Urban Sea Systems and why they are important: A preliminary characterization

Publication Date

9-15-2025

Document Type

Article

Publication Title

Estuarine Coastal and Shelf Science

Volume

322

DOI

10.1016/j.ecss.2025.109274

Abstract

We identify three components that comprise Urban Seas Systems: 1) one or more port cities, 2) the proximal marine portion of the system connected directly to the open ocean, and 3) the entire enclosing watershed feeding surface runoff into the sea including both natural and human influences. These “systems of systems” commonly host large, culturally diverse populations, major industries, transportation hubs, and academic or government research establishments. As such, Urban Sea Systems have become crucial hubs in our global/regional supply chain networks providing goods, jobs, and markets for most nations. Yet, owing to the declining quality of the runoff, the urban-suburban effluent, and the shipping-transport activities, these marine sectors have become some of the most polluted and anthropogenically impacted places on earth. Given that there are more than 200 such systems, in the ensemble, they may well be the most intense “hot spots” of human impacts on our combined ocean-atmosphere system. Balancing the strengths and shortcomings of complex Urbans Sea Systems must begin with insightful interaction of many stakeholder expectations. Long-term responsible stewardship will require bold, next generation approaches to managing such complex systems. As an early step toward those solutions, we outline below a preliminary characterization of Urban Seas. We focus herein on three distinctly different systems: 1) The Salish Sea, located on the west coast of the North America, extends across the Canadian-U.S. border and is adjacent to an active convergent plate boundary; 2) The Chesapeake Bay on the Atlantic coast of North America is located along a passive continental margin with six states sharing jurisdiction over its watershed-maritime sectors; and 3) The Island of Oahu Hawaii, a passive intra-plate island example of an Urban Sea System. In our characterization, we seek to assemble a viable rubric to enhance discussions of many different types of these systems. Although each Urban Sea System is unique, many experience similar challenges and stresses. The Salish, Chesapeake, and Oahu systems differ considerably, therefore characterizing the similarities and différences can offer enhanced insights to many such systems. The threat of hazards, like volcanism, earthquakes, tsunamis, mass wasting, floods, wild-fires, sea level rise along with major storm events, and land subsidence can inform deliberations about many systems. Increased pollution and debris-loading from the watersheds, impacts of climate change, declining fisheries, and implementation of renewable alternative energy potential can directly affect all Urban Sea System outflow into our global ocean.

Funding Sponsor

Commission Géologique du Canada

Department

Moss Landing Marine Laboratories

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