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- Oxidative stress response in gill and liver of Liza saliens, from the Esmoriz-Paramos coastal lagoon, PortugalPublication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Ferreira, Marta S.; Salgado, Maria AntóniaTissue-specific responses against oxidative stress and lipid peroxidation were analyzed in wild adult mullet (Liza saliens) caught in the Portuguese coastal lagoon Esmoriz-Paramos. Parameters measured were catalase (CAT), superoxide dismutase (SOD), and glutathione- S-transferase (GST) activities in liver and gill tissues and lipid peroxidation. The enzyme activities were related to gill histopathological alterations, as well as to heavy metals (Cu and Zn) concentrations in these tissues. Gill epithelium of L. saliens showed histological alterations, such as epithelial hyperplasia resulting in lamellar fusion, epithelial lifting, vasodilatation, and lamellar aneurisms, with a prevalence ranging from 62% to 92%. The highest Cu content was found in liver (379 mg kg-1), while the highest Zn content was observed in gill (119 mg kg-1). SOD and CAT activities showed differences between gill and liver. The highest activities found were SOD in gill (10.1 U/mg protein) and CAT in liver (39.2 mmol/min/mg protein). In gill, CAT activity was negatively related to both Cu levels and gill lifting, while a positive relationship was found between SOD activity and fish age. The positive relationship between Cu and CAT activity in liver suggests that an increase in metabolic level is related to Cu-induced oxidative stress. The decrease in gill CAT activity can be due to osmotic stress caused by damaged gill epithelium. CAT activity in liver is an appropriate biomarker of oxidative stress in the Esmoriz-Paramos lagoon.
- Bioaccumulation of metals by Mugil saliens under chronic exposure to contamined sediments: Gill histopathological changesPublication . Fernandes, Conceição; Monteiro, Sandra Mariza; Fontaínhas-Fernandes, A.; Salgado, Maria AntóniaThe Esmoriz/Paramos coastal lagoon, is a habitat of ecological importance due to the presence of unique animal and plant species. During the past few years its immersed area has been gradually reduced due to effluent discharges and siltation. The major contaminants in the lagoon are derived from a multitude of nonpoint sources associated with urbanization and industrial activities within the watershed. Heavy metals are probably a class of pollutants contributing to the observed decline of fish species. The metal content in the water and sediments in the lagoon were investigated as well as gill metal bioaccumulation and gill histopathological changes of the grey leaping mullet, Mugil saliens.
- Can fish adopt the same defence strategy in gill and liver to face chronic metal exposure?Publication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Carrola, João; Salgado, Maria Antónia
- Changes in plasma electrolytes and gill histopathology in wild Liza saliens from the Esmoriz-Paramos coastal lagoon, PortugalPublication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Monteiro, Sandra Mariza; Salgado, Maria AntóniaThe Esmoriz-Paramos is a lagoon of great ecological significance located on the Northwest coast of Portugal. The quality of water and sediment within this ecosystem has been gradually degraded due to the discharges of mostly untreated industrial waste and domestic sewage. Contaminants include heavy metals that can be taken up by fish from water, food, sediments, and suspended particulate material. Fish inhabiting polluted water bodies tend to accumulate many chemicals in high concentrations, even when the environmental contamination levels are low (Colombo et al. 1995). The leaping grey mullet (Liza saliens) is one of a few dominant species living in this environment. This species may contact xenobiotics in the water column or, when feeding, in the sediments.
- Metabolic and structural role of major fish organs as an early warning system in population assessmentPublication . Fernandes, Conceição; Afonso, António Manuel dos Santos; Salgado, Maria AntóniaThere are thousands of pollutants that affect aquatic environment and their effects have long been a concern and cause of research. This number grows annually since new compounds and formulations are synthesized. At present the concept of pollution involves knowledge of environmental fate and effects of chemical pollutants and their impacts on both, ecosystems and on social and economic development. Some aquatic environments are vital because of their critical ecological and economic importance. There are numerous lakes, lagoons and coastal lagoons playing a social and economic role on adjacent human populations, as they support fishing and recreational activities, and an ecological role, as they also support a characteristic flora and fauna, becoming important habitats. Additionally, several of these fresh waters reservoirs become a vital supply of potable water. In many cases, even in sub-lethal concentrations, aquatic pollutants affect structure and normal functioning of natural populations as they can cause impacts at multiple levels of organization, including cells, tissues, organs, individuals and community level. Several aquatic species can be used to study these issues and fish has been proved to be a suitable test-organism. Fish organs, such as liver, spleen and kidney can be very helpful to understand the response mechanisms to pollutant exposure. Fish liver is the main target organ of dietary route and the central metabolic organ, where detoxification mechanisms occur; spleen is involved in development of circulating blood cells, as well as immunity; and kidney is involved with excretion and thus, with electrolyte balance and acid-base regulation. Moreover, the anterior part of kidney supports the main pool of several fish leukocyte types. Assessment of coastal and shallow lagoon waters is a top priority among environmental monitoring activities, due to high ecological and economical importance of these relevant resources. In particular in enclosed communities, such as lakes and lagoons, this issue is enhanced according to the abundance and diversity of wildlife and increased need for water quality. Fish are relatively sensitive to changes in the environment and toxic effects of pollutants may start to occur in the cell and in metabolic pathways, before significant alterations in behaviour or morphology can be identified. The knowledge of normal metabolic processes of these major fish organs and alterations induced by exposure to pollutants can be a tool for an early warning system in the evaluation and analysis of the wealth of a fish population and their natural environment.
