Wind Effects for Floating Algae Dynamics in Eutrophic Lakes

Yuchao Zhang,Min Zhang,Steven Loiselle,Tao Han,Yuanyuan Jing,Minqi Hu,Pengfei Zhan,Lai Lai,Kun Shi

doi:10.3390/rs13040800

Abstract

Wind-speed decline is an important impact of climate change on the eastern Asian atmospheric circulation. Although wind does not determine algae biomass in eutrophic lakes, it is a decisive factor in the formation and severity of algae blooms. Based on 2000–2018 MODIS images, this study compared the effects of wind speed on algal blooms in three typical eutrophic lakes in China: Lake Taihu, Lake Chaohu and Lake Dianchi. The results indicate that climate change has different effects on the wind speed of the three lakes, but a common effect on the vertical distribution of algae. A wind speed of 3.0 m/s was identified as the critical threshold in the vertical distribution of chlorophyll-a concentrations in the three study lakes. The basic characteristics of the periodic variation of wind speed were different, but there was a significant negative correlation between wind speed and floating algal bloom area in all three lakes. In addition, considering lake bathymetry, wind direction could be used to identify locations that were particularly susceptible to algae blooms. We estimated that algal bloom conditions will worsen in the coming decades due to the continuous decline of wind, especially in Lake Taihu, even though the provincial and national governments have made major efforts to reduce eutrophication drivers and restore lake conditions. These results suggest that early warning systems should include a wind-speed threshold of 3.0 m/s to improve control and mitigation of algal blooms on these intensively utilized lakes.

Highlights

Harmful algae blooms (HABs), usually associated with floating cyanobacteria, have international consequences on the availability of freshwater resources, with implications on health and economic activities [1,2]
Direct drivers of algal bloom formation, extension and permanence are influenced by changes to key local meteorological conditions, including air temperature, precipitation and wind speed [3,4,5]
The Moderate Resolution Imaging Spectroradiometer (MODIS) data were downloaded from the National Aeronautics and Space Administration (NASA) EOS Data Gateway (EDG)

Summary

Introduction

Harmful algae blooms (HABs), usually associated with floating cyanobacteria, have international consequences on the availability of freshwater resources, with implications on health and economic activities [1,2]. 2 of 11 Wind influenced processes link meteorology, lake circulation and lake bathymetry through stratification, nutrient dynamics and trophic states [6,7,8]. Recent studies indicate tha climate change is expected to reduce wind speed in the eastern Asian atmospheri meteorology, lake circulation and lake bathymetry through stratification, nutrient dynamics circulation [9]. A secondary decreasedproduction, wind speed favors lake on stratification, but the influence with surface waters [10,11,12,13]. In either deep or used shallow the link between wind regime and HABs dynamics of early warning the changes in waterThese withdrawal based predicted or actua can be defined andsystems used for or management purposes. China Environmental Quality Bulletin 2019, Ministry of Ecology and Environment of China

Algal Bloom Monitoring

Wind Dynamics

4.4.Discussion

Implications for Administrators

Conclusions