Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Parasite loads a cause of salmon mortality, linked to land use changes

16.08.2011
A recent study suggests that parasites in fish, including threatened species of Oregon coho salmon, may have more profound impacts on fish health than has been assumed, and could be one of the key mechanisms by which habitat and land use changes cause salmon mortality.

It’s not just the presence or absence of parasites that is important, the research found, but their numbers that can build up over years or decades and ultimately cause major impacts.

The study will be published soon in the journals Aquaculture, Journal of Parasitology, and International Journal of Parasitology. It was done by researchers from Oregon State University and other agencies, and concluded that heavy loads of parasites can affect salmon growth, weight, size, immune function, saltwater adaptation, swimming stamina, activity level, ability to migrate and other issues. Parasites drain energy from the fish as they grow and develop.

“We’ve known for a long time that salmon and other fish are affected by parasites, so that isn’t new,” said Mike Kent, an OSU professor of microbiology. “Because parasites have been present for decades, they have often been dismissed as a cause of increasing salmon mortality.

“But we’re now getting a better appreciation that it’s the overall parasite load that is so important,” he said. “The higher levels of mortality only show up with significant increases in the parasite burden.”

And that increase in parasite numbers, Kent said, is a slow, gradual response to warmer waters and heavier nutrient loads that can be a result of logging, agriculture, inadequate streamside protection and other land use or management changes over many years.

“Salmon can actually tolerate a fairly wide range of temperatures, it’s not just the fact a stream is warmer that’s killing them, in and of itself,” he said. “We now believe that some of these forces are leading to heavier parasite loads. This could be important in understanding declining salmon populations.”

Some of the digenean parasites that can infect salmon and other fish have complex life cycles, which include passage through the intestinal tracts of birds that eat fish, producing eggs and then infecting snails. Snails thrive in warmer water with higher nutrient loads from common fertilizers.

It’s been historically difficult to study these issues in salmon, Kent said, because they migrate and cannot be easily analyzed, as fish can when they are trapped in a lake or pond.

In the new study, researchers did both laboratory and field analysis of fish in Oregon’s West Fork Smith River. The impact of parasites on fish health were much more severe in a part of the river where water moved more slowly and nearby logging and agricultural practices increased water temperature and nutrient loads. Fish in this area had parasite infestations about 80 times higher than those higher up in the tributary.

The various impacts on fish health, the researchers said, could affect their ability to survive. Fish size influences juvenile overwinter survival, for instance, and swimming ability that’s essential to avoiding predators.

“Understanding why certain salmon populations are heavily infected with these parasites, which likely are driven by landscape characteristics, could help in management or recovery planning,” the scientists wrote in their conclusion, “given that our data indicates that severity of these infections are associated with survival.”

The study was done by scientists from OSU and the Oregon Cooperative Fish and Wildlife Research Unit. The corresponding author was Jayde Ferguson, a doctoral student in the OSU Department of Microbiology, and other collaborators included researchers from the OSU Department of Statistics, College of Veterinary Medicine, and Carl Schreck in the Department of Fisheries and Wildlife. The research was supported by the Oregon Department of Fish and Wildlife.

About the OSU College of Science: As one of the largest academic units at OSU, the College of Science has 14 departments and programs, 13 pre-professional programs, and provides the basic science courses essential to the education of every OSU student. Its faculty are international leaders in scientific research.

The study this story is based on is available online: http://hdl.handle.net/1957/22084

Michael Kent | EurekAlert!
Further information:
http://www.oregonstate.edu

Further reports about: College OSU Parasitology Science TV Wildlife fish health parasite wasps salmon populations

More articles from Ecology, The Environment and Conservation:

nachricht Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>