Featured Research

from universities, journals, and other organizations

Scientists Find Cause Of Dead Crabs, Fish Off Coast

Date:
August 1, 2002
Source:
Oregon State University
Summary:
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.

NEWPORT, Ore. - 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.


Story Source:

The above story is based on materials provided by Oregon State University. Note: Materials may be edited for content and length.


Cite This Page:

Oregon State University. "Scientists Find Cause Of Dead Crabs, Fish Off Coast." ScienceDaily. ScienceDaily, 1 August 2002. <www.sciencedaily.com/releases/2002/08/020801081242.htm>.
Oregon State University. (2002, August 1). Scientists Find Cause Of Dead Crabs, Fish Off Coast. ScienceDaily. Retrieved July 26, 2014 from www.sciencedaily.com/releases/2002/08/020801081242.htm
Oregon State University. "Scientists Find Cause Of Dead Crabs, Fish Off Coast." ScienceDaily. www.sciencedaily.com/releases/2002/08/020801081242.htm (accessed July 26, 2014).

Share This




More Plants & Animals News

Saturday, July 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How to Make Single Serving Smoothies: Howdini Hacks

How to Make Single Serving Smoothies: Howdini Hacks

Howdini (July 24, 2014) Smoothies are a great way to get in lots of healthy ingredients, plus they taste great! Howdini has a trick for making the perfect single-size smoothie that will save you time on cleanup too! All you need is a blender and a mason jar. Video provided by Howdini
Powered by NewsLook.com
Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Newsy (July 24, 2014) A new study claims a set of prehistoric T-Rex footprints supports the theory that the giant predators hunted in packs instead of alone. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins