Dietary exposure to chemicals alters the diversity of microbiome communities and can lead to pathophysiological changes in the gastrointestinal system. The organochlorine pesticide dieldrin is a persistent environmental contaminant that bioaccumulates in fatty tissue of aquatic organisms. The objectives of this study were to determine whether environmentally-relevant doses of dieldrin altered gastrointestinal morphology and the microbiome of zebrafish. Adult zebrafish at ∼4 months of age were fed a measured amount of feed containing either a solvent control or one of two doses of dieldrin (measured at 16, and 163.5 ng/g dry weight) for 4 months. Dieldrin body burden levels in zebrafish after four-month exposure were 0 (control), 11.47 ± 1.13 ng/g (low dose) and 18.32 ± 1.32 ng/g (high dose) wet weight [mean ± std]. Extensive histopathology at the whole organism level revealed that dieldrin exposure did not induce notable tissue pathology, including the gastrointestinal tract. A repeated measure mixed model analysis revealed that, while fish gained weight over time, there were no dieldrin-specific effects on body weight. Fecal content was collected from the gastrointestinal tract of males and 16S rRNA gene sequencing conducted. Dieldrin at a measured feed dose of 16 ng/g reduced the abundance of Firmicutes, a phylum involved in energy resorption. At the level of class, there was a decrease in abundance of Clostridia and Betaproteobacteria, and an increase in Verrucomicrobiae species. We used a computational approach called predicted relative metabolomic turnover (PRMT) to predict how a shift in microbial community composition affects exchange of metabolites. Dieldrin was predicted to affect metabolic turnover of uroporphyrinogen I and coproporphyrinogen I [enzyme]−cysteine, hydrogen selenide, selenite, and methyl-selenic acid in the fish gastrointestinal system. These pathways are related to bacterial heme biosynthesis and selenium metabolism. Our study demonstrates that dietary exposures to dieldrin can alter microbiota composition over 4 months, however the long-term consequences of such impacts are not well understood.

The interaction of xenobiotics is common in aquatic ecosystems; therefore, we wanted to evaluate if trenbolone (TB) modulates the effects of 17α-ethinylestradiol (EE2). Male eelpout (Zoarces viviparus) were exposed to 5 ng L−1 EE2 continuously for 19 d (EE2-C) or discontinuously (11 d, EE2-D) alone or in combination with low (50 ng L−1, TBL) or high (500 ng L−1, TBH) concentrations of TB (19 d). Exposure to EE2 caused reduced gonadosomatic index, increased plasma vitellogenin concentrations, up-regulated vtg and era mRNA expression and severe alterations in gonadal histology. TBL and TBH did not affect plasma vitellogenin, era or vtg mRNA expression. TBL and TBH did not counteract the EE2-induced increase in plasma vitellogenin and reduction in 11-ketotestosterone whereas TBH counteracted the EE2 induced increase in vtg and era mRNA expression. Exposure to TBH and EE2-C + TBH lead to severe gonadal histology alterations. TBL and EE2-D + TBH exposed fish showed less histopathological alterations.

The aim of this novel research was to determine the toxic burden of increased elements in water resources on the inhabitant wild animals (squirrels, turtles, bats), using particle induced x-ray emission (PIXE) and histopathological approaches. PIXE analysis of skin, muscle, lung, liver and kidney revealed significant increase in Al, Cl, Fe, Mg, Mn, Si and V. Moreover, data clearly reflect a significant (P < 0.001) deposition of toxic elements (Al, Cl, Fe and K) in the lung producing interstitial/proliferative pneumonitis, intra-alveolar hemorrhages, and thickening of alveolar capillary walls. The results obtained from the liver samples emphasized that majority of the animals were intoxicated with Cl, Mg, S, Si and V, which have produced profound deterioration and swelling of the hepatocytes. Likewise, histopathology of the kidney sections spotlighted severe nephritis and degenerative changes, which could be associated with the elevated amount of Al, Cl and Mg. This data undoubtedly provide relevant information on the heavy burden of toxic elements and their pathological outcomes in wild animals and highlight their potential risks for human exposure. Thus, the information provided is critical for developing effective strategies in dealing with health hazards associated with elemental exposures.

The bivalve Scrobicularia plana, an important species for the structure and functioning of estuarine and coastal mudflats, was studied in thirteen sites from NW France differing by their degree of contamination to document the presence of reproduction impairments (intersex, sex ratio, gonadosomatic indices) in relation to the condition revealed by using hepatosomatic and condition indices. In agreement with recent studies in other European estuaries, intersex was revealed in all the studied estuaries, including sites the chemical and ecological status of which is considered “good” according to the criteria of the European Water Framework Directive. The presence of endocrine disrupting chemicals (EDCs) could result in such disturbances. Our results re-inforce the concern linked to the subtle effects of EDCs, which are active at very low doses, often in the absence of any major sign of toxicity. However at this stage, no clear link may be established between intersex and population effects.

