Effects of spatial and environmental factors on benthic a macroinvertebrate community

Abstract

Interactions between terrestrial and aquatic systems influence the structure of river habitats and, consequently, affect their benthic macroinvertebrate composition. The aim of this study was to evaluate the effects of spatial and environmental variables (local physical and chemical variables of water and regional landscape characteristics) on the benthic macroinvertebrate community of the Pandeiros River Basin. Biotic and abiotic variables were evaluated at 20 sampling sites distributed across the primary sub-basins of the Pandeiros River Basin. We found that the macroinvertebrates were primarily affected by environmental variables. The most important environmental variables were pebble proportion and water conductivity at the local scale (7.2% of explained variation) and elevation and nonforest areas at the regional scale (6.9% of explained variation). The spatial variables were representative only in shared explained variation with the environmental matrices (local-spatial = 0.2% and regional-spatial = 2%; all matrices combined = 4.4%). Sampling sites with higher non-forest areas, lower elevations, and steeper slopes presented low pebble fractions and higher electrical conductivities. Habitat diversity was lower when the percentage of pebbles decreased, resulting in decreased taxonomic richness and diversity in macroinvertebrate communities. High electrical conductivities and non-forest areas also had negative effects on macroinvertebrate density due to the loss of habitat diversity. We conclude that higher proportions of pebbles in the substrate and higher altitudes were likely the primary variables for positive effects on the taxonomic richness and density of macroinvertebrate communities.

Factors that drive zooplankton diversity in Neo-Tropical Savannah shallow lakes

“…The lake's sediment was quite muddy and even unstable during this study, with the allochthonous deposition of sediments around the lake. This situation confirms the influence of the environmental quality of the pond derived from the land uses in the area (Lopes et al, 2014;Rezende et al, 2014).…”

“…Nabout et al (2006) also got similar phytoplankton composition in geographically proximate floodplain shallow lakes, even with different geomorphological characteristics and degrees of human impact (Xiong et al, 2016). Therefore, in deterministic processes based on niche theory, the species have different ecological requirements, leading to different responses to environmental gradients (Heino et al, 2015a, b;Xiong et al, 2016), and increasing the beta diversity in heterogenic systems (Rezende et al, 2014).…”

“…turbidity and total nitrogen) and biotic interactions (e.g. increase of environmental heterogeneity by macrophytic) that filters and select persistent species within a community, as observed in other tropical lentic systems (Lopes et al, 2014;Rezende et al, 2014). As example, a checklist done for Cladocerans in five shallow lakes evaluated by this study (Bonita, Cedro, Gansos, Joaquim Medeiros and Carás) showed a peculiar composition of this micro fauna, specially associated to environmental condition (shallow systems with a macrophyte dense cover) when they are situated in protected areas (Sousa & Elmoor-Loureiro, 2012;Anton-Pardo et al, 2015).…”

Generalized Linear Models to Identify Key Hydromorphological and Chemical Variables Determining the Occurrence of Macroinvertebrates in the Guayas River Basin (Ecuador)

“…The importance of elevation in determining the water quality has often been reported [14,53,54]. However, its impacts often depend on several physical and chemical variables that are correlated with the altitude, such as temperature and oxygen levels, the type of substrates (coarser sediment is present more at a higher elevation), flow velocity and the level of disturbance related to land use and waste water discharges, due to less intensive human activities at higher elevation.…”

“…The study of the Intag cloud forest region in northwestern Ecuador also used the BMWP-Col index; however, no relation between environmental variables and macroinvertebrates was identified [13]. Other studies used macroinvertebrate richness and composition to define temporal and spatial changes [8,14]. A biological index for the region is still lacking, despite several new indices that have been developed to better study the water quality, such as the Índice Multimétrico del Estado Ecológico para Ríos Altoandinos (IMEERA) [15], the Andean Biotic Index (ABI) [16] and the Neotropical Low-land Stream Multimetric Index (NLSMI) [2].…”