To punish or not to punish: Lessons from reef fish and saber-tooth blennies

ScienceDaily (Nov. 5, 2010) — Researchers have experimentally shown that some species of reef fish will enact punishment on the parasitic saber-tooth blennies that stealthily attack them from behind and take a bite, even though their behavior offers no immediate gain. The study, published online Nov. 4 in Current Biology, a Cell Press publication, shows that punishment ultimately serves all members of the reef fish species well.

In future attacks, blennies are more likely to go after "free-riding" individuals that don't take the time or expend the energy to punish their enemies, the researchers show, suggesting that reef fish punish blennies for reasons that are self-serving. Their self-serving behavior nonetheless creates a "public good." When given a choice, blennies are more apt to switch to another species for their next attack after their previous fare has punished them.

"Our study shows that public goods may arise due to self-serving behavior and without any consideration of the benefits to other group members," said Andrea Bshary of the University of Neuchâtel in Switzerland.

Cooperation in groups can be difficult to explain, since it would seem that "free riders" would win out as they take advantage of the efforts of their peers without contributing themselves. Human studies have explained this conundrum in two ways. Those who contribute may gain from the positive reputation it affords them, which may increase others' willingness to help them at another time. Alternatively, people might cooperate if cheaters can be punished. That raises another question: When does it make sense to punish, given that punishment has immediate costs to both the punisher and the punished?

To explore that question, Bshary and her colleague Redouan Bshary turned to scalefin anthias and the blennies they are known to chase. In this case, it was clear that the reef fish couldn't be acting out of concern for their close kin, because the shoaling fish are generally unrelated to one another.

In laboratory tests, the researchers showed that blennies were less likely to target a colored Plexiglas plate that had earlier chased them off than one that didn't. This showed the chasing behavior to be a bona fide example of punishment; chasing blennies has no immediate benefit, because the parasites almost always bite once per attack. The punishment instead leads to future gains as blennies become less likely to attack punishers.

In observational studies in a natural setting, the researchers found that punishment increased the likelihood that blennies would go for another species in their next attack. This means that all members of a species win when one of them punishes a blenny. Finally, the researchers showed in experiments that at least some blennies could tell the difference between look-alike pairs of plates in which one "punished" them and the other did not, and they would selectively bite nonpunishers. As a result, free riders are at a disadvantage.

The findings in fish suggest that humans, too, might sometimes appear to work together in the real world for reasons that are directly self-serving at their core, the researchers say. They point out that their study differs in an important regard from standard tests of game theory in humans in that the blennies interacted with only one individual of their own choosing. In human experiments, people often interact in groups.

"As a consequence," the researchers write, "it is always clear which individual of a shoal has to punish the blenny for its cheating. A victim cannot expect others to do the punishment, because they did not have a negative experience. We think that such conditions often apply to humans as well, in which punishment is a self-serving response to being cheated while benefiting the community as well. A person whose house gets broken into or who gets attacked by robbers will have to take action (call the police or fight back) even though all the neighbors may profit from this."

The researchers include Andrea Bshary, and Redouan Bshary, of University of Neuchatel, Institute of Biology, Neuchatel, Switzerland.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Cell Press, via EurekAlert!, a service of AAAS.

Journal Reference:

Andrea Bshary, and Redouan Bshary. Self-Serving Punishment of a Common Enemy Creates a Public Good in Reef Fishes. Current Biology, 2010; DOI: 10.1016/j.cub.2010.10.027

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Most river flows across the US are altered by land and water management

ScienceDaily (Nov. 3, 2010) — The amount of water flowing in streams and rivers has been significantly altered in nearly 90 percent of waters that were assessed in a new nationwide USGS study. Flow alterations are a primary contributor to degraded river ecosystems and loss of native species.

"This USGS assessment provides the most geographically extensive analysis to date of stream flow alteration," said Bill Werkheiser, USGS Associate Director for Water. "Findings show the pervasiveness of stream flow alteration resulting from land and water management, the significant impact of altered stream flow on aquatic organisms, and the importance of considering this factor for sustaining and restoring the health of the Nation's streams and ecosystems."

Flows are altered by a variety of land- and water-management activities, including reservoirs, diversions, subsurface tile drains, groundwater withdrawals, wastewater inputs, and impervious surfaces, such as parking lots, sidewalks and roads.

"Altered river flows lead to the loss of native fish and invertebrate species whose survival and reproduction are tightly linked to specific flow conditions," said Daren Carlisle, USGS ecologist and lead scientist on this study. "These consequences can also affect water quality, recreational opportunities and the maintenance of sport fish populations."

For example, in streams with severely diminished flow, native trout, a popular sport fish that requires fast-flowing streams with gravel bottoms, are replaced by less desirable non-native species, such as carp. Overall, the USGS study indicated that streams with diminished flow contained aquatic communities that prefer slow moving currents more characteristic of lake or pond habitats.

"Management practices related to water demand continue to alter stream flows in many places," said Jeff Ostermiller, Water Quality Manager with the Utah Division of Water Quality. "Understanding the ecological effects of these flow alterations helps water managers develop effective strategies to ensure that water remains sufficiently clean and abundant to support fisheries and recreation opportunities, while simultaneously supporting economic development."

Annual and seasonal cycles of water flows -- particularly the low and high flows -- shape ecological processes in rivers and streams. An adequate minimum flow is important to maintain suitable water conditions and habitat for fish and other aquatic life. High flows are important because they replenish floodplains and flush out accumulated sediment that can degrade habitat.

"While this study provided the first, national assessment of flow alteration, focused studies within specific geographic regions will provide a better understanding of the ecological effects of altered stream flows, which can be more effectively applied to local water management challenges," said Carlisle.

The severity and type of stream flow alteration varies among regions, due to natural landscape features, land practices, degree of development, and water demand. Differences are especially large between arid and wet climates. In wet climates, watershed management is often focused on flood control, which can result in lower maximum flows and higher minimum flows. Extremely low flows are the greatest concern in arid climates, in large part due to groundwater withdrawals and high water use for irrigation.

