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Trace metals in the soft tissues of scaup ducks (Aythya marila L.) wintering in Gdańsk bay, Baltic sea
The Science of the Total Environment, 65 (1987) 203-213 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
203
TRACE METALS IN THE SOFT TISSUES OF SCAUP DUCKS (A YTHYA M A R I L A L.) WINTERING IN GDAI~ISK BAY, BALTIC SEA
PIOTR SZEFER
Department of Analytical Chemistry Medical Academy, al. K. Marksa 107, PL 80-416 Gdadsk (Poland) JERZY FALANDYSZ
Veterinary Hygiene Research Station ul. Kartuska 249, PL 80-125 Gdatlsk (Poland) (Received November 20th, 1986; accepted J a n u a r y 20th, 1987)
ABSTRACT The concentrations of iron, zinc, manganese, copper, lead, cadmium, cobalt and nickel were determined in 107 pooled tissues of scaup ducks (Aythya marila L.). Distinct differences in concentrations of some metals in various tissues were observed; no significant sex-related variations for any of the metals were noted. Results obtained in this study show t h a t kidney contained the maximum concentration of cadmium, while liver had the highest levels of copper and manganese. Both liver and stomach were characterized by maximum levels of zinc; iron was detected, sometimes at highly elevated levels, in lung and liver. Transfer of metals analysed along a food chain from prey represented by molluscs to predator, i.e. scaup duck, was quantified with a transfer factor.
INTRODUCTION
In recent years the trace metal composition of waterfowl populations has attracted the interest of ecologists because of the increasing concentrations of metals in aquatic ecosystems. Waterfowl eat large quantities of fish, invertebrates and aquatic plants. Many of the organisms which serve as food take up or concentrate trace metals from the surrounding environment and the potential for a food chain or trophic concentration effect is large in waterfowl ecosystems (Koranda et al., 1979; Ohlendorf, 1979). Scaup duck is at a high level in the food chain. In one of our earlier studies (Szefer and Falandysz, 1986) we presented data of trace metal concentrations in bones of scaup duck from Gdahsk Bay. In this study we examine the soft tissues and feathers of this species for concentrations of eight metals. SOME CHARACTERISTICS OF THE GDAI~ISK BAY AREA WITH RESPECT TO FOOD HABITS OF SCAUP DUCK
Gdaflsk Bay creates favourable conditions for marine life and is an important area of the southern Baltic for a number of wintering and migrating 0048-9697/87]$03.50
© 1987 Elsevier Science Publishers B.V.
204 waterfowl. Scaup duck is an omnivorous species, breeding in Scotland, Scandinavia and the tundra of Northern Asia and America. The Gdafisk area appears to be an intermediate station in the migration of this duck towards the south. It winters at greater densities in the coastal regions of western Europe and the Mediterranean Sea. The main diet of this duck consists largely of benthic invertebrates in winter, and also submerged plants in summer (Sokotowski, 1958). An abundance of zoobenthic organisms and partly submerged aquatic plants is a major factor in the attraction of Gdafisk Bay to migratory waterfowl. However, during the last decade the abundance of submerged waterfowl food plants has changed radically; the area occupied by Zostera marina, Furcellaria fasigiata and Fucus vesiculosus has significantly diminished as macrophytes were industrially exploited in the 1960s as raw material for the production of agar-agar and alginates. However, their place has been taken by other species such as Zannichellia, Ruppia and Pilayella. The phytobenthos biomass is between 0 and 553 g m 2 (Plifiski, 1982). Considerable changes are also observed in the distribution and composition of the bottom fauna; 41 species and 3 taxons are present in bottom fauna with a biomass estimated to be between 0.01 and 243gm -2. The mean percentage share of molluscs amounts to 93.7% of the biomass (Wenne and Wiktor, 1982). A distinct decrease in the percentage of crustacea in the biomass of zoobenthic organisms with an increase in mo|luscs is observed (Wenne and Wiktor, 1982). Such changes in the structure of bottom fauna increase the significance of molluscs as sources of nutrition for diving ducks (e.g. scaup duck) for which molluscs constitute the main source of food. MATERIALS AND METHODS One hundred and seven samples were prepared from scaup ducks taken from fishing nets in Gdafisk Bay between the 1980-81, 1981-82, 1982-83 and 1983-84 wintering seasons. The ducks showed no macroscopic pathological changes. Representative tissues were isolated from specimens and immediately weighed (feathers were dried at 110°C before weighing). The pooled samples were placed on an asbestos wire gauze, slowly combusted in a gas burner flame and then heated in a quartz crucible. The partly incinerated samples were digested with a mixture of hot concentrated nitric and perchloric acids. The residue was heated in 1 M hydrochloric acid to dissolve the chlorides and then transfered into an acid-washed volumetric flask. Cadmium, lead, copper, nickel, cobalt and manganese were determined directly from the solution by atomic absorption spectroscopy (AAS); iron and zinc were determined after appropriate dilution. Mixed standards were prepared containing known concentrations of all metals in 1 M hydrochloric acid. To check for matrix interference, mixed standards containing trace metals together with a quantity of calcium equivalent to that in the samples were analysed. The concentration ranges of metals
205 in the standards were as follows (#gml-~): 4-160 for copper, 0.1-4 for cobalt, 0.1-16 for lead, 0.1-12 for nickel, 0.08-2.4 for cadmium, 0.8-8 for manganese, 20-80 for zinc and 30-1000 for iron. The concentrations of calcium in the samples analysed (determined by the AAS) were very variable and ranged from 50 #g g-~ in breast muscle to 1600 gg g-1 wet wt. in eyeballs; stomach contents contained, on average, 120mg Ca g-~ dry wt. The technique of standard addition analysis was used to control the quality of the data. The range of the standards depended upon the concentration of metals in respective tissues. The average recovery for spiked samples was: 90% for iron, 82% for zinc, 80% for manganese and copper, 88% for lead, and 85% for cadmium, cobalt and nickel. RESULTS AND DISCUSSION
Iron The maximum concentrations of iron were found in liver and lung followed by kidney and the lowest in brain, skin and glandula uropygialis (Table 1). For comparison, all tissues obtained from Gdafisk Bay long-tailed duck (Clangula hyemalis), i.e. liver, stomach, heart and muscle, contained higher levels of iron (Szefer and Falandysz, 1983) than respective tissues of scaup duck. Higher concentrations of iron in liver than in kidney have also been found in marine birds from Puget Sound, Washington, and Imperial and Sacramento Valleys, California (Riley et al., 1983; Koranda et al., 1979). The values for brain, heart and lung obtained in this study are comparable to those found in pintail duck (Anas acuta) (Koranda et al., 1979). Mean iron levels in the feathers of female and male scaup duck were 900 and 1700 pg g-~ dry wt., respectively (Table 1); these values are from about three to four times higher than those of long-tailed duck from the same area (Szefer and Falandysz, 1983). Doi and Fukuyama (1983) also found elevated and variable concentrations of iron (from 200 to > 600 #g g-~ dry wt.) in barbs of tail feathers of Temminck's cormorant (Phalacrocorax filamentosus).
