Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




WATER WORLD
Overfishing of sharks endangers reefs: Australian study
by Staff Writers
Sydney (AFP) Sept 19, 2013


Scientists studying reefs off Australia said Thursday sharks play a fundamental role in the health of coral, and overfishing of them made reefs more vulnerable to global warming and weather disasters.

A research team, led by Mark Meekan from the Australian Institute of Marine Science (AIMS), studied the impact of sharks at the Rowley Shoals and Scott Reefs 300 kilometres (185 miles) off northwest Australia over 10 years.

"Where shark numbers are reduced we see a fundamental change in the structure of food chains on reefs," said Meekan.

"We see increasing numbers of mid-level predators such as snappers, and a reduction in the numbers of herbivores such as parrot fishes.

"The parrot fishes are very important because they eat the algae that would otherwise overwhelm young corals on reefs recovering from natural disturbances."

When coral dies algae grows over it, compromising its ability to regrow. Meekan said the herbivorous fishes chewed out small spaces so regrowth could take place.

The study compared the impact of cyclones and bleaching events on the marine-protected Rowley Shoals, where fishing is banned, with the neighbouring Scott Reefs, where Indonesian fishermen -- mostly from West Timor -- are allowed to catch sharks.

It found less coral and more algae on the fished reefs after a major disturbance, which Meekan said was significant as the pressures of global warming increased.

"With many of the changes from a warming climate already locked in, there may be little we can do to prevent increased frequency of disturbances on coral reefs in the near future," he said.

"However, this is not the case with the loss of reef sharks."

Meekan said the findings showed that declining global reef shark populations due to overfishing was of "great concern" because it would leave the coral structures more vulnerable to bleaching events from warmer, more acidic oceans, and to large cyclones.

Even small no-fishing zones in reef areas could provide valuable feeding sites for sharks, maintaining a delicate ecosystem balance ensuring that algae-eating species could thrive.

A major AIMS study last year of the Great Barrier Reef, off Australia's east coast, found that coral cover had more than halved in the past 27 years due to storms, bleaching linked to climate change and the predatory crown-of-thorns starfish.

Intense tropical cyclones -- 34 in total since 1985 -- were responsible for the bulk of the damage, accounting for 48 percent, with 10 percent due to severe bleaching events in 1998 and 2002. The intensity of cyclones was increasing as the world's oceans warmed.

The rate of decline had increased substantially, with two-thirds of the coral cover lost since 1998. Intervals between disturbances were generally too short to allow recovery, which takes between 10-20 years.

According to the team their shark study, published in the latest edition of peer-reviewed scientific journal PLOS ONE, had offered a "unique opportunity" to isolate and examine the impacts of sharks on an entire reef ecosystem's health in a way not attempted before.

.


Related Links
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
Unexpected interaction between ocean currents and bacteria
Odense, Denmark (SPX) Sep 18, 2013
For the first time, researchers have successfully demonstrated an interaction between ocean currents and bacteria: The unexpected interaction leads to the production of vast amounts of nitrogen gas in the Pacific Ocean. This takes place in one of the largest oxygen free water masses in the world - and these zones are expanding. This can ultimately weaken the ocean's ability to absorb CO2. ... read more


WATER WORLD
Chang'e-3 lunar probe sent to launch site

Sixteen Tons of Moondust

Scientists say water on moon may have originated on Earth

Moon landing mission to use "secret weapons"

WATER WORLD
Explosive flooding said responsible for distinctive Mars terrain

Upgrade to Mars rovers could aid discovery on more distant worlds

Investigating 'Coal Island' Rock Outcrop

Terramechanics research aims to keep Mars rovers rolling

WATER WORLD
Voyager's departure from the heliosphere

NASA study is enough to make a person want to stay in bed

Voyager 1 spacecraft reaches interstellar space

Q and A: John Richardson and John Belcher on Voyager 1's crossing and interstellar exploration

WATER WORLD
Last Days for Tiangong

China civilian technology satellites put into use

China to launch lunar lander by end of year: media

China launches three experimental satellites

WATER WORLD
ISS Orbit to Be Raised Ahead of Crew Arrival

ISS Releases a White Stork and Awaits a Swan

Three astronauts back on Earth from ISS: mission control

ISS Crew Completes Spacewalk Preps

WATER WORLD
Decontamination continues at Baikonur after Proton abortive launc

Russia launches three communication satellites

Arianespace remains the global launch services leader

Russian space official denies report of problem in Soyuz return

WATER WORLD
ESA selects SSTL to design Exoplanet satellite mission

Coldest Brown Dwarfs Blur Lines between Stars and Planets

NASA-funded Program Helps Amateur Astronomers Detect Alien Worlds

Observations strongly suggest distant super-Earth has water atmosphere

WATER WORLD
Catalysts team up with textiles

Raytheon, Falck Schmidt unveil remotely operated long-range surveillance system

Banishing explosive sparks in underground mines

Yahoo Japan develops 3D search engine-printer




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal 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