ISSN: 0029-8549 (printed version)
ISSN: 1432-1939 (electronic version)
Abstract Volume 109 Issue 2 (1997) pp 259-264
Michael H. Horn
Department of Biological Science, California State University at Fullerton, Fullerton, CA 92834, USA fax: (714) 773-3426; e-mail: mhorn@fullerton.edu
Received: 1 May 1996 /Accepted: 1 August 1996
Abstract Studies were conducted at the La Selva Biological Station in the Atlantic lowlands of Costa Rica and in a greenhouse in California to assess the potential role of a Neotropical fish in dispersing the seeds of a rain forest tree. Feeding experiments showed that the seeds of Ficus glabrata H. B. K., a major, canopy-forming riparian tree, require approximately 18-36 h to pass through the digestive tract of Brycon guatemalensis Regan, an abundant riverine fish whose adult diet consists largely of leaves and fruits of this fig tree. The seeds were still viable after passing through the fish's gut but germinated somewhat more slowly than seeds that had been left in the fig exposed to air or floated in water. Stem elongation of seedlings from seeds that had passed through the fish's gut was faster than that of seeds in the other two treatments. Placement of seeds upstream may be more important than enhanced germination for plants such as Ficus that produce large numbers of seeds. Radio telemetry showed that five of six tagged fish had moved distances of 0.1-1 km upstream; seven other fish with transmitters, including three large males, were not relocated and may have moved into tributary streams for spawning or feeding. These findings suggest that Brycon can disperse large numbers of Ficus seeds and help maintain the upstream populations of the tree.
Key words Brycon guatemalensis · Ficus glabrata · Gut passage time · Seed germination · Radio telemetry
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