Environmental, spatial, and land-use determinants as key drivers of phytoplankton in urban lakes

Abstract

The increasing occupation of urban spaces reflects denser populations in these areas. In this context, access to nature has become essential to a high quality of life, blue spaces are becoming more common in cities. However, the impact of urbanization on these ecosystems is still unclear. This study aimed to identify environmental, spatial, and landscape factors influencing phytoplankton biovolume in urban lakes during different hydrological periods. Data were collected from 14 lakes in Goiânia, Goiás, Brazil, during the dry and rainy periods between 2020 and 2023. This included samples of phytoplankton, as well as data on local environmental conditions, landscape, and spatial factors. The linear models showed that biovolume increase with richness, and with Shannon-Wiener diversity index. Using NMDS (non-metric multidimensional scaling), we found that biovolume values in the lakes during the hydrological periods were associated with phytoflagellates and green algae. During the rainy period, variance partitioning explained 8.9% of the variation, with significant contributions from the landscape, environmental, and spatial factors. During the dry period, 11.2% of the variation was explained, with significant contributions from the landscape, environmental, spatial factors, and a combined effect of the landscape and environmental factors. Using Structural Equation Modelling we found a negative influence of physicochemical parameters and nutrients and a positive influence of landscape on phytoplankton biovolume. These results therefore provide an initial understanding of the factors structuring biodiversity in tropical urban aquatic ecosystems, as well as their influence on the ecosystem services these ecosystems provide.