Abstract
Abstract. The aim of this study was to investigate the role of the seagrass Posidonia oceanica on the cycling of a wide set of trace elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ga, Li, Mn, Ni, Pb, Rb, Sr, Tl, V and Zn). We measured the concentration of these trace elements in different compartments of P. oceanica (leaves, rhizomes, roots and epiphytes) in a non-polluted seagrass meadow representative of the Mediterranean and calculated the annual budget from a mass balance. We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability. Epiphytes were the compartment, which showed the greatest concentrations for most trace elements. Thus, they constitute a key compartment when estimating trace element transfer to higher trophic levels by P. oceanica. Trace element translocation in P. oceanica seemed to be low and acropetal in most cases. Zn, Cd, Sr and Rb were the trace elements that showed the highest release rate through decomposition of plant detritus, while Cs, Tl and Bi showed the lowest. P. oceanica acts as a sink of potentially toxic trace elements (Ni, Cr, As and Ag), which can be sequestered, decreasing their bioavailability. P. oceanica may have a relevant role in the cycling of trace elements in the Mediterranean.
Highlights
Seagrass meadows are considered one of the most valuable habitats in coastal areas (Orth et al, 2006) and rank among the most productive habitats (Pergent et al, 1997; Duarte and Chiscano, 1999)
We provide novel data on accumulation dynamics of many trace elements in P. oceanica compartments and demonstrate that trace element accumulation patterns are mainly determined by plant compartment rather than by temporal variability
The principal component analysis (PCA) plot based on trace element concentrations in all P. oceanica compartments grouped samples according to plant compartments
Summary
Seagrass meadows are considered one of the most valuable habitats in coastal areas (Orth et al, 2006) and rank among the most productive habitats (Pergent et al, 1997; Duarte and Chiscano, 1999). P. oceanica biomass can have very different fate according to the part of the plant. While around 29 % of its produced biomass, mainly rhizomes and roots, is buried in the sediment, the rest of it, mainly leaves, is mineralized, either in situ or in adjacent ecosystems (Pergent et al, 1994). Oceanica leaves account for a substantial part of the primary production of the seagrass meadows (Lepoint et al, 1999). Epiphytes constitute a considerable and preferential food resource for herbivores (Tomas et al, 2005), and along with leaves, rhizomes, and roots is a main compartment of the plant in matter fluxes of this ecosystem
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