Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Earth Science News .




WATER WORLD
Are Fish Near Extinction?
by Staff Writers
Tel Aviv, Israel (SPX) Jun 30, 2014


Dr. Holzman based his study on the problematic nature of fish reproduction.

"An end to seafood by 2050?" "Fish to disappear by 2050?" These sensational media Are Fish Near Extinction?s were the result of a 2010 report by the United Nations Environment Program, declaring that over-fishing and pollution had nearly emptied the world's fish stocks. That scarcity portends disaster for over a billion people around the world who are dependent on fish for their main source of protein.

Now, a new study by Dr. Roi Holzman and Victor China of the Department of Zoology at Tel Aviv University's George S. Wise Faculty of Life Sciences has uncovered the reason why 90% fish larvae are biologically doomed to die mere days after hatching.

With this understanding of the mechanism that kills off the majority of the world's fish larvae, leaving only a marginal proportion to populate the world's oceans, "We can help find a solution to the looming fish crisis in the world," said Dr. Holzman.

The research, published in PNASand conducted at the Inter-University Institute for Marine Sciences in Eilat, Israel, suggests that "hydrodynamic starvation," or the physical inability to feed due to environmental incompatibility, is the reason so many fish larvae perish.

Survival strategies
"By focusing on the constraints placed on larvae survival, we have a better chance of producing higher quality mariculture," a specialized branch of aquaculture involving the cultivation of marine organisms for food and other products in the open ocean, said Dr. Holzman. "If we can produce better fish, this will have huge implications for our ability to maintain fish populations."

Dr. Holzman based his study on the problematic nature of fish reproduction. Nearly all fish species reproduce externally - they release and abandon their sperm and eggs into the water, providing no parental care. The fertilized eggs then hatch in the water within a couple of days and the hatching larvae must sustain themselves.

When attached to a yolk sac (a membranous sac attached to an embryo that provides early nourishment in the form of yolk), these premature organisms can survive for a period of two or three days, but once the larvae, with poorly developed fins and gills, open their mouths, they start dying in droves.

"We thought, something is going on during this period, in which the proportional number of larvae dying is greatest," said Dr. Holzman. "Our goal was to pinpoint the mechanism causing them to die. We saw that even under the best controlled conditions, 70% of fish larvae were dying within the two weeks known as the 'critical period,' when the larvae detach from the yolk sac and open their mouths to feed," said Dr. Holzman. "What was going on? We turned to physics as a source of the problem."

Eating soup with a fork
The physical structure of the larvae and their flawed interaction with the physical environment provided the answer Dr. Holzman was looking for. Over the course of two years, he and doctoral student Victor China observed fish larvae at three significant points in their development (at the beginning, middle, and end of that "critical period" - eight, 13, and 23 days old).

They found that the "stickiness" of the water - the viscosity of the surrounding ocean water - was hampering the larvae's attempts to feed.

"All that determines the larvae's feeding ability is viscosity - not age, not development. Only their interaction with the surrounding water," said Dr. Holzman.

"Because the water molecules around you have weak electrical bonds, only a thin layer sticks to your skin - a mere millimeter thick. If you're a large organism, you hardly feel it. But if you're a three-millimeter-sized larva, dragging a millimeter of water across your body will prevent you from propelling forward to feed. So really, it's all about larval size, and its ability to grow fast and escape the size where it feels the water as viscous fluid."

The researchers found that in less viscous water, the larvae improved their feeding ability. In theory, they can be expected to increase their survival rate. "We conclude that hydrodynamic starvation is the reason for their dying," said Dr. Holzman. "Imagine eating soup with a fork - that's what it's like for these larvae. They're not developed enough at the critical point to adopt the constrained feeding strategy of adult-sized, better-developed fish."

Armed with this knowledge of the larvae's biological flaw, the researchers are currently patenting a solution to maintain higher survival rates among fish larvae populations.

.


Related Links
Tel Aviv University
Water News - Science, Technology and Politics






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





WATER WORLD
Scientists discover oldest reef constructed by animals
Windhoek, Namibia (UPI) Jun 27, 2013
Scientists say they've located the oldest animal-built reef on Earth among the dry, land-locked sands of Namibia, evidence of the first animals to barricade themselves behind hard, protective shells. It's often said that technology mimics nature, but nearly as often, nature mimics nature. Such was the case 550 million years ago, scientists say, when coral-like creatures called Cloudina ... read more


WATER WORLD
Abandoned children fear as US troops eye Philippines

We Can Eliminate the Major Tornado Threat in Tornado Alley

Malaysia gets new transport minister amid MH370 crisis

Surviving without money, German woman's year-long adventure

WATER WORLD
Ghost writing the whip

Strange physics turns off laser

A breakthrough in creating invisibility cloaks, stealth technology

NIST technique could make sub-wavelength images at radio frequencies

WATER WORLD
Familiar yet strange: Water's 'split personality' revealed by computer model

Are Fish Near Extinction?

Can Coral Save Our Oceans?

The ENSO Signal and The Noise

WATER WORLD
One-well program in arctic waters starts for Gazprom division

Penguin colonies may move and adapt to climate change

Japan considering new base on Antarctica

Melting and refreezing of deep Greenland ice speeds flow to sea

WATER WORLD
Straw albedo mitigates extreme heat

Reorganization of crop production and trade could save China's water supply

Comparison study of planting methods shows drilling favorable for organic farming

Organic agriculture boosts biodiversity on farmlands

WATER WORLD
Double tropical storms dump heavy rains in Mexico

Victoria's volcano count rises

Online deluge washes away China 'piggyback' official

Strong quake strikes off N.Zealand's Kermadec Islands: USGS

WATER WORLD
China to re-open Somalia embassy: Beijing

Cameroon battles Nigeria's Boko Haram in remote border city

Suicide blast kills three in northeast Nigeria: residents

Chinese VP lauds better ties with African workers

WATER WORLD
Scientists chart a baby boom - in southwestern Native Americans from 500 to 1300 A.D.

Monkeys' facial features evolved to prevent crossbreeding

Advanced CLARITY Method Offers Faster, Better Views of Entire Brain

Humans have been changing Chinese environment for 3,000 years




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.