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Science Behind the Scenery: Cordell Bank National Marine Sanctuary

Point Reyes National Seashore

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[Dan Howard] Cordell Bank is a submerged island with, uh, highest pinnacles are about 120 feet below the surface of the water. The upper pinnacles are totally covered with sponges and little strawberry anemones, ascidians, which is another invertebrate that encrusts on the rock. The cover on the upper pinnacles and...and shallower reef areas on the Bank is over 100%. Animals growing on top of animals.

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One of the projects that were doing out at Cordell Bank right now is trying to characterize the habitats and get some quantitative estimates of fish abundance, identify the invertebrates that live on the bank, and describe the distribution of those invertebrates on the bank.

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We've gone to using a manned submersible. And an observer—a biologist—sits in the front of the sub, identify areas on the bank that we want to monitor, go down to as deep as 1,200 feet. We'll count and identify fishes. We have a video camera mounted on the outside of the submersible that's filming everything that we're seeing.

But, then, we'll also bring those tapes back to the lab after the cruise. Somebody reviews the tapes and identifies the fish. We have lasers that tell us how large the fish are. Then we come back through the tape a second time and characterize the different substrate types, like boulder, reef, bedrock, mud, sand.

And then, what we hope to do is to start to get an idea, not only how many fish we have, of what kind, and where they are, but, then, if we can associate them with a particular kind of habitat Then we can start to get a feel for how much of that habitat we have and we can make some guesses about how many fish might be where on the bank.

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The bank is about four and a half miles wide by about nine and a half miles long. Up on the northwest edge of the bank, the relief is extreme. You'll hit granitic walls that are 50 to 60 feet high, and then it will run along a ridge, and then it will drop straight off. The relief on Cordell Bank is absolutely spectacular.

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We want to be able to describe how things change over time. How the fish abundance or species composition changes over time. We have a second major effort that is looking at the water column and those animals that live above the water, such as seabirds. We, also, will drop a, um, instrument that measures temperature, salinity, light penetration It also men...measures chlorophyll, which gives us an idea of...of, um, how many phytoplankton are in the water. And if we do this year after year, we start to get a feel for...productivity...and how that varies from one year to the next.

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There's only four eastern boundary currents. And there's only four of these areas in the world. The west coast of North America being one. An oceanographic phenomenon that's associated with these eastern boundary currents is upwelling. Upwelling, really, is responsible for bringing nutrients up into the nearshore area. And Cordell Bank just happens to be in the center of the California Current upwelling system. Point Reyes, being one of the major features in the California Current upwelling system. And you'll see in satellite images, pictures of ocean temperature, color-coded. And, so, you get these deep blues and purples, which represent cold, nutrient-rich water that's upwelled right next to the coast, sitting right on the edge of the continental shelf.

And, so, you'll get a lot of oceanic species, such as the albatross and the shearwaters, and these birds that never visit land, except when they're nesting, are common inhabitants around Cordell Bank. As well as the blue whales and the humpback whales that are...these are oceanic species, but you'll get them in close proximity to really subtidal species that, typically, you see right near shore, like the anemones and the sponges.

And, so, the biological diversity at the bank is...is just fabulous, because you get the offshore component and the near shore component right in the same area. So, really, in terms of diversity out there, it's one of the most biologically diverse places along our coast.

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In the 1850s, George Davidson was returning from a survey trip up the north coast of California when he was enveloped in a thick layer of fog. And knowing that he was getting near Point Reyes, he dropped the lead line overboard. And expecting to find 300 to 400 feet on the continental shelf, he actually...the lead line stopped at about 120 feet.

In 1869, or after the Civil War, they started getting reports again of this high spot or shoal...off a Point Reyes. And George Davidson sent Edward Cordell out to try and relocate the bank. And it took Cordell a while, and...and, finally, he was drawn to this area by an abundance of wildlife.

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Cordell Bank is a destination feeding ground for blue whales and humpback whales...in the summer and fall. And the reason that these whales migrate to Cordell Bank from...Central America and Mexico is to feed on the krill. Krill are really one of the keystone species out there at Cordell Bank. Everything feeds on krill.

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The threats to Cordell Bank could be environmental or they could be human induced. The environmental threats, such as El Niños, global warming, we don't have any control over. The human threats, we may have some control over.

Cordell Bank was designated as a National Marine Sanctuary in 1989. Until the early '70s, the oceans were seen as limitless—the resources were limitless, we couldn't possibly affect the conditions of the oceans by getting rid of our garbage and our trash. In the middle '60s and early '70s, people started to understand we could harm the oceans. And we were. The sanctuary program was created to try and protect some of these national treasures that have significant biological or cultural resources

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Description

The fifth part of the ten-part Science Behind the Scenery documentary featuring Cordell Bank National Marine Sanctuary Manager Dan Howard talking about the discovery of Cordell Bank and the research that is occurring to better understand what is out there.