- Can fish adopt the same defence strategy in gill and liver to face chronic metal exposure?Publication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Carrola, João; Salgado, Maria Antónia
- Heavy metal contamination in a mugil wild population of a coastal lagoonPublication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Cabral, David; Carrola, João; Salgado, Maria AntóniaPolluted sediments usualy contain complex chemical mistures that may have synergistic and/or antagonistic effects on target organisms. Establishing causality in the 1ieId, is thus, particularly difficulty and the biomarker responses recorded in whole sediment toxicity assays are o correlactive nature only
- Bioaccumulation of heavy metals in Liza saliens from the Esmoriz-Paramos coastal lagoon, PortugalPublication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Peixoto, Francisco P.; Salgado, Maria AntóniaHeavy metal (Cu and Zn) concentrations in liver, gills, and muscle of leaping grey mullet, Liza saliens, from the Portuguese Esmoriz–Paramos coastal lagoon were measured to evaluate their bioaccumulation as a function of sediment contamination. The highest metal concentrations were observed in the liver (254mg Cu kg 1) and gills (114 mgZn kg 1). Bioaccumulation factors (BAFs) were found to follow the order: Cu-liver4Cu-gills4Cu-muscle and Zn-gills4Zn-liver4Zn-muscle. The highest BAFs were observed in the organs mainly implicated in metal metabolism and a significant positive relationship was found between BAFs and fish age. These results suggest the loss of homeostatic capacity of L. saliens under chronic metal exposure leading to bioaccumulation. Furthermore, Cu-liver and Zngills accumulation can be good environmental indicators of metal stress in L. saliens
- Histopathological gill changes in wild leaping grey mullet (Liza saliens) from the Esmoriz-Paramos coastal lagoon, PortugalPublication . Fernandes, Conceição; Fontaínhas-Fernandes, A.; Monteiro, Sandra Mariza; Salgado, Maria AntóniaThe histopathological changes are among the most recognized responses to environmental stressors, namely heavy metals. Liza saliens were sampled, in the Portuguese Esmoriz-Paramos coastal lagoon to assess their gill histopathological response to Cu and Zn contaminated sediments. A lesion prevalence index, severity, and extension scores of each lesion, as well as an assessment value (severity extension), were determined to evaluate the effect of environmental heavy metal exposure. The main histopathological changes observed were aneurisms, hyperplasia, lifting, and vasodilation. A high prevalence for each lesion (65–85%) was found, in addition to a high number of simultaneous lesions. Vasodilation and hyperplasia were the lesions that showed higher prevalence indexes. Lifting, followed by hyperplasia, were the lesions with highest assessment value. The prevalence of the number of the lesions found in L. saliens collected from the Esmoriz-Paramos lagoon was high when compared with mullet caught in the sea. A previous work revealed that fish collected in the lagoon showed elevated Cu and Zn levels in their gills, in a positive correlation with age. However, no positive correlation was observed between assessment value and gill metal levels.
- Metabolic mechanisms of adaptation to chronic metal exposure: a case studyPublication . Fernandes, Conceição; Salgado, Maria Antónia; Fontaínhas-Fernandes, A.Metals are contaminants of great concern due to their persistence and potential toxic effects. Some heavy metals like lead have no function in biological systems, while others such as copper and zinc are essential for metabolism of living organisms, including fish. Nevertheless they may exert harmful effects, depending upon concentration. Fish can be exposed to trace metals via two main exposure routes, waterborne and dietary and their accumulation can reach high concentrations, with time of exposure, even when the environmental contamination levels are low. Toxicity of trace metals to fish is strongly dependent upon abiotic and biotic factors that influence metal uptake and bioaccumulation. Some fish species have demonstrated the ability to inhabit polluted water bodies, probably adjusting metabolic mechanisms to cope with exposure to contaminants. Mullet is one of these species resistant to adverse environments that can be used as model to investigate fish metabolic changes of adaptation. The habitat under research is a small polluted coastal lagoon (Northwest coast, Portugal), where leaping grey mullet, Liza saliens, were exposed to heavy metals in water and sediments and accumulated high concentrations of Cu and Zn in their tissues. The unique characteristics of this small lagoon, such as its narrow communication with the sea, allowed the fingerlings to enter the lagoon but not the adults to escape, resulting in fish permanency in the lagoon for their life spans and consequently a long time exposure to contaminants. A sample of adult mullet was monitored using different biomarkers levels to assess chronic toxicity effects. Morphological indices of fish condition and gill osmoregulatory responses were evaluated, as well as metal accumulation in two main organs, gill and liver. At the biochemical level the antioxidant responses in tissues were measured to evaluate free radical oxidants generation and plasma enzyme activities were also measured. To complement the evaluation of metal effects on fish histological alterations were also assessed, as they provide a definite biological end-point of historical exposure were also assessed to complement the impact evaluation. The results showed a different pattern of responses in each organ and a different strategy to adjust to Cu and Zn chronic exposure. The use of biomarkers has been useful to monitor the health of fish inhabiting polluted ecosystems, and it could additionally reveal important adaptations to pollutantinduced stress. This case study allowed a long-term and more realistic evaluation of the fish stress responses to pollution, since fish lived in this habitat for 6 to 12 years. Understanding the potential effects of trace metals and the physiological mechanisms of adaptation, to face chronic exposure, seems crucial for population conservation purposes.
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