In laboratories across the Salish Sea, Canadian scientists have just revealed what was invisible: a checklist of 924 diatom taxa, the microscopic foundation of one of the world's most vital ocean regions. By pulling together 11,469 historical and new records spanning from 1800s inventories to today's molecular sequencing, researchers led by Andrew Simon at the University of Alberta and Mark Webber at IMERSS have created the first comprehensive baseline of diatoms in this northeast Pacific bioregion—answering a direct call from the United Nations.
Why this matters becomes clear when you consider what diatoms do. These single-celled photosynthetic microalgae are responsible for roughly 20% of global photosynthesis and form the very base of marine food webs, yet they remain largely invisible to policymakers and the public. The Salish Sea, traditional territory of the Coast Salish peoples and home to nine million people, is experiencing rapid urbanization, industrial growth, and increased marine shipping. Diatom populations respond quickly to changes in water quality and pollution, making them powerful early-warning indicators of ecosystem stress. Without knowing what diatoms live here now, scientists cannot measure what changes tomorrow will bring.
The research team's work directly addresses a key recommendation from the UN Global Compact's recent "Plankton Manifesto," which highlighted how these microscopic organisms are crucial for addressing climate change, biodiversity loss, and pollution. The manifesto specifically urged the scientific community to develop comprehensive plankton atlases to biomonitor marine ecosystem health. This Salish Sea checklist—published in the Biodiversity Data Journal—does exactly that.
What makes this achievement particularly significant is how the team assembled it. Historical records of Salish Sea diatoms have been fragmented since early inventories in the 1800s, with only scattered surveys across the twentieth and twenty-first centuries. "The Salish Sea has long been studied for its rich marine biodiversity," Simon explains. "Yet, until now, the history of research on its primary producers has been fragmented, and we have lacked a consolidated baseline record." The researchers integrated literature, microscope analysis, and molecular sequencing—bridging the gap between academic researchers and community scientists in a way that demonstrates sustained collaboration between institutions and local expertise.
The implications ripple across entire ecosystems. Diatoms are vital to shorebirds and shellfish, fish and marine mammals—organisms that depend on their abundance and diversity. Mark Webber, IMERSS's resident diatomist, puts it simply: "This baseline provides a reference point for understanding changes that could ripple across the entire web of life." The checklist will now support researchers and policymakers in environmental assessments as they monitor whether the Salish Sea is thriving or deteriorating.
The work also demonstrates how plankton research at the local level can unlock solutions for global challenges. As the research team concludes, their partnership model—combining community expertise and observation with access to microscopy and molecular technologies—shows how to bridge gaps between citizen science and institutional capacity. With this new baseline in place, the Salish Sea becomes a reference point for understanding not just its own health, but how entire marine ecosystems respond to change.