Can Nassarius reticulatus be used as a bioindicator for Hg contamination? Results from a longitudinal study of the Portuguese coastline

Abstract

The focus of this work is to explore the use of the netted whelk, Nassarius reticulatus (L.), as an indicator of mercury (Hg) contamination, by assessing the concentration of Hg in the sediments and in the whelk along the entire Portuguese coast. Total Hg concentrations ranged from below the detection limit (0.01 ng absolute mercury) up to 0.87 mg kg À1 dry weight (dwt) in sediments and between 0.06 and 1.02 mg kg À1 (dwt) for organisms, with no significant differences between males and females. Although organic mercury was not detected in the sediments, it represented, on average, 52% of the total Hg in the whelk tissues, and as high as 88% in some cases, suggesting mercury accumulation from dietary intake. Significant negative correlations were found between the total Hg concentrations in the sediments and the log 10 of Hg concentrations in whelk tissues males (r = À0.64; P < 0.01) and females (r = À0.52; P < 0.01) indicating that the species is a poor indicator of Hg contamination. Nevertheless, since the highest concentrations of organic mercury in the whelk tissues were found in the least contaminated areas, this species must be highly relevant in the trophic web, namely on the possible biomagnification of mercury. The high dietary mercury accumulation from feeding on carrion and the low bioavailability of mercury to whelks in estuarine sediments may be the basis of the mercury accumulation pattern in N. reticulatus.

Indicators of sediment and biotic mercury contamination in a southern New England estuary

“…Research in other estuarine and coastal environments reported similar biota-sediment mercury relationships (Hammerschmidt and Fitzgerald, 2004), and recent advances in mercury isotope analysis have verified that sediments are a dominant source of Hg to biota (Gehrke et al, 2011a). Other investigations, however, have reported no relationship between sediment and biota Hg, including the whelk Nassarius reticulates (Coelho et al, 2006), amphipod Leptocheirus plumulosus (Lawrence and Mason, 2001), and polychaete Nereis diversicolor (Muhaya et al, 1997). Similarly, in this study, no significant relationship was detected between the total Hg of crabs and sediments (Fig.…”

“…The increased Hg accumulation factors in these taxa are attributed to their respective habit at preferences and foraging ecology. Nereid polychaetes and several species of mollusks examined in this study are classified as benthic infauna, which in turn favors the additional uptake of inorganic Hg and MeHg via direct contact with sediments and pore water (Wang et al, 1998; Coelho et al, 2006). Killifish, in contrast, maintain a relatively high trophic status in the estuary (increased δ 15 N signature), and therefore experience elevated BSAFs because MeHg biomagnifies in estuarine food webs (Chen et al 2008).…”

Pattern and pathways for mercury lifespan bioaccumulation in Carcinus maenas

“…The trace metal content of organisms is therefore a common tool in monitoring programs of metal pollution in the marine environment, since it provides a time-integrated measure of metal availability (Saiz-Salinas et al, 1996). Focus has been given to macroinvertebrate species, namely benthic bivalve and gastropod molluscs, found to be effective bioaccumulators (Byrne and O'Halloran, 2001;Liang et al, 2004;Roméo et al, 2005;Coelho et al, 2006a). Differences in experimental design (e.g.…”

Pattern and annual rates of Scrobicularia plana mercury bioaccumulation in a human induced mercury gradient (Ria de Aveiro, Portugal)

“…The accumulation processes of these contaminants in aquatic organisms will determine, in part, the enhancement of their adverse effects on the biota (Byrne and O'Halloran, 2001;Coelho et al, 2005Coelho et al, , 2006Usero et al, 2005). In the particular case of mercury, a highly deleterious environmental pollutant that has both natural and anthropogenic sources (Gustin, 2003;Nriagu and Becker, 2003;OSPAR Commission, 2004), contamination problems are enhanced when it enters the food chain.…”

“…The trace metal content of organisms has been commonly used in biomonitoring programs of metal pollution in the marine environment, and provides a time-integrated measure of metal availability (Saiz-Salinas et al, 1996). Most research in this area has been performed on macroinvertebrate species, namely benthic bivalve and gastropod molluscs, known to be effective bioaccumulators (Mikac et al, 1996;Byrne and O'Halloran, 2001;Liang et al, 2004;Roméo et al, 2005;Coelho et al, 2006). There is, however, a lack of criteria homogeneity and comparison between different studies.…”