Session Lead: Eric Schott (UMCES Institute of Marine and Environmental Technology)
Co-Lead(s): Sarah Preheim, Maya Gomes
Session Format: Oral presentations + discussion
Session Description:
The 2025 Chesapeake Bay Program report (A Critical Path Forward for The Chesapeake Bay Program Beyond 2025) reframes the restoration of the Bay with a focus on habitat restoration, and in the context of regional or local partnerships. The long-term goal of meeting nutrient reduction targets and decreasing deep channel hypoxia has not been abandoned. Instead the goal have been refined to include increasing the quantity and quality of tidal shallow water fish habitat and in areas closer to shore. A key barrier to creating quality fish habitat is localized hypoxia and anoxia, which typically occurs in the spring through autumn. Consequently, habitat volume and access to benthic foraging is restricted in the months that fish are most active. Localized hypoxia and anoxia can also impact nitrogen cycling, trophic energy transfer, redox state and therefor bioavailability of trace metals, and biological mercury processing. The resolution of anoxic stratification in late summer or autumnal “turn overs” can be dramatic, with upwelling of sulfide-rich anoxic waters that kills fish and other aerobic nekton. Deep water upwelling can also bring sulfur metabolizing bacteria to the surface, in what is sometimes termed a “pistachio tide”.
In 2025, Baltimore’s Inner Harbor experienced a 3 week-long pistachio tide where the upwelling of sulfidic, anoxic waters killed up to 100,000 menhaden. It also fueled a bloom of green sulfur bacteria that sent strong sulfide odors over 3 km away and made the downtown waterfront area unpleasant. The location and severity of this disaster was surely related to both local natural and anthropogenic conditions, because stratification and anoxia are often worsened by human modifications to shores and waterways. Additionally, urban and suburban runoff can be locally intense, bringing warm water that carries nutrients and contaminants to the upper layers of locally deep waters. Chesapeake Bay shorelines and nearshore habitats are dramatically engineered for ports and harbors, both contemporary and historical. Therefore localized hypoxia has resulted in pistachio tides and other types of blooms that compromise habitat restoration in many settings in Chesapeake Bay. The search for solutions will require a solid understanding of what factors drive local hypoxia, and a collaborative approach to re-engineering the system to minimize factors when possible.
This session invites presentations on studies, data, or ideas that can contribute to minimizing local hypoxia, especially in highly engineered locations. This may include definition of hypoxic areas, measurements or models that visualize the spatiotemporal extent of localized hypoxic areas, or the impacts on invertebrate and fish habitat. It may also address other forces that impinge on local hypoxic zones such as runoff, seasonal patterns, or legacy sediments. Approaches may range from classic field or remote sending methods, continuous monitoring data, or new analytical techniques. There may be opportunities for deep learning strategies to investigate the causes and consequences of localized hypoxia, with the goal of using knowledge to predict or develop mitigation strategies to protect Chesapeake Bay’s living resources.