The re-emergence of seasonal hypoxia in Lake Erie: Causes and implications

Abstract

Hypoxia is an extreme environmental condition occurring where dissolved oxygen is present at concentrations /L. During the mid-late 20th century, Lake Erie began experiencing exaggerated seasonal hypoxia in its central basin as a result of anthropogenic phosphorous loading. The seasonal hypoxia began impacting aquatic organisms negatively, such as benthic macroinvertebrates, and the Canada-US Great Lakes Water Quality Agreement (GLWQA) was signed in 1972 to address and combat the issue through monitoring and reduction of phosphorous loading. After 1972, hypoxic conditions were observed to decrease for a short while. However, during the early 1990s, seasonal hypoxia as a result of algal blooms began to emerge once again in the central basin of Lake Erie. The goal of this paper is to address and discuss the causes of the re-emergence of hypoxic events, the impact of hypoxia on Lake Erie’s ecosystem and aquatic organisms, the implications of climate change as it relates to hypoxic events, and current management efforts relating to hypoxia. This paper was written for ENV 466 (Great Lakes Issues) as a literature review on an issue facing the Great Lakes.