Physical-chemical determinant properties of biological communities in continental semi-arid waters

Abstract

Throughout human history, water has undergone changes in quality. This problem is more serious in dry areas, where there is a natural water deficit due to climatic factors. The aims of this study, therefore, were (i) to verify correlations between physical attributes, chemical attributes and biological metrics and (ii) from the biological attributes, to verify the similarity between different points of a body of water in a tropical semi-arid region. Samples were collected every 2 months, from July 2009 to July 2011, at seven points. Four physical attributes, five chemical attributes and four biological metrics were investigated. To identify the correlations between the physicochemical properties and the biological metrics, hierarchical cluster analysis (HCA) and canonical correlation analysis (CCA) were applied. Nine classes of phytoplankton were identified, with the predominance of species of cyanobacteria, and ten families of macroinvertebrates. The use of HCA resulted in the formation of three similar groups, showing that it was possible to reduce the number of sampling points when monitoring water quality with a consequent reduction in cost. Group I was formed from the waters at the high end of the reservoir (points P1, P2 and P3), group II by the waters from the middle third (points P4 and P5), and group III by the waters from the lower part of the reservoir (points P6 and P7). Richness of the phytoplanktons Cyanophyceae, Chorophyceae and Bacillariophyceae was the attribute which determined dissimilarity in water quality. Using CCA, it was possible to identify the spatial variability of the physicochemical attributes (TSS, TKN, nitrate and total phosphorus) that most influence the metrics of the macroinvertebrates and phytoplankton present in the water. Low macroinvertebrate diversity, with a predominance of indicator families for deterioration in water quality, and the composition of phytoplankton showing a predominance of cyanobacteria, suggests greater attention to the management of water resources.

Aquatic insects decline in abundance and occupy low‐quality artificial habitats to survive hydrological droughts

“…Water pH and conductivity (as a proxy for total dissolved solids) may increase slightly in lentic systems during extended droughts (Ludovisi & Gaino, ; Mosley et al., ) and changes in pH and conductivity ranges shape aquatic insect communities (Kietzka et al., ; da Rocha et al., ). We found that dragonfly diversity in natural ponds and beetle diversity in artificial reservoirs were highest where pH was close to neutral, implying that habitats deviating from neutral pH were dominated by single, generalist species.…”

“…High insect species richness, diversity, and abundance is associated with water clarity (O'Neill et al. ; da Rocha et al., ). Increased turbidity, as a result of lower frequencies of water replenishment, has a strong limiting effect on aquatic insect occupancy.…”

“…High insect species richness, diversity, and abundance is associated with water clarity (O'Neill et al 2015;da Rocha et al, 2016).…”

Estimating concentrations of chlorophyll-a and suspended sediments in a continental aquatic ecosystem using remote sensing

“…There was an increase in the concentration of suspended sediments in the reservoir between the periods under evaluation (Figure 4). Due to the processes of soil erosion, entrainment and deposition, the concentration was higher in June 2018 ( Figure 4B), aggravated by the degrading action of man on the environment (LOPES et al, 2011;CHAVES et al , 2019); as a consequence, water sources are being altered (ALMEIDA et al, 2016;ROCHA et al, 2016;ANDRADE et al, 2020).…”

Desenvolvimento de Casa de Vegetação automatizada em pequena escala

“…Além disto, grande parte das cidades apresenta deficiência na rede de esgotos, valendo-se de seus rios como sumidouros de esgotos. O excesso de nitrogênio, fósforo e carbono orgânico leva a proliferação de microrganismos heterotróficos e processos de eutrofização crônica em riachos, rios, lagoas e reservatórios(Rocha et al, 2016). Desta forma, o presenta trabalho teve por objetivos: (I) apresentar um diagnóstico baseado no monitoramento das variáveis hidroquímicas em período chuvoso; (II) analisar espacialmente o comportamento das variáveis desde as nascentes na Chapada do Araripe até a foz do rio na cidade Icó/CE.A área de estudo está localizada no Sul do Ceará na Região do Cariri, correspondendo à bacia do rio Salgado (Figura 1).…”