Duckling responses to lake acidification: Do black ducks and fish compete? [Dietary overlap, dietary selectivity]

This study focused on two pairs of ponds in Maine, USA, that were physically similar but which had markedly different acidities. Salmon Pond (pH 6.3) had fish, while 120 m away, Mud Pond (pH 4.5) was fishless. The second pair, Killman Pond (pH 6.5) and Unnamed Pond (pH 4.8), 14 km distant, were also...

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Bibliographic Details
Published in:Oikos 1986-07, Vol.47 (1), p.26-32
Main Authors: Hunter, M.L, Jones, J.J. (Maine Univ., Orono (USA). Wildlife Dept.), Gibbs, K.E, Moring, J.R
Format: Article
Language:English
Subjects:
ACIDIFICACION
ACIDIFICATION
AMBIENTE ACUATICO
Anas rubripes
Animal and plant ecology
Animal, plant and microbial ecology
Animals
AQUATIC ENVIRONMENT
Autoecology
BEHAVIOUR
Biological and medical sciences
BIOLOGICAL COMPETITION
CANARD
COMPETENCIA BIOLOGICA
COMPETITION BIOLOGIQUE
COMPORTAMIENTO
COMPORTEMENT
Diet
Ducklings
DUCKS
FISHES
Freshwater
Freshwater fishes
Fundamental and applied biological sciences. Psychology
HABITAT
HABITATS
Invertebrates
MILIEU AQUATIQUE
Mud
PATO
PECES
POISSON (ANIMAL)
Ponds
Salmon
Waterfowl
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Summary:This study focused on two pairs of ponds in Maine, USA, that were physically similar but which had markedly different acidities. Salmon Pond (pH 6.3) had fish, while 120 m away, Mud Pond (pH 4.5) was fishless. The second pair, Killman Pond (pH 6.5) and Unnamed Pond (pH 4.8), 14 km distant, were also physically similar but again the circumneutral pond had fish and the acidic pond was fishless. Imprinted black duck ducklings, Anas rubripes, kept on the acidic ponds grew faster than those on the circumneutral ponds. Differences in behavior also indicated that the acidic ponds were better duckling habitat. Ducklings on the acidic ponds spent less time searching and moving, and more time feeding and resting, than ducklings on the circumneutral ponds. There was substantial overlap in the diets of trout and ducks; two of the three indices calculated indicated that ducklings sharing a circumneutral pond with fish had diets that were more similar to the fish's diets than to the diets of ducklings on acidic ponds. Sweep-net samples of invertebrate abundance and comparisons of benthic invertebrate abundance inside and outside fish exclosure cages indicated that the presence of fish decreased invertebrate abundance. These results support the idea that ducklings and fish compete for invertebrates and that, under certain circumstances, the negative effect of acidification on fish may produce a beneficial effect for ducklings. /// Данное исследование сосредоточено на двух парах прудов в штате МЭН, США, сходных по физическим свойствам, но существенно различающихся по кислотности. В Лососевом пруду (рН 6,3) имеется рыба, а в Гразном пруду (рН 4,5) рыбы нет. Вторая пара - пруд Киллман (рН 6,5) и пруд Безимянный (рН 4,8) находятся на расстоянии 14 км и также сходны по физческим показателям; в пруду с реакцией, близкой к нейтральной, рыба имеется а в закисленном пруду - рыбы нет. Утята черной утки Anas rubripes, содержащиеся на закисленных прудах, росли быстрее, чем в прудах с нейтральной реакцией. Различия в поведении также показали, что закисленные пруды - лучшие местообитания для утят. Утята на закисленных прудах тратят меньше времени на поиск и движения и больше - на питание и отдых, чем на прудах с нейтральной реакцией. Имело место существенное перекрывание в диете форели и уток; два из трех рассчитанных показателей свидетельствуют, что утята, обитающие в прудах с водой нейтральной реакции, вместе с рыбой, питаются пищей, более сходной с таковой у рыб, чем на закисленных
ISSN:0030-1299
1600-0706
DOI:10.2307/3565916