CS35 Trophic Dynamics
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
ManatungeJ, Saitama University, Saitama, Japan, jagath@post.saitama-u.ac.jp
Asaeda, T, , Saitama University, Saitama, Japan, asaeda@post.saitama-u.ac.jp
 
PREY SIZE SELECTIVITY OF PLANKTIVORES FORAGING IN STRUCTURALLY COMPLEX HABITATS
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The efficiency of visual predators may often be affected by complexity of habitat. However, relatively few studies have examined how vegetation structure influences the prey selectivity of planktivores. Assuming that both planktivores and their prey reside in vegetated areas, we explored how increasing stem density influences the prey selection behavior of Pseudorasbora parva preying on Daphnia pulex. We simulated these habitats in laboratory experiments with artificial vegetation of six densities and conducted a series of foraging experiments with four fish (60 mm TL) and a prey density of 10 prey/1 of known initial size structure. We determined the final size structure of remaining prey after 3, 6, 9 and 12 minutes. We found a consistent pattern of decreasing tendency of fish to select large-sized prey with increasing density of vegetation. Fish selected the largest size class at low stem densities, and did not exercise selectivity and consumed prey in direct proportion to availability in high complexity habitats. These results suggest that vegetation density can have an impact on prey selectivity, and the mechanism can be described using optimal foraging theory.