Spatial scale and the diversity of macroinvertebrates in a Neotropical catchment

Abstract

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.

Benthic macroinvertebrate community structure in a stream of the north-west region of Paraná State, Brazil

“…The invertebrates were classified into functional feeding groups (FFG), gathering-collector, filtering-collector, predator, scraper and shredder, based on Brazilian and Neotropical literature (Fernández & Domínguez 2001, Cummins et al 2005, Costa et al 2006, Wantzen & Wagner 2006. For those taxa belonging to more than one functional group, the individuals were divided between each possible trophic category (Ligeiro et al 2010a). Nematoda, Diptera and Ostracoda were not classified due to their many feeding habits.…”

Effect of leaf decomposition stage and water temperature on fragmentation activity of a shredder invertebrate species in lotic ecosystems

“…The attractiveness of a given leaf detritus for invertebrates depends on the chemical composition, physical structure, stage of microbial colonization and decomposition level of the detritus, which can vary with the exposure time in the aquatic environment (Ligeiro et al, 2010). Most studies in tropical streams has sought to expand the knowledge about the infl uence of interspecifi c variation in the quality of senescent detritus on the fragmentation by invertebrates, either for food or for producing larval case (Moretti et al, 2009;Navarro et al, 2013).…”

Diversity and distribution of mollusks along the Contas River in a tropical semiarid region (Caatinga), Northeastern Brazil

“…Several features allow this invasive species to dominate, including the capability of aestivating (Abílio et al 2007), tolerance to low dissolved-oxygen concentrations, high temperatures (Mitchell & Brandt 2005), and brackish and saline waters, and also because it can reproduce parthenogenetically (see references in Santos et al 2012). The dominance of M. tuberculata in rivers and reservoirs of semiarid regions in northeastern Brazil has been mentioned in the literature (e.g., Abílio et al 2006, Santana et al 2009, Lima et al 2013. Melanoides tuberculata is also considered to be responsible for the decline or extirpation of some native Brazilian species, such as members of Biomphalaria and Pomacea (see references and discussion in Vidigal et al 2005).…”

“…Records of wide distribution of mollusk communities along rivers, as recorded in the present study, are rare in studies of macroinvertebrates conducted in many Brazilian regions, especially when the studies use a Surber sampler. In these cases, the malacofauna is generally undersampled, and the records indicate a much localized occurrence (e.g., Ligeiro et al 2010, Hepp et al 2010. Thus, the use of an inappropriate sampler to collect mollusks seems to not have affected knowledge of the diversity of the Contas River malacofauna.…”