Environmental factors affecting chlorophyll-a concentration in tropical floodplain lakes, Central Brazil

Abstract

Chlorophyll-a (Chl-a) has been widely used in the assessment and monitoring of aquatic environments. Local and regional factors can influence Chl-a concentrations; moreover, the connection between terrestrial and aquatic ecosystems is a major paradigm within aquatic ecology. Here, we investigate the spatial distribution of Chl-a concentrations in a tropical savannah floodplain in Central Brazil using a broad spatial data set (a 900-km north-south transect; 30 lakes). We determine the relative importance of local environmental variables (limnological and morphometric) and regional (land use) and spatial distances (spatial eigenvector) on Chl-a concentrations using partial linear regression. We evaluate the direct and indirect effects of local and regional variables on Chl-a with a path analysis. Our results indicate spatially autocorrelated patterns wherein lakes in closer proximity showed more similar levels of Chl-a than more distant lakes. Local environmental factors explained most variance in Chl-a (R = 0.28; P = 0.02); more specifically, both lake area and total nitrogen significantly (P< 0.05) explained Chl-a concentrations (direct effects). Meanwhile, regional factors neither directly nor indirectly predicted Chl-a. Thus, internal processes, such as the resuspension of sediment (which is frequent in tropical floodplains), rather than external influences, were the main factors that explained Chl-a concentrations in this study. The importance of local variables in structuring Chl-a concentration may be used to guide the conservation of the aquatic ecosystems in these tropical floodplain lakes.

Spatial and Temporal Variations of Water Quality and Trophic Status in Xili Reservoir: a Subtropics Drinking Water Reservoir of Southeast China

“…Chlorophyll a is an important pigment in photosynthesis of phytoplankton. Chlorophyll a is commonly used to characterize the algal biomass, and then to describe the degree of eutrophication in water bodies [6][7][8] . Chlorophyll a concentration was 3.56-31.62 μg/L in Xili reservoir.…”

A review of spatial statistical approaches to modeling water quality

“…As scale can be an issue in these kinds of weights matrices, some researchers construct eigenvectors at different scales. For instance, De Oliveira Marcionilio et al (2016) calculated their weights matrix using eight different distance classes (50–450 m, with an interval of 50 m) to incorporate the effect of scale on their analysis. The SSN modeling approach was initially proposed to incorporate weights based on the stream distance, flow volume, or stream order.…”

“…Most papers used a standard weights matrix derived using a binary coded sites-by-edges table and distance between the sites. Some modify it based on the distance classes (De Oliveira Marcionilio et al, 2016). The majority of papers report RSAC of the model, except Strangway et al (2017).…”

Environmental Factors Influencing Chlorophyll-a Concentration in Tri An Reservoir, Vietnam

“…Chlorophyll-a (Chl-a) concentration is widely recognized as a proxy for phytoplankton biomass and used in eutrophication studies worldwide [2]. Moreover, Chl-a is an essential indicator of water quality [3,4] and the method for obtaining its concentration is more straightforward and faster than the classical analysis of phytoplankton biomass [5]. Thus, Chl-a has been widely used in the assessment and monitoring of aquatic environments [4].…”