Manganese Manganese concentrations were generaly highest in liver followed by kidney and stomach (Table 1). The mean manganese concentration of breast muscle (0.44 #g g- 1 wet wt.) is somewhat higher than that (0.25 ~g g- 1) obtained for long-tailed duck from the same area (Szefer and Falandysz, 1983). According to Koranda et al. (1979), liver, kidney, lung, brain and heart of pintail duck of Imperial Valley contained 15.9, 12.9, 2.6, 2.0 and 1.9pg Mn g 1 dry wt., respectively; these values are very similar to those obtained for organs of scaup-duck studied here.
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208 Manganese and zinc concentrations in feathers display considerable variability (4.1-75.0 pg g-1 dry wt.). The mean value obtained in this study is nearly four times higher than those reported for long-tailed duck analysed previously (Szefer and Falandysz, 1983). The concentrations of manganese in different parts of feathers of aquatic birds from Nemuro City ranged from 1 to 122 #g gdry wt. (Doi and Fukuyama, 1983).
Zinc The liver and stomach were characterized by maximum levels of zinc; the mean concentration of this metal in the remaining tissues showed the least variability, i.e. from 10.5#gg -1 for skin to 23/zgg 1 for kidney and eyeballs (Table 1). For comparison, mean zinc concentrations of liver and kidney of greater scaup (Aythya marila) from Chesapeake Bay, U.S.A. were 107 and 75pgg 1 dry wt., respectively (Di Giulio and Scanlon, 1984a). These values, converted to wet weight basis, are similar to those observed for this species in the present study. The concentrations of zinc in liver, muscle, stomach and heart (Table 1) are nearly twice those obtained for long-tailed duck from the same area (Szefer and Falandysz, 1983). Data obtained by other authors (Koranda et al., 1979; Riley et al., 1983; Di Giulio and Scanlon, 1984a, b) also show higher levels of zinc and copper in liver than in kidney of waterfowl. The zinc values for brain, lung and heart (Table 1) are comparable (after conversion to a dry wt. basis) to those of pintail duck from Imperial Valley (Koranda et al., 1979). The mean concentrations of zinc in feathers of both male and female scaup duck were 130 and 120/zgg -1 dry wt. respectively (Table 1). Similar values ( l l 0 p g g-~) were reported for long-tailed duck by Szefer and Falandysz (1983). The values obtained here are comparable to those (88.0-98.8/zgg -1 drywt.) found in the feather shaft of some species of wader from the Dutch Wadden Sea (Goede and Bruin, 1984). According to these authors the feather vane is suitable as a monitoring tissue for zinc.
Copper As for zinc, the copper levels were generally higher in the liver than in the kidney (Table 1). The values are comparable to those observed in the same organs of greater scaup from Chesapeake Bay (Di Giulio and Scanlon, 1984a). These authors (1984b) found that cadmium ingestion increased concentrations of copper and zinc in kidney of juvenile mallard (Anas platyrhynchos). According to Di Giulio and Scanlon (1984a) the liver of greater scaup (Aythya marila) from Chesapeake Bay was characterized by a significantly higher mean concentration of copper than that of oldsquaw (Clangula hyemalis) from this region. It is noteworthy that a similar interspecies tendency is also observed from the same two species wintering in the Gdafisk Bay area; the mean level of copper in liver of scaup duck analysed here is an order
209
of magnitude higher than that of long-tailed duck studied previously. The muscle, stomach and heart of the latter species also had (compared with scaup duck) much lower amounts of copper (Szefer and Falandysz, 1983; present paper). The levels of copper in feathers (Table 1) show a distinct agreement with data (5-13 gg g- ~dry wt.) obtained by Doi and Fukuyama (1983) for red-breasted merganser (Mergus serrator) from Nemuro City, Japan. Similar mean values of 6.3 and 5.3 gg g-1 dry wt. were also obtained for feathers of Gdahsk Bay longtailed duck and S. African cormorants, respectively (Greichus et al., 1977, 1978; Szefer and Falandysz, 1983).
Lead Feathers contained the highest mean concentration of lead (4.2#gg ' dry wt., Table 1). Liver and kidney of scaup duck studied here contained levels of this element similar to those reported for the same species from Chesapeake Bay (Di Giulio and Scanlon, 1984a). The levels of lead were high in breast muscle (0.10#g g-~ wet wt.) (Table 1), about three times higher than those found in the analogous tissue of long-tailed duck, and similar to those found in muscle of the white-tailed eagle (Haliae~tus albicilla) of Szczecin Lagoon (Falandysz and Szefer, 1983). According to Koranda et al. (1979) the concentration of lead in muscle of land birds (sparrowhawk and pheasant) from Imperial Valley, California ranged from 2.2 to 69.7#gg -~ drywt. Lead levels in breast muscle of lead-dosed ducks varied between 0.6 and 3.2 #g g- ~wet wt. (Longcore et al., 1974). On the basis of feeding experiment data with waterfowl, Scanlon et al. (1980) and Di Giulio and Scanlon (1984b) suggest that elevated liver lead levels were due in most instances to factors other than ingestion of contaminated foods, such as lead shot. The concentrations of lead in feathers (Table 1) were in accordance with those reported previously for long-tailed duck (Szefer and Falandysz, 1983). Goede and de Voogt (1985) found that the levels of lead in kidney and feather of waders of the Dutch Wadden Sea ranged from 0.44 to 1.52 and from 1 to 3 #g g-1 dry wt. respectively. These levels are comparable to those obtained in the present study.
Cadmium The mean concentration of cadmium in scaup duck was about three times higher in kidney than in liver (Table 1). Di Giulio and Scanlon (1984a) also obtained higher values for kidney (7.40 #g g- 1dry wt.) than for liver (1.56 #g g- 1) for the same species from Chesapeake Bay; a similar distribution of cadmium has been reported for other waterfowl (Connors et al., 1975; Wiemeyer et al., 1980; Riley et al., 1983). According to Di Giulio and Scanlon (1984b) kidney appears to be generally preferred to liver for monitoring ingestion of cadmium and lead when analytical detection limits are critical.