We exposed female European starlings to a pentabromodiphenyl ether (Penta-BDE) mixture through subcutaneous implants, and examined levels and profiles of polybrominated diphenyl ethers (PBDEs) together with reproductive effects. Sum PBDE levels increased significantly in the serum of the exposed females from 218 ± 43 to 23,400 ± 2035 pg/ml. Sum PBDE concentrations in the eggs of the exposed group ranged from 130 ± 12 to 220 ± 37 ng/g wet weight (ww). The profile in serum after egg laying was very similar to that in eggs. There were no detectable levels of HO-PBDEs in both serum and eggs. Fewer females of the exposed group initiated egg laying compared to the control group, although the difference was not significant. In addition, egg weight and volume were significantly higher in the exposed group. These results suggest that, at the investigated exposure levels (150 μg sum PBDEs/bird), PBDEs may have a negative effect on reproductive performance.

Marine pollution, overrepresented by plastic, is a growing concern worldwide. However, there is little knowledge on occurrence and detrimental impacts of marine debris in cetaceans. To partially fill in this gap of knowledge, we aimed to investigate the occurrence and pathologies associated with foreign bodies (FBs) in a large cohort of cetaceans (n = 465) stranded in the Canary Islands. The Canary Islands shelter the greatest cetacean biodiversity in Europe, with up to 30 different species, of which nine are regularly present year around. We found at least one ingested FB in 36 out of 465 (7.74%) studied cetaceans, involving 15 different species, including eight out of the nine (80%) cetacean species present year-round in the Canary Islands. Risso's dolphin was the species most affected, followed by sperm whale, beaked whale and mysticetes. Plastic FB were the most common item found (80.56%). FB was directly associated with death in 13/36 (36.11%) animals. Poor body condition and deep diving behavior were found to be risk factors for FB ingestion, whereas the adult age was a protective factor. To the authors knowledge this is the first study that use statistical analysis to investigate risk and protective factors for FB ingestion. This study also provides insights of the potential impact caused by ingested FBs on the animal's health and mortality. This knowledge is critical to better understand and assess the impact of FB in cetaceans setting the scientific basis for prospective impact monitoring and future conservation policies.

Few studies were made regarding the pulmonary effects of exposure to volcanogenic air pollution, representing an unrecognized health risk for humans inhabiting non-eruptive volcanically active areas (10% of world human population). We tested the hypothesis whether chronic exposure to air pollution of volcanogenic origin causes lung injury, using wild mice (Mus musculus) as model. Lung injury was determined using histological morphometric parameters, inflammatory status (InfS) and the amount of black silver deposits (BSD). Mice exposed to volcanogenic air pollution have decreased percentage of alveolar space, alveolar perimeter and lung structural functionality (LSF) ratio and, increased alveolar septal thickness, amount of BSD and InfS. For the first time it is evidenced that non-eruptive active volcanism has a high potential to cause lung injury. This study also highlights the usefulness of M. musculus as bioindicator species, and of the developed biomarker of effect LSF ratio, for future animal and/or human biomonitoring programs.

Although the use of tributyltin in antifouling paints has been banned, this compound is still a serious pollutant of the marine environment. This paper describes a unique study in which European flounder (Platichthys flesus) were chronically (8 months) exposed to bis(tri-n-butyltin)oxide (TBTO) in the water under controlled laboratory conditions. Residue levels in selected tissues (liver, muscle) and general health status indices were measured and the effects on several organs (gills, liver, mesonephros, ovary/ testis, spleen, and gastrointestinal tract) were examined histopathologically. Additionally, morphometric analysis of the thymus was performed. The major finding is that exposure of flounder to 5 mg TBTO/l over a period of 8 months, resulting in body burdens comparable to high field levels, induced significant reduction of thymus volume, possibly affecting immunocompetence of the animals. Chronic exposure of European flounder to tributyltin is therefore likely to affect the general health status of this species in heavily polluted aquatic environments.

Stabled livestock reared in housed conditions are often subjected to intensive treatments with veterinary drug, which residues may be present in livestock meat ingested by scavengers, but nothing is known about their presence in eggs of wild birds and their potential detrimental effects on breeding success. We searched for residues of veterinary drugs and other toxicants in infertile and embryonated unhatched eggs of griffon vultures (Gyps fulvus) and red kites (Milvus milvus), two threatened avian scavengers. Quinolones (ciprofloxacin and enrofloxacin) were found in most unhatched eggs of both scavenger species clearly associated with severe alterations in the development of embryo cartilage and bones that could preclude embryo movements and subsequently normal development, pre-hatch position and successful hatching. The detrimental effects on developing eggs of veterinary drugs from livestock operations may help to explain reduced breeding success of avian scavengers. Fluoroquinolones used in livestock farming and found in eggs of avian scavenger caused severe alterations in embryo cartilage and bone development.

Northwest Atlantic leatherback sea turtles (Dermochelys coriacea) are endangered and low hatch success limits potential for population recovery. We examined essential and nonessential metal concentrations in 43 eggs from nests on St. Kitts to determine if there was a relationship with hatch success. Whole homogenized embryos and undeveloped eggs contained detectable concentrations of arsenic, barium, copper, iron, selenium, vanadium, and zinc, but not beryllium, cadmium, chromium, cobalt, lead, mercury, molybdenum, and thallium. Of detected metals, only vanadium concentrations negatively correlated with hatch success (P = 0.01). Manganese and vanadium were associated with pneumonia occurring in the nest, and arsenic with renal mineralization. This study adds to the knowledge regarding baseline values for environmental contaminants in sea turtles, supporting the trend that leatherback eggs have relatively low concentrations of toxic metals, lacking a strong relationship with hatch success, and normally contain the essential elements copper, iron, selenium, and zinc.