Pleuston communities are buffered from regional flood pulses: the example of ostracods in the Paraná River floodplain, Brazil

Abstract

1. It is widely acknowledged that sudden, large-scale flood pulses are drivers of benthic and planktonic biodiversity change in floodplains. The impact of such pulses on pleuston (biotic communities associated with root systems of floating plants) remains to be demonstrated. Here, we investigate the effects of local and regional drivers on seasonal changes in abundance and diversity of ostracod communities in pleuston. 2. Temporal and spatial distribution patterns of species richness, abundance, diversity and evenness of ostracods associated with the floating water hyacinth, Eichhornia crassipes, in a lentic environment from the upper Paraná River floodplain, were investigated in relation to local, as well as regional, environmental factors. Ostracods were sampled monthly over an annual cycle (March 2004-February 2005. Twenty-seven species were found, representing the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Both diversity and abundance of ostracod communities showed seasonal changes, although species turn-over during the year was limited. 3. We tested two hypotheses concerning the causality of these fluctuations: seasonal recruitment and influx of allochthonous ostracods during the flood pulse. Our results indicate that seasonal recruitment is more likely to be the driver of fluctuations in relation to the flood pulse. We postulate that pleuston communities are buffered against possible detrimental effects of flood pulses.

Spatial and temporal patterns of ciliate species composition (Protozoa: Ciliophora) in the plankton of the Upper Paraná River floodplain

“…In this way, some authors have attributed the flood pulse as the main factor structuring the distinct aquatic communities in the Upper Paraná River floodplain (Lima et al, 1998;Bonecker et al, 2005). On the other hand, some studies have suggested that the spatial heterogeneity in floodplain systems, including the differences in the hydrodynamic and connectivity, is an important factor on the communities' organization, more than the temporal changes determined by the flood pulse (Velho et al, 2004;Higuti et al, 2007).…”

Biodiversity of non-marine ostracods (Crustacea, Ostracoda) in the alluvial valley of the upper Paraná River, Brazil

“…Also beta diversity was relatively low, as similarity in ostracod communities between the various lakes, rivers and channels was high. This is illustrated by the community of Manezinho, a relatively small backwater of the main Paraná River channel, where the pleuston (root systems) of Eichhornia crassipes (only one of several possible host plants) turned out to comprise 27 species, half the total gamma diversity of the entire alluvial valley (Higuti et al, 2007).…”

“…benthos, phytoplankton, zooplankton, fish and/or macrophytes . However, Higuti et al (2007) argued that meiobenthic groups, such as ostracods, in pleuston (floating root systems) might actually be buffered from the putatively detrimental effects of sudden flood pulses, as floating plants will simply follow changing water levels with minimal changes in environmental conditions. Therefore, flood pulses are expected to mainly affect benthic habitats (including the littoral), and the fact that most habitats in the present study are indeed floating plants might explain the lower relevance of the regional factor 'system'.…”

“…These communities are referred to as pleuston (Esteves, 1998;Por and Rocha, 1998;Por, 2002). In this way, the ostracods constitute one of these pleuston communities in the Paraná River floodplain (Higuti et al, 2007).…”

Checklist de ostrácodes (Crustacea, Ostracoda) dulcícolas do Pantanal Sul Mato-grossense, Brasil

“…Entre os crustáceos de água doce, cladóceros e copépodos têm sido relativamente bem explorados em nosso país, tanto em termos ecológicos como em estudos sobre taxonomia. Por outro lado, a despeito de os ostrácodes serem abundantes na maioria dos corpos de água, ainda existem poucos estudos em ambientes aquáticos continentais brasileiros (Würdig & Freitas, 1988;Higuti, 2006;Higuti et al, 2007Higuti et al, , 2009bHiguti et al, , 2010Miranda, 2008;Mormul et al, 2010;Pereira, 2010;Matsuda, 2011;Chaves 2012;Matsuda et al 2015a,b;Higuti & Martens, 2016).…”