210
The concentrations of cadmium in muscle and heart of Gdafisk Bay scaup duck (Table 1) were ~ 2-3 times higher than those of long-tailed duck from the same area (Szefer and Falandysz, 1983). In the liver of this last species the mean level of cadmium (0.68 #g g- 1 wet wt.) was somewhat higher than in scaup duck studied here (Table 1). In the feathers of scaup duck, the mean level of cadmium (0.34 gg g 1 dry wt.) was nearly three times higher than in long-tailed duck taken from the same region (Szefer and Falandysz, 1983). The cadmium concentrations in the vane and shaft of some waders from the Dutch Wadden Sea ranged from 0.34 to 0.84 and from < 0.05 to 0.12/~gg -1 drywt., respectively (Goede and de Bruin, 1984; Goede and de Voogt, 1985).
Cobalt and nickel The levels of cobalt in all tissues analysed were relatively low and ranged from 0.03 gg g-1 in breast muscle to 0.21 pg g-1 wet wt. in tongue. The feathers contained a mean value of 0.45/~g Co g- ~ dry wt. (Table 1). The mean levels of cobalt in leg muscle, liver, heart and stomach of scaup duck (Table 1) were similar to those found in long-tailed duck (Szefer and Falandysz, 1983). The liver and kidney contained levels of cobalt (Table 1) comparable to those, i.e. 0.30 and 0.63/~g g-1 dry wt., respectively, reported for glaucous-winged gulls from Puget Sound, U.S.A. (Riley et al., 1983). The highest levels of nickel were found in feathers (2.4 pg g- 1 dry wt.) and tongue (0.19 #g g- 1 wet wt.) (Table 1). The metal concentrations in muscle, liver, stomach, heart and feathers of scaup duck are higher than those in the corresponding tissue of long-tailed duck (Szefer and Falandysz, 1983). Individual white-tailed eagle of Szczecin Lagoon contained levels of nickel similar to those found in scaup duck tissues determined in the present study (Falandysz and Szefer, 1983).
Estimation of metal transfer along the trophic level scaup duck (consumer)-molluscs and seaweed (diet) The main route of entry of pollutants in wild animals is through food. Some pollutants tend to be progressively concentrated through successive trophic levels; the trace metal concentrations in some tissues of ducks may reflect the degree of contamination of aquatic environments. Therefore the food content of scaup duck stomach was examined to determine diet; stomach contents consisted mainly of shells of Mya arenaria and fine mineral particles, generally called "grit" (removed before chemical analysis). According to Sokolowski (1958) the scaup duck diet consists of molluscs in winter, and molluscs and seaweed in summer. Bearing this in mind, metal levels in scaup duck and stomach contents are compared with those in principal invertebrates and seaweed collected in wintering area of the duck (Table 2). The approximate elemental composition of scaup duck was calculated on the basis of soft tissue
211
TABLE 2 Total c o n c e n t r a t i o n s of trace metals 0~g g ' dry wt.) in scaup duck, its s t o m a c h contents, and potential food, i.e. in zoo- and fitobenthos from Gdahsk Bay Species or type of organism
Aythya marila ~ Stomach c o n t e n t s Molluscs b
Mytilus edulis Cardiurn glaucum Mya arenaria Macoma balthica
Fe
Zn
Mn
Cu
Pb
Cd
Co
Ni
2.1 27.4
0.30 1.50
0.3 5.0
0.6 15.2
500 720
100 12
7 26
11.5 3.8
2900 670 1350 1380
40 18 32 82
110 26 88 15
1.0 1.0 2.6 6.4
20 18 31 25
0.61 0.10 0.28 0.08
0.5 0.2 0.6 0.4
13 15 21 13
5150
63
230
30.0
31
0.36
1.5
14
3270 2300 1250
115 200 28
750 700 1600
5.9 6.4 3.1
21 15 32
0.49 0.61 0.56
1.0 0.5 0.8
Crustaceab
Mesidothea entomon Seaweed ¢ Chlorophyta Phaeophyta Spermatophyta
3.7 5.2 3.9
a D a t a calculated from Szefer and Falandysz (1986); this paper. b D a t a calculated from Szefer (1986), Szefer and Szefer (1985); unpublished d a t a also utilized. c D a t a t a k e n from Szefer and Skwarzec (1986).
data (present paper) and bone data (Szefer and Falandysz, 1986). Calculated data were converted from wet to dry weight basis using the ratio reported by Scanlon (1982). As can be seen from Table 2, compared with the remaining metals, zinc and copper are generally higher in whole specimens of scaup duck than in their stomach contents and their potential food (molluscs, seaweed Spermatophyta). Vermeer and Peakall (1979) also reported higher values of zinc and copper and lower values of lead in liver of the greater scaup (Aythya marila) from British Columbia compared with its food. Metal transfer along the two trophic levels of the food chain, i.e. from mollusc (prey) to scaup duck (predator) is quantitatively estimated by the transfer factor, TF, as follows (Amiard et al., 1980):
-
-
TF
-
Ca Cp
where Cc and Cp are the metal concentration in the predator (consumer) and prey (diet), respectively. The TF values are generally < 1 for cadmium, lead, nickel, manganese, cobalt and iron, and > 1 for zinc and copper (Table 3). Therefore, we conclude that there is probably no biomagnification in scaup duck for most metals analysed with the exception of zinc and copper. In summary there are no significant sex-related variations in the levels of metals analysed. However, considerable variability is observed for most metal concentrations in different tissues - - the highest levels of cadmium were in the
212 TABLE 3 Mean transfer factors (TF) calculated for trace metals in scaup duck with respect to lower trophic levels represented by molluscs, crustacea and seaweed Trophic relation consumer-potential prey
Fe
Zn
Mn
Cu
Pb
Cd
Co
Ni
Scaup duck-molluscs Scaup duck-crustacea Scaup duck-seaweed
0.32 0.10 0.22
2.3 1.6 0.9 (3.6) a
0.12 0.03 0.01
4.2 0.4 2.3
0.09 0.07 0.09
1.1 0.8 0.7
0.7 0.2 0.4
0.04 0.04 0.14
Calculated for trophic relation: scaup
duck-Spermatophyta.
