Testing the impact of contaminated sediments from the southeast marine coast of Tunisia on biota: a multibiomarker approach using the flatfish Solea senegalensis

Revealing the environmental pollution of two estuaries through histopathological biomarkers in five fishes from different trophic guilds of northeastern Brazil

Estuaries in Brazil are mostly anthropically affected due to the discharge of industrial and domestic effluents. In two of them, the Santa Cruz Channel Estuary (ITAP) and Sirinhaém River Estuary (SIR), historically affected by mercury pollution and sugarcane industry in Northeast Brazil, we assessed environmental pollution using liver and gill histopathological biomarkers in fish from different trophic levels. Liver samples exhibited serious damages such as hepatic steatosis, necrosis, and infiltration. The gills showed moderate to severe changes, such as lifting of epithelial cells, lamellar aneurysm, and rupture of lamellar epithelium. Most of the changes in the liver and gills were reported for species Centropomus undecimalis and the Gobionellus stomatus, which were considered as good sentinels of pollution. The combination of biomarker methodologies was efficient in diagnosing the serious damage to the species, reinforcing the need for monitoring the health of the ecosystems evaluated.

Effects of Eutrophication on Plankton Abundance and Composition in the Gulf of Gabès (Mediterranean Sea, Tunisia)

Phytoplankton and Copepoda were investigated in the industrialized Gabès coast (Mediterranean Sea, Tunisia) to understand consequences of the Eutrophication Grade on the community composition. In the past 40 years, intensive agrochemical activities have developed in Gabès, discharging wastewater along the coast. In parallel, Gabès City has experienced a rapid demographic expansion (population: 131,000) that further increased sewage discharged into the sea. The present study was carried out in the Gulf of Gabès in March 2014. The abiotic analysis of seawater showed high concentrations of nutrients and eutrophication in all the studied fifteen stations. A growing eutrophic gradient was revealed from Zarrat to Gannouche. During this study, 42 phytoplankton taxa and 24 Copepoda taxa were identified. Bacillariophyta were the most abundant group, ranging from 67.7% to 89.2% of total phytoplankton specimens. Chaetoceros costatus, Euglena acusformis, and Thalassiosira sp. showed a positive correlation with Eutrophication Index (profited of nutrient availability). Therefore, the Shannon–Weaver diversity index of phytoplankton and Copepoda showed negative correlations with Eutrophication Index. The relatively high H′ values for phytoplankton suggest that the eutrophicated waters of Gulf of Gabès are not a hostile environment for them. Among Copepoda, Oithona similis, and Euterpina acutifrons seem to be insensible species to eutrophication.

Assessing effects of chronic heavy metal exposure through a multibiomarker approach: the case of Liomys irroratus (Rodentia: Heteromyidae)

Wild animals that inhabit inside mine tailings which contain heavy metals are an excellent study model to conduct ecotoxicological studies that analyze chronic metal exposures at low doses (realistic exposures). This study was conducted in Huautla, Morelos, Mexico, in a mining district where 780,000 tons of wastes were deposited in open air. Liomys irroratus is a small mammal species that lives inside these mine tailings. A multibiomarker approach study was performed to analyze metal bioaccumulation levels (biomarker of exposure) by inductively coupled plasma mass spectrometry, DNA damage levels (biomarker of early effects) through the alkaline comet assay, and population genetic structure and diversity (biomarker of permanent effects), using seven microsatellite loci, in 75 L. irroratus individuals, from two mine tailings and one reference site. Concentrations of aluminum, copper, iron, nickel, lead, and zinc were statistically higher in the liver of exposed individuals. Significant DNA damage levels were registered in the mine tailings groups. Aluminum, lead, and nickel had the highest contribution to the genetic damage levels observed, while aluminum and nickel had the highest contribution to genetic diversity effects. A positive and significant relationship was detected between individual genetic diversity (internal relatedness) and genetic damage (DNA single-strand breaks). Genetic structure of L. irroratus populations revealed that the main source of genetic variation was located within populations. We consider that multibiomarker studies in environmental settings using sentinel species are valuable for environmental risk assessment and ecological responses in chronic exposed populations.

Effects of pollution on marine organisms

This review covers selected 2019 articles on the biological effects of pollutants, including human physical disturbances, on marine and estuarine plants, animals, ecosystems, and habitats. The review, based largely on journal articles, covers field, and laboratory measurement activities (bioaccumulation of contaminants, field assessment surveys, toxicity testing, and biomarkers) as well as pollution issues of current interest including endocrine disrupters, emerging contaminants, wastewater discharges, marine debris, dredging, and disposal. Special emphasis is placed on effects of oil spills and marine debris due largely to the 2010 Deepwater Horizon oil blowout in the Gulf of Mexico and proliferation of data on the assimilation and effects of marine debris microparticulates. Several topical areas reviewed in the past (e.g., mass mortalities ocean acidification) were dropped this year. The focus of this review is on effects, not on pollutant sources, chemistry, fate, or transport. There is considerable overlap across subject areas (e.g., some bioaccumulation data may be appeared in other topical categories such as effects of wastewater discharges, or biomarker studies appearing in oil toxicity literature). Therefore, we strongly urge readers to use keyword searching of the text and references to locate related but distributed information. Although nearly 400 papers are cited, these now represent a fraction of the literature on these subjects. Use this review mainly as a starting point. And please consult the original papers before citing them.

Biological responses and toxicopathic effects elicited in Solea senegalensis juveniles on exposure to contaminated sediments under laboratory conditions

Whole-sediment toxicity assays contribute to elucidating the intricate association between the presence of contaminants in sediments and their toxicopathic effects in benthic fish. In the present study, Solea senegalensis juveniles were exposed under laboratory conditions to contaminated whole-sediments for 7 and 28 days. Sediments were obtained from a low to moderately polluted estuary, a highly polluted harbour and from the mixture of both field-collected sediments. Biometry data were recorded. Liver, brain, gills, and gonads were dissected out and processed to determine markers of oxidative stress, neurotoxicity and lysosomal biomarkers, and histopathology. Analyses of sediment granulometry and chemical profiles indicated different degrees of toxicity and suggested a distinct release of pollutants from each sediment in relation with their physicochemical properties. Interestingly, biological responses were in agreement with contaminant levels reported in source sediments. The most distinct toxicopathic effects were detected upon exposure to the harbour's sediment and particularly on day 28. Overall, enhanced hepatic glutathione-S-transferase activity and lysosomal enlargement were detected in all experimental groups, demonstrating a toxic effect from all sediments whilst catalase inhibition, lysosomal membrane destabilisation, changes in lysosomal content and liver histopathology were most pronounced in soles exposed to the harbour's sediment. The Integrative Biomarker Response index (IBR/n) evidenced that exposure to the three sediments caused an impact of diverse magnitude in sole health (IBR/n_Harbour > IBR/n_Mixture > IBR/n_Estuary). The magnitude of biological responses essentially depended on the presence of contaminants in source sediments, which seemed to be altered by the conditions imposed by whole-sediment toxicity assays.