Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists find cause of dead crabs, fish off coast

31.07.2002


An unusual combination of oceanic and atmospheric events may be to blame for a mysterious and sudden die-off of numerous crabs, fish and invertebrate animals off the central Oregon coast during the past two weeks.

Oregon State University researchers who are studying near-shore ecosystems say extremely low oxygen levels - especially in the lower water column - appear to be the culprit.

"Though we are just beginning to amass the evidence, it appears that there has been a confluence of events relating to coastal upwelling and wind patterns," said Jane Lubchenco, the Wayne and Gladys Valley Professor of Marine Biology at OSU. "There isn’t any sign that this was the result of human activities. It appears to be a natural event, albeit an unusual one."



Scientists first began to suspect a problem in mid-July. Oregon Department of Fish and Wildlife staff members who were surveying the near-shore ocean off Cape Perpetua with a remotely operated vehicle were surprised to find no live fish swimming in an area that in previous years had been densely populated with rockfish. This time, they saw only dead sculpins and invertebrates on the ocean floor.

Calls to ODFW soon began coming in from crabbers, who were pulling up pots that were full of Dungeness crabs, other shellfish, octopus, other invertebrates and fish - and most of them were dead. Then small numbers of dead fish and other sea life began washing ashore near Seal Rock, between Newport and Waldport on the central Oregon coast.

"Some of the crabbers offered to set their pots in certain places and ways to help us learn more," said Dave Fox, marine habitat project leader with ODFW. "There has been a real cooperative effort between the crabbers and the scientists from OSU to help us determine what happened."

Initially, Fox said, the crabbers were concerned the deaths may have been caused by naturally occurring toxins. ODFW sent samples to the Oregon Department of Agriculture for testing, and those tests came back negative. A team of scientists led by Jane Huyer from OSU’s College of Oceanic and Atmospheric Sciences has been monitoring ocean conditions off Newport and off Heceta Head several years, and as part of their routine research measured seawater conditions in mid-July. Huyer reported that the water contained some of the lowest oxygen levels the researchers had ever seen near shore.

Huyer said there is always a large pool of very low oxygen water at depths 2,500 feet below the surface, but this does not normally affect marine life near the coast.

Lubchenco is co-principal investigator for another ongoing research project called the Partnership for Interdisciplinary Studies of Coastal Oceans, or PISCO. Bruce Menge, also co-principal investigator for PISCO, and his team of field researchers recorded more of the same - dead wolf eels, Dungeness crabs and sculpins as well as smaller numbers of dead ling-cod and other rockfish at sites along the central coast. Further water samples taken by PISCO scientists aboard the university’s research ship, the R/V Elakha, provided evidence to explain the mysterious die-off.

"What we found were surprisingly low levels of oxygen in the water column - as low as one or two milligrams per liter, which classified it as hypoxic," said Francis Chan, a post-doctoral researcher on the PISCO project. "That means it cannot sustain most marine life.

"It is almost an unprecedented event around here," he added. "We have a lot of researchers who have been studying this part of the coast for more than 25 years who have never seen such a situation."

Brian Grantham, a research associate in OSU’s Department of Zoology, said the low oxygen levels may have been the result of strong upwelling and unusual atmospheric conditions. From spring through early fall, he said, upwelling brings colder, deeper and more oxygen-depleted water close to shore. There, the high-nutrient waters are exposed to sunlight and microscopic marine plants grow abundantly. As these decay and sink, they consume some of the remaining oxygen in the water.

When summer winds are weak, the surface waters are warm, and there is reduced mixing of oxygen from the surface to the bottom. This allows the low values of oxygen at the bottom to persist and intensify, in effect, smothering much of the sea life in the area.

"If this happens for a day or two, the fish and crabs probably survive," Grantham said. "But over a period of time, perhaps 3-5 days or longer, the oxygen deprivation becomes deadly. It seems to affect the animals that stay hunkered down in one spot, particularly sculpins, wolf eels, worms and young fish. The larger fish may have the ability to swim away and find patches of water that have more oxygen."

Lubchenco said the scientists are not yet sure how widespread the hypoxic zone is, the extent of the damage to sea life, or how long it will last. OSU researchers are planning to collect more samples and download data from PISCO’s network of environmental monitoring stations during the next few days to determine if low oxygen levels are still present, and to identify the physical boundaries of the problem.

ODFW also plans to take out its ROV off Cape Perpetua beginning Aug. 24.

The researchers from OSU and ODFW both reported that the water in the hypoxic zone was murky and there was an odor in the air - "kind of a strong, low-tide smell you’d find in the bay," Fox said.

Oregon is not alone in facing unusual low-oxygen phenomena. The so-called "Dead Zone" in the Gulf of Mexico is experiencing widespread loss of marine life, though the problems there are caused by agricultural runoff via the Mississippi River, said Karina Nielsen, an OSU post-doctoral researcher with PISCO. A more relevant and naturally occurring hypoxic zone takes place off South Africa, she added.

"They have an upwelling system that is similar to that of Oregon, and almost every year for the past 10 years they have seen rock lobsters literally walk out of the water and onto the beach," Nielsen said. "They are desperately looking for oxygen."

The Oregon hypoxic zone is "an unusual event that appears to be naturally occurring," according to Lubchenco. "This is exactly why the research we are doing on near-shore ecosystems is so critical - to better understand the mechanisms behind such events, and increase our ability to respond to them in the most appropriate manner," she said.

ODFW officials are interested in learning if hypoxia has affected other parts of the coast, Fox said. Crabbers and fishermen who encounter unusual numbers of dead marine life are asked to call 541-867-4741.


###
The Partnership for Interdisciplinary Studies of Coast Oceans is a five-year, $20 million project funded by the David and Lucile Packard Foundation. OSU is the lead institution for the study, which also includes Stanford University, the University of California at Santa Cruz, and the University of California at Santa Barbara.

By Mark Floyd, 541-737-0788

SOURCES: Jane Lubchenco (OSU), 541-737-5337; Brian Grantham (OSU), 541-737-5359; Dave Fox (ODFW), 541-867-0300, ext. 228


Jane Lubchenco | EurekAlert!
Further information:
http://www.orst.edu/

More articles from Ecology, The Environment and Conservation:

nachricht Emissions from road construction could be halved using today’s technology
18.05.2020 | Schwedischer Forschungsrat - The Swedish Research Council

nachricht When every particle counts: IOW develops comprehensive guidelines for microplastic extraction from environmental samples
11.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

Im Focus: I-call - When microimplants communicate with each other / Innovation driver digitization - "Smart Health“

Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.

When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...

Im Focus: When predictions of theoretical chemists become reality

Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.

Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...

Im Focus: Rolling into the deep

Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.

A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

New 5G switch provides 50 times more energy efficiency than currently exists

27.05.2020 | Information Technology

Return of the Blob: Surprise link found to edge turbulence in fusion plasma

27.05.2020 | Physics and Astronomy

Upwards with the “bubble shuttle”: How sea floor microbes get involved with methane reduction in the water column

27.05.2020 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>