Intensive aquaculture affects lake's trophic status and aquatic floral diversity†

Abstract

This study aims to assess the impact of intensive aquaculture on a lake that has experienced significant anthropogenic impacts. Specifically, it investigates the consequences of aquaculture activities, such as Trapa cultivation (water chestnut) and fish rearing, on the lake's water quality, trophic state, and floristic diversity, with a primary emphasis on algae and macrophytes. Satellite imageries spanning the last five decades, from 1976 to 2022, were analyzed to understand the impact of urbanization and changes in land use and land cover within the lake's catchment. The study found that aquaculture activities negatively impacted algae and macrophytes' diversity, dominance, and community structure in the freshwater lake. The study reported a total of 61 algal species from five families during both sampling phases. Dominant species belonged to the Chlorophyceae and Euglenophyceae families, alongside several diatom species. Notably, the reported algal species served as bioindicators of organic pollution, as assessed by the algae pollution index. During the second year of sampling, intensive fish-rearing activities disrupted the macrophytic diversity, which was replaced by the proliferated growth of planktonic algae, resulting in the biotic shift of the lake's floristic diversity. The study provides valuable insights into the effective management of lakes impacted by intensive aquaculture, shedding light on the intricate relationships between aquaculture practices and the ecological dynamics of freshwater ecosystems in developing countries.