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Vol. 47 No. 5, 2008
Taxonomic and Size Structures of Aquatic Macroinvertebrate Assemblages in Different Habitats of Tropical Streams, Costa Rica
Romina E. Principe
La Selva Biological Station, Organization for Tropical Studies, Puerto Viejo de Sarapiquí, Heredia, 41001, Costa Rica
Romina E. Principe (2008)
Taxonomic and size structures of macroinvertebrate assemblages
associated with different habitats of tropical streams of Costa Rica
were analyzed. Surber samples were taken in riffle and run
habitats in 2 streams. Invertebrates were identified and
measured, and the biomass was estimated. The taxonomic richness
and total abundance were higher in riffle habitats.
Correspondence analysis showed a clear separation between riffle and
run samples. The IndVal method identified the characteristic
assemblages in each habitat type. Tricladida, Hydrachnidia,
Leptophlebiidae, Hydropsychidae, Simulium
sp., Corynoneurini, Orthocladiinae, and Empididae showed significant
indicator values for riffle habitats; whereas Bivalvia, Tanypodinae,
and Chironomini were the characteristic taxa from runs. The
length-frequency distribution of riffles differed from that in runs in
both streams as measured by Kolmogorov-Smirnov tests. The largest
organisms were found in run habitats, with macroinvertebrates belonging
to the 1st size class being the most abundant in riffles.
Although larger organisms were found in runs, differences in total
biomass between habitats were not observed due to the high number of
small invertebrates collected in riffles. The size spectrum for
the entire benthic community showed that the total biomass was
relatively equitably distributed among the size classes, although a
peak was suggested for medium size classes. When the size
spectrum was separately analyzed in each habitat, a peak was also
suggested in riffles. Differences in the physical attributes of
riffles and runs were clearly reflected in the taxonomic composition of
the size spectra. Patterns observed in taxonomic and size
structures may indicate different ecological functioning at the habitat
level in the tropical streams studied.
Key words: Benthos, Size spectra, Organism distribution, Community structure, Lotic ecosystem.
*Correspondence: Tel: 54-0358-4676167. Fax: 54-0358-4676230. E-mail:rprincipe@exa.unrc.edu.ar
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