A closer look at the main actors of Neotropical floodplain food webs: functional classification and niche overlap of dominant benthic invertebrates in a floodplain lake of Paraná River

Abstract

ABSTRACT. Functional classifi cation of animals is necessary to enhance the predictive power of food web models. However, while there is a large database for functional classifi cation of benthic invertebrates (Functional Feeding Groups, FFG) in the temperate zone, the attribution of individual species of riverine invertebrates is still in its infancies in the Neotropical Region. Diff erent authors hypothesized that diet breadth was larger in the Tropics, however detailed analyses are scarce. In the present study we aimed at classifying dominant benthic taxa of the Middle Paraná River fl oodplain (Argentina) into trophic guilds by diet and niche overlap analysis. We sampled twelve taxa of benthic invertebrates from a fl oodplain lake during low water season and performed a gut content analysis as a baseline for FFG classifi cation. We also used available diet information of other common taxa for statistical analysis. Then, we compared the variance of niche overlap, using Pianka's index, with that of simulated null model. After that we grouped taxa using Morisita similarity index with a threshold of 0.6 and compared niche overlap with null models within and between FFGs. Observed variance of niche overlap was greater than expected by chance, confi rming the presence of FFGs among analyzed taxa. Considering trophic similarity of species, we identifi ed four FFGs: collectors, omnivores, herbivores and predators. Niche overlap was greater than expected by stochastic null models within FFGs, and smaller between FFGs. Nearly one third of analyzed taxa were classifi ed in a diff erent FFG than their congeners of the Holarctic region. This result indicates that classifi cations performed in the Holarctic region should be used with care in the Neotropical region, even in subtropical systems.

Evaluation of Soil Biodiversity in Alpine Habitats through eDNA Metabarcoding and Relationships with Environmental Features

“…For example, studies on the ecological role of families or communities would make it possible to understand in a functional way the role that these families play in soil and the functions of the ecosystem to which they belong. Some studies have already classified invertebrates using functional classifications, such as trophic classifications, based on their role in the food webs of organisms [50,51] or classifications based on the relation between invertebrate attributes and environmental features [52]. If a better understanding of ecosystem functions can be developed, there will be a corresponding simplification when it comes to evaluating the associated ecosystem services.…”

Spinitectus asperus and Klossinemella iheringi , intestinal nematodes of Prochilodus lineatus (Pisces, Prochilodontidae) from the alluvial plain of the Middle Paraná River, Argentina

“…Its trophic habits are detritivores, having been recognized that it feeds mainly on epiphyton and the organic matter of the benthos (Emiliani & Brandi 1972, Bowen et al 1984, Bayo & Cordiviola de Yuan 1996. In studies carried out in the fl oodplain of the Middle Paraná River, the remarkable signifi cance of the detritus energy pathway has been evidenced (Marchese et al 2014, Saigo et al 2016.…”