Illegal mining impacts on freshwater Potamonautid crab in a subtropical Austral highland biosphere reserve

Tatenda Dalu*, Timothy Dube, Farai Dondofema, Ross N. Cuthbert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)
1 Downloads (Pure)

Abstract

The contamination of surface water by heavy metals, especially mercury, has become a global issue. This problem is particularly exacerbated in rivers and reservoirs situated in developing nations. Therefore, the objective of this study was to evaluate the effects of illegal gold mining activities on freshwater Potamonautid crabs and to quantify the mercury levels in 49 river sites under three land use classes: communal areas, national parks and timber plantations. We used a combination of field sampling, multivariate analysis and geospatial analyst tools to quantify mercury concentrations in relation to crab abundances. Illegal mining was prevalent throughout the three land use classes, with mercury (Hg) being detected in 35 sites (71.5 %). The mean range of Hg concentrations detected across the three–land uses was as follows: communal areas 0–0.1 mg kg−1, national parks 0–0.3 mg kg−1 and timber plantations 0–0.06 mg kg−1. Mean Hg geo–accumulation index values showed strong to extreme contamination in the national park, with strong contamination observed for communal areas and timber plantations; furthermore, the enrichment factor for Hg concentrations in the communal and national park areas showed extremely high enrichment. Two crab species (i.e., Potamonautes mutareensis, Potamonautes unispinus) were found in the Chimanimani area, with P. mutareensis being the dominant taxa in the region across all the three land use areas. The national parks had higher total crab abundances than communal and timber plantation areas. We observed negative and significant K, Fe, Cu and B effects on total Potamonautid crab abundances, but surprisingly not for other metals such as Hg which might reflect their widespread pollution. Thus, illegal mining was observed to impact the river system, having a serious impact on the crab abundance and habitat quality. Overall, the findings of this study underscores the need to address the issue of illegal mining within the developing world as well as to establish concerted effort from all stakeholders (e.g., government, mining companies, local communities, and civil society groups) to help protect the less charismatic and understudied taxa. In addition, addressing illegal mining and protecting understudied taxa aligns with the SDGs (e.g. SDG 15-life on land) and contributes to global efforts to safeguard biodiversity and promote sustainable development.
Original languageEnglish
Article number165251
JournalScience of the Total Environment
Early online date04 Jul 2023
DOIs
Publication statusEarly online date - 04 Jul 2023

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