Macroalgae response to a mercury contamination gradient in a temperate coastal lagoon (Ria de Aveiro, Portugal)

Abstract

Primary producers represent an important pathway for mercury incorporation in aquatic food webs. With eutrophication processes occurring worldwide, macroalgae may represent a substantial pool of mercury, as a result of its high growth rate and capacity to bind trace metals. The main aim of this work was to evaluate the response of the macroalgae to a human-induced environmental mercury gradient in a temperate coastal lagoon, by assessing the total and organic mercury contamination levels of the dominant species (Enteromorpha, Fucus and Gracilaria). Total mercury in the plant tissues ranged from 0.02 to 2.1 mg g ÿ1 dwt. Fucus was the most contaminated algae, followed by Gracilaria and Enteromorpha. As a whole, organic mercury never exceeded 15% of total mercury content, but tended to increase with distance to metal source on all macroalgae indicating complex physiological responses from these primary producers in areas of high and low mercury concentrations. Sessile macroalgae may be important mercury immobilisation agents, while free-floating algae (Enteromorpha) play an important role in mercury transport from contaminated areas (G10 g ha ÿ1 ) to other areas of the lagoon and even to coastal waters. Based on the present results the use of macroalgal biomass from contaminated areas for direct or indirect human use (e.g. agricultural, industrial and food purposes) may result in health risks, due to the high bioaccumulation capacity (as high as 10 4 the dissolved mercury concentrations).

Mercury contamination in invertebrate biota in a temperate coastal lagoon (Ria de Aveiro, Portugal)

“…Research on the fate and behavior of mercury in the nearby area of the discharge has so far focused mainly on identifying the major impacted areas, quantifying the level of contamination and assessing the response of mercury to physicochemical changes in sediment and water (Pereira et al, 1998a,b). Determinations of mercury concentrations in marine biota are limited to plankton (Monterroso et al, 2003), estuarine macroalgae (Coelho et al, 2005) and sea bass (Abreu et al, 2000), hence further work is required on other species, especially edible varieties with economic interest.…”

Effect of Industrial Wastewater on Fish in Karoon River

“…above discharge point) (0.08 µg.g -1 ). Various studies of coastal environments have shown that accumulation of Hg in several organisms varies along a concentration gradient of anthropogenic Hg (Coelho et al, 2005).…”

The response of benthic foraminifera to pollution and environmental stress in Ria de Aveiro (N Portugal)

“…The tidal prism of the lagoon, for (maximum) spring tide and (minimum) neap tide, is estimated as 136.7 x 10 6 m 3 and 34.9 x 10 6 m 3 , respectively (Lopes tion (Plecha et al, 2010) or high sedimentation (Lopes and Dias, 2007), salinity variation (Almeida et al, 2005;Vaz et al, 2005), oxygen depletion (Lopes et al, 2008;Lopes and Silva, 2006) and pollutant accumulation (e.g. Pereira et al, 2005Pereira et al, , 1998a, may affect benthic foraminifera assemblages in this system. One of the most problematic factors affecting the abundance of foraminifera in Ria de Aveiro is current velocity.…”

“…These areas are also affected by chemical contaminants related to anthropic actions. In Estarreja Channel, for example, industrial and urban effluents have been discharged, for several years, by the industrial plant north of the village of Estarreja, the so-called 'Complexo Químico de Estarreja' (e.g., Pereira et al, 2009Pereira et al, , 2006Pereira et al, , 2005Pereira et al, , 1998aPereira et al, , b, 1995Válega et al, 2008;Coelho et al, 2006Coelho et al, , 2005Ramalhosa et al, 2006;Monterroso et al, 2003;Abreu et al, 2000).…”