May 22, 2006
Nutrient Rich Waters of the Inside Passage
Submitted by Cruise West Exploration Leader, Peter Rumm
One afternoon while on the Wilderness Inside Passage Itinerary, we were off the coast of Baranof Island near Red Bluff Bay. After five years of cruising and exploring this area I am still awestruck by the scene Mother Nature presents. We noticed a whale spout or two very close to shore, there were harbor porpoise feeding near the whales, as if that was not enough a pod of killer whales passed by. Salmon were jumping out of the water everywhere as if nature was providing an endless fountain of fish. The mountains behind this scene were snow capped and reached 4,500 feet straight up for from sea level. The scene could not have been have been dreamed up or perhaps only by the artist Wyland himself. But such scenes do exist and we soaked it up with the warm sun on our faces and we became lost in time transfixed by an abundance that was Eden like.
Why so much life in one place? Often our guests expect these deep dark cold waters to contain less life than other places they have visited such as Hawaii or the Caribbean. But nothing could be further from the truth. The cold waters we cruise through support some of the greatest varieties and abundance of marine life found anywhere in the world. We commonly see lions main jelly fish with diameters of about a foot or more, however they have been documented at 8 feet across with tentacles over a hundred feet long! The giant pacific octopus with a world record of 600 pounds, although they average 50-90 pounds are found in the waters of the Inside Passage. Often while exploring the intertidal zone we come across sea stars (star fish) the size of dinner plates and bigger! My friends and I found an 11-foot long squid, dead, on Cape Fanshaw one summer. And historically just off the coast of Alaska, the largest animal on the planet, the blue whale use to be frequently spotted, unfortunately due to poor stewardship and over hunting the sighting of blue whales in the gulf of Alaska are now fleeting and unconfirmed.
Cold water has the ability to trap and hold in important gases such as oxygen and carbon dioxide. Marine life just like terrestrial life use and exchange these gases between plants and animals. The colder the water the more these life-sustaining gases are likely to be available. Also as you move closer to the polar regions of the world you have longer summer sunlit days. These are the two perfect conditions to support the first step in the food chain, phytoplankton. Phytoplankton is simply a fancy term for algae growing in the water, some of it almost to small to see, uses the suns energy to photosynthesize, reproduce or “bloom.” Algae booms in the northern latitudes are massive, almost giving the water a pea green appearance. These blooms then support the second step in the food chain, enormous blooms of zooplankton or larval (baby) fish and crabs others may be tiny shrimp like creatures called krill. Just like cows grazing in a field, the zooplankton “grazes” on the phytoplankton. It is the abundance of these first two steps in the food chain that drive the rest of the marine ecology in Southeast Alaska. There is so much phyto and zooplankton that it feeds everything from the sea anemones hanging on the sides of rocks looking like large heads of broccoli, to the salmon and the mighty 45-50 ton humpback whales that we see on our journey.
The third and final ingredient that keeps these waters so rich and abundant with life is its proximity to land, and a shallow sea bottom. The heavy rains from the rainforest wash nutrients back into the sea. Strong ocean currents and changing tides cause upwelling (stirs up) any benthic (bottom dwelling) creatures that may reside there. This upwelling caused by tidal movement ensures that all of these nutrients will be available to every type and size creature in the food chain. This is why we particularly have good luck finding feeding frenzies as described earlier around points of land or coast lines where the shallow waters are stirred up by strong tidal movements.
For more information on this subject, check out this wonderful page on Ocean Food Chains that I found on the Southampton Oceanography Centre.
Posted by Peter on May 22, 2006 9:18 AM
TrackBacks
TrackBack Link for this entry
(Right-click on this link to copy the URL)
videos 
booked guests