Stories tagged estuary

Feb
05
2010

When you visit a doctor, he or she usually uses a medical device to measure your vital signs, such as heart rate, blood pressure and temperature. The doc might also draw some blood to test in the laboratory for its biochemical composition. Environmental scientists do similar activities to determine the health of an estuary. But an estuary is huge in comparison to a human being; getting enough data to draw meaningful conclusions can be challenging.

LOBO's launch in the Columbia River: Watch video
LOBO's launch in the Columbia River: Watch videoCourtesy CMOP

Here’s where LOBO, CMOP’s Land/Ocean Biogeochemical Observatory, comes in. WET Labs, Inc. senior research scientist Andrew Barnard, Ph.D. and CMOP researcher Joe Needoba, Ph.D. have teamed up to develop innovative methods to collect high quality, long-term data sets to improve scientific understanding of the vital signs of the Columbia River estuary.

Traditionally, any effort to monitor the “biogeochemistry” of a body of water requires scientists to board a ship, collect water samples, transport them back to a lab, and then measure the nutrients in the water. These trips are expensive and time-consuming and yet they only provide a “snapshot” of the estuary’s biogeochemical vital signs at the time of the shipboard sampling trip. Barnard and Needoba decided to approach the problem by utilizing an oceanographic monitoring platform made by Satlantic and customizing it with enhanced capabilities and improved water quality sensors.

LOBO is a water quality monitoring device that takes hourly measurements of nitrate, salinity, temperature, chlorophyll, turbidity, conductivity, depth, dissolved oxygen, oxygen saturation, and colored dissolved organic matter (CDOM).

LOBO is part of the Science and Technology University Research Network (SATURN), an end-to-end coastal margin observatory at CMOP. The data will provide the center with a better understanding of the ecosystem and composition of the water in the Columbia River and its estuary.
“What we are trying to do is establish a monitoring system that allow us to gain an understanding of the variability of the water quality, not only every hour but over weeks, months, and years,” said Needoba. “What this will tell us is how the estuary is behaving and responding to various forcing factors.”

LOBO is currently located in the Lower Columbia River and uses cellular telemetry to relay data every hour to a web site. The web interface lets anyone with and internet connection who is interested graph and download an individual variable or multiple variables, on a single day or over multiple days.

Sample reading from LOBO: The figure on the left shows a sample reading from LOBO of the levels of CDOM and dissolved oxygen from January 1 to January 5, 2009. The figure on the right plots hourly readings of water quality.
Sample reading from LOBO: The figure on the left shows a sample reading from LOBO of the levels of CDOM and dissolved oxygen from January 1 to January 5, 2009. The figure on the right plots hourly readings of water quality.Courtesy CMOP

The LOBO system will serve as an important biogeochemical data node within CMOP. “What we are doing in the Columbia River estuary is part of a larger project within CMOP to provide a framework of water quality measurements to scientists studying the estuary and coastal ocean,“ said Needoba.
The next step is to use the upcoming CMOP research cruises to verify that the data from the LOBO mooring is representative of the estuary as a whole. Needoba plans to use future research cruises to study the variability associated with different regions of the estuary and ensure that the aspects of the water quality his team measures in one specific site can be extrapolated to the entire estuary.

Barnard and his group at WET Labs, Inc. intend to expand the LOBO's biogeochemical monitoring capabilities by adding a new sensor to measurement dissolved phosphate in the water. “We will use our latest and greatest technology to create better capabilities for long term measurements and monitoring,” said Barnard.

Feb
05
2010

One way to determine the health of an estuary is to test some of its “vital signs”. Important vital signs in rivers and estuaries include things that affect the quality of the water for the health of the various living organisms that call that water home. If there are toxic materials, or even too much of a good thing, like oxygen, organism throughout the food chain can suffer.

One such vital sign can be the development in rivers and estuaries of “red tides”. This term is used to describe large “blooms” of phytoplankton in coastal waters. Phytoplankton are tiny floating plants. They obtain energy through the process of photosynthesis and must therefore live in the well-lit surface layer, where they account for half the photosynthetic activity on our planet. “Red tides” don’t have to be either red or associated with tides, but they concern scientists, because they can produce toxins that can overwhelm other organisms in the water.

Plankton bloom: Plankton bloom flows under Astoria bridge.
Plankton bloom: Plankton bloom flows under Astoria bridge.Courtesy Alex Derr, CMOP

CMOP is studying a plankton bloom that is dominated by one type of organism called Myrionecta rubra. The organism is technically a eukaryotic protist, a single-celled organism that floats in the water column. Under certain environmental conditions, the cells grow exponentially to millions of cells per liter of water within a few days. The cells are red and the shear numbers of them reflect the sun’s light and enhance their red color in the water.

Myrionecta rubra
Myrionecta rubraCourtesy CMOP

CMOP researchers Herfort and Peterson traveled to Astoria to collect samples of the plankton bloom. They gathered samples in both the dense red water and in clear patches of water. These samples helped them compare the conditions in the water and the influences the red tide organism might have on its environment.
CMOP scientists have already analyzed several samples collected during previous year’s blooms. Herfort and Zuber use molecular biology techniques to look at the genetic fingerprints of these organisms and others associated with the bloom. This molecular work is carried out in collaboration with Lee Ann McCue Ph.D., a scientist from Pacific Northwest National Laboratory, who performs genetic sequence analysis. Herfort said, “Our data will improve our understanding of the ecological impact of Myrionecta rubra bloom on the Columbia River estuary.”
Red tide, close-up
Red tide, close-upCourtesy CMOP

Eventually whatever caused the Myrionecta rubra to grow rapidly will change and they will no longer have a source of nutrients. Peterson stated, “When they die, they decompose and bacteria can feed on the decomposed material. This growth of bacteria then draws down the oxygen in the water around them while they are respiring”. So while the bloom itself is not toxic in this case, here’s where another vital sign comes in: the bacteria’s respiration may have a harmful effect to other species, by depleting oxygen available to them. (Due to a great deal of water flow and flushing in the Columbia River, this is currently not a danger.)

What's next?

Unanswered questions that CMOP researchers are exploring include:

  • Is the Myrionecta rubra an important “vital sign” for the estuary?
  • What controls the timing and behavior of the bloom?

The CMOP research team wants to start answering these and other questions by using a combination of physiological studies, molecular work, and observations and simulations from their end-to-end coastal margin observatory (SATURN). They hope this will provide clues about the factors that lead to plankton blooms, and ultimately improve the ability to predict these events.