Journal Article

Widespread global increase in intense lake phytoplankton blooms since the 1980s

Ho, Jeff C., Michalak, Anna M., Pahlevan, Nima

2019

Overview

Freshwater blooms of phytoplankton affect public health and ecosystem services globally 1 , 2 . Harmful effects of such blooms occur when the intensity of a bloom is too high, or when toxin-producing phytoplankton species are present. Freshwater blooms result in economic losses of more than US$4 billion annually in the United States alone, primarily from harm to aquatic food production, recreation and tourism, and drinking-water supplies 3 . Studies that document bloom conditions in lakes have either focused only on individual or regional subsets of lakes 4 – 6 , or have been limited by a lack of long-term observations 7 – 9 . Here we use three decades of high-resolution Landsat 5 satellite imagery to investigate long-term trends in intense summertime near-surface phytoplankton blooms for 71 large lakes globally. We find that peak summertime bloom intensity has increased in most (68 per cent) of the lakes studied, revealing a global exacerbation of bloom conditions. Lakes that have experienced a significant ( P  < 0.1) decrease in bloom intensity are rare (8 per cent). The reason behind the increase in phytoplankton bloom intensity remains unclear, however, as temporal trends do not track consistently with temperature, precipitation, fertilizer-use trends or other previously hypothesized drivers. We do find, however, that lakes with a decrease in bloom intensity warmed less compared to other lakes, suggesting that lake warming may already be counteracting management efforts to ameliorate eutrophication 10 , 11 . Our findings support calls for water quality management efforts to better account for the interactions between climate change and local hydrological conditions 12 , 13 . Analyses show that the peak intensity of summertime phytoplankton blooms has increased in 71 large lakes globally over the past three decades, revealing a worldwide exacerbation of bloom conditions.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/705/1046 / 704/106/286 / 704/158/2459 / Algorithms / Analysis / Chemical properties / Climate Change / Contamination / Distribution / Drinking water / Economic aspects / Economic impact / Ecosystem assessment / Ecosystem services / Environmental aspects / Environmental Monitoring / Eutrophication / Food production / Humanities and Social Sciences / Hydrology / Image resolution / International aspects / Lakes / Landsat / Landsat satellites / Local climates / multidisciplinary / Phytoplankton / Phytoplankton bloom / Plankton / Public health / Quality management / Remote sensing / Satellite Imagery / Science / Science (multidisciplinary) / Time series / Tourism / Toxins / Trends / Water bloom / Water Quality / Water quality management / Water supply