The study identified over 1,000 unimpaired streams to use as reference points to create stream flow models. The models were applied to estimate expected flows for 2,888 additional streams where the USGS had flow monitoring gauges from 1980-2007. The estimated values for the 2,888 streams were compared to actual, measured flows to determine the degree to which streams have been altered.

This study was conducted by the USGS National Water-Quality Assessment Program.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by United States Geological Survey.

Journal Reference:

Daren M Carlisle, David M Wolock, Michael R Meador. Alteration of streamflow magnitudes and potential ecological consequences: a multiregional assessment. Frontiers in Ecology and the Environment, 2010; : 101025105601059 DOI: 10.1890/100053

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Helping fish get rid of the 'Ich'

ScienceDaily (Nov. 1, 2010) — Copper sulfate has emerged as an effective treatment for Ichthyophthirius multifiliis, also known as "Ich," a protozoan parasite that appears as white spots on infected fish, according to a U.S. Department of Agriculture (USDA) scientist.

Aquatic toxicologist David Straus with USDA's Agricultural Research Service (ARS) investigated copper sulfate as a method to control both Ich in catfish and a fungus -- Saprolegnia -- on catfish eggs. Straus works at the ARS Harry K. Dupree Stuttgart National Aquaculture Research Center in Stuttgart, Ark. ARS is the chief intramural scientific research agency of USDA, and this research supports the USDA priority of promoting international food security.

Ich is considered the most prevalent parasite worldwide in ornamental fish, baitfish and food fish, according to Straus. Ich is less common in U.S. aquaculture because of management techniques, but when it occurs, it can kill all the fish in a pond or raceway. It is calculated that Ich was directly responsible for $1.2 million in losses to the catfish industry in 2003.

The freshwater fungus Saprolegnia is another major pathogen in fish culture, killing eggs and invading wounds and lesions on juvenile and adult fish.

Straus found copper sulfate is an effective treatment for Ich on fish and fungus on eggs. According to Straus, copper sulfate is the only practical treatment to control Ich in catfish ponds that average about 10 acres in area. It is easy to use, effective and inexpensive, and is safe for the user to handle.

Current approved treatments for fungus on eggs, such as formalin and hydrogen peroxide, are much more expensive. Also, both compounds are hazardous, and there are human safety concerns as well as required storage precautions.

Copper sulfate is not currently approved by the U.S. Food and Drug Administration for therapeutic use in aquaculture, but regulatory action has been deferred pending the outcome of Straus' ongoing research. The chemical is approved by the U.S. Environmental Protection Agency as an algicide and molluscicide. Fish farmers use copper sulfate to control cyanobacteria that cause off-flavor in fish, and to control snails that transmit parasitic flatworms to fish.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by USDA/Agricultural Research Service.

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New fish feeds made from fish byproducts

ScienceDaily (Nov. 5, 2010) — Fish byproducts may be a new source of fish feed, thanks to research by U.S. Department of Agriculture (USDA)-funded scientists in Hawaii.

Research scientist Dong-Fang Deng and her colleagues with the Oceanic Institute in Waimanalo, Hawaii, are collaborating with USDA food technologist Peter Bechtel to develop the new fish feeds. Bechtel is with the USDA Agricultural Research Service (ARS) Subarctic Agricultural Research Unit in Kodiak, Alaska. ARS is the USDA's principal intramural scientific research agency.

The scientists are taking fish parts that would normally be discarded-head, tail, bone, skin and internal organs-and fashioning them into feeds for shrimp and fish. They are currently testing the feeds on Pacific threadfin (Polydactylus sexfilis)-or "moi" as Hawaiians call it-and Pacific white shrimp (Litopenaeus vannamei).

The researchers then characterize the nutrient composition of the feeds, evaluate their ability to attract the shrimp and moi, estimate the food's digestibility and assess the growth of the animals. Recent tests have shown that many of the Alaska fish parts work well as feeding stimulants, which entice the shrimp to eat the plant-protein-based feed to which fish byproducts had been added.

In an earlier ARS-funded study with moi, former Oceanic Institute scientist Ian Forster found that the nutritional quality of feeds made with discarded portions of Alaskan pollock and cod was equivalent to that of feed made from Norwegian fishmeal, generally regarded as the highest standard in the aquaculture feed industry. Forster and his colleagues found the same result when feeds were tested on shrimp.

According to Deng, the scientists are currently examining how to best use fish byproducts to develop practical feeds that are nutritionally balanced, cost effective and safe for the environment.

Details about these feed studies have been published in the Journal of the World Aquaculture Society and the Journal of Aquatic Food Product Technology.

Read more about this and other ARS aquaculture research in the October 2010 issue of Agricultural Research magazine: http://www.ars.usda.gov/is/AR/archive/oct10/leftovers1010.htm

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by USDA/Agricultural Research Service. The original article was written by Stephanie Yao.

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Mysterious link between ancient lizard fossil in Africa and today's Komodo dragon in Indonesia

ScienceDaily (Nov. 17, 2010) — University of Alberta researchers have unearthed a mysterious link between bones of an ancient lizard found in Africa and the biggest, baddest modern-day lizard of them all, the Komodo dragon, half a world away in Indonesia.

Biologists Alison Murray and Rob Holmes say the unique shape of the vertebrae links the 33-million-year-old African lizard fossil with its cousin the Komodo, which has only been around for some 700,000 years.

"The African fossil was found on the surface of a windswept desert," said Holmes. "It's definitely from the lizard genus Varanus and there are more than 50 species alive today, including Komodos and other large lizards."

Holmes says the telltale African vertebrae fossils belonged to a lizard that was about a metre- and-a-half long whose ability to swim may be key to figuring out how more than 30 million years later its ancestors turned up on the other side of the world.

Holmes says the ancient African Varanus specimen was found on land that was once the bottom of a river or small lake. "Whether the animals lived in the water or surrounding land, we don't know, but we do know that some modern day species of Varanus are comfortable swimming in fresh water."

The researchers agree that fresh-water swimming wouldn't get the African lizard all the way to Indonesia. Murray says the mystery of how the animals spread deepens when you consider ancient world geography. "From about 100 million years ago until 12 million years ago, Africa was completely isolated, surrounded by ocean, but somehow they got out of Africa during that period," said Murray. "That's why this paper is important because there was no known land connection."

