Spatial scale and the diversity of macroinvertebrates in a neotropical catchment
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2010-02
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1. Lotic ecosystems can be studied on several spatial scales, and usually show high
heterogeneity at all of them in terms of biological and environmental characteristics.
Understanding and predicting the taxonomic composition of biological communities is
challenging and compounded by the problem of scale. Additive diversity partitioning is a
tool that can show the diversity that occurs at different scales.
2. We evaluated the spatial distribution of benthic macroinvertebrates in a tropical
headwater catchment (S.E. Brazil) during the dry season and compared alpha and beta
diversities at the scales of stream segments, reaches, riffles and microhabitats (substratum
types: gravels, stones and leaf litter). We used family richness as our estimate of diversity.
Sampling was hierarchical, and included three stream segments, two stream reaches per
segment, three riffles per reach, three microhabitats per riffle and three Surber sample
units per microhabitat.
3. Classification analysis of the 53 families found revealed groups formed in terms of
stream segment and microhabitat, but not in terms of stream reaches and riffles. Separate
partition analyses for each microhabitat showed that litter supported lower alpha diversity
(28%) than did stones (36%) or gravel (42%). In all cases, alpha diversity at the
microhabitat scale was lower than expected under a null model that assumed no
aggregation of the fauna.
4. Beta diversity among patches of the microhabitats in riffles depended on substratum
type. It was lower than expected in litter, similar in stone and higher in gravel. Beta
diversities among riffles and among reaches were as expected under the null model. On
the other hand, beta diversity observed was higher than expected at the scale of stream
segments for all microhabitat types.
5. We conclude that efficient diversity inventories should concentrate sampling in different
microhabitats and stream sites. In the present study, sampling restricted to stream
segments and substratum types (i.e. excluding riffles and stream reaches) would produce
around 75% of all observed families using 17% of the sampling effort employed. This
finding indicates that intensive sampling (many riffles and reaches) in few stream
segments does not result in efficient assessment of diversity in a region.
Descrição
v. 55, p. 424-435, 2010.
Palavras-chave
Beta diversity, Cerrado, Diversity partitioning, Hierarchy, Taxa richness
Citação
LIGEIRO, Raphael.; MELO, Adriano S.; CALLISTO, Marcos. Spatial scale and the diversity of macroinvertebrates in a neotropical catchment. Freshwater Biology (Print), v. 55, p. 424-435, 2010. Disponível em: <http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2427.2009.02291.x/epdf>.