Environmental drivers of the benthic macroinvertebrates community in a hypersaline estuary (Northeastern Brazil)

Abstract

Introduction The estuarine community of benthic macroinvertebrates spatially varies in response to changes in environmental variables in these ecosystems. Understanding this variability helps our understanding the mechanisms structuring these communities. Aim Assess the structural aspects of the benthic macroinvertebrate community in a hypersaline estuary, and to relate to environmental variables that influence the community structure along the estuary. Methods The study was conducted at Tubarão river estuary in May 2015. We sampled two estuarine areas (upper and lower), and in each zone were sampled six points composed of two replicas, one sampled in sandy bottom and the other in muddy bottom. Samples of benthic macroinvertebrates and estuarine environmental variables were collected. Environmental drivers of the benthic macroinvertebrate community were determined by Distance-based Linear Models analysis. The contribution of individual species to the dissimilarity between the areas and substrate types were determined by analysis of the percentage of similarity. Results The composition of benthic macroinvertebrate community differed between the upper and lower areas, although it was similar between the muddy and sandy bottoms. The variation in the benthic community between areas was mainly related to the influence of salinity in the upper area. In the lower area, the variation of the macroinvertebrates was related to salinity, associated with other variables in the sandy (temperature, turbidity and dissolved oxygen) and muddy (temperature, total dissolved solids and dissolved oxygen) substrates. Taxa which contributed most to the dissimilarity between the upper and lower areas were Nereididae (17.89%), Anomalocardia brasiliana (15%) and Cirratulidae (10.43%). Conclusions Salinity was the main driver of the structural aspects of the benthic macroinvertebrate community in the upper area of the estuary, although in the lower area a set of variables have structured benthic macroinvertebrates in the hypersaline estuary studied. In addition, the largest mangrove cover and less influence of the tide, may have favored the greater abundance of macroinvertebrates in the upper area.

Spatial scale drives diversity patterns of benthic macroinvertebrate communities in tropical estuaries

“…The substantial salt incursion into these ecosystems, together with a reduced continental influence, favors the establishment and survival of marine species throughout the entire ecosystems, which explains the higher diversity observed along all zones in these estuaries. In semi‐arid tropical estuaries, benthic organisms are adapted to abrupt environmental variations, not only in terms of salinity, but in relation to other environmental parameters (e.g., sediment type, pH, temperature, redox potential) (Nebra et al 2016; Medeiros et al 2016 b ). Due to the absence of a clear longitudinal environmental gradient in these ecosystems, seasonal environmental variations seemed to have a greater effect on the structuring of the total beta diversity of estuarine macrobenthic communities, changing the relative importance of species replacement (drought period) and richness difference (rainy season) components.…”

Environmental heterogeneity influences life‐form richness and species composition but not species richness of aquatic macrophytes in tropical coastal rivers

“…Especially in coastal wetlands, studies on benthic macroinvertebrate and fish assemblages have found that their richness and diversity may be supported by the variation in ecosystem characteristics, environmental gradients, and heterogeneity (Medeiros et al, 2016; Teichert, Lepage, Chevillot, & Lobry, 2018). Although global patterns of variation in macrophyte communities have also been related to EH (Alahuhta et al., 2017), its relative importance to other spatial factors at regional and local scales is not well known.…”

Niche overlap of benthic macrofauna in a tropical estuary: diurnal variation

“…Based on the precipitation standards, the climate of the region is characterized by higher evaporation rates and a lower pluviometric index with the rainy season occurring between February and May and the dry season occurring between June and January (INMET 2017). Additionally, the freshwater input comes from subterranean waters and from the lower precipitation of the region (Queiroz & Dias 2014, Medeiros et al 2016.…”

“…Estuarine dynamics are influenced by seasonal, monthly & daily variations, and consequently the concentrations of organic matter, nutrients, and water level can oscillate during these periods (Dyer 1979). These variations come from chemical, physical and biological alterations, causing changes at spatial and temporal scales in the functioning of biological communities (Officer & Lynch 1981;Day et al 2012;Medeiros et al 2016).…”