Hamouda Beyrem

By Ahmed Nasri, Patricia Aïssa, Hamouda Beyrem and Ezzeddine Mahmoudi

Marine ecosystems have great economic and ecological value, as they provide good services and habitats for a variety of organisms. However, the marine environment is under anthropogenic stressors. The Mediterranean basin is one of the most threatened ecosystems, where urban and industrial waste is becoming a growing risk for coastal marine habitats integrity. The Bizerte lagoon represents a major coastal lagoon and is an example of such an aquatic environment continuously exposed to pollutants. Marine nematodes are the most diverse metazoans and represent an excellent model for the environmental monitoring because they can be easily sampled and maintained under experimental conditions. Nematode communities are investigated for the analysis of taxonomic diversity and ecological indices. Currently, we present here to evaluate the ecological quality based on the description of nematode assemblages using biological traits and functional groups. This relatively new approach allows obtaining insight into the status of marine coastal ecosystems.

Part of the book: Nematodes

By Ahmed Nasri, Takoua Mhadhbi, Mohamed Allouche, Amel Hannachi, Hary Demey, Patricia Aïssa, Hamouda Beyrem and Ezzeddine Mahmoudi

Marine ecosystem represents an ecologically and economically important water bodies for human and animal living. Their increasing pollution by persistent organic pollutants has represented a major environmental alarm during the last years. In the current study, we examined the occurrence, local distribution and ecotoxicological menace of organic pollutants, comprising brominated flame retardants (BFR), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) in different matrices from the Northern Tunisian Coastal Ecosystem (Bizerte lagoon). The pollutant existence in this biome is related with a negative impact on the biocenosis health. Many approach including (i) chemical analyses; (ii) taxonomic structure and ecological indices analyses; (iii) and biochemical experimental studies, were investigated to determine the ecosystem quality and the contaminant effects. Our chapter introduces the baseline information on the organic contaminations extent and toxicological impact, as well as, it contribute to evaluate the ecological quality of this marine coastal ecosystem.

Part of the book: Persistent Organic Pollutants (POPs)

By Ahmed Nasri, Patricia Aïssa, Ezzeddine Mahmoudi, Hamouda Beyrem and Véronique Perrier

Endocrine-disrupting chemicals (EDCs), including polychlorinated biphenyls (PCBs), bisphenol A (BPA), pharmaceutical drugs, and pesticides, affect a variety of hormone-regulated physiological pathways in humans and wildlife. The occurrence of these EDCs in the aquatic environment is linked with vertebrates’ health alteration. EDCs exhibit lipophilic characteristics and bind to hydrophobic areas of steroid receptors, such as the estrogen receptor, which are involved in vertebrate developmental regulation. Mainly, EDCs modify the transcription of several genes involved in individual homeostasis. Zebrafish conserve many developmental pathways found in humans, which makes it an appreciated model system for EDCs research studies, especially on early organ development. In the current chapter, we emphasize on latest published papers of EDCs effects on lateral line regeneration in zebrafish larvae. Similarly, we describe other special impacts of EDCs exposure. In conclusion, we make the case that the zebrafish lateral line exposed to EDCs can provide important insights into human health.

Part of the book: Persistent Organic Pollutants (POPs)

By Ahmed Nasri, Amel Hannachi, Mohamed Allouche, Abdelwaheb Aydi, Patricia Aïssa, Hamouda Beyrem and Ezzeddine Mahmoudi

Coastal ecosystems are exposed to pollution by various contaminants due to several anthropogenic activities. Numerous pollutants, such as pesticides, drugs, metals, Polycyclic Aromatic Hydrocarbons (PAHs), Brominated flame retardants (BFRs), and Microplastics (MPs), transported in the water column tend to persist in the sediments. Among the Tunisian coastal areas, the Bizerte and Ghar El Melh lagoons are exposed to several pollutants resulting from different activities, such as agriculture, urbanization, and industrialization. Consequently, sediments are intensely dirtied by a wide range of pollutants. Due to their relatively short life cycles and high turnover rates, free-living nematodes reacted quickly to environmental changes. This most dominant meiobenthic taxon, has been mainly exploited as indicator of disturbance because of its ubiquity, high abundance, and taxonomic diversity. In this current chapter, we cited the different environmental pollutants effects and show the importance of nematodes as bio-indicator species in environmental monitoring.

Part of the book: The Toxicity of Environmental Pollutants