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Journal of BirdLife Australia
RESEARCH ARTICLE

Foraging behaviour and diet of American Oystercatchers in a Patagonian intertidal area affected by nutrient loading

Germán Oscar García A B D , Juan Pablo Isacch A B , Agustina Gómez Laich A C , Mariano Albano A B , Marco Favero A B , Daniel Augusto Cardoni A B , Tomás Luppi A B and Oscar Iribarne A B
+ Author Affiliations
- Author Affiliations

A Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida Rivadavia 1917, C1033AAJ Buenos Aires, Argentina.

B Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3250, B7602AYJ Mar del Plata, Argentina.

C Centro Nacional Patagónico (CENPAT) – CONICET, Boulevard Brown 2915, U9120ACD Puerto Madryn, Argentina.

D Corresponding author. Email: garciagerman@argentina.com

Emu 110(2) 146-154 https://doi.org/10.1071/MU09066
Submitted: 28 July 2009  Accepted: 7 January 2010   Published: 26 May 2010

Abstract

Eutrophication increases the biomass of opportunistic green macroalgae that covers intertidal zones, and macroalgal blooms may affect the intertidal invertebrate community and predation of invertebrates by shorebirds. In San Antonio Bay, Argentina, eutrophication from the discharge of wastewater from a coastal town produces periodic macroalgal blooms. Our aim was to assess if macroalgal blooms affect the foraging behaviour and diet of the American Oystercatcher (Haematopus palliatus). A macroalgal transplant experiment was performed in order to evaluate how epifaunal species respond to a macroalgal canopy. The availability of prey for Oystercatchers, and their foraging behaviour and diet, were analysed in two paired channels with different nutrient loadings. Oystercatchers generally ate the most profitable prey and avoided prey with a profitability value lower than the mean rate of energy intake. During the macroalgal blooms, Oystercatchers avoided two prey species with high profitability values, shifting their foraging strategy and feeding onto a suboptimal prey but with a high encounter rate. Our results suggest that nutrient loadings and the macroalgal blooms that they generate have effects on the diet and foraging behaviour of Oystercatchers, which results in an increase of the average rate of energy intake of Oystercatchers foraging along the channel subject to a macroalgal bloom.


Acknowledgements

We thank P. Gómez Laich for language editing and P. Gonzalez for helpful comments in an earlier version. We appreciate the improvements in English language usage made by P. Lowther through the Association of Field Ornithologists’ program of editorial assistance. We thank M. Narvarte and R. González (from Instituto de Biologia Marina y Pesquera ‘Alte Storni’) for logistical assistance. This work was supported by grants from CONICET (PIP 2851) and Universidad Nacional de Mar del Plata.


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