Predation on Recent marine ostracod populations of southwestern Spain

Abstract

This paper analyzes evidences of predation observed in ostracod populations collected in the southwestern Spanish shelf (0–70 m depth). Examination of seventy-two samples and almost 17,300 specimens allowed recovering more than 135 bored valves and carapaces. Percentages of bored specimens are very low (< 2%), with the highest values in isolated samples with low to very low ostracod densities. Two main types of boreholes can be distinguished: a) Oichnus paraboloides Bromley, accounting for over 70% of the total boreholes; and b) Oichnus simplex Bromley. Boreholes are concentrated mainly in the central and dorsal areas of the valves. Borehole diameter shows a positive but not significant correlation with the sizes of the predated valves. This diameter is usually higher in shallow marine areas. Predation affects the most abundant species of this shallow marine environment (mainly adults and the last juvenile instars). Ornamentation seems to be secondary in the predatory strategy.