Rocky Reefs
Much of Olympic Coast National Marine Sanctuary's underwater landscape mirrors its coastline.
Where the lowland is gentle, the beaches and underwater environment are also gentle - the seafloor
a mix of broad gravel, sand and silt flats. But the coastline found in the northern part of the
sanctuary – rocky cliffs, broad terraces of bedrock exposed at low tide, seastacks, islets and
barely-submerged wash rocks – reflects what lies underwater. Where the shore ends abruptly in
jumbled rocks, the same landforms extend seaward, beneath the waves and out of sight.
Rocky reef habitats in the sanctuary teem with life. In the ocean, "structure" is the key to
habitat. A jumbled underwater landscape provides such structure. Crevices and caves offer shelter.
Channels and passageways are "highways" connecting different parts of the convoluted underwater
reef realm and allowing fish roam with relative protection. Animal life clings to every surface,
creating food and complex micro-environments for invertebrates and fishes. In the upper layers of
water where sunlight penetrates, seaweeds thrive. Deeper, in the darkness of the sea floor, rocky
environments support corals, sponges and a host of other organisms. Rockfish claim territories
where the subtle topography creates currents and eddies that concentrate drifting food and give
them shelter in the current so they can conserve energy.
Many rocky reefs on the Olympic Coast represent islands on the seafloor and are surrounded by broad
expanses of sandy seafloor. Among these "islands" fish like lingcod, sculpins, greenling and
rockfish breed, rear their young and feed, often staying in the same vicinity for life. The Pacific
giant octopus, sea urchins, predatory sea stars and other invertebrates thrive in these food-rich,
oxygen-rich and diverse habitats.
Contact for page content: Robert Steelquist
indicates a link leaves the site. Please view our