Abstract
To estimate the impact of aggregate mining on a marine ecosystem, fish assemblages and phytoplankton communities were analyzed using environmental DNA metabarcoding. Metabarcoding analysis revealed 152 fish amplicon sequence variants (ASVs) (88 in September and 118 in February), which were assigned to 29 orders, 62 families, 104 genera, and 114 species (73 in September and 89 in February). Heatmap analysis showed that the fish assemblages in the mining area clearly differed from those in the surrounding area and that Pagrus major, Lateolabrax japonicus, Zeus faber, and Eopsetta grigorjewi were significantly more abundant there than in the surrounding area. In the phytoplankton community in September, the phyla Cyanobacteria and Haptophyta differed significantly between the mining area and its surroundings. By contrast, no such significant differences were identified in February, presumably due to the low temperature impeding phytoplankton growth. Taking these findings together, mining activities clearly affect fish and phytoplankton communities, but further long-term study is required to assess their impacts on marine ecosystems.
Highlights
To meet increasing demands for either residential or industrial construction, considerable amounts of sand and gravel are currently extracted from the marine continental shelf instead of depleted rivers or estuaries (Kim and Grigalunas, 2009)
We analyzed the impacts of aggregate mining on the fish assemblages and phytoplankton communities in Exclusive Economic Zone (EEZ), the southern sea of Korea, using environmental DNA (eDNA) metabarcoding analysis
Statistical analyses showed a clear difference in fish assemblages between the mining sites and the surrounding area
Summary
To meet increasing demands for either residential or industrial construction, considerable amounts of sand and gravel are currently extracted from the marine continental shelf instead of depleted rivers or estuaries (Kim and Grigalunas, 2009) Mining activities for such aggregates are often accompanied by physical changes at the sites, such as the creation of pits and furrows of various sizes, or environmental changes in the vicinity, such as changes in the sediment composition (Birklund and Wijsman, 2005; Kim and Grigalunas, 2009). Suspended sediment (SS) containing organic matter, nutrients, or other contaminants (e.g., heavy metals) is released by mining activities Such SS can spread up to approximately 20 km away from the mining site, impacting on the neighboring ecosystem (Birklund and Wijsman, 2005; Jones et al, 2016; Won et al, 2017). The discrepant or limited information from previous studies is due to the use of traditional survey methods (e.g., visual surveys and trawling), which are expensive, laborious, and timeconsuming, making it difficult to conduct large-scale surveys with statistically meaningful sample sizes
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