kidney and the highest levels of copper and manganese in liver. Maximum levels of iron and zinc were found in lung and stomach, respectively; somewhat lower levels of these metals were found in liver. The data obtained in the present study are compared with long-tailed duck data presented in one of our earlier publications (Szefer and Falandysz, 1983). The metal concentrations in some tissues showed considerable variability, both within and among the two species. Such variation may be related to seasonal changes in protein and fat content, suggested by various authors (Parslow, 1973; Osborn, 1979; Di Giulio and Scanlon, 1984a). Other factors, such as differences in geographical distribution of the two species o f duck before they arrive in the Gdafisk Bay area, and time spent in this area before collection, may also be responsible for the variability. Transfer factors results indicate that there is probably no biomagnification in scaup duck for most metals studied here, with the exception of zinc and copper. ACKNOWLEDGEMENTS
This work was supported by grant WWF/IUCN 3165, Investigation of Trace Metals in Scaup duck in Gdafisk Bay; World Wildlife Fund/International Union for Conservation of Nature and Natural Resources. REFERENCES Amiard, J.-C., C. Amiard-Triquet, C. Metayer, J. M a r c h a n d and R. Ferre, 1980. Etude du transfert de Cd, Pb, Cu et Zn dans les chaines trophiques neritiques et estuariennes. I. Etat dans l'estuaire interne de la Loire (France) au cours de l'ete 1978. Water Res., 14: 665~73. Connors, P.G., V.C. Anderlini, R.W. Risebrough, M. Gilbertson and H. Hays, 1975. Investigations of heavy metals in Common Tern populations. Can. Field Nat., 89: 157-162. Di Giulio, R.T. and P.F. Scanlon, 1984a. Heavy metals in tissues of waterfowl from the Chesapeake Bay, USA. Environ. Pollut. (Ser. A), 35: 2948. Di Giulio, R.T. and P.F. Scanlon, 1984b. Effects of cadmium and lead ingestion on tissue concentrations of cadmium, lead, copper and zinc in mallard ducks. Sci. Total Environ., 39: 103-110. Doi, R. and Y. Fukuyama, 1983. Metal content in feathers of wild and zoo-kept birds from Hokkaido, 1976-78. Bull. Environ. Contam. Toxicol., 31: 1~8.
213 Falandysz, J. and P. Szefer, 1983. Metals and organochlorines in a specimen of White-tailed Eagle. Environ. Conserv., 10: 256-258. Goede, A.A. and M. de Bruin, 1984. The use of bird feathers parts as a monitor for metal pollution. Environ. Pollut. (Ser. B), 8: 281-298. Goede, A.A. and P. de Voogt, 1985. Lead and cadmium in waders from the Dutch Wadden Sea. Environ. Pollut. (Ser. A), 37: 311-322. Greichus, Y.A., A. Greichus, B.D. Amman, D.J. Call, D.C.D. Hamman and R.M. Pott, 1977. Insecticides, polychlorinated biphenyls and metals in African lake ecosystems. I. Hartbeespoort Dam, Transvaal and Vo~lvlei Dam, Cape Province, Republic of South Africa. Arch. Environ. Contamin. Toxicol., 6: 371-383. Greichus, Y.A., A. Greichus, H.A. Draayer and B. Marshall, 1978. Insecticides, polychlorinated biphenyls and metals in African lake ecosystems. II. Lake Mc Ilwaine, Rhodesia. Bull. Environ. Contam. Toxicol., 7: 444-453. Koranda, J.J., M. Stuart, S. Thompson and C. Conrado, 1979. Biogeochemical studies of wintering waterfowl in the Imperial and Sacramento Valleys. Lawrence Livermore Laboratory, Livermore, CA, UCID-18288, October, pp. 1-119. Longcore, J.R., R. Andrews, L.N. Locke, G.E. Bagley and L.T. Young, 1974. Toxicity of lead and proposed substitute shot to mallards. Fish and Wildlife Service. Special Scientific Report - Wildlife No. 183. Washington, DC, USDI, 23 pp. Ohlendorf, H.M., 1979. Archiving wildlife specimens for future analysis. Monitoring environmental materials and specimen banking. In: N.P. Luepke (Ed.), Proceedings of the International Workshop, Berlin (West), 23-28 October 1978. Martinus Nijhoff, The Hague, pp. 491-504. Osborn, D., 1979. Seasonal changes in fat, protein and metal content of the liver of the starling Sturnus vulgaris. Environ. Pollut., 19: 145-155. Parslow, J.L.F., 1973. Mercury in waders from the Wash. Environ. Pollut., 5: 295-304. Plihski, M., 1982. The distribution and biomass of phytobenthos in the internal part of Puck Bay. Stud. Mater. Oceanol., 39:195-217 (in Polish, with English abstract). Riley, R.G., E.A. Crecelius, R.E. Fitzner, B.L. Thomas, J.M. Gurtisen and N.S. Bloom, 1983. Organic and inorganic toxicants in sediment and marine birds from Puget Sound. NOAA Technical Memorandum NOS OMS 1, NOAA, Rockville MD., 125 pp. Scanlon, P.F., 1982. Wet and dry weight relationships of mallard (Anas platyrhynchos) tissues. Bull. Environ. Contam. Toxicol., 29: 615-617. Scanlon, P.F., V.D. Stotts, R.G. Oderwald, T.J. Dietrick and R.J. Kendall, 1980. Lead concentrations in livers of Maryland waterfowl with and without ingested lead shot present in gizzards. Bull. Environ. Contain. Toxicol., 25: 855~60. Sokolowski, J., 1958. Ptaki Ziem Polskich. Pa~stwowe Wydawnictwo Naukowe, Warszawa, Vol. 2, 569 pp. Szefer, P., 1987. Some metals in benthic invertebrates in Gdafisk Bay. Mar. Pollut. Bull., 17: 503-507. Szefer, P. and J. Falandysz, 1983. Investigations of trace metals in long-tailed duck (Clangula hyemalis L.) from the Gdafisk Bay. Sci. Total Environ., 29: 269-278. Szefer, P. and K. Szefer, 1985. Occurrence of ten metals in Mytilus edulis L. and Cardium glaucum L. from the Gdafisk Bay. Mar. Pollut. Bull., 16: 446-450. Szefer, P. and J. Falandysz, 1986. Trace metals in the bones of scaup ducks (Aythya marila L.) wintering in the Gdahsk Bay, Baltic Sea. Sci. Total Environ., 53: 193-199. Szefer, P. and B. Skwarzec, 1987. The concentration of elements in some seaweed from coastal region of the southern Baltic and in the Zarnowieckie Lake. Oceanologia, in press. Vermeer, K. and D.B. Peakall, 1979. Trace metals in seaducks of the Fraser Delta intertidal area, British Columbia. Mar. Pollut. Bull., 10: 189-193. Wenne, R. and K. Wiktor, 1982. Benthic fauna of the inshore waters of Gda~sk Bay. Stud. Mater. Oceanol., 39:137-171 (in Polish, with English abstract). Wiemeyer, S.N., T.G. Lamont and L.N. Locke, 1980. Residues of environmental pollutants and necropsy data for Eastern United States ospreys, 1964-1973. Estuaries, 3: 155-167.