Murray says one unproven theory of how Varanus moved out of Africa is that over millions of years, small land masses or micro-plates may have moved from one place to another, carrying their fauna with them.

The work of the U of A researchers and various co-authors runs counter to some prevailing theories about the origins of some ancient fossil types found in Africa including Varanus lizards and some fresh-water fish. "The assumption for several types of ancient African fossils is that the animals didn't originate in Africa but came there from Asia," says Holmes. "But the fossil record of Varanus shows exactly the opposite path of migration."

The work of Murray and Holmes and various co-authors was published in the journal Palaeontology.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Alberta, via EurekAlert!, a service of AAAS.

Journal Reference:

Robert B. Holmes, Alison M. Murray, Yousry S. Attia, Elwyn L. Simons, Prithijit Chatrath. Oldest known Varanus (Squamata: Varanidae) from the Upper Eocene and Lower Oligocene of Egypt: support for an African origin of the genus. Palaeontology, 2010; 53 (5): 1099 DOI: 10.1111/j.1475-4983.2010.00994.x

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FDA review on transgenic salmon too narrow, experts say

ScienceDaily (Nov. 19, 2010) — The review process being used by the Food and Drug Administration to assess the safety of a faster-growing transgenic salmon fails to weigh the full effects of the fish's widespread production, according to analysis by a Duke University-led team in the journal Science.

The salmon, whose genome contains inserted genes from two other fish species, could become the first genetically modified animal approved for human consumption in the United States.

The FDA held two days of hearings in September to assess the fish's human and environmental health risks. The period for public comment ends this month. A final FDA decision could be imminent.

The concern, Duke economist Martin D. Smith says, is that the new animal drug application process FDA is using to review the transgenic salmon evaluates its safety only by comparing its nutritional profile to an equivalent portion of nonmodified salmon, and screening it for known toxins and allergens.

Smith said such a process ignores the potential health and environmental effects of salmon production and consumption -- both positive and negative -- that might stem from the fish's faster growth and less need for feed.

"These market impacts could dwarf any small differences in nutritional content," says Smith, associate professor of environmental economics at Duke's Nicholas School of the Environment.

A smarter approach, Smith and his coauthors argue, would be for FDA -- or if necessary, Congress -- to broaden the interpretation of the terms "safe" and "health" in FDA statutes so its review process can include an evaluation of the overall safety of the new fish compared to other protein sources that it might replace, such as beef.

"Instead of focusing on the safety of a food taken one portion at a time or whether it was produced through genetic modifications or through classic breeding, a more useful approach would be to evaluate whether society is better off overall with the new product on the market than without it," says Jonathan B. Wiener, William R. and Thomas L. Perkins Professor of Law at Duke Law School.

This fuller assessment would require FDA regulators to take into consideration factors currently unaccounted for, such as public health impacts that could occur if, as is likely, increased production of transgenic farmed salmon leads to lower retail prices and increased consumption.

"Lower prices for salmon would have significant public health benefits," Smith explained. "Consumers would have access to a less expensive source of healthy protein and omega-3 fatty acids, which have well-documented health benefits."

A broader review would also allow a fuller assessment of potential environmental impacts, such as pollution from farmed salmon waste; disease; increased harvesting of the wild fish used to feed farmed salmon; and the escape of genetically modified salmon into the wild, where they could affect wild salmon stocks through gene transfer or increased competition for resources.

The National Environmental Policy Act mandates FDA to assess significant environmental impacts from market expansion of the products it approves, yet the narrow scope of the current review process for new animal drugs presents "an incomplete picture" of these risks and benefits for transgenic salmon, the researchers write in their analysis.

"The approval of genetically modified salmon will set an important precedent for other transgenic animals intended for human consumption," Smith says. "It's essential that FDA establishes an approval process that assesses the full portfolio of impacts to ensure that such decisions serve society's best interests." FDA administrators need to weigh the benefits of such assessments against the costs and delays they likely would incur, he says.

If conducting a full assessment of transgenic salmon would take too long, a reasonable compromise would be to use existing studies to develop scenarios of market growth and the broader impacts to human and environmental health that may occur as a result.

Frank Asche of the University of Stavanger, Norway, and Atle G. Guttormsen of the Norwegian University of Life Sciences co-authored the Science paper with Smith and Wiener.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Duke University, via EurekAlert!, a service of AAAS.

Journal Reference:

Smith, et al. Genetically Modified Salmon and Full Impact Assessment. Science, 19 November 2010: 1052-1053. DOI: 10.1126/science.1197769

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New ocean acidification study shows added danger to already struggling coral reefs

ScienceDaily (Nov. 13, 2010) — Over the next century, recruitment of new corals could drop by 73 percent, as rising carbon dioxide levels turn the oceans more acidic, suggests a new study led by scientists at the University of Miami Rosenstiel School of Marine and Atmospheric Science. The research findings reveal a new danger to the already threatened Caribbean and Florida reef Elkhorn corals.

"Ocean acidification is widely viewed as an emerging threat to coral reefs," said Rosenstiel School graduate student Rebecca Albright. "Our study is one of the first to document the impacts of ocean acidification on coral recruitment."

Albright and colleagues report that ocean acidification could compromise the successful fertilization, larval settlement and survivorship of Elkhorn corals. The research results suggest that ocean acidification could severely impact the ability of coral reefs to recover from disturbance, said the authors.

Elkhorn coral, known as Acropora palmata, is recognized as a critical reef-building species that once dominated tropical coral reef ecosystems. In 2006, Elkhorn was included on the U.S. Endangered Species List largely due to severe population declines over the past several decades.

The absorption of carbon dioxide by seawater, which results in a decline in pH level, is termed ocean acidification. The increased acidity in the seawater is felt throughout the marine food web as calcifying organisms, such as corals, oysters and sea urchins, find it more difficult to build their shells and skeletons making them more susceptible to predation and damage.

Recent studies, such as this one conducted by Albright and colleagues, are beginning to reveal how ocean acidification affects non-calcifying stages of marine organisms, such as reproduction.

