FYS: Turnover in Baltimore Harbor

3 Credits.

Baltimore Harbor is a vital resource to Baltimore and surrounding regions. When temperatures drop in the fall, the surface waters become dense and sink, bringing bottom waters to the surface. This type of turnover is common in many water bodies. However, due to anthropogenic changes, these turnover events can cause phytoplankton blooms that color the water in dramatic green or mahogany hues and lead to fish kills and bad odors. In Fall of 2025, the turnover brought sulfide-filled waters fueled a bloom of green sulfur oxidizing bacteria and emitted a rotten-egg smell even documented by influencers on social media. Other years do not see these types of blooms. In this class, students will visit the Harbor to make water quality measurements and collect samples to document this year’s turnover event. Students will experience some of the uncertainties involved in natural science research – sometimes these blooms happen and sometimes they do not. Regardless of if a bloom happens in Fall 2026, students will use their observations along with other sources including publicly available water quality, hydrological, and weather data, news stories, and peer-reviewed papers to ask: 1) Why do these blooms happen in some years and not others?, 2) What role does land-use change play in the blooms?, and 3) How might these blooms be prevented in the future? Through the course, students will gain knowledge in how Earth and Planetary Scientists study coastal ecosystems and how interdisciplinary knowledge and approaches can address environmental challenges that impact urban waterways and the communities that surround them.