applications, which increases their potential for release to the environment, causing ecotoxicological problems. Bivalve mollusks are susceptible targets for nanoparticles toxicity, since nanomaterials can enter the cells by endocytosis mechanisms. Limnoperma fortunei (golden mussel) are validated for biomonitoring purposes and have a wide distribution in the South of Brazil, where it can be collected throughout the year. The aim of this study was to evaluate the influence of ZnO-NP on the redox metabolism by enzymatic and non-enzymatic antioxidant defense assessment in addition to DNA damage by DNA fragmentation assay in L. fortunei after exposure to ZnO-NP. Adult bivalves were placed in contact with 1, 10, and 50 µg mL-1 ZnO-NP during three incubation times: 2, 4 and 24 h. Ionic Zn release, enzymatic and non-enzymatic antioxidant activity, oxidative damage to lipids and proteins and DNA damage were evaluated. Oxidative damage to proteins and lipids were observed after 4 h exposure and returned to baseline levels after 24 h. Superoxide dismutase levels decreased after 4 h exposure and increased after 24 h. No significant alteration was observed in catalase activity or even DNA double strand cleavage. The dissociation of ZnO may occur after 24 h, releasing ionic zinc (Zn2+) by hydrolysis, which was confirmed as the ionic Zn concentration increased following 24 h exposure. In conclusion, ZnO-NP were able to induce oxidative stress in exposed golden mussels. The golden mussel is capable to modulate its own antioxidant defences in response to oxidative stress and seems to be able to hydrolyse the nanoparticle and consequently release Zn2+ into the cellular compartment.

BIOACCUMULATION OF METALS AND EVALUATION OF GOLDEN MUSSELS ENCRUSTED ON DIFFERENT SCREENS OF NET CAGES

This study aimed to evaluate the characterization and bioaccumulation of metals of the golden mussel encrusted in the screens of net cages installed in the reservoir of Itaipu Binacional. The experimental design was completely randomized, composed of two types of screens (PVC and Bezinal) distributed on four sides (Sides I, II, III, and IV) of the net cage. The total mass, the average mass, and the dimensions (width, height, and length) of the mollusks were evaluated. The mussels adhered to the Bezinal screen presented a higher average mass, length, height, and width than those colonized on the PVC screen (p <0.05). However, the PVC screen provided a greater (p <0.05) total mass of encrusted mussels. Regardless of the screen used, the average mass and length of mussels had higher values on Side I (p <0.05) than to the Sides II and IV, but not different from Side III. The mussels evaluated showed high levels of metals, and those encrusted in the Bezinal screen presented higher levels of Al, Zn and Cr than the individuals on the PVC screen (p <0.05). The use of a Bezinal screen is more efficient than a PVC screen, as an antifouling material. Mussels with shorter lengths had a higher incidence on the PVC screen. The mussels encrusted in the Bezinal screen bioaccumulate higher content of Al, Zn, and Cr. The type of screen used in the net cages influences the mass and size of adhered mussels, as well as can interfere with the metal accumulation in the golden mussel.

Limnoperna fortunei - Updating the geographic distribution in the Brazilian watersheds and mapping the regional occurrence in the Upper Uruguay River basin

Limnoperna fortunei is an invasive alien species (IAS) that cause serious ecological and economic problems in Brazilian freshwater environments. Due to its high dispersion capacity and the lack of new records in peer-reviewed journals we carried out an extensive survey to update the distribution of L. fortunei in the Brazilian hydrographic basins. We also performed a detailed investigation of its distribution in the Upper Uruguay River basin using a molecular method. We presented new records, showing the invasion in new basins and a wide distribution in the basins previously infested. Additionally, we confirmed that the Upper Uruguay River is fully colonized by the golden mussel, being distributed in the lentic, lotic, and transitional lotic/lentic environments presented in this region. This update is an important tool for the implementation of guidelines and the development of safety protocols and sanitary barriers to avoid the dispersion of this IAS to new environments..

Optimized and validated protocol to the detection of the invasive bivalve Limnoperna fortunei from eDNA plankton samples

We optimized a methodology for plankton environmental DNA detection of the invasive golden mussel and validated it in samples from a Southern Brazil reservoir. Limnoperna fortunei is a successful invasive alien species that causes significant impacts on freshwater ecosystems. We adjusted and validated the methodology to detect L. fortunei in plankton samples, with a SYBR Green assay. Based on the standard curve analysis, the observed theoretical minimal qPCR detection level was 0.0005625 ng.µL-1 (R2 = 0.99) at a PCR quantification cycle of 14.09–29.56. We also presented a practical guide to be used in monitoring and detection of L. fortunei. The optimized protocol was efficient in detecting L. fortunei and can be used to monitor already infested environments or invasions in new environments.

Population structure of the invasive golden mussel (Limnoperna fortunei) on reservoirs from five Brazilian drainage basins

The golden mussel (Limnoperna fortunei) is a freshwater bivalve that was introduced in South America almost 30 years ago, likely through ballast water of Asian ships. Since then, it has spread across the continent, causing both economic and environmental impacts. The study of the population structure of an invasive species may bring valuable insights towards understanding its pattern of dispersion, which in turn will help to create more effective management plans. Here, we have compared mussel populations from 5 different Brazilian reservoirs and tested for the presence of geographic genetic structure. In order to obtain a high number of single nucleotide variants (SNVs) at good cost-benefit, we have for the first time applied the double digest restriction-site associated DNA sequencing (ddRAD-seq) protocol for the golden mussel. The ddRAD-seq protocol allowed us to obtain 2046 SNVs, which were then used to assess population structure by applying three independent methodologies: Principal Component Analysis (PCA), Bayesian Clustering and Phylogenetic Tree. All methodologies have indicated absent geographic structure.