Development of a short-term chronic toxicity test with a tropical mysid

A review of the order mysida in marine ecosystems: What we know what is yet to be known

Mysids have a high ecological importance, particularly by their role in marine food chains as a link between the benthic and pelagic realms. Here we describe the relevant taxonomy, ecological aspects such as distribution and production, and their potential as ideal test organisms for environmental research. We also highlight their importance in estuarine communities, trophic webs, and their life history, while demonstrating their potential in addressing emergent problems. This review emphasizes the importance of mysids in understanding the impacts of climate change and their role in the ecology of estuarine communities. Although there is a dearth of research in genomic studies, this review emphasizes the relevance of mysids and their potential as a model organism in environmental assessment studies of prospective or retrospective nature and highlights the need for further research to enhance our understanding of this group's ecological significance.

Levels of hydrocarbons and toxicity of water-soluble fractions of maritime fuels on neotropical invertebrates

Accidents involving fuels and oil spills are among the main sources of hydrocarbons to the marine ecosystems and often damage the biota. Diesel and bunker oil are two examples of fuels with broad application that release hydrocarbons to the aquatic environment and little is known about their toxicity on tropical organisms. This study aimed to assess the toxicity of the water-soluble fraction (WSF) of diesel and bunker oils to neotropical marine invertebrates. Commercial fuels were purchased for WSF extraction, analyzed for total petroleum hydrocarbons (TPH), and polycyclic aromatic hydrocarbons (PAHs), and acute and chronic toxicity determined. The WSF analyzed contained varied levels of TPH and PAHs mixtures, especially low molecular weight PAHs; bunker WSF presented higher amounts of TPH and PAHs. Both WSFs tested produced significant mortality of the brine shrimp Artemia salina, affected the reproduction rate of the copepod Nitokra sp, and impaired the embryo-larval development of the mussel Perna perna and of the sea urchin Lytechinus variegatus. In general WSF from diesel was more toxic to the organisms tested, but bunker WSF was more toxic to embryos of L. variegatus. Toxicity started from concentrations of 3% WSF, which can be environmentally relevant after an oil spill, indicating that marine biota may be adversely affected in short term.

Acute toxicity assay using mysid as an alternative test organism in the assessment of the aqueous fraction of sediment

The evaluation of sediment quality through biological testing of the aqueous fraction can be applied in dredging situations and is associated with a small number of confounding factors. The use of test organisms that are relatively resistant to contaminants is recommended when working with complex mixtures such as sediments. In this study, the sensitivity of the mysid Mysidopsis juniae to ammonia (NH₃) and metals was investigated in acute toxicity laboratory tests and the results were compared to those obtained in the traditional test with sea urchin embryos and larvae. The ability of the toxicity identification and evaluation (TIE) technique, with the use of EDTA and sodium thiosulfate, to indicate the factors responsible for adverse effects was determined. The results indicate that mysids are almost 5 times more resistant than the sea urchin to ammonia (NH₃), more sensitive to Cd²⁺ and Ni²⁺ and more resistant to Zn²⁺ and Pb²⁺. With the TIE technique and with the use of EDTA as a complexing agent, a greater resolution was observed in the diagnosis of the presence of the metals Cd²⁺ and Ni²⁺, which could be applied to the aqueous fraction of the sediment.

Chemical Contents of Disposed Light Sticks Affect the Physiology of Rocky Crab Pachygrapsus transversus and Gray Shrimps Litopennaeus vanammei

Light-sticks shine resulting from a chemiluminescent reaction between two components kept separate by a glass ampoule. Light-stick baits are discarded in the ocean after being used in longline fishing. The traditional Brazilian community of Costa dos Coqueiros, Brazil, uses the discarded light-sticks chemical contents found on beaches as medicine for rheumatism and mycoses. This study assessed the effects that light-sticks (chemical contents) have on Pachygrapsus transversus and Litopennaeus vanammei. Assays of metabolic changes involved rates of ammonia excretion and oxygen consumption. The EC50-60 min to juveniles and adults P. transversus were 0.0004% and 0.0046%, respectively; and L. vanammei revealed a susceptible species: EC50-60 min of 0.0006% for oxygen uptake and 0.0072% for ammonia excretion, and also was observed a hormesis effect in the ammonia excretion. Light-stick contents could promote significant metabolic changes in rocky crabs and gray shrimp. Educational actions are needed that make the population aware of and avoid the dangerous misuse of the light-sticks.

