Methylmercury accumulation in tissues and its effects on growth and appetite in captive great egrets

Citation
Mg. Spalding et al., Methylmercury accumulation in tissues and its effects on growth and appetite in captive great egrets, J WILDL DIS, 36(3), 2000, pp. 411-422
Citations number
54
Categorie Soggetti
Veterinary Medicine/Animal Health
Journal title
JOURNAL OF WILDLIFE DISEASES
ISSN journal
00903558 → ACNP
Volume
36
Issue
3
Year of publication
2000
Pages
411 - 422
Database
ISI
SICI code
0090-3558(200007)36:3<411:MAITAI>2.0.ZU;2-8
Abstract
To test the hypothesis that fledging wading birds would be more at risk fro m mercury toxicosis than younger nestlings, captive great egret nestlings w ere maintained as controls or were dosed from 1- to 14-wk-old with 0.5 or 5 mg methylmercury chloride/kg wet weight in fish. Birds dosed with 5 mg/kg suffered from subacute toxicosis at wk 10-12. Growing feather concentration s were the most closely correlated with cumulative mercury consumed per wei ght. Blood concentrations of mercury increased more rapidly after 9 wk in a ll groups when feathers stopped growing. Total mercury accumulated in tissu es in concentrations in the following order: growing scapular feathers > po wderdown > mature scapular feathers > liver > kidney > blood > muscle > pan creas > brain > bile > fat > eye. The proportion of total mercury that was methylated depended upon tissue type and dose group. Selenium accumulated i n liver in direct proportion to liver mercury concentrations. After wk 9, a ppetite and weight index (weight/bill length) declined significantly in bot h dosed groups. At current exposure levels in the Everglades (Florida, USA) mercury deposited in rapidly growing feathers may protect nestlings from a dverse effects on growth until feathers cease growing.