Lead Toxicity in Mute Swans

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SUMMARY Tissue lead levels in Mute swans Cygnus olor (Gmelin) were investigated. The selection of tissues for diagnosis of acute lead poisoning is discussed. Three categories of swan mortality were defined: (1) acute lead poisoning; (2) collisions and (3) other reasons. In most tissues, lead concentrations were highest according to the cause of death in order: lead poisoning > collisions > other causes. Elevated blood lead levels and haematological disorders were detected in swans which had collided with objects. The possible role of elevated lead in causing collisions in Mute swans is discussed. - 113 -
INTRODUCTION Lead poisoning through the ingestion of discarded anglers' weights or spent gunshot is known to be a major cause of mortality in Mute swans [Cygnus olor, (Gmelin), Birkhead, 1982; O'Halloran et al., 1987a)]. Conclusive evidence that death i·s due to lead · · poisoning, however, can only be achieved through chemical analyses of tissues. The most widely used tissue for the diagnosis of lead poisoning in birds is the liver and frequently only a single tissue sample is taken. Roscoe et al., (1979); and Anders et al., (1982) attempted to determine the flux of lead in the bodies of caged birds by feeding them lead. They then extrapolated the results to the field situation. The validity of extrapolating experimental results to the field situation has been questioned, because of the contrasting pattern and duration of exposure to pollutants in the two situations (Hutton, 1980). While high tissue lead levels are diagnostic of birds which have died from lead poisoning, there is a need to investigate sub-lethal effects. Some workers have demonstrated the immuno-suppressive effects of lead in birds (Franson, 1986), while others have shown a change in reproductive performance (e.g. Elder, 1954). Hunter and Wobesser (1980) found encephalopathy and peripheral neuropathy in lead poisoned M a 11 ar d A nas p 1 a t yrync h os (L) • These Changes preceded anaemia which was induced following the feeding of lead pellets. Acute lead poisoning is considered to be responsible for the deaths of a large proportion of Mute swans, but an additional cause of mortality is collision wit h over-h ea d power c ables · Bi.rkhead and Perrins (1986) suggest that sub-lethal doses of lead may have an effect on high degree co-ordination in Mute swans. Sub-lethal levels - 114 -
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0004067t:.7 1~11111 /I llll II llll
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This thesis is dedicated to my moth
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ABSTRACT Lead toxicity in Mute swan
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- what are the best methods for the
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Benson, W.W., Brock, O.W., Gabrica,
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CHAPTER 1 DETERMINATION OF HAEMOGLO
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MATERIALS AND METHODS Blood was obt
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standards are now available, it is
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I ' ABSTRACT The use of blood lead
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developed and (c) information on bl
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MATERIALS AND METHODS Study sites.
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Swans were sexed by cloacal examina
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Red blood cell protoporphyrin .. Th
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RESULTS Blood Lead Levels Diel vari
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16.00 24.CO 2.00 7.00 - ~ ~--1_ J l
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for corrected lead values (ug /g Rb
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Table 2. Blood lead levels of indiv
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30 20 (A) n = 357 10 0-.99 1- 2- 3-
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Blood lead is very labile (Chamberl
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median value of lead in April is si
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elevated lead levels. (2) Haemoglob
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Chisolm, J.J. & Browne, D.R. (1975)
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Ohi, G., Seki, H., Akiyama, K. & Ya
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CHAPTER 3: SECTION 1 LEAD POISONING
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mammals' (Finley et al. 1976). This
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commute from areas up to 20km away
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TABLE 1: Causes of death in Irish s
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I 4. Coiled shot: malleable stainle
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CHAPTER 3: SECTION 2 LEAD POISONING
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I INTRODUCTION The importance of le
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42,000 anglers visit the State each
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MATERIALS AND METHODS Study sites B
Page 67 and 68: 30KM f Fig.l Map of Ireland indicat
Page 69 and 70: lead. X-ray. They were subsequently
Page 71 and 72: RESULTS Blood levels Blood lead lev
Page 73 and 74: I Table.II Proportion of lead poiso
Page 75 and 76: I of the gizzard and oesophagus and
Page 77 and 78: Table IV. 11 (of 41) X-rayed swans
Page 79 and 80: Table V. Median water lead levels (
Page 81 and 82: of pellets had occured. What is sig
Page 83 and 84: irds by Bellrose (1959) in the U.S.
Page 85 and 86: I the pellets as they moved in shor
Page 87 and 88: i Chamberlain, A.G. (1985). Predict
Page 89 and 90: Ong, C.N. & Lee, W.R. (1980). Inter
Page 91 and 92: SUMMARY Reference levels of some bi
Page 93 and 94: I adults, immatures, females and ma
Page 95 and 96: I centrifugation in microhaematocri
Page 97 and 98: RESULTS All blood samples included
Page 99 and 100: Table 1. Mean (± s.e.) maximum and
Page 101 and 102: Table 3. Haematological and biochem
Page 103 and 104: Table 5. Haemoglobin, haematocrit a
Page 105 and 106: Table 6. Age, sex, blood lead level
Page 107 and 108: DISCUSSION The normal range of haem
Page 109 and 110: considered when using protoporphyri
Page 111 and 112: I the blood constituents, reflectin
Page 113 and 114: REFERENCES Bates, F.Y., Barnes, D.M
Page 115 and 116: i Lucas, A.M. and Jamroz, C. (1961)
Page 117: CHAPTER 5 TISSUE LEAD LEVELS AND HA
Page 121 and 122: I r MATERIALS AND METHODS Collectio
Page 123 and 124: I RESULTS Tissue lead levels Tissue
Page 125 and 126: Table 1. Tissue lead levels (ug/ g)
Page 127 and 128: Table 3 Age, sex, blood lead level
Page 129 and 130: DISCUSSION Tissue lead levels have
Page 131 and 132: which had collided had raised blood
Page 133 and 134: REFERENCES Anders, E., Dietz, D.D.,
Page 135 and 136: O'Halloran, J., Myers, A.A. and Dug
Page 137 and 138: many others for helping to catch sw
Page 139 and 140: APPENDIX 1 LEAD LEVELS IN MUTE SWAN
Page 141 and 142: intense fishing in summer and large
Page 143 and 144: area of 4m 2 , were taken. The samp
Page 145 and 146: levels of the birds on the Lee also
Page 147 and 148: i oesophagus, proventriculus and gi
Page 149 and 150: in blood. In general, healthy birds
Page 151 and 152: toxic lea? l~vels. The post-mortem
Page 153 and 154: London area. Part 2 Biological Effe
Page 155 and 156: Prelin1inary results of ringing Mut
Page 157 and 158: Ringed Mute S1rans ?f the. 61 I r~~
Page 159: Acknowledgments Ringed Mute S1ra11s
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Lead Toxicity in Mute Swans

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