203
TRACE METALS IN THE SOFT TISSUES OF SCAUP DUCKS (A YTHYA M A R I L A L.) WINTERING IN GDAI~ISK BAY, BALTIC SEA
PIOTR SZEFER
Department of Analytical Chemistry Medical Academy, al. K. Marksa 107, PL 80-416 Gdadsk (Poland) JERZY FALANDYSZ
Veterinary Hygiene Research Station ul. Kartuska 249, PL 80-125 Gdatlsk (Poland) (Received November 20th, 1986; accepted J a n u a r y 20th, 1987)
ABSTRACT The concentrations of iron, zinc, manganese, copper, lead, cadmium, cobalt and nickel were determined in 107 pooled tissues of scaup ducks (Aythya marila L.). Distinct differences in concentrations of some metals in various tissues were observed; no significant sex-related variations for any of the metals were noted. Results obtained in this study show t h a t kidney contained the maximum concentration of cadmium, while liver had the highest levels of copper and manganese. Both liver and stomach were characterized by maximum levels of zinc; iron was detected, sometimes at highly elevated levels, in lung and liver. Transfer of metals analysed along a food chain from prey represented by molluscs to predator, i.e. scaup duck, was quantified with a transfer factor.
INTRODUCTION
In recent years the trace metal composition of waterfowl populations has attracted the interest of ecologists because of the increasing concentrations of metals in aquatic ecosystems. Waterfowl eat large quantities of fish, invertebrates and aquatic plants. Many of the organisms which serve as food take up or concentrate trace metals from the surrounding environment and the potential for a food chain or trophic concentration effect is large in waterfowl ecosystems (Koranda et al., 1979; Ohlendorf, 1979). Scaup duck is at a high level in the food chain. In one of our earlier studies (Szefer and Falandysz, 1986) we presented data of trace metal concentrations in bones of scaup duck from Gdahsk Bay. In this study we examine the soft tissues and feathers of this species for concentrations of eight metals. SOME CHARACTERISTICS OF THE GDAI~ISK BAY AREA WITH RESPECT TO FOOD HABITS OF SCAUP DUCK
Gdaflsk Bay creates favourable conditions for marine life and is an important area of the southern Baltic for a number of wintering and migrating 0048-9697/87]$03.50
© 1987 Elsevier Science Publishers B.V.
204 waterfowl. Scaup duck is an omnivorous species, breeding in Scotland, Scandinavia and the tundra of Northern Asia and America. The Gdafisk area appears to be an intermediate station in the migration of this duck towards the south. It winters at greater densities in the coastal regions of western Europe and the Mediterranean Sea. The main diet of this duck consists largely of benthic invertebrates in winter, and also submerged plants in summer (Sokotowski, 1958). An abundance of zoobenthic organisms and partly submerged aquatic plants is a major factor in the attraction of Gdafisk Bay to migratory waterfowl. However, during the last decade the abundance of submerged waterfowl food plants has changed radically; the area occupied by Zostera marina, Furcellaria fasigiata and Fucus vesiculosus has significantly diminished as macrophytes were industrially exploited in the 1960s as raw material for the production of agar-agar and alginates. However, their place has been taken by other species such as Zannichellia, Ruppia and Pilayella. The phytobenthos biomass is between 0 and 553 g m 2 (Plifiski, 1982). Considerable changes are also observed in the distribution and composition of the bottom fauna; 41 species and 3 taxons are present in bottom fauna with a biomass estimated to be between 0.01 and 243gm -2. The mean percentage share of molluscs amounts to 93.7% of the biomass (Wenne and Wiktor, 1982). A distinct decrease in the percentage of crustacea in the biomass of zoobenthic organisms with an increase in mo|luscs is observed (Wenne and Wiktor, 1982). Such changes in the structure of bottom fauna increase the significance of molluscs as sources of nutrition for diving ducks (e.g. scaup duck) for which molluscs constitute the main source of food. MATERIALS AND METHODS One hundred and seven samples were prepared from scaup ducks taken from fishing nets in Gdafisk Bay between the 1980-81, 1981-82, 1982-83 and 1983-84 wintering seasons. The ducks showed no macroscopic pathological changes. Representative tissues were isolated from specimens and immediately weighed (feathers were dried at 110°C before weighing). The pooled samples were placed on an asbestos wire gauze, slowly combusted in a gas burner flame and then heated in a quartz crucible. The partly incinerated samples were digested with a mixture of hot concentrated nitric and perchloric acids. The residue was heated in 1 M hydrochloric acid to dissolve the chlorides and then transfered into an acid-washed volumetric flask. Cadmium, lead, copper, nickel, cobalt and manganese were determined directly from the solution by atomic absorption spectroscopy (AAS); iron and zinc were determined after appropriate dilution. Mixed standards were prepared containing known concentrations of all metals in 1 M hydrochloric acid. To check for matrix interference, mixed standards containing trace metals together with a quantity of calcium equivalent to that in the samples were analysed. The concentration ranges of metals
205 in the standards were as follows (#gml-~): 4-160 for copper, 0.1-4 for cobalt, 0.1-16 for lead, 0.1-12 for nickel, 0.08-2.4 for cadmium, 0.8-8 for manganese, 20-80 for zinc and 30-1000 for iron. The concentrations of calcium in the samples analysed (determined by the AAS) were very variable and ranged from 50 #g g-~ in breast muscle to 1600 gg g-1 wet wt. in eyeballs; stomach contents contained, on average, 120mg Ca g-~ dry wt. The technique of standard addition analysis was used to control the quality of the data. The range of the standards depended upon the concentration of metals in respective tissues. The average recovery for spiked samples was: 90% for iron, 82% for zinc, 80% for manganese and copper, 88% for lead, and 85% for cadmium, cobalt and nickel. RESULTS AND DISCUSSION
Iron The maximum concentrations of iron were found in liver and lung followed by kidney and the lowest in brain, skin and glandula uropygialis (Table 1). For comparison, all tissues obtained from Gdafisk Bay long-tailed duck (Clangula hyemalis), i.e. liver, stomach, heart and muscle, contained higher levels of iron (Szefer and Falandysz, 1983) than respective tissues of scaup duck. Higher concentrations of iron in liver than in kidney have also been found in marine birds from Puget Sound, Washington, and Imperial and Sacramento Valleys, California (Riley et al., 1983; Koranda et al., 1979). The values for brain, heart and lung obtained in this study are comparable to those found in pintail duck (Anas acuta) (Koranda et al., 1979). Mean iron levels in the feathers of female and male scaup duck were 900 and 1700 pg g-~ dry wt., respectively (Table 1); these values are from about three to four times higher than those of long-tailed duck from the same area (Szefer and Falandysz, 1983). Doi and Fukuyama (1983) also found elevated and variable concentrations of iron (from 200 to > 600 #g g-~ dry wt.) in barbs of tail feathers of Temminck's cormorant (Phalacrocorax filamentosus).
