Bioindicators include algae, macrophytes, zooplanktons, insects, bivalves, molluscs, gastropods, fish, amphibians, and others. Changes in aquatic ecosystems are often attributed to anthropogenic disturbances, including pollution. Major contributors to aquatic pollution include wastewater, metals and metalloids, industrial effluents, contaminated sediments, nutrients, polycyclic aromatic hydrocarbons, flame retardants, persistent organic pollutants, pharmaceuticals and illicit drugs, emerging contaminants (such as microplastics and engineered nanoparticles), pesticides, herbicides, and endocrine disruptors.