"Reproductive failure of young coral species is an increasing concern since reefs are already highly stressed from bleaching, hurricanes, disease and poor water quality," said Chris Langdon, associate professor at the Rosenstiel School and co-author of the study, published in the Proceedings of the National Academy of Sciences.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Miami Rosenstiel School of Marine & Atmospheric Science.

Journal Reference:

Rebecca Albright, Benjamin Mason, Margaret Miller, Chris Langdon. Ocean acidification compromises recruitment success of the threatened Caribbean coral Acropora palmata. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1007273107

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Scientists call for protection of Australia's subtropic seas

ScienceDaily (Nov. 21, 2010) — Leading scientists and marine managers have called for a greater national effort to protect vital 1000-kilometre stretches of ocean bordering the middle of Australia's eastern and western coastlines.

In a major statement entitled The Coffs Harbour Subtropical Reefs Declaration, they urge increased focus and better management for reefs south of the Great Barrier Reef and WA tropical coral zone, explaining that these more southerly areas are expected to become critical refuges for northern tropical marine life under global warming.

The declaration follows a workshop by researchers and marine managers at Coffs Harbour in September which concluded that the subtropics will play a key role in safeguarding Australia's tropical marine life as ocean warming drives it southwards -- especially if northern coral reefs die off, as some scientists fear.

The Coffs Harbor Declaration was made by a new expert group called the Sustainable Subtropical Reefs Alliance (SuSRA), which has been established to advocate for greater ocean research and conservation on coastal areas between Sydney and Bundaberg on the east coast and Perth and Shark Bay on the west coast. Among its signatories are scientists from five of Australia's east coast universities -- Tasmania, Sydney, Southern Cross, Queensland and James Cook, marine park managers, and the CSIRO (Queensland and Western Australia).

"The subtropics are really about life on the edge -- where tropical and temperate marine species meet and mix in a rich diversity. There is already evidence that tropical species are migrating southwards in response to warming, making the subtropics all the more important," explains Professor John Pandolfi of the ARC Centre of Excellence for Coral Reef Studies and the University of Queensland.

"Unfortunately we only have a limited understanding of what's out there and what's happening to it, on which to base our future management -- and this gap in our knowledge needs to be closed quickly, so we can integrate the management of our entire coastal regions better."

The eastern subtropical coastline, and increasingly the west too, are among Australia's fastest-growing regions, throwing surging human pressures on ocean ecosystems, says Dr Maria Beger of UQ. "These environments are already under major stress from changing climate and oceanic currents -- and to this we are adding increased activities like pollution, runoff, coastal development and fishing.

"We need to ensure we protect the resilience of this region, as well as the northern coral zones. At the same time, the future of our central coastal communities, their industries and their lifestyle depends on preserving a healthy marine environment."

The Coffs Harbour Declaration states that the eastern and western coasts of Australia are amongst the longest latitudinal tracts of subtropical coastal marine habitat in the world, encompassing beaches, rocky foreshores, offshore islands, shoals and reefs.

Changes in fish and coral distribution now being observed by scientists have made it imperative to re-evaluate conservation plans for the central coasts and strengthen them where necessary, it states.

The declaration highlights 7 priorities for improving the management of Australia subtropical marine environment:

Integrate science and resource management across federal, state and local agencies to ensure better planning and management of subtropical marine areas;Study how social, economic and political factors affect the management of coastal resources and the services they in turn provide to coastal communities;Understand the existing ecology and map existing coastal habitat;Evaluate threats to marine resources from land-based activities, benchmark their past and current status and monitor changes;Determine pathways for tropical marine 'invaders' moving into the subtropics due to climate change, and the impact on local species;Determine which sites (refugia) are critical to preserving subtropical marine fish, corals and other species in the event of profound environmental change;Investigate natural variability of existing subtropical marine areas (so as to detect unusual changes).

The declaration concludes: "We call upon practitioners, managers, researchers, funding bodies and governments to recognise that these priority areas require urgent attention and investment to enable effective and efficient decision making for the future of subtropical reefs."

View the entire declaration Here.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by ARC Centre of Excellence in Coral Reef Studies.

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Climate change remains a real threat to corals

ScienceDaily (Oct. 13, 2010) — Hopes that coral reefs might be able to survive, and recover from, bleaching caused by climate change may have grown dimmer for certain coral species, according to new research by University at Buffalo marine biologists published this week in PLoS One.

The research shows, for the first time, that while hard corals can take up from the environment new stress-tolerant algae that provide critical nutrients, the coral may not be able to sustain the relationship with these algae over a long period, a process known as symbiosis.

The findings may mean that certain types of coral will not be able to adapt rapidly enough to survive global warming, says the study's lead author, Mary Alice Coffroth, PhD, UB professor of geological sciences in the College of Arts and Sciences.

"Our findings suggest that not all corals can maintain a long-term symbiosis with these stress-tolerant strains of algae," says Mary Alice Coffroth, PhD, UB professor of geological sciences in the College of Arts and Sciences and lead author.

"That's the problem," she says, "if they can't take up the stress-tolerant symbionts, or if they take them up but can't maintain the symbiosis with them, as we found, then they likely won't be able to adapt rapidly enough to survive global warming."

The demise of coral reefs deprives fish of food and shelter, which reduces reef fish populations and marine diversity.

Co-authors on the paper include Eleni L. Petrou, a recent UB Honors College undergraduate who worked in Coffroth's lab as well as Daniel M. Poland, a recent PhD graduate and Jennie C. Holmberg, a former graduate student, both of whom worked in Coffroth's lab, and Daniel A. Brazeau, research associate professor in UB's Department of Pharmaceutical Sciences.

During the past two decades, Coffroth explains, coral reefs, known as the rain forests of the sea for their incredible biological diversity, have suffered bleaching events due to high water temperatures and light levels that cause them to literally "spit out" their algal symbionts, which provide their sustenance. Severe bleaching can lead to coral death.

In recent years, though, it has been reported that some corals appear to respond to rising sea temperatures by acquiring new stress-tolerant symbionts from the environment, which could allow them to survive the warmer oceans caused by climate change.