Manganese Manganese concentrations were generaly highest in liver followed by kidney and stomach (Table 1). The mean manganese concentration of breast muscle (0.44 #g g- 1 wet wt.) is somewhat higher than that (0.25 ~g g- 1) obtained for long-tailed duck from the same area (Szefer and Falandysz, 1983). According to Koranda et al. (1979), liver, kidney, lung, brain and heart of pintail duck of Imperial Valley contained 15.9, 12.9, 2.6, 2.0 and 1.9pg Mn g 1 dry wt., respectively; these values are very similar to those obtained for organs of scaup-duck studied here.
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208 Manganese and zinc concentrations in feathers display considerable variability (4.1-75.0 pg g-1 dry wt.). The mean value obtained in this study is nearly four times higher than those reported for long-tailed duck analysed previously (Szefer and Falandysz, 1983). The concentrations of manganese in different parts of feathers of aquatic birds from Nemuro City ranged from 1 to 122 #g gdry wt. (Doi and Fukuyama, 1983).
Zinc The liver and stomach were characterized by maximum levels of zinc; the mean concentration of this metal in the remaining tissues showed the least variability, i.e. from 10.5#gg -1 for skin to 23/zgg 1 for kidney and eyeballs (Table 1). For comparison, mean zinc concentrations of liver and kidney of greater scaup (Aythya marila) from Chesapeake Bay, U.S.A. were 107 and 75pgg 1 dry wt., respectively (Di Giulio and Scanlon, 1984a). These values, converted to wet weight basis, are similar to those observed for this species in the present study. The concentrations of zinc in liver, muscle, stomach and heart (Table 1) are nearly twice those obtained for long-tailed duck from the same area (Szefer and Falandysz, 1983). Data obtained by other authors (Koranda et al., 1979; Riley et al., 1983; Di Giulio and Scanlon, 1984a, b) also show higher levels of zinc and copper in liver than in kidney of waterfowl. The zinc values for brain, lung and heart (Table 1) are comparable (after conversion to a dry wt. basis) to those of pintail duck from Imperial Valley (Koranda et al., 1979). The mean concentrations of zinc in feathers of both male and female scaup duck were 130 and 120/zgg -1 dry wt. respectively (Table 1). Similar values ( l l 0 p g g-~) were reported for long-tailed duck by Szefer and Falandysz (1983). The values obtained here are comparable to those (88.0-98.8/zgg -1 drywt.) found in the feather shaft of some species of wader from the Dutch Wadden Sea (Goede and Bruin, 1984). According to these authors the feather vane is suitable as a monitoring tissue for zinc.
Copper As for zinc, the copper levels were generally higher in the liver than in the kidney (Table 1). The values are comparable to those observed in the same organs of greater scaup from Chesapeake Bay (Di Giulio and Scanlon, 1984a). These authors (1984b) found that cadmium ingestion increased concentrations of copper and zinc in kidney of juvenile mallard (Anas platyrhynchos). According to Di Giulio and Scanlon (1984a) the liver of greater scaup (Aythya marila) from Chesapeake Bay was characterized by a significantly higher mean concentration of copper than that of oldsquaw (Clangula hyemalis) from this region. It is noteworthy that a similar interspecies tendency is also observed from the same two species wintering in the Gdafisk Bay area; the mean level of copper in liver of scaup duck analysed here is an order
209
of magnitude higher than that of long-tailed duck studied previously. The muscle, stomach and heart of the latter species also had (compared with scaup duck) much lower amounts of copper (Szefer and Falandysz, 1983; present paper). The levels of copper in feathers (Table 1) show a distinct agreement with data (5-13 gg g- ~dry wt.) obtained by Doi and Fukuyama (1983) for red-breasted merganser (Mergus serrator) from Nemuro City, Japan. Similar mean values of 6.3 and 5.3 gg g-1 dry wt. were also obtained for feathers of Gdahsk Bay longtailed duck and S. African cormorants, respectively (Greichus et al., 1977, 1978; Szefer and Falandysz, 1983).
Lead Feathers contained the highest mean concentration of lead (4.2#gg ' dry wt., Table 1). Liver and kidney of scaup duck studied here contained levels of this element similar to those reported for the same species from Chesapeake Bay (Di Giulio and Scanlon, 1984a). The levels of lead were high in breast muscle (0.10#g g-~ wet wt.) (Table 1), about three times higher than those found in the analogous tissue of long-tailed duck, and similar to those found in muscle of the white-tailed eagle (Haliae~tus albicilla) of Szczecin Lagoon (Falandysz and Szefer, 1983). According to Koranda et al. (1979) the concentration of lead in muscle of land birds (sparrowhawk and pheasant) from Imperial Valley, California ranged from 2.2 to 69.7#gg -~ drywt. Lead levels in breast muscle of lead-dosed ducks varied between 0.6 and 3.2 #g g- ~wet wt. (Longcore et al., 1974). On the basis of feeding experiment data with waterfowl, Scanlon et al. (1980) and Di Giulio and Scanlon (1984b) suggest that elevated liver lead levels were due in most instances to factors other than ingestion of contaminated foods, such as lead shot. The concentrations of lead in feathers (Table 1) were in accordance with those reported previously for long-tailed duck (Szefer and Falandysz, 1983). Goede and de Voogt (1985) found that the levels of lead in kidney and feather of waders of the Dutch Wadden Sea ranged from 0.44 to 1.52 and from 1 to 3 #g g-1 dry wt. respectively. These levels are comparable to those obtained in the present study.
Cadmium The mean concentration of cadmium in scaup duck was about three times higher in kidney than in liver (Table 1). Di Giulio and Scanlon (1984a) also obtained higher values for kidney (7.40 #g g- 1dry wt.) than for liver (1.56 #g g- 1) for the same species from Chesapeake Bay; a similar distribution of cadmium has been reported for other waterfowl (Connors et al., 1975; Wiemeyer et al., 1980; Riley et al., 1983). According to Di Giulio and Scanlon (1984b) kidney appears to be generally preferred to liver for monitoring ingestion of cadmium and lead when analytical detection limits are critical.
