The lentic and lotic characteristics of habitats determine the distribution of benthic macroinvertebrates in Mediterranean rivers

Abstract

1. The importance of flow-related factors to benthic organisms, as well as the role of habitat conditions in shaping aquatic communities during low-flow periods, have been recognised. Despite this, the preferences of macroinvertebrates to the ratio of lentic to lotic habitats at the reach scale have not been accurately quantified in most instances. 2. Aquatic invertebrates and habitat features in a range of temporary rivers in Sardinia were investigated. The investigation focused on the flow-related characteristics that contribute to defining the lentic-lotic condition of the river reaches. The relation of habitat features to benthic taxa distributions was assessed using multidimensional scaling. The main aim of the paper was to quantify the responses of taxa to the different lentic and lotic habitat conditions by applying hierarchical logistic regressions. Finally, taxon optima were aligned along the lentic-lotic gradient and the responses of different taxonomic groups compared. 3. Unbroken waves and imperceptible flow were correlated with benthic taxa variability, suggesting local hydraulics and turbulence have a major role in regulating community composition. The overall lentic-lotic character of the river reaches was also clearly related to the benthic taxa distribution. More than 80% of taxa were significantly related to the lentic-lotic gradient, and an asymmetrical response curve was the predominant model. 4. Benthic groups showed taxon optima clustered in different ranges of the lentic-lotic gradient. Odonata, Coleoptera, Hemiptera, and Mollusca preferred clearly lentic conditions. Diptera mainly ranged on the lotic side of the gradient, while Trichoptera were relatively uniformly distributed across the gradient. Ephemeroptera taxa clustered in intermediate lentic-lotic conditions, with two species preferring extremely lentic habitats. In general, optima converged at intermediate and extremely lentic conditions, presumably due, respectively, to the coexistence of different lentic and lotic features and to the highly diverse environmental characteristics under extremely lentic situations. 5. These results support the conclusion that dissimilar ecological factors act on benthic taxa along the lentic-lotic range and species favouring different lenticlotic conditions are subjected to pressures of different nature. This should not

Spatial patterns of macrobenthos taxonomic and functional diversity throughout the ecotones from river to lake: A case study in Northern China

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Geodiversity as a potential indicator of stream health in ecological quality assessment systems

“…Several studies have shown, so far, a positive link between heterogeneous habitat conditions and freshwater biodiversity, but studies that directly link geodiversity with freshwater biodiversity are still scarce. For instance, macroinvertebrate communities are known to be affected by local habitat features, such as the channel dimensions, the water flow velocity and the substrate type (Buffagni, 2021;Graeber et al, 2017;Karaouzas, Theodoropoulos, et al, 2019;Theodoropoulos et al, 2020), but only a few studies have examined the relationship between stream geodiversity and macroinvertebrate diversity (Kärnä et al, 2018(Kärnä et al, , 2019. Kärnä et al (2019) found a strong indication of a positive effect of catchment and local geodiversity on benthic macroinvertebrate and diatom species richness and suggested that geodiversity could be used as a proxy indicator for assessing stream species richness, with particular emphasis placed on the role of geodiversity as an additional tool for biodiversity conservation.…”

Are protected areas effective in preserving Alpine stream morphology and biodiversity? A field study in the oldest Italian National Park

“…All sampled reaches were characterized by a prevailing siliceous substrate, an altitude ranging from 1200 to 1900 m a.s.l., and similar human activities nearby (hiking, summer tourism, and pasture) but different levels of morphological alterations. To quantify them, we applied the South European River Habitat Survey (hereafter RHS) and related indices (Buffagni, 2004;Buffagni & Kemp, 2002;Raven et al, 1998): the Habitat Quality Assessment (HQA), the Habitat Modification Score (HMS), and the Lentic-Lotic River Descriptor (LRD). We also examined the available climatic data prior to the two sampling years (data available for the meteorological station inside the GPNP, located in Ceresole, and available from 1999; www.arpa.piemonte.it).…”