Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fat chance for hosts

09.09.2003


New study shows parasitic flatworms take destiny by the tail



In the research article "Larval swimming overpowers turbulent mixing and facilitates transmission of a marine parasite," appearing in the September issue of the Ecological Society of America’s journal Ecology, Jonathan Fingerut of the University of California-Los Angeles and colleagues describe the results of the first study to examine larval behavior versus passive-transport processes under natural and simulated water flow conditions.

H. rhigedana is one of the most common parasitic flatworms found in southern California. Sexual reproduction takes place in definitive host birds, which defecate the parasite’s eggs into marshes. The first swimming larval stage (miracidia) infect the California horn snail, causing castration and other sublethal effects. Asexual reproduction ensues, producing tens of free-swimming cercariae per snail per day, which encyst on other snails and crabs as second intermediate hosts. Birds which eat the snails and crabs complete the parasite’s life cycle.


Fingerut and his colleagues Cheryl Ann Zimmer and Richard Zimmer, also of UC-Los Angeles, wanted to determine what explains the unusually high transmission rate of H. rhigedana’s cercariae (second larval stage). The larvae encyst up to 100 percent of the local snail and crab second intermediate hosts, an especially astonishing feat since this larval stage has but four hours to locate and infect its host.

The researchers examined the range of variation and effect on larval swimming of relevant physical factors (light, temperature, salinity and water flow). They also used new laser and digital video imaging technologies to identify active versus passive transport of the larvae.

"In our still water experiments, we found that exposure to light caused cercariae to swim straight toward the bottom of the water body where they were likely to encounter their hosts," says Fingerut. "And while salinity had no impact on either swim speed or direction, a 33 percent increase in water temperature led to a 71 percent increase in the larvae’s swim speeds, bringing the larvae to the bottom faster."

When the researchers looked at the same variables in slow-moving water conditions, they found similar results: the cercariae swam determinedly towards the bottom, prevailing over the slow-moving water currents. However, fast-moving water bodies overwhelmed the larvae’s ability to control their movements and they were distributed throughout the water column, much like passive particles. Water temperature had no effect in this setting.

"Our study indicates that whether adaptive or fortuitous, parasite transmission is largely controlled by the cercariae and not by the vagaries of flow," the investigators conclude.


Founded in 1915, the Ecological Society of America (ESA) is a scientific, non-profit, organization with 8000 members. Through ESA reports, journals, membership research, and expert testimony to Congress, ESA seeks to promote the responsible application of ecological data and principles to the solution of environmental problems. For more information about the Society and its activities, access ESA’s web site at: www.esa.org.

Annie Drinkard | EurekAlert!
Further information:
http://www.esa.org

More articles from Ecology, The Environment and Conservation:

nachricht Dune ecosystem modelling
23.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Understanding animal social networks can aid wildlife conservation
23.06.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>