Metal Accumulation and Metallothionein Response in Fucus spiralis

Abstract

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 as 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, from January to October 2015. MT and metal concentrations were quantified during winter, spring, summer, and autumn seasons. Linear regression analysis showed few relationships between MT and metal concentrations, apart from in summer. During summer, significant positive relationships existed between MT concentrations and iron (R 2 = 0.631), nickel (R 2 = 0.486), tin (R 2 = 0.579), and lead (R 2 = 0.415). 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. However, during summer, rates of photosynthesis and growth increase, which may increase metal toxicity, due to the inhibition of photosynthesis and growth. Thus, MT may be induced in order to prevent disruption. This study suggests that the use of MT as a biomarker for metal pollution in F. spiralis may not be a sensitive biomarker at low levels of metal pollution. However, MT concentrations in F. spiralis may respond to metal exposure when natural processes are vulnerable to pollution. The potential for MT to be used as a biomarker in Fucus spp. has been highlighted, warranting further research to develop a promising cosmopolitan bioindicator for metal pollution.