Harmful algal blooms

Low dissolved oxygen levels put aquatic life in Puget Sound at risk – but not everywhere. A combination of careful monitoring efforts and powerful computer models are now enabling scientists to identify which areas of our regional waters are most prone to low oxygen levels, when, and why. This article is part of a series of reports funded by King County about the quest to define healthy oxygen levels in Puget Sound.

Chronic stress from lack of oxygen can make aquatic organisms more vulnerable to disease, pollution, or predation. Low oxygen can also result in reduced habitat for some species. Aquatic species may escape, acclimate, adapt, or die with exposure.

The Washington State Department of Ecology has reached one hundred Eyes Over Puget Sound reports. Since 2011, Ecology has provided aerial observations and documented visible features at the surface of Puget Sound from a floatplane. This unique perspective from the air featured Puget Sound's natural beauty, its oceanographic complexity, and its ecological treasures. It also raised awareness of the challenges that the water body is facing today. Our image-rich documentation of known eutrophication indicators ranges from algal and Noctiluca blooms to macroalgae, jellyfish, and human stressors. It provides a visually captivating time-capsule of issues facing Puget Sound. The report is rich in educational and outreach material, inspired numerous news reports, and drew academic and public attention during the period of marine heat wave of the north Pacific, The Blob.

How do excess nutrients trigger low oxygen conditions in Puget Sound and what do those conditions mean for the species that live here?

Diverse communities of microscopic organisms called phytoplankton make up the base of the aquatic food web. In that role, they are essential to the tiny animals that eat them, but phytoplankton are not dependent on others. Thanks to chlorophyl, these tiny organisms can generate their own energy from nutrients and sunlight. Despite their critical importance to a great diversity of sea life in Puget Sound, phytoplankton can also contribute to low-oxygen conditions, and some can be harmful in other ways.

A new report from the Puget Sound Ecosystem Monitoring Program details the effects of a changing climate on Puget Sound in 2019, and documents how these changes moved through the ecosystem to affect marine life and seafood consumers.