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 Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

nachricht How to detect water contamination in situ?
22.09.2016 | Tomsk Polytechnic University (TPU)

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: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

 
Latest News

New switch decides between genome repair and death of cells

27.09.2016 | Life Sciences

Nanotechnology for energy materials: Electrodes like leaf veins

27.09.2016 | Physics and Astronomy

‘Missing link’ found in the development of bioelectronic medicines

27.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>