ELSEVIER PII: S0269-749 I (97)00046-S Environmental Pollution, Vol. 96, No. 3, pp. 335-341, 1997 ~) 1997 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0269-7491/97 $17.00 + 0.00 LEAD SHOT PELLETS IN THE EBRO DELTA, SPAIN: DENSITIES IN SEDIMENTS AND PREVALENCE OF EXPOSURE IN WATERFOWL Rafael Mateo, a Albert Martlnez-Vilalta b and Raimon Guitart a aLaboratory of Toxicology, School of Veterinary, Universitat Autdnoma de Barcelona, E-08193 Bellaterra, Spain bEbro Delta Natural Park, Plaea 20 de Maig. E-43850 Deltebre, Spain (Received 6 November 1996; accepted 14 March 1997) Abstract Lead (Pb) poisoning has been found to be a serious prob- lem for waterfowl in some southern European countries, but few studies have been conducted in Spain. In order to obtain these data, studies were made in the Ebro delta, a Spanish Ramsar site, during 1992 and 1993. Lead shot densities in the first 20cm of sediment ranged from <8900 to 2661000 shot ha -1. A similar proportion of birds had lead shot in the gizzard and elevated liver lead ( > 5 ~tg g - i D W ) concentrations. Northern pintail and common pochard (both with declining populations in Europe) showed the highest levels of shot ingestion, with 70.8 and 69.2%, respectively. Body condition index in the northern pintail was negatively correlated with the num- ber of pellets in the gizzard and liver Pb concentration. Levels of exposure were higher than in other northern countries of the western Palearctic flyway, where lead shot have been banned recently. © 1997 Elsevier Science Ltd Keywords: Lead poisoning, waterfowl, lead pellets, grit, Spain. INTRODUCTION Waterfowl hunting practised every year from the same hides, in some cases for many decades, produces high densities of lead (Pb) shot pellets in the surrounding 250m (Mudge, 1984). Ducks feeding during the winter season in these hunted marshes have a high probability of ingesting lead shot pellets, when feeding or gritting. Shot pellets retained in the gizzard are ground by the abrasive action of the grit and dissolved by the acid secretions of the proventriculus, and lead salts are absorbed into the blood stream of birds, producing the well known signs of lead poisoning (Lumeij, 1985; Friend, 1987). The first records of lead poisoning in waterfowl were described more than 100 years ago, and it has become a well known problem in the USA since the 1950s (Bellrose, 1959). In the western Palearctic, several studies (Pain, 1990a; IWRB, 1995) have demon- strated that lead shot, spent by hunters, generate not 335 just a regional problem but an international one for wintering and migrating wildfowl, although the magni- tude of the problem may vary from country to country. For example, in the Camargue (Rhone delta) in France (Pain, 1990b) and Evros delta in Greece (Pain and Handrinos, 1990) some of the highest incidences of lead poisoning for waterfowl described anywhere were found. In Spain, shot present in the gizzards of 25% of mal- lards (Anas platyrhynchos) from the Ebro delta (Guitart et al., 1994), and two outbreaks of lead poisoning mor- tality in greater flamingos (Phoenicopterus ruber) in Dofiana (Ramo et al., 1992) and El Fondo (Mateo et al., 1997) suggested that lead shot was a serious hazard for wildfowl. The Ebro delta, where hunting is permitted, is the most important wetland on the Spanish Mediterranean coast with a midwinter census (January 1985-1996) of 68156 Anatidae (maximum 88819) and 11 167 coots (Fulica atra) (maximum 20 236). This paper extends the research on lead poisoning in waterfowl and shot den- sities in the sediments of several hunting areas of this wetland. MATERIALS AND METHODS Sediment analysis For the determination of lead pellet densities, 50-100 samples of sediment were collected from four different areas (Fig. 1) in the Ebro delta, in spring and summer of 1993. Calaix de Mar at the Buda Island (40.42N 00.52E) is a part of a coastal lagoon of 381 ha with intensive hunting activities, especially since 1981. Encanyissada lagoon (40.41N 00.41E) is a zone of 555ha, where hunting has been practised for over 100 years; samples were taken in two transects in the open water and in the reed belt around the lagoon. Punta de la Banya (40.34N 00.42E) is a salt marsh of 1000ha, where hunting was banned in 1980, but had supported a very low hunting pressure until then. La Llanada (40.40N 00.44E) is an area of 842 ha of mainly rice fields, and it is one of the most heavily hunted sites in the Ebro delta.