Marine Crustaceans as Bioindicators: Amphipods as Case Study

Abstract

A bioindicator species can be defined as “an organism that provides information on the environmental conditions of its habitat by its presence or absence, and its behavior.” In this sense, crustaceans present many biological and ecological characteristics that make them particularly useful as bioindicators (e.g., widespread distribution in different habitats and geographical areas, key role in community functioning, great diversity of life history strategies). Within Crustacea, the order Amphipoda has been considered an especially relevant and suitable group due to its direct development and its special sensibility to disturbances, among other reasons. Crustaceans can be used in biomonitoring studies in a wide variety of habitats (e.g., both soft- and hard-bottom substrata from intertidal to deep environments) and for different types of environmental stressors. An extensive amount of literature has reported the sensitivity of crustacean species to heavy metal contamination, sewage and desalination discharges, or engineering and aquaculture activities, among others. Special emphasis has been placed on the role of crustaceans in the most used indexes (e.g., AMBI, BENTIX, BOPA) developed to establish the environmental quality of European coastal and marine areas. Crustaceans are one of the groups with a higher contribution to those indexes, although their presence is not necessarily indicative of low environmental disturbances. Within amphipods, the importance of the family Caprellidae as a monitoring tool in environmental programs (e.g., trace metal or tributyltin pollution) is highlighted. Alien crustaceans can also play a pivotal role as bioindicators of anthropogenic pressures, and their likely influence on the accuracy of ecological assessment programs should be taken into account. Finally, there is an increasing need to improve our scarce taxonomic knowledge in many crustacean groups since that information is vital for the correct development of monitoring tools. Studies dealing with the species’ ecological and biological traits are also encouraged in order to understand the potential application of these species as bioindicators.

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