Metal Accumulation and Metallothionein Response in Fucus Spiralis

Seaweeds are established sentinels for metal contamination and are utilised for biomonitoring. Metallothionein (MT) is a protein that is induced by metal exposure, and has been widely used as a biomarker for metal pollution. MT has not been reported in spiral wrack (Fucus spiralis), but has been identified in bladder wrack (Fucus vesiculosus), where it has been suggested to be a protective mechanism against metal exposure. This study aimed to evaluate the potential use of MT in F. spiralis as a biomarker for metal pollution for the first time. Samples were collected from Poole Harbour, UK, over a year-long period in 2015. MT and metal concentrations were quantified during winter, spring, summer, and autumn. Linear regression analysis showed few relationships between MT and metal concentrations throughout most seasons. However, during summer, significant positive relationships existed between MT concentrations and iron (R2 = 0.631), nickel (R2 = 0.486), tin (R2 = 0.579), and lead (R2 = 0.415). Furthermore, MT concentrations were significantly higher in summer than in other seasons. It is possible that for most of the year, metal concentrations in Poole Harbour are not high enough to elicit a MT response in F. spiralis, as it is a metal tolerant species. This suggests that the use of MT as a sensitive biomarker for metal pollution in F. spiralis, at low levels of metal pollution, is limited. However, increased toxicity of metals, and vulnerability of seaweeds to metals, may become pertinent in summer months as metals inhibit photosynthetic processes and growth. This may have caused MT to relate to metal concentrations more closely during summer, as it responds to the increased effects of metals. Therefore, the potential for using MT in F. spiralis as a biomarker for metal pollution may be restricted to summer months in temperate regions, at least at low metal concentrations. Further research is required to fully evaluate the use of MT in Fucus spp., addressing uncertainties of seasonal variation, and MT response in severely polluted environments.