The Ocean as a Physical Environment
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Isolated by wind, water, and time, geological landforms have eroded into seastacks. |
To the human observer, the ocean is oddly two dimensional, a stark horizon separating the sky from
the reflecting, undulating water. What we don't see is the continuation of a landscape that extends
completely beneath the horizon. What is also invisible to us is the profound interaction between
the atmosphere and the ocean.
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Sedimentary rock provides essential habitat for seabirds and marine mammals. |
The underwater landscape is an extension of coastal landforms, shaped by
coastal geological processes.
Much of it is covered with sediment that has been carried into the ocean by glaciers, wind or water.
Olympic Coast National Marine Sanctuary contains three major submarine canyons, the Nitinat,
Juan de Fuca and Quinault canyons.
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Ocean conditions have a profound effect on the weather. |
Together, ocean and atmosphere form the global climate system
in which energy from the sun and water, in its twin forms of vapor and liquid, are constantly
in flux. Sunlight heats the ocean. Seawater evaporates and carries heat back into the sky. This
relationship, played out at vast scale, creates weather systems that can originate in the tropics,
travel the ocean's breadth, and end as snowstorms in mountain ranges deep within the North
American continent.
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Winter storms and crashing waves contribute to the dynamics of the Olympic Coast landscape. |
As climate drives weather, weather creates wind that pushes at the ocean surface, creating
waves that carry physical energy across the ocean and spills it onto shore.
Prevailing weather on the Olympic Coast varies from low-pressure weather systems that dominate in
the winter, to high-pressure weather systems that dominate in the summer. Winter "lows" bring
rainy weather and waves that pound the coast from the west and southwest. Summer "highs" bring
sunny weather and waves that come from the north and northwest.
The Japan, California and Davidson currents
all affect the Olympic Coast. The Japan Current connects the "blue," or open ocean, to the "green"
or coastal ocean. The California and Davidson currents connect north to south, with currents along
the coast that alternate direction between the seasons. Each of the currents affects the distribution
of marine life as well as the distribution of marine debris that is carried on the sea's surface.
Tsunamis, waves generated by earthquakes and underwater landslides,
are a potent risk on the Olympic Coast. Geologic records of tsunamis, left as telltale deposits of
sand sometimes miles from the coastline, remind us that on the "Pacific Ring of Fire," an
earthquake in Asia can trigger devastating waves on the Olympic Coast. Likewise, earthquakes here
have brought havoc to coastal communities as far away as Japan.
Physical processes in the ocean have a strong influence on biological productivity. Summer
upwelling drives the explosive production of phytoplankton ("plant" plankton),
which, in turn, produces food for zooplankton ("animal" plankton), forage fish and predators.
The process is driven by winds from the north, that carry warmer surface water offshore. Cold,
nutrient-rich water from along the continental shelf and submarine canyons rises to take its place,
carrying nutrients into the sunlight zone. This triggers plankton blooms and drives the entire
marine food chain.
Life in the ocean is affected by ocean chemistry. Ocean chemistry
is affected by living processes. Plankton blooms sometimes create toxic conditions for other
organisms when the plankton themselves produce substances that are toxic in the food chain. These
are known as Harmful Algal Blooms. Hypoxia,
or unusually low oxygen conditions, occur when the sudden death of plankton blooms depletes oxygen
in seawater, depriving fish and other organisms of this necessary life-sustaining substance.
Our entire ocean system is responding to changes in carbon dioxide levels in the atmosphere. As
carbon dioxide is taken up in seawater, subtle changes in the ocean’s acidity are being observed.
Known as ocean acidification, these changes may have dramatic effects on
marine organisms with calcium in the skeletons and shells. Scientists are racing the clock to
understand these changes and their effects on marine life.
Contact for page content: Robert Steelquist
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