Macrophytes as passive bioindicators of trace element pollution in the aquatic environment

Pollution with trace elements is considered a global problem due to their persistence, nondegradability, and toxicity to living organisms. Aquatic ecosystems are often the final sinks for trace elements, but these pollutants are quickly diluted and difficult to detect and, therefore, comprehensive monitoring of pollution is needed to implement appropriate control measures and prevent irreversible damage to these habitats. Bioindication is one of the recommended methods as it provides information not only on the pollution level but also on the bioavailability of elements and their biological impact. The paper is a synthetic review of the knowledge about the use of macrophytes as passive bioindicators (accumulator taxa) of trace element pollution in aquatic ecosystems. Various aspects of bioindication using accumulator aquatic plants are discussed: the criteria defined for the organisms used in biogeochemical bioindication, advantages of plants as accumulative bioindicators, general trends in the uptake, and accumulation of pollutants by macrophytes (including differences between life forms, organs, and seasons). The use of various groups of macrophytes in accumulative bioindication is described in detail with an emphasis on the relationship between element levels in plant tissues and their habitat as well as performance in the detection of pollution gradients. Knowledge gaps and limitations in the field of bioindication using accumulative macrophytes are indicated and the future perspective is outlined.