Journal of the Marine Biological Association of the United Kingdom



Research Article

Siphon nipping of the bivalve Amiantis purpurata by the electric ray Discopyge tschudii in Mar del Plata, Argentina


Florencia  Arrighetti a1c1, Juan Pablo  Livore a1 and Pablo E.  Penchaszadeh a1
a1 Facultad de Ciencias Exactas y Naturales–UBA & Museo Argentino de Ciencias Naturales, Avenida Angel Gallardo 470 (1405) Buenos Aires, Argentina

Article author query
arrighetti f   [Medline] [Google Scholar
livore jp   [Medline] [Google Scholar
penchaszadeh pe   [Medline] [Google Scholar

Abstract

A total of 67 Discopyge tschudii was captured. Individuals were sexed, measured and their stomach content analysed. Siphon tips of the bivalve Amiantis purpurata from each stomach were individually counted, weighed and their length and width measured. The size–frequency distribution of the local population of A. purpurata was surveyed for two years. Siphons of A. purpurata were the main food item in 90% of individuals having stomach contents. The clam population was markedly bimodal, with 24 mm and 46 mm mean shell length for the younger and older size-classes, respectively. Grazing by D. tschudii on A. purpurata varied with size and sex of the fish. Small rays mainly ingested small siphons and large rays large siphons. Nipped siphon tips were longer in male than in female rays.

(Received May 17 2004)
(Accepted May 9 2005)


Correspondence:
c1 e-mail: flora@bg.fcen.uba.ar