Coffroth says that the UB research shows that while the corals they studied were able to acquire new stress-tolerant symbiont strains from the water, they were unable to maintain that symbiosis for very long.

After about five weeks, the proportion of new symbionts within the coral had declined dramatically and after 14 weeks was no longer detectable in the corals.

"While it's true that coral can be flexible in the kinds of symbionts they take up, that will only work within limits," she says. "It's possible that the new symbionts were either unable to multiply in the host or to compete with the existing residual populations of symbionts in the coral.

"Our findings suggest that if a coral that doesn't naturally host this kind of stress-tolerant symbiont, it cannot acquire it from the environment."

She noted that the outlook may be more promising for corals that naturally harbor the stress-resistant symbionts. These symbionts appear to be able to protect corals from sea temperatures that are one-to-two degrees higher than normal; however, Coffroth cautions that most estimates predict that by 2100 global warming will cause sea temperatures to rise by as much as two-to six-degrees above current temperatures.

The UB researchers studied Porites divaricata, a common shallow-water scleractinian coral found throughout the Caribbean.

The coral samples were retrieved from a site within the Florida Keys National Marine Sanctuary; in the laboratory, the scientists induced bleaching by exposing the coral to incremental increases in water temperatures until it reached 33 degrees C, about 91 degrees F.

The research was funded by the National Science Foundation and a grant from the UB Honors College Research and Creative Activities Fund.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University at Buffalo.

Journal Reference:

Ross Thompson, Mary Alice Coffroth, Daniel M. Poland, Eleni L. Petrou, Daniel A. Brazeau, Jennie C. Holmberg. Environmental Symbiont Acquisition May Not Be the Solution to Warming Seas for Reef-Building Corals. PLoS ONE, 2010; 5 (10): e13258 DOI: 10.1371/journal.pone.0013258

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Call to heal the world's coral reefs

ScienceDaily (Oct. 6, 2010) — There is still time to save the world's ailing coral reefs, if prompt and decisive action can be taken to improve their overall health, leading marine researchers say.

Writing in the journal Trends in Ecology and Evolution, eminent marine scientists from Australia and the USA have called for an international effort to improve the resilience of coral reefs, so they can withstand the impacts of climate change and other human activities.

"The world's coral reefs are important economic, social and environmental assets, and they are in deep trouble. How much trouble, and why, are critical research questions that have obvious implications for formulating policy and improving the governance and management of these tropical maritime resources," explains Jeremy Jackson from the Scripps Institution of Oceanography.

The key to saving the reefs lies in understanding why some reefs degenerate into a mass of weeds and never recover -- an event known as a 'phase shift' -- while on other reefs the corals manage to bounce back successfully, showing a quality known as resilience.

This underlines the importance of managing reefs in ways that promote their resilience, the researchers say.

They presented evidence that coral decline due to human activity has been going on for centuries, but has been particularly alarming in the past 50 years. In all some 125,000 square kilometres of the world's corals have disappeared so far.

The most recent global report card (2008) estimated that 19% of all reefs were effectively lost, another 15% were critical and likely to be lost in 10-20 years, and a further 20% are under threat from local human pressures (already experiencing 20-50% loss of corals). The remaining 46% of reefs were at low risk from direct human impacts, but were nevertheless vulnerable to climate change and ocean acidification.

"We have a very good scientific understanding of what causes reefs to decline -- what we now need is a clearer picture of how to help them back onto the reverse trajectory," says lead author Professor Terry Hughes from the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University.

Taking an optimistic view, the researchers argue there is compelling evidence from sites in Hawaii, Australia's Great Barrier Reef, the Caribbean, Bahamas and Philippines that the degradation and disappearance of corals can be arrested and reversed with the right management:

In Hawaii, where ending sewage discharges allowed corals in Kanehoe Bay to recoverIn Australia, where weed-eating fish played a decisive role in keeping seaweed down while the corals fought backIn the Caribbean where recovering sea urchin populations are helping to keep down weed and allow corals to recoverIn the Bahamas and Philippines, where controls on over fishing for parrot fish and other weed-eaters, also helped to restore coral cover.

"The coral reef crisis is a crisis of governance," says co-author Peter Mumby from the University of Queensland.

The team has formulated the scientific lessons from resilient reefs into a set of management advice which governments can adopt to give coral reefs a fighting chance:

Empower and educate local people to look after their own reefsChange land uses that cause damaging runoff and sedimentControl not only fishing, but also fish markets to protect herbivorous fishIntegrate resilience science with reef management and support for local communities in restoring their reefsImprove laws that protect coral reefs globally"Confront climate change as the single most important issue for coral reef management and conservation by sharply reducing greenhouse gas emissions."

On climate change they caution: "Without urgent action, unchecked global warming and ocean acidification promise to be the ultimate policy failures for coral reefs. Although it is possible to promote the recovery of reefs following bouts of bleaching via local actions such as improving water-quality and protecting herbivores, these interventions alone cannot climate-proof reefs."

"The clear message from our research, and that of other marine scientists, is that the world's coral reefs can still be saved… if we try harder," Prof. Hughes says.

Their article "Rising to the challenge of sustaining coral reef resilience" by Terry P. Hughes, Nicholas A.J. Graham, Jeremy B.C. Jackson, Peter J. Mumby and Robert S. Steneck appears in the latest issue of Trends in Ecology and Evolution (TREE).

The future of Australia's and the world's coral reefs is the focus of a major scientific symposium in Canberra on October 7 and 8, at the Australian Academy of Science's Shine Dome.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by ARC Centre of Excellence in Coral Reef Studies.

Journal Reference:

Terry P. Hughes, Nicholas A.J. Graham, Jeremy B.C. Jackson, Peter J. Mumby, Robert S. Steneck. Rising to the challenge of sustaining coral reef resilience. Trends in Ecology & Evolution, 2010; DOI: 10.1016/j.tree.2010.07.011

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Squid studies provide valuable insights into hearing mechanisms

ScienceDaily (Oct. 15, 2010) — The ordinary squid, Loligo pealii -- best known until now as a kind of floating buffet for just about any fish in the sea -- may be on the verge of becoming a scientific superstar, providing clues about the origin and evolution of the sense of hearing.

