Metal Accumulation and Metallothionein Response in Fucus Spiralis

A C Jensen,I D Williams,J F P Oaten,M C Gibson,M D Hudson

doi:10.11159/ijepr.2017.001

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.

Highlights

Biomonitoring, whereby organisms are used to measure environmental pollution, has advantages over direct measurements of chemical contaminants in the environment, such as seawater or sediment concentrations
The use of MT in F. spiralis as a sensitive biomarker of metal pollution at low concentrations, as subjected in Poole Harbour, is shown here to be limited, as MT does not appear to be consistently induced by metal exposure
During summer, concentrations of MT increase, and linear regression analysis reveals significant positive relationships with Ni, Pb, Sn, and Fe. This may be due to increased toxicity of metals, and vulnerability of seaweeds to metals, as they inhibit photosynthetic processes and growth, which becomes pertinent in summer months

Summary

Introduction

Biomonitoring, whereby organisms are used to measure environmental pollution, has advantages over direct measurements of chemical contaminants in the environment, such as seawater or sediment concentrations It provides an exclusive measure of the bioavailable pollutants, which have the greatest potential to impact organisms, ecosystems, and human health, and discounts pollutants not taken up by organisms [1]. It allows the measurement of pollutants accumulated over an organism’s lifetime, which reduces fluctuations in pollutant concentrations [2]. Seaweeds are advocated as bioindicators in temperate coastal waters due mainly to their high abundances and immobility [5] They often dominate metal contaminated habitats [6] as they are resistant to metal pollution [7].

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