210
The concentrations of cadmium in muscle and heart of Gdafisk Bay scaup duck (Table 1) were ~ 2-3 times higher than those of long-tailed duck from the same area (Szefer and Falandysz, 1983). In the liver of this last species the mean level of cadmium (0.68 #g g- 1 wet wt.) was somewhat higher than in scaup duck studied here (Table 1). In the feathers of scaup duck, the mean level of cadmium (0.34 gg g 1 dry wt.) was nearly three times higher than in long-tailed duck taken from the same region (Szefer and Falandysz, 1983). The cadmium concentrations in the vane and shaft of some waders from the Dutch Wadden Sea ranged from 0.34 to 0.84 and from < 0.05 to 0.12/~gg -1 drywt., respectively (Goede and de Bruin, 1984; Goede and de Voogt, 1985).
Cobalt and nickel The levels of cobalt in all tissues analysed were relatively low and ranged from 0.03 gg g-1 in breast muscle to 0.21 pg g-1 wet wt. in tongue. The feathers contained a mean value of 0.45/~g Co g- ~ dry wt. (Table 1). The mean levels of cobalt in leg muscle, liver, heart and stomach of scaup duck (Table 1) were similar to those found in long-tailed duck (Szefer and Falandysz, 1983). The liver and kidney contained levels of cobalt (Table 1) comparable to those, i.e. 0.30 and 0.63/~g g-1 dry wt., respectively, reported for glaucous-winged gulls from Puget Sound, U.S.A. (Riley et al., 1983). The highest levels of nickel were found in feathers (2.4 pg g- 1 dry wt.) and tongue (0.19 #g g- 1 wet wt.) (Table 1). The metal concentrations in muscle, liver, stomach, heart and feathers of scaup duck are higher than those in the corresponding tissue of long-tailed duck (Szefer and Falandysz, 1983). Individual white-tailed eagle of Szczecin Lagoon contained levels of nickel similar to those found in scaup duck tissues determined in the present study (Falandysz and Szefer, 1983).
Estimation of metal transfer along the trophic level scaup duck (consumer)-molluscs and seaweed (diet) The main route of entry of pollutants in wild animals is through food. Some pollutants tend to be progressively concentrated through successive trophic levels; the trace metal concentrations in some tissues of ducks may reflect the degree of contamination of aquatic environments. Therefore the food content of scaup duck stomach was examined to determine diet; stomach contents consisted mainly of shells of Mya arenaria and fine mineral particles, generally called "grit" (removed before chemical analysis). According to Sokolowski (1958) the scaup duck diet consists of molluscs in winter, and molluscs and seaweed in summer. Bearing this in mind, metal levels in scaup duck and stomach contents are compared with those in principal invertebrates and seaweed collected in wintering area of the duck (Table 2). The approximate elemental composition of scaup duck was calculated on the basis of soft tissue
211
TABLE 2 Total c o n c e n t r a t i o n s of trace metals 0~g g ' dry wt.) in scaup duck, its s t o m a c h contents, and potential food, i.e. in zoo- and fitobenthos from Gdahsk Bay Species or type of organism
Aythya marila ~ Stomach c o n t e n t s Molluscs b
Mytilus edulis Cardiurn glaucum Mya arenaria Macoma balthica
Fe
Zn
Mn
Cu
Pb
Cd
Co
Ni
2.1 27.4
0.30 1.50
0.3 5.0
0.6 15.2
500 720
100 12
7 26
11.5 3.8
2900 670 1350 1380
40 18 32 82
110 26 88 15
1.0 1.0 2.6 6.4
20 18 31 25
0.61 0.10 0.28 0.08
0.5 0.2 0.6 0.4
13 15 21 13
5150
63
230
30.0
31
0.36
1.5
14
3270 2300 1250
115 200 28
750 700 1600
5.9 6.4 3.1
21 15 32
0.49 0.61 0.56
1.0 0.5 0.8
Crustaceab
Mesidothea entomon Seaweed ¢ Chlorophyta Phaeophyta Spermatophyta
3.7 5.2 3.9
a D a t a calculated from Szefer and Falandysz (1986); this paper. b D a t a calculated from Szefer (1986), Szefer and Szefer (1985); unpublished d a t a also utilized. c D a t a t a k e n from Szefer and Skwarzec (1986).
data (present paper) and bone data (Szefer and Falandysz, 1986). Calculated data were converted from wet to dry weight basis using the ratio reported by Scanlon (1982). As can be seen from Table 2, compared with the remaining metals, zinc and copper are generally higher in whole specimens of scaup duck than in their stomach contents and their potential food (molluscs, seaweed Spermatophyta). Vermeer and Peakall (1979) also reported higher values of zinc and copper and lower values of lead in liver of the greater scaup (Aythya marila) from British Columbia compared with its food. Metal transfer along the two trophic levels of the food chain, i.e. from mollusc (prey) to scaup duck (predator) is quantitatively estimated by the transfer factor, TF, as follows (Amiard et al., 1980):
-
-
TF
-
Ca Cp
where Cc and Cp are the metal concentration in the predator (consumer) and prey (diet), respectively. The TF values are generally < 1 for cadmium, lead, nickel, manganese, cobalt and iron, and > 1 for zinc and copper (Table 3). Therefore, we conclude that there is probably no biomagnification in scaup duck for most metals analysed with the exception of zinc and copper. In summary there are no significant sex-related variations in the levels of metals analysed. However, considerable variability is observed for most metal concentrations in different tissues - - the highest levels of cadmium were in the
212 TABLE 3 Mean transfer factors (TF) calculated for trace metals in scaup duck with respect to lower trophic levels represented by molluscs, crustacea and seaweed Trophic relation consumer-potential prey
Fe
Zn
Mn
Cu
Pb
Cd
Co
Ni
Scaup duck-molluscs Scaup duck-crustacea Scaup duck-seaweed
0.32 0.10 0.22
2.3 1.6 0.9 (3.6) a
0.12 0.03 0.01
4.2 0.4 2.3
0.09 0.07 0.09
1.1 0.8 0.7
0.7 0.2 0.4
0.04 0.04 0.14
Calculated for trophic relation: scaup
duck-Spermatophyta.