In a hangar-like research building at the Woods Hole Oceanographic Institution (WHOI), biologist T. Aran Mooney is exploring virtually uncharted waters: Can squid hear? Is their hearing sensitive enough to hear approaching predators? How do squid and other marine species rely on sound to interact, migrate, and communicate? Will the burgeoning cacophony of sound in the ocean disrupt marine life's behavior and threaten their survival?

"The sound in the ocean is increasing…commercial shipping, oil and gas exploration…those make a lot of noise," Mooney says. "And you don't know how that is going to affect the animal unless you know what it hears."

Mooney, a postdoctoral scholar at WHOI, has undertaken seminal investigations into the hearing of this seminal creature in the marine food web. His study is published Oct. 15, in the Journal of Experimental Biology.

"Almost every type of marine organism feeds somehow off the squid," says Mooney. Not just fish, but also many birds, seals, sea lions, and dolphins and toothed whales depend heavily on squid. Whales, according to Mooney, consume some 320 metric tons of squid a year; people eat another 280 metric tons annually.

Mooney says it may be the squid's role as a predator's entrée that holds the key to understanding the importance of hearing among squid and other ocean creatures. This is because predator avoidance is a key pressure for evolving hearing capabilities. If you can hear your predators approaching, you have a better chance of avoiding them. Eventually, he said, a better understanding of how squid hear may shed light on human hearing as well.

Despite their importance in the marine food web, little is known about how well squid hear and whether they rely on hearing to navigate, sense danger, and communicate with each other. Until recently, it wasn't clear that they even hear at all.

It is known now, through the work of Mooney and others, that the squid hearing system has some similarities and some differences compared to human hearing. Squid have a pair of organs called statocysts, balance mechanisms at the base of the brain that contain a tiny grain of calcium, which maintains its position as the animal maneuvers in the water. These serve a function similar to human ear canals.

Each statocyst is a hollow, fluid-filled sac lined with hair cells, like human cochlea. On the outside of the sac, the hair cells are connected to nerves, which lead to the brain. "It's kind of like an inside-out tennis ball," Mooney said, "hairy on the inside, smooth on the outside."

The calcium grain, called a statolith, enables the squid to sense its position in the water, based on which hair cells it's in contact with at a given moment. Normally it rests near the front of the sac, touching some of the hair cells.

When a squid moves quickly -- as it does when it flees an approaching predator -- the heavy calcium stone lags behind slightly before catching up to the hair cells. "Kind of like your stomach on a roller coaster," Mooney said. "The hair cells are very sensitive and can detect the calcium statolith lagging behind, then catching up."

Structurally, the statocyst "is analogous to our auditory system," said Mooney, who began his hearing research while working on his Ph.D. at the University of Hawaii. The statocyst, he thinks, "is on its way to becoming an ear" like the more familiar ears of vertebrates.

But to what extent does it function as an ear? "One of the obvious questions is, 'Can this acceleration-sensing 'ear' to also detect sounds?' Then, if they can hear sounds 'Do squid hear their predators coming?' " Mooney asked.

To find out if squid have true, functioning "ears," Mooney tests whether the nerves coming from the statocysts send impulses in response to sound. He anesthetizes a squid and attaches an electrode just under the skin near the nerves that extend from the statocysts. He attaches another sensor into the squid's back to get baseline measurements of electrical signals, because that part of the body should not respond to sounds.

He then lowers the squid into a shallow, 3-foot-wide tank. Also in the tank is a speaker that can emit a broad range of sound frequencies -- pure tones repeated about 1,000 times for each frequency. He then records the 1,000 responses to each. Averaging those 1,000 responses reduces the natural, random electrical noise in the body yielding the electrical signals, in millivolts, that occur along the nerves after each tone. This hearing test method is similar to those used to checking hearing in human infants.

His preliminary findings indicate that nerve responses showed the squid "actually do hear," he said. "But they only hear up to a certain frequency, about 500 Hz, which is pretty typical of a lot of fish that don't hear very well." Humans hear from about 20-20,000 Hz. Squid also do not detect the very high frequency sounds of dolphin echolocation clicks.

That may help explain why squid are such a prolific food source: They may not always hear well enough to get out of the way of approaching predators. But when Mooney and his post-doc advisor [name?] put the squid in a CT scanner, they found that squid may avoid predators in another way: they are almost the same density as water. That is, when squid were scanned in water, the CT could not image the squid body, illustrating that squid are nearly transparent to sound. This would likely make them very difficult for echolocating predators to detect. So, perhaps, squid could not take the evolutionary leap to adapt ears to detect very high frequencies, but being close in density to water is advantageous for several reasons, including avoiding predators.

Still, its auditory mechanisms have been good enough to make squid successful in an evolutionary sense. What, then, is the main purpose of the squid's hearing system?

Mooney said his work falls under the heading of "sensory biology," the study of how animals use their sensory systems to figure out the world around them. After the initial tests to see how sensitive squid are to sounds and their frequency range, he next studies will be to try to determine how important those abilities are to the animal. Do squid rely on sound to interact, migrate, communicate?

In one set of experiments Mooney will move the speakers to different positions and measure the nerves' response to see if they sense the location of that speaker.

"It's been suggested that a primary evolutionary drive behind hearing is to locate where the sound source is," he said. "If your mother is calling to you, you have to know where your mother is. If there's a predator coming you'd better darn well know where that predator is coming from so that you can get out of the way."

Another question Mooney wants to pursue is how much -- if at all, squid are affected by sounds of human origin in the ocean. Loud sounds, whether a sudden explosion or continuous ship traffic, might cause squid to migrate unnaturally just to escape the racket.

Mooney also thinks squid statocysts can tell scientists a lot about how ears originated and evolved.

"Humans, fish, and lots of animals use hair cells to detect sound and movement. Their hair cell structures are similar to squid, but also quite different," said Mooney. "There is probably a basic structure which evolved millions of years ago, but vertebrates and invertebrates have taken quite different evolutionary paths since.

