Bioaccumulation of metals in intertidal zoantharians of the Canary Islands: Potential use as bioindicators

In the context of ocean warming, thermophilic organisms such as zoantharians are becoming increasingly widespread worldwide. Zoantharians exhibit high resistance to habitat degradation and environmental change, which has led to a growing research interest in this group. These organisms thrive in intertidal habitats of Tenerife (Canary Islands), an environment particularly vulnerable to metal contamination due to its proximity to the coast, where anthropogenic pressures are concentrated. Thus, this study aimed to evaluate metal concentrations in three intertidal zoantharian species (Palythoa aff. clavata, Zoanthus pulchellus and Isaurus tuberculatus) across different locations in Tenerife, representing the first ecotoxicological assessment in zoantharians. The three species showed high metal concentrations, demonstrating their capacity to bioaccumulate metals. Results indicated that Z. pulchellus and P. aff. clavata accumulated higher levels of most metals compared to I. tuberculatus, likely reflecting differences in feeding strategies and dependence on photosynthesis. Metal bioaccumulation levels of Z. pulchellus and P. aff. clavata, particularly in relation to Fe and Al, suggest their potential use as bioindicators of metal pollution in intertidal environments should be further investigated. Overall, these results enhance our understanding of metal exposure in intertidal habitats and support the inclusion of intertidal zoantharians as sentinels of coastal ecotoxicological monitoring studies.