Bioaccumulation of total mercury, copper, cadmium, silver, and selenium in green turtles (Chelonia mydas) stranded along the Potiguar Basin, northeastern Brazil

Study on the relationship between trace elements and microbiological profiles in organs and tissues, for an innovative ecological perspective on the health of sea turtle Caretta caretta

Environmental factors, particularly exposure to marine contaminants, can compromise immune function in marine species, including sea turtles, increasing their susceptibility to bacterial and viral infections. In this context, the present study analyzes trace element bioaccumulation and bacterial presence in organs and tissues of stranded loggerhead turtles (Caretta caretta) from the Tyrrhenian coast of Southern Italy and explores the potential associations between contaminant levels and bacterial infections. Liver, kidney, muscle, and blood from 36 loggerhead turtles were analyzed for 17 trace elements, classified as essential (e.g., zinc and selenium) and non-essential (toxic) elements (e.g., cadmium, lead, mercury). Results highlighted organ-specific differences in trace element concentrations, attributable to the roles of these organs in detoxification and storage mechanisms. Bacteriological analyses revealed a wide range of bacterial species, mainly gram-negative strains of the families Vibrionaceae, Enterobacteriaceae and Shewanellaceae, as well as some gram-positive bacteria of the families Enterococcaceae and Streptococcaceae. No statistically significant correlation was observed between toxic element concentrations and bacterial presence; however, mercury levels exhibited a slight tendency to be associated with bacterial colonization, warranting further investigation. This study provides valuable data on the accumulation of contaminants and bacterial profiles in Caretta caretta. These results will contribute to ecological risk assessments and improve conservation strategies aimed at reducing the impact of pollution on marine species.

A novel highly selective FRET sensor for Fe(III) and DFT mechanistic evaluation

A novel FRET-based sensor has been designed and developed through the conjugation of naphthyl and rhodamine via propylamine spacer, Naph-Rh. The naphthyl moiety serves as a FRET donor due to its emission spectrum overlapping with the rhodamine B absorption band. Naph-Rh exhibited a selectivity for sensing Fe³⁺ over other metal ions with a visual color change and fluorescent enhancement. The ratio of the Naph-Rh and Fe³⁺ was determined to be 1:1 based on Job's plot analysis with a detection limit of 83 nM. The probe exhibited a linear response to Fe³⁺ in the range of 0-120 μM. Furthermore, the density functional theory (DFT) calculations of Naph-Rh were carried out to rationalize the design and portray the plausible Fe³⁺ sensing mechanism.

Spatial trends of trace elements bioaccumulation in the most endangered dolphin from the Southwestern Atlantic Ocean: The franciscana (Pontoporia blainvillei)

Trace elements bioaccumulation patterns can be an important tool to assess differences among cetaceans' populations. In this work, their use as potential chemical markers to differentiate franciscanas (Pontoporia blainvillei) populations was evaluated. Franciscanas were collected from three states in southeastern Brazil, which comprise three different Franciscana Management Areas (FMAs): Espírito Santo (FMA Ia), southern Rio de Janeiro (FMA IIa), and central São Paulo (FMA IIb). The concentrations of As, Cd, Cu, Fe, Hg, Mn and Zn were determined in the muscle, liver and kidney of the animals. Cadmium was the most valuable chemical marker to differentiate stocks, separating at least FMA IIa from the others. The higher Cd levels in FMA IIa, along with dietary information, indicate that the predominant consumption of cephalopods by this population is the main reason for the differences found. Additionally, environmental characteristics of the areas should also be considered as divergent sources of trace elements. Our findings suggest that non-essential trace elements, such as Cd, can be successful markers to differentiate populations. The Mn concentrations in FMA Ia raised concern and must be carefully monitored, as well as other elements that compose the iron ore tailings that have impacted the Espírito Santo coastal area. Additionally, this is the first study to report trace element concentration in the franciscanas from FMA IIa (southern Rio de Janeiro). Trace element concentrations found in franciscanas may represent different contamination levels in their preys and environments, which might pose specific threats to distinct populations. Therefore, our findings are important to characterize and differentiate franciscana populations and to guide precise management and conservation actions for the distinct stocks of this endangered species.