The tropical brown alga Lobophora variegata as a bioindicator of mining

19 20 Previous field and laboratory studies have identified the alga Lobophora variegata as a good 21 candidate for biomonitoring metal contamination in the New Caledonia lagoon which is 22 subjected to intensive and extensive metal inputs from land-based mining activities. The aim 23 of this work was to further assess the bioindicative potential of this species by investigating, 24 in the field, its bioaccumulation capacity for local key contaminants, i.e. Algae from clean and contaminated sites were cross-transplanted for a 26 period of three months in order to determine the in situ uptake and depuration kinetics of the 27 nine elements. Results indicate that algae transplanted to the contaminated site displayed a 28 significant linear increase in concentration with time for In contrast, algae transplanted to the clean site did not show major depuration of these 30 elements, except for Co. Overall, L. variegata showed a rapid temporal response in metal 31 uptake, especially for the elements intensively released into the coastal environment of New 32 Caledonia (viz., Co, Cr, Mn and Ni). This species appears therefore as an excellent 33 bioindicator species of metal contamination in this area. Our results also provide background 34 information necessary for using L. variegata under in situ experimental conditions so as to 35 provide better quantitative information on ambient metal contamination levels. The wide 36 distribution of L. variegata in tropical areas further enhances its potential as a bioindicator 37 species of metal contamination in other tropical coastal environments. 38 39 40