"By learning more about squid hearing and squid hair cells, we might learn what is important in human hearing and human hair cells, or other animals for that matter," he said. "Down the road, squid ears and hair cells might be models for examining human hearing. But that's just speculative right now. We need to learn more about the basic functioning of squid ears first."

Paul Nachtigall, a biologist at the University of Hawaii who advised Mooney on his doctoral research on hearing and echolocation in whales and dolphins, said Mooney's research on squid hearing mechanisms and the ecological uses of hearing in squid are "groundbreaking."

"Aran was launched out of here with great success," said Nachtigall, "and his rocket appears to have reached stage two prior to reaching a stellar orbit."

Mooney's work with squid is funded by The Grass Foundation and a WHOI Independent study award from the Andrew W. Mellon Fund for Innovative Research.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Woods Hole Oceanographic Institution.

Journal Reference:

T. A. Mooney, R. T. Hanlon, J. Christensen-Dalsgaard, P. T. Madsen, D. R. Ketten, P. E. Nachtigall. Sound detection by the longfin squid (Loligo pealeii) studied with auditory evoked potentials: sensitivity to low-frequency particle motion and not pressure. Journal of Experimental Biology, 2010; 213 (21): 3748 DOI: 10.1242/jeb.048348

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View the original article here

Helping fish get rid of the 'Ich'

ScienceDaily (Oct. 28, 2010) — Copper sulfate has emerged as an effective treatment for Ichthyophthirius multifiliis, also known as "Ich," a protozoan parasite that appears as white spots on infected fish, according to a U.S. Department of Agriculture (USDA) scientist.

Aquatic toxicologist David Straus with USDA's Agricultural Research Service (ARS) investigated copper sulfate as a method to control both Ich in catfish and a fungus -- Saprolegnia -- on catfish eggs. Straus works at the ARS Harry K. Dupree Stuttgart National Aquaculture Research Center in Stuttgart, Ark. ARS is the chief intramural scientific research agency of USDA, and this research supports the USDA priority of promoting international food security.

Ich is considered the most prevalent parasite worldwide in ornamental fish, baitfish and food fish, according to Straus. Ich is less common in U.S. aquaculture because of management techniques, but when it occurs, it can kill all the fish in a pond or raceway. It is calculated that Ich was directly responsible for $1.2 million in losses to the catfish industry in 2003.

The freshwater fungus Saprolegnia is another major pathogen in fish culture, killing eggs and invading wounds and lesions on juvenile and adult fish.

Straus found copper sulfate is an effective treatment for Ich on fish and fungus on eggs. According to Straus, copper sulfate is the only practical treatment to control Ich in catfish ponds that average about 10 acres in area. It is easy to use, effective and inexpensive, and is safe for the user to handle.

Current approved treatments for fungus on eggs, such as formalin and hydrogen peroxide, are much more expensive. Also, both compounds are hazardous, and there are human safety concerns as well as required storage precautions.

Copper sulfate is not currently approved by the U.S. Food and Drug Administration for therapeutic use in aquaculture, but regulatory action has been deferred pending the outcome of Straus' ongoing research. The chemical is approved by the U.S. Environmental Protection Agency as an algicide and molluscicide. Fish farmers use copper sulfate to control cyanobacteria that cause off-flavor in fish, and to control snails that transmit parasitic flatworms to fish.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by USDA/Agricultural Research Service.

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New fisheries system will save about $20 million, researchers find

ScienceDaily (Oct. 5, 2010) — Some fisheries in the United States are poised to undergo major changes in the regulations used to protect fish stocks, and Iowa State University researchers have estimated that the new system will be an economic boon to the fishing industry.

Quinn Weninger and Rajesh Singh, both associate professors in economics, estimated harvesting costs under the old system and compared that to the newly proposed fishing regulations that lift many restrictions that cause inefficiency while still limiting amounts to be harvested.

Their analysis focused on the Pacific Groundfish fishery, which manages fishing in waters off the Northwest coast of the United States, and found the Groundfish fleet could save between $18 million and $22 million annually under the new regulatory system.

Pacific Groundfish fishery is one of several fisheries around the country that monitors fish harvest by location and types of fish. Similar economic conclusions would apply to other areas and other fish types, according to Weninger.

"What we've tried to do is come up with the cost savings that would be involved when we change from the old to the new system," he said.

The new system controls catch amounts through a system of tradable fishing permits and allocates a certain amount of fish to be harvested by each fisherman each year, said Weninger. The amount of each fisherman's total harvest is determined by the total number of permits he holds.

Fisheries managers, who are National Marine Fisheries Service employees, monitor fish stocks and calculate the total harvest that will allow fish numbers to remain at sustainable levels while letting fishermen survive economically.

Under the new system, for example, if a fisherman owns 1 percent of the permits, that fisherman can harvest 1 percent of the total amount of fish, which is chosen annually by the manager.

The new regulations begin by allocating permits to active fishermen based on that fisherman's past annual haul of fish. A key feature is that the permits can be bought and sold, allowing more flexibility for fishermen.

Under the old system, fishermen faced a host of regulations designed to ensure the fleet did not overfish the resource.

These regulations included imposing gear restrictions, seasonal closures, area closures, limits on the number of boats, bimonthly catch limits and other regulations that make harvesting fish less and less efficient and more costly.

"Prior to the new system, an entire years' halibut was harvested in two, six-hour openings," said Weninger. "We're talking about thousands of boats going out there and filling their boats to the point of sinking on the way home with all of these fish."

While the new system has gained popularity in recent years, little was known about how much money would be saved industry-wide.

Weninger and Singh answered that question.

The $18 million to $22 million savings for the Pacific Groundfish fishery will result mainly from reducing the size of the fishing fleet from around 117 vessels, to around 40 to 60 that will be required to catch the government-set limit. That is a reduction of more than 50 percent.

"Basically the revenues stay the same [under the new system], but you're able to harvest those fish at a fraction of the cost," Weninger said.

The old systems had too many redundant boats providing the same service, he added.

The findings are published in the journal Marine Resource Economics.

Weninger said the cost savings could eventually lower prices at the supermarket.

