Complex ocean behavior studied with 'artificial upwelling'

Sep 02, 2008

A team of scientists is studying the complex ocean upwelling process by mimicking nature – pumping cold, nutrient-rich water from deep within the Pacific Ocean and releasing it into surface waters near Hawaii that lack the nitrogen and phosphorous necessary to support high biological production.

The researchers are harnessing the power of the ocean to conduct their experiments, using the up-and-down motion of waves to pump deep water to the surface. Their next step is to create a pump that can withstand the rigors of the rugged Pacific and then see if the biology follows the physics.

"During our first test, the ocean destroyed our pump in one day," said Angelicque "Angel" White, a post-doctoral researcher at Oregon State University and a member of the scientific team. "Initially, the system worked and we were able to bring cold water to the surface and control the depth of its release. Now we need to work on the engineering aspect."

The theory behind the experiment has just been published in the journal, Marine Ecology Progress Series. The initial test of the pumps and their effect in the open ocean is the focus of a documentary that is scheduled to be broadcast Sept. 5 on the Discovery Channel.

This experiment was funded in part by the National Science Foundation and the Betty and Gordon Moore Foundation. White and lead investigators Ricardo Letelier of OSU and David Karl of the University of Hawaii are part of the NSF-funded Center for Microbial Oceanography: Research and Education (C-MORE) based in Hawaii, which Karl directs.

The scientists stress that the goal of creating artificially induced upwelling is to understand how marine microbial ecosystems respond to large-scale perturbations, "a critical step if we want to understand the risks of manipulating these large ecosystems in order to solve global greenhouse buildup," said Letelier, a professor in OSU's College of Oceanic and Atmospheric Sciences.

"This is not a new concept," Letelier said. "It was proposed in 1976 that scientists could use wave energy to pump water from the depths to the surface and fuel plankton growth. But there are many nuances; simply bringing nutrients to the surface can result in the wrong kinds of biological growth. It also can bring water enriched with carbon dioxide, which can de-gas into the atmosphere.

"If you're adding more CO2 than subtracting by fertilizing the ocean," he added, "you're running the wheel in the wrong direction."

The answer, Letelier says, may be to pump water that contains specific ratios of nutrients – particularly nitrogen and phosphorous – to carbon dioxide by targeting different depths. At their research site north of Hawaii, where the ocean is about 4,500 meters deep, the bottom layers of water have too much CO2 because of the decaying organisms that have sunk to the floor.

Their studies have shown, however, that water at a depth of 300 to 700 meters has the proper ratio of nitrogen and phosphorus to trigger a two-stage phytoplankton bloom. The researchers believe that upwelling with water from that depth will first cause a bloom of diatoms, which are a common type of plankton – often single-celled. The diatoms will consume the nitrogen, leaving some amount of phosphorus in the water, which will stimulate a second-stage bloom of nitrogen-fixing cyanobacteria. These blooms are often observed during summer months in open ocean waters, Letelier said.

In previous field experiments, the researchers were able to create stage-one diatom blooms by mixing deep and surface water in large incubation bottles, but they need to conduct additional studies in the ocean to see if the second stage of blooms actually occurs following additions of deep water. If the pumps had survived the ocean, White said, they may have been able to generate these blooms.

"We were able to pump about 50 cubic meters of water per hour using the wave energy," she said, "which is a small amount compared to the vastness of the ocean. If we want to generate a bloom in an area of one-square kilometer, we would need to replace about 10 percent of the surface waters with upwelled water, which would take about a month at the rate we pumped."

The scientists used undersea gliders in their Hawaii study to monitor the water from the pump so they have an idea how widely and quickly it disperses, and how much of an impact it can have on surface waters.

"We know a lot about how upwelling works and the physics of the ocean," Letelier said, "but there also are things we don't know, which is why this study is so important. In this open ocean area near Hawaii, for example, phytoplankton blooms occur in the summer when there are almost no nutrients at the surface and the winds generally are calm. What triggers the blooms and where are the nutrients coming from? We need to know.

"These vast, seemingly barren regions comprise more than two-thirds of our oceans and nearly 40 percent of the entire Earth," he added. "It is a large area of exchange between the atmosphere and the ocean and understanding large-scale interactions is critical to understanding climate change."

Some scientists have looked at iron fertilization as a way to trigger biological growth in nutrient-poor areas of the ocean, but "everything responds to iron," Letelier said. "You can't control what grows."

The researchers believe they can control plankton growth by determining which species respond to specific nutrients, and then adjusting the rate of nutrient feeding by the frequency and duration of water pumping.

"These vast regions of the open ocean may be perfect for sequestering carbon," Letelier said, "but before we can begin to seriously consider a large-scale intervention, we must better understand how the biology responds by using perturbations on a small scale. We're getting there."

Source: Oregon State University

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User comments : 6

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GrayMouser
1 / 5 (4) Sep 02, 2008
Isn't this having an effect on the ocean's natural processes? At the very least they are bringing cold deep waters up and dumping them in the warm surface waters.
Keys1337
5 / 5 (2) Sep 02, 2008
Isn't this having an effect on the ocean's natural processes? At the very least they are bringing cold deep waters up and dumping them in the warm surface waters.
Uhh... Yeah... that's the experiment.
agg
1.8 / 5 (5) Sep 02, 2008

I hope there's no runaway Oxygen effect. It will cause Algore to burn off all his fat.
russg
1 / 5 (1) Sep 03, 2008
While Letilier et al are correct in their pitch for their artificial upwelling technology and we ought to have a better understanding of plankton blooms, the staggering progressive extinction of ocean green plants 26% lost in the N. Pacific in 30 years represents a crisis that cannot defer to wait for insatiable academic satisfaction.

We can and must engage in ocean ecorestoration to bring back ocean plants to the levels they, and we, enjoyed 30 years ago which can be done without expectation of harm or ill effects. Iron micronutrient replenishment is the most cost and ecologically effective means to attain this goal. While the academics and polemics engage in endless debate the patient, Mother Ocean, lies dying from the double impact of fossil CO2.

The first carbon bomb already airborne and impacting on the oceans now carries sufficient acidifying and micronutrient limiting CO2 to change ocean chemistry and ecology so drastically that what will remain is a bacterial sea. While we fiddle with minor reductions of CO2 emissions and academic polemics the ocean acidfication and ecological conflagration continues apace to destroy it.

Only photosynthesis by green plants in the ocean has any possibility of countering the terawatts of fossil CO2 poisoning. With eco-restoration of the ocean plants they will harvest and employ terawatts of solar powered photosynthesis to compete for ocean CO2 changing it into life instead of death.

Read more at planktos-science.com
GrayMouser
not rated yet Sep 07, 2008
Isn't this having an effect on the ocean's natural processes? At the very least they are bringing cold deep waters up and dumping them in the warm surface waters.
Uhh... Yeah... that's the experiment.


Did they file an Environmental Impact Study? Any changes humans make are unnatural...
Velanarris
not rated yet Sep 08, 2008
Isn't this having an effect on the ocean's natural processes? At the very least they are bringing cold deep waters up and dumping them in the warm surface waters.
Uhh... Yeah... that's the experiment.


Did they file an Environmental Impact Study? Any changes humans make are unnatural...


No of course they didn't because anything we do that gets us grant money is ok, anything others do to make money I should get in grants should be banned because it's bad!!!!

Hypocritical politically motivated foolishness.