Treebeard's Stumper Answer
Dunn Middle School is off to Catalina Island next week, so the ocean is on my mind. We all know about food chains and recycling, but isn't the ocean different? Here on land, plants and animals live and die, and their waste is quickly recycled back into the food chain by scavengers, especially bacteria and fungi. But in the deep ocean, the detritus of life sinks into the abyss, out of reach. There are scavengers in the depths, but they mostly stay there. How are marine ecosystems possible? Why doesn't the ocean run out of raw materials?
The ocean floor at Catalina Island is rich in life and remarkably clean, thanks to bottom-dwelling decomposers like lobsters and sea cucumbers. The deep ocean is different, and organic material accumulates in the cold dark abyss. But what goes down comes up in the natural process of upwelling. This brings nutrient-rich bottom water back to the surface and back into the food chain. Upwelling zones like Point Conception on the outer edge of the Santa Barbara channel are busy with life. They support the world’s most productive fisheries.
Treebeard and Julie getting ready to do some research at Catalina Island, while DMS students share lunch with
Jean-Michel Cousteau. The wetsuits are as uncomfortable as they (and we) look, but they feel better in the water.
We had a great time on our Dunn Middle School trip to Catalina Island. You can read some of the kids' impressions in the DMS Friday Newsnote (22 Sep 2000).
We stayed at the Catalina Environmental Leadership Program (CELP) camp at Howlands Landing on the California side of the island, a few miles from the Catalina Isthmus. This camp is sponsered by Catalina Island Camps and Jean-Michel Cousteau's Ocean Futures Society. It was our good fortune that Jean-Michel Cousteau and marine biologist Dr. Richard Murphy were our guides, along with a great group of naturalists. What a treat! There are photos of our adventure on the DMS Catalina Trip page. It was a special treat for me that the CELP program director, Patrick Bacalis, remembered me as Treebeard from his 6th grade school trip to the Santa Barbara County Schools' Outdoor School many years ago, where I got started teaching kids. That's the real reward for teaching!
In coastal areas like the kelp forests around Catalina Island, there are classic examples of food chains/webs. Giant Kelp uses air bladders to rise to the surface to capture the sun's energy and grow, providing habitat for many fish and other creatures. Kelp Snails eat the kelp. Octopus is a a predator that uses its beak to drill neat holes in the snails' shells and consume them. Fish eat the octopus, utilizing the sun's energy a step or two removed. Animal waste sinks to the bottom and the garbage cleaners of the kelp forest such as lobsters and sea cucumbers take it in. As Dr. Richard Murphy eloquently says, "What comes out of them is cleaner than what went into them." The ocean bottom in these coastal waters seems much cleaner than the forest ecosystems I'm used to. Organic detritus disappears quickly in a classic food chain that we could see on our dives.
The coastal kelp forest is remarkably clean, thanks to bottom-dwelling decomposers like sea cucumbers. That's the
back-end in the picture! "What comes out of them is cleaner than what went into them." Photos by Dr. Richard Murphy.
Deep ocean waters are different. Organic waste sinks beyond the reach of these shallow-water decomposers, away from the sunlight and warmth and oxygen of the surface. Upwelling is an oceanographic process that brings these deep, nutrient-rich waters back to the surface. Upwelling occurs in places like Chile, Point Conception on our central California coast, and West Africa, where winds and currents push the coastal waters away from the coast. When the deep waters are brought back to the surface, they explode with the diversity of life we saw at Catalina. One source on the Web says, "Only about 1/1000 of the oceans' surfaces have natural upwelling, but these areas account for nearly half (44%) of the world's food fish." But that's not enough to sweep the entire ocean floor clean. Organic sediments collect.
We can see layers in the atmosphere in the clouds, which make physical gradients visible. We experience layering in lakes when the surface is warm, but it's freezing cold a few feet down when we jump in! At Mono Lake, Yellowstone, and the Salmon River, there are hot springs that are too hot, and they won't mix with cold water to be comfortable because they stay in separate layers. It's either too hot or too cold because the waters won't mix.
There are layers and sharp gradients in the ocean too. There are many factors:
- Ocean currents distribute warm water from the equator to the poles.
- Cold water sinks and warm water floats on top because of the density difference.
- Metabolism works better when it's warm.
- Salty water is more dense, so it sinks under less salty water.
- Fresh water floats on top of salt water.
