Assessing biological diversity and thermodynamic indicators in the dam decommissioning process. (February 2020)

• Record Type: Journal Article
• Authors: Linares, Marden S.; Callisto, Marcos; Marques, João Carlos
• Is Part Of: Ecological indicators. Volume 109(2020)
• Publication Date: 2020-02
• Subjects: Benthic macroinvertebrates -- Diversity -- Eco-exergy -- Tropical shallow lakes -- Water level fluctuation; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2019.105832
• Languages: English
• ISSNs: 1470-160X

Abstract

Highlights: Benthic assemblages have different taxonomic structure in a regulated lake. The regulated lake has less complex benthic macroinvertebrate assemblages. We recommend eliminating Pandeiros Dam to restore the regulated lake. Abstract: Water level regulation is one of the most common anthropogenic disturbances of lentic ecosystems, which is especially evident in shallow lakes. The objective of this study was to assess the ecological effects of water level regulation in a shallow lake using thermodynamic indicators to support decision makers in a dam decommissioning process. For that we tested three hypotheses: 1) the regulated lake supports lower taxonomic diversity than the naturally fluctuating lake; 2) the structure of the benthic macroinvertebrate assemblage is different in the regulated lake than in the naturally fluctuating lake; 3) the regulated lake supports less complex benthic macroinvertebrate assemblages than the naturally fluctuating lake. Our results show that the first hypothesis, tested using taxa richness, Shannon-Wiener and Simpson diversity indices, was not validated. The second hypothesis was tested using taxonomic composition and was validated, with the two types of lakes exhibiting dissimilar macroinvertebrate assemblages. The third hypothesis, tested using two thermodynamic based indicators, eco-exergy and specific eco-exergy, was partially supported, which was illustrated, overall, by higher eco-exergy (degree of complexity) of the benthic assemblages in the naturally fluctuating lake, although the specific eco-exergies (capacities to use external energy resources) were similar. As a whole, our results endorse the importance of natural water level fluctuations as a driving force in shallow lake ecosystems and reinforced the idea that dam decommissioning is a good option for restoring natural conditions in this type of ecosystem.