kidney and the highest levels of copper and manganese in liver. Maximum levels of iron and zinc were found in lung and stomach, respectively; somewhat lower levels of these metals were found in liver. The data obtained in the present study are compared with long-tailed duck data presented in one of our earlier publications (Szefer and Falandysz, 1983). The metal concentrations in some tissues showed considerable variability, both within and among the two species. Such variation may be related to seasonal changes in protein and fat content, suggested by various authors (Parslow, 1973; Osborn, 1979; Di Giulio and Scanlon, 1984a). Other factors, such as differences in geographical distribution of the two species o f duck before they arrive in the Gdafisk Bay area, and time spent in this area before collection, may also be responsible for the variability. Transfer factors results indicate that there is probably no biomagnification in scaup duck for most metals studied here, with the exception of zinc and copper. ACKNOWLEDGEMENTS
This work was supported by grant WWF/IUCN 3165, Investigation of Trace Metals in Scaup duck in Gdafisk Bay; World Wildlife Fund/International Union for Conservation of Nature and Natural Resources. REFERENCES Amiard, J.-C., C. Amiard-Triquet, C. Metayer, J. M a r c h a n d and R. Ferre, 1980. Etude du transfert de Cd, Pb, Cu et Zn dans les chaines trophiques neritiques et estuariennes. I. Etat dans l'estuaire interne de la Loire (France) au cours de l'ete 1978. Water Res., 14: 665~73. Connors, P.G., V.C. Anderlini, R.W. Risebrough, M. Gilbertson and H. Hays, 1975. Investigations of heavy metals in Common Tern populations. Can. Field Nat., 89: 157-162. Di Giulio, R.T. and P.F. Scanlon, 1984a. Heavy metals in tissues of waterfowl from the Chesapeake Bay, USA. Environ. Pollut. (Ser. A), 35: 2948. Di Giulio, R.T. and P.F. Scanlon, 1984b. Effects of cadmium and lead ingestion on tissue concentrations of cadmium, lead, copper and zinc in mallard ducks. Sci. Total Environ., 39: 103-110. Doi, R. and Y. Fukuyama, 1983. Metal content in feathers of wild and zoo-kept birds from Hokkaido, 1976-78. Bull. Environ. Contam. Toxicol., 31: 1~8.
213 Falandysz, J. and P. Szefer, 1983. Metals and organochlorines in a specimen of White-tailed Eagle. Environ. Conserv., 10: 256-258. Goede, A.A. and M. de Bruin, 1984. The use of bird feathers parts as a monitor for metal pollution. Environ. Pollut. (Ser. B), 8: 281-298. Goede, A.A. and P. de Voogt, 1985. Lead and cadmium in waders from the Dutch Wadden Sea. Environ. Pollut. (Ser. A), 37: 311-322. Greichus, Y.A., A. Greichus, B.D. Amman, D.J. Call, D.C.D. Hamman and R.M. Pott, 1977. Insecticides, polychlorinated biphenyls and metals in African lake ecosystems. I. Hartbeespoort Dam, Transvaal and Vo~lvlei Dam, Cape Province, Republic of South Africa. Arch. Environ. Contamin. Toxicol., 6: 371-383. Greichus, Y.A., A. Greichus, H.A. Draayer and B. Marshall, 1978. Insecticides, polychlorinated biphenyls and metals in African lake ecosystems. II. Lake Mc Ilwaine, Rhodesia. Bull. Environ. Contam. Toxicol., 7: 444-453. Koranda, J.J., M. Stuart, S. Thompson and C. Conrado, 1979. Biogeochemical studies of wintering waterfowl in the Imperial and Sacramento Valleys. Lawrence Livermore Laboratory, Livermore, CA, UCID-18288, October, pp. 1-119. Longcore, J.R., R. Andrews, L.N. Locke, G.E. Bagley and L.T. Young, 1974. Toxicity of lead and proposed substitute shot to mallards. Fish and Wildlife Service. Special Scientific Report - Wildlife No. 183. Washington, DC, USDI, 23 pp. Ohlendorf, H.M., 1979. Archiving wildlife specimens for future analysis. Monitoring environmental materials and specimen banking. In: N.P. Luepke (Ed.), Proceedings of the International Workshop, Berlin (West), 23-28 October 1978. Martinus Nijhoff, The Hague, pp. 491-504. Osborn, D., 1979. Seasonal changes in fat, protein and metal content of the liver of the starling Sturnus vulgaris. Environ. Pollut., 19: 145-155. Parslow, J.L.F., 1973. Mercury in waders from the Wash. Environ. Pollut., 5: 295-304. Plihski, M., 1982. The distribution and biomass of phytobenthos in the internal part of Puck Bay. Stud. Mater. Oceanol., 39:195-217 (in Polish, with English abstract). Riley, R.G., E.A. Crecelius, R.E. Fitzner, B.L. Thomas, J.M. Gurtisen and N.S. Bloom, 1983. Organic and inorganic toxicants in sediment and marine birds from Puget Sound. NOAA Technical Memorandum NOS OMS 1, NOAA, Rockville MD., 125 pp. Scanlon, P.F., 1982. Wet and dry weight relationships of mallard (Anas platyrhynchos) tissues. Bull. Environ. Contam. Toxicol., 29: 615-617. Scanlon, P.F., V.D. Stotts, R.G. Oderwald, T.J. Dietrick and R.J. Kendall, 1980. Lead concentrations in livers of Maryland waterfowl with and without ingested lead shot present in gizzards. Bull. Environ. Contain. Toxicol., 25: 855~60. Sokolowski, J., 1958. Ptaki Ziem Polskich. Pa~stwowe Wydawnictwo Naukowe, Warszawa, Vol. 2, 569 pp. Szefer, P., 1987. Some metals in benthic invertebrates in Gdafisk Bay. Mar. Pollut. Bull., 17: 503-507. Szefer, P. and J. Falandysz, 1983. Investigations of trace metals in long-tailed duck (Clangula hyemalis L.) from the Gdafisk Bay. Sci. Total Environ., 29: 269-278. Szefer, P. and K. Szefer, 1985. Occurrence of ten metals in Mytilus edulis L. and Cardium glaucum L. from the Gdafisk Bay. Mar. Pollut. Bull., 16: 446-450. Szefer, P. and J. Falandysz, 1986. Trace metals in the bones of scaup ducks (Aythya marila L.) wintering in the Gdahsk Bay, Baltic Sea. Sci. Total Environ., 53: 193-199. Szefer, P. and B. Skwarzec, 1987. The concentration of elements in some seaweed from coastal region of the southern Baltic and in the Zarnowieckie Lake. Oceanologia, in press. Vermeer, K. and D.B. Peakall, 1979. Trace metals in seaducks of the Fraser Delta intertidal area, British Columbia. Mar. Pollut. Bull., 10: 189-193. Wenne, R. and K. Wiktor, 1982. Benthic fauna of the inshore waters of Gda~sk Bay. Stud. Mater. Oceanol., 39:137-171 (in Polish, with English abstract). Wiemeyer, S.N., T.G. Lamont and L.N. Locke, 1980. Residues of environmental pollutants and necropsy data for Eastern United States ospreys, 1964-1973. Estuaries, 3: 155-167.