- Cold water holds more dissolved oxygen that warm water. Active trout and salmon need cold water for it's high oxygen content.
- Sunlight doesn't penetrate very far under water, so the plants (and waves) that produce dissolved oxygen stay near the surface.
- Surface waters hold the most oxygen.
- Marine algae capture atmospheric CO2 and take it to the depths when they die, removing CO2 from the atmosphere.
The deep ocean is cold and dark and anoxic (without oxygen), just the right conditions to produce oil in the depths. The Black Sea gets it's name from the color of its sediments, not its water. The oxygen-rich fresh water surface water from the Danube and other rivers is a cap on deeper, anoxic, salt water. There's no natural upwelling to mix the deep organic sediments with the surface ecosystems that could use them. Here is a place where oil is being made. Similar conditions occured world-wide during the Cretaceous period, and around 60% of our current petroleum reserves are from the Cretaceous Age. When we burn fossil fuels in our homes and cars, it's really the last step in an ancient food chain that goes back many millions of years. We're bringing deep ocean organic sediments back into surface food chains to be used again!
What goes down does finally come up, but there might be a cost when too much comes up at once. When I was a kid in the 50s, there was talk about the coming ice age. Now it's global warming. But there might be a connection. Melting ice caps would produce a lot of fresh water that could make a low density cap on the ocean and stop natural upwelling deep ocean waters from reaching the surface, just like warm El Niño waters ruin the fishery in Chile. This could upset the global "conveyor belt" of ocean currents that distribute extra heat from the equator around the planet. This could actually produce a cooling trend. There's evidence that this has happened before. A recent article in Time Magazine says:
Roughly 12,000 years ago, at the end of the last Ice Age, a natural warming sent freshwater from melting glaciers flowing out of the St. Lawrence River into the North Atlantic, all but shutting down the Gulf Stream and plunging Europe into a 1,300-year deep freeze. The more that becomes known about this period, named the Younger Dryas (after a tundra plant), the more scientists fear that the rapid melting of ice could cause the catastrophe to recur.
I called this stumper "deep secrets", but I didn't really appreciate how deep it goes into the Earth's cycles. Here are some links for further research:
- I recommend the Catalina Environmental Leadership Program (CELP) program for school groups looking for a great outdoor adventure. This camp is sponsered by Catalina Island Camps and Jean-Michel Cousteau's Ocean Futures Society. CELP is a new program competing with the Catalina Island Marine Institute (CIMI). I've been to CIMI camps with school groups at both Toyon Bay and Cherry Cove, and they also run a fine program.
- By chance, Time Magazine ran a cover story on the changing climate in the Arctic and The Big Meltdown in their September 4, 2000 issue just before our school Catalina trip. Polar Bears and tourists are confused. They discuss how global warming could cause a new cooling trend.
- The UNL Virtual Classroom webserver is a good Web resource on Oceanography, but there's no index page right now, so you have to click through their directory listing. I learned a lot from their pages on Ocean Circulation and Seawater.
- The NOAA El NiñoPage has info and links about El Niño and La Niña effects on the global climate. Now we're hearing about the Pacific Decadal Oscillation. I figure we're still coming out of the last Ice Age so global change is the norm. It's interesting that our human civilization and dominance of the planet falls in this geologically insignificant time period. In the old debate between gradualism and catastrophism, quick changes are gaining significance!
- We met Jean-Michel Cousteau at the CELP camp, but I don't think many of our kids appreciated who he is. Graybear wrote:If the kids didn't understand who he is and who his father was, they need to learn. Jacques was a pioneer in diving, inventing lots of diving equipment, including the Aqualung - the first SCUBA, underwater camera equipment, etc. A good byte of trivia surrounds the wearing of an orange wool cap when diving.I took Graybear's advice and put Jacques Cousteau to the kids at school as a stumper. They found all the facts, but I don't think they understood the impact of the man on people like Graybear and me. Jacques Cousteau had no advanced degrees. He followed his heart and had a real gift for communicating his enthusiasms. He was an outsider scientist/inventer working on his own who let us follow along. Michael Faraday is another independent soul I admire from a century back, lecturing to (us) kids about candle flames after everything else he did. They made a difference.
- Jean-Michel Cousteau is doing his own independent work speaking for the planet. He left us in the middle of our Catalina week to address NASA at the Air and Space Museum in Washington, DC. You can read his address. Jean-Michel heads the Ocean Futures Society located in Santa Barbara.
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