46 WILD / READING THE WILD PACIFIC / 07

The Ocean Is Breathing

The water off the peninsula can change without the tide explaining it. Sometimes the wind is bringing a deeper part of the Pacific toward the light.

A metaphor for upwelling

The ocean does not breathe like lungs. Here, breathing is a way to picture an exchange: surface water moves away from the coast and deeper water rises to replace it. Scientists call this upwelling. It is a wind-driven process, distinct from the daily rise and fall of tides.

Wind sets water in motion

Along the Pacific Northwest, north winds common in spring and summer favor offshore transport of surface water. Earth’s rotation helps turn the net movement to the right of the wind in the Northern Hemisphere. Colder, nutrient-rich water rises near shore to replace the water moved offshore.

Why this working coast depends on it

Nutrients support microscopic algae, which help feed marine food webs. Shellfish filter plankton from the water. Conditions on the outer coast help shape the water reaching estuaries such as Willapa Bay, though tides, river input and mixing matter too. Upwelling is not a guarantee of good shellfish-growing conditions.

The exchange can reverse

Southerly winds often favor onshore transport and downwelling, pushing surface water toward the coast and downward. These patterns vary with weather and season. Productive water can also bring challenges: deeper water may be low in oxygen, and some algal blooms produce toxins. Color, clarity and smell cannot tell you whether shellfish are safe.