Acute and chronic effects of innovative antifouling nanostructured biocides on a tropical marine microcrustacean

This study aimed to investigate the toxicity of innovative antifouling nanostructured biocides DCOIT and silver associated to silica nanocapsules (SiNC) on the tropical microcrustacean Mysidopsis juniae. The toxicity of the tested compounds can be summarized as follows (acute tests): DCOIT > SiNC-Ag > SiNC-DCOIT > SiNC-DCOIT-Ag > SiNC > Ag; (chronic tests): SiNC-Ag > SiNC-DCOIT-Ag > DCOIT > Ag > SiNC, although it was not possible to determine the chronic toxicity of SiNC-DCOIT. In general, our data demonstrated that mysids were more sensitive than most temperate species, and it was possible to conclude that the combination SiNC-DCOIT-Ag showed less acute toxicity in comparison to the isolated active compounds, reinforcing data obtained for species from temperate environments on the potential use of nanomaterial to reduce toxicity to non-target species. However, despite representing less risk to the environment, the compound SiNC-DCOIT-Ag is still very toxic to the non-target tropical mysid.

Toxicity of a mixture of monoaromatic hydrocarbons (BTX) to a tropical marine microcrustacean

This study evaluated the toxicity of benzene, toluene, and xylenes (BTX), isolated and in binary mixtures to Mysidopsis juniae. The organisms were exposed to BTX, and combined effect patterns were predicted by applying the theoretical models of Concentration Addition and Independent Action. According to the LC50 of the isolated compounds, xylene (16.1 ± 2.4 mg L^-1) was considered the most toxic, followed by toluene (38.0 ± 5.3 mg L^-1) and, lastly, benzene (78.0 ± 2.9 mg L^-1). The binary combinations showed deviations from additivity, with exposure to the xylene-benzene mixture presenting as antagonistic, while the xylene-toluene and toluene-benzene mixtures were better explained by a dose ratio deviation, with toluene being responsible for the antagonistic pattern. This study provides new insights into toxicity prediction of a BTX mixture, which adds value to the risk assessment procedure over evaluation of chemical hazards on a case-by-case basis.

Analysis of vitellogenin by histochemical method as an indicator of estrogenic effect in male Danio rerio exposed to metals

Several chemicals present in the aquatic environment have the ability to alter the endocrine system of aquatic organisms, including the metals cadmium (Cd) and zinc (Zn). In males, a tool to analyze this effect is the vitellogenin (VTG) detection, a protein with defined function in the yolk production and subsequent aid to embryo-larval development. This protein is produced just by females and can be detected by simple and cheap methods such as histochemical method. Thus, this study aimed to analyze the capacity of Cd and Zn to induce VTG production in Danio rerio males and determine whether the histochemical labeling method is efficient to study estrogenic effects in this species. For this, D. rerio adult males were exposed chronically (21 days) to 0.25 and 1 μg/L of Cd and 120 and 180 μg/L of Zn, values allowed by the Brazilian and American legislation to aquatic life protection. After which, the organisms were submitted to a histological process as preparation to liver VTG marking by histochemical method and subsequent qualitative analysis of this protein in zebrafish's liver. After analyzes, it was possible observed that Cd and Zn are capable of inducing VTG production in D. rerio males and that the histochemistry method is efficient for detection of estrogenic effects in this species.