Influence of grazer type and abundance on plant-herbivore interactions in streams

✍ Scribed by Gary A. Lamberti; Stanley V. Gregory; Linda R. Ashkenas; Judith L. Li; Alan D. Steinman; C. David McIntire

• Publisher: Springer
• Year: 1995
• Tongue: English
• Weight: 837 KB
• Volume: 306
• Category: Article
• ISSN: 1573-5141
• DOI: 10.1007/bf00017689

✦ Synopsis

Grazer-periphyton interactions were investigated in 11 laboratory streams holding a range of densities of three herbivore taxa during a 32-d experiment . Effects of grazers on algae were strongest with Dicosmoecus gilvipes caddisflies, intermediate with Juga silicula snails, and weakest with Baetis spp . mayflies . Algal standing crop, export, and gross primary production declined logarithmically with increasing grazer density . Algal turnover rate, however, increased with grazer abundance . At high densities of all grazers, responses in most algal parameters converged, suggesting that high grazing pressure, regardless of taxon, will similarly affect periphyton . Growth of both Dicosmoecus caddisflies and Juga snails was density-dependent, with the highest growth rates occurring at the lowest densities . Caddisflies displayed high growth rates but low efficiency in resource use . Snails had lower growth rates but were more efficient in resource use . The coexistence of Dicosmoecus and Juga, or other competing herbivores, in natural streams may be related to these fundamental differences in life history strategies .