Wednesday, May 28, 2008 - 9:30 AM
390

Who eats more in tropical streams: Shrimp or insects?

Nelmarie Landrau, Biology, Institute for Tropical Ecosystem Studies, Via Madrid SJ65 Valle San Juan, Trujillo Alto, PR 00976

Consumers play an important role decomposing leaf litter in streams. However, we know little about their individual roles. Our objectives for this research were to determine the role of macro invertebrates in the process of leaf decay and to determine whether the availability of nutrients affects the role that biota plays in the process of leaves decomposition. The hypotheses for this research were: (1) nutrients accelerate leaf breakdown and lead to high rates of decomposition when macro invertebrates are also present; (2) shrimp will have a higher rate of decomposition than insects. The study was conducted in an artificial stream facility for three weeks and applying the following treatments: nutrients and leaves with shrimp (Xiphocaris) and no nutrients with leaves and shrimp (Xiphocaris); nutrients and leaves with aquatic insect (Ephemeroptera) and no nutrients with leaves and aquatic insect (Ephemeroptera) and the controls were leaves with nutrients and only leaves without nutrients. Cecropia leaves were used, which were pre-conditioned for different amounts of time before starting the treatments. We measured leaf weight changes for each treatment. Leaves exposed to shrimps with and without nutrients had the highest effects on leaf weight change by day. Mayfly effects were larger than shrimp effects for both nutrient treatments by biomass of organism.


Web Page: Xiphocaris, Ephemeroptera, tropical stream

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