Ecotoxicological study on lead shot from hunting in the Padule di Fucecchio marsh (Tuscany, Italy)

Ingestion of lead shot has been recognised as an important cause of death in waterbirds for over a century. Chemical dissolution (oxidation) of lead shot in aquatic environments can make lead more available, distributing it throughout the aquatic ecosystem. The extent of the phenomenon has rarely been investigated in Italy and no systematic information is available for Italian wetlands. We investigated lead shot density and lead concentrations in sediment of the Padule di Fucecchio (Tuscany), one of the largest inland marshes in Italy (2000 ha), in order to evaluate the impact of lead shot from hunting. Moreover, to assess lead accumulation in organisms, red swamp crayfish, Procambarus clarkii (Girard 1852), was chosen as a bioindicator. The results showed a high lead shot density (0-311 shot . m(-2)). Although lead concentrations and lead shot density were slightly less in protected areas than in hunting areas, contamination was widespread throughout the marsh, with a mean lead concentration of 115.6 mg . kg(-1) d.w.. Crayfish were subject to heavy uptake of lead, with high concentrations in gut contents (43.84 +/- 47.48 mg . kg(-1) d.w.) and hepatopancreas (3.217 +/- 4.850 mg . kg(-1) d.w.). A detailed map of lead contamination was plotted using sediment data. Thematic mapping is a valuable support for environmental remediation and reserve management and assessment of lead contamination concomitant with the banning of lead shot in the area provides a useful database for long-term monitoring of the effectiveness of the ban.