Another benefit for consumers is the availability of fresh fish. In the past, since all the halibut had to be harvested in just a few hours, consumers had to settle for frozen fish for much of the year. Now, with the expanded time window to catch fish, there will be fresh halibut available for more of the year, he said.

Another benefit is safety. Since fishermen won't be required to fish during a time preset by the government regulations regardless of weather conditions, they can fish when conditions are favorable and fishing is safer.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Iowa State University.

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Worst coral death strikes at Southeast Asia

ScienceDaily (Oct. 21, 2010) — International marine scientists say that a huge coral death which has struck Southeast Asian and Indian Ocean reefs over recent months has highlighted the urgency of controlling global carbon emissions.

Many reefs are dead or dying across the Indian Ocean and into the Coral Triangle following a bleaching event that extends from the Seychelles in the west to Sulawesi and the Philippines in the east and include reefs in Sri Lanka, Burma, Thailand, Malaysia, Singapore, and many sites in western and eastern Indonesia.

"It is certainly the worst coral die-off we have seen since 1998. It may prove to be the worst such event known to science," says Dr Andrew Baird of the ARC Centre of Excellence for Coral Reef Studies and James Cook Universities. "So far around 80 percent of Acropora colonies and 50 per cent of colonies from other species have died since the outbreak began in May this year."

This means coral cover in the region could drop from an average of 50% to around 10%, and the spatial scale of the event could mean it will take years to recover, striking at local fishing and regional tourism industries, he says.

The bleaching event has also hit the richest marine biodiversity zone on the planet, the 'Amazon Rainforest' of the seas, known as the Coral Triangle (CT), which is bounded by Indonesia, Malaysia and the Philippines.

"Although the Coral Triangle is the richest region for corals on Earth, it relies on other regions around its fringes to supply the coral spawn and fish larvae that help keep it so rich," Dr Baird explains. "So there are both direct and indirect effects on CT reefs which will affect their ability to recover from future disturbance."

"Also the reefs of the region support tens of millions of people who make their living from the sea and so plays a vital role in both the regional economy and political stability. For example, in Aceh, northern Sumatera, where the bleaching is most severe, a high proportion of the people rely on fishing and tourism for their livelihoods. While it may take up to two years for some fish species to be affected by the loss of coral habitat, fisheries yields will decline and this combined with a drop in the number of SCUBA divers visiting could have major long-term effects on the local economy."

The cause of the bleaching event was a large pool of super-hot water which swept into the eastern Indian Ocean region several months ago, shocking the corals and causing them to shed the symbiotic algae that nourish them, thereby losing color and "bleaching." If the corals do not regain their algae they starve to death.

According to the National Oceanic and Atmospheric Administration's Coral Hotspots website, sea surface temperatures in the region peaked in late May, 2010, and by July the accumulated heat stress was greater than in 1998. Local dive operators recorded water temperatures of 34 C, over 4 degrees higher that than long term average for the area.

The event was first detected on reefs in Aceh by marine ecologists from Wildlife Conservation Society, CoECRS and Syiah Kuala University. They already rate it as one of the worst coral diebacks ever recorded.

"My colleagues and I have high confidence these successive ocean warming episodes, which exceed the normal tolerance range of warm-water corals, are driven by human-induced global warming. They underline that the planet is already taking heavy hits from climate change -- and will continue to do so unless we can reduce carbon emissions very quickly.

"They also show this is not just about warmer temperatures: it is also threatening the livelihoods of tens of millions of people and potentially the stability of our region."

Dr Baird said it was not yet clear whether Australia would suffer a similar coral bleaching event this year: this would emerge only with the arrival of warmer waters from the north in January/February 2011. The previous worst events to strike the Great Barrier Reef were in 1998 and 2002 when over 40% of the reefs along the length of the GBR were affected.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by ARC Centre of Excellence in Coral Reef Studies.

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Large-scale fish farm production offsets environmental gains, assessment finds

ScienceDaily (Oct. 28, 2010) — Industrial-scale aquaculture production magnifies environmental degradation, according to the first global assessment of the effects of marine finfish aquaculture (e.g. salmon, cod, turbot and grouper) released Oct. 27, 2010. This is true even when farming operations implement the best current marine fish farming practices, according to the findings.

Dr. John Volpe and his team at the University of Victoria developed the Global Aquaculture Performance Index (GAPI), an unprecedented system for objectively measuring the environmental performance of fish farming.

"Scale is critical," said Dr. Volpe, a marine ecologist. "Over time, the industry has made strides in reducing the environmental impact per ton of fish, but this does not give a complete picture. Large scale farming of salmon, for example, even under even the best current practices creates large scale problems."

The fish farming industry is an increasingly important source of seafood, especially as many wild fisheries are in decline. Yet farming of many marine fish species has been criticized as causing ecological damage. For instance, the researchers' found that the relatively new marine finfish aquaculture sector in China and other Asian countries lags in environmental performance.

Dr. Volpe added, "The fastest growing sector is Asia, where we found a troubling combination of poor environmental performance and rapidly increasing production."

With support from the Lenfest Ocean Program, Dr. Volpe and his team developed GAPI, which uses 10 different criteria to assess and score environmental impacts. Incorporating information such as the application of antibiotics and discharge of water pollutants, GAPI allows researchers to gauge which farmed species and countries of production have the best or worst environmental performance. The researchers examined the environmental impact of marine fish farming per ton of fish produced and the cumulative environmental impact for each country producing a major farmed species.

"GAPI provides a valuable tool for developing environmentally responsible fish farming. Governments can use GAPI to inform policies and regulations to minimize the environmental footprint of fish farming. Farmers can use it to improve production practices. And buyers can use it to compare and select better, more environmentally friendly seafood options," said Chris Mann, senior officer and director of the Pew Environment Group's Aquaculture Standards Project, which collaborated on the work.

For further information on GAPI, including a summary of the methodology and findings, please visit www.lenfestocean.org.

The GAPI 2010 report released Oct. 27 is based on 2007 data, the most recent year for which data for all aquaculture indicators are available. GAPI analysis will be updated periodically as additional data becomes available. For additional information, updated research and analysis, please see the GAPI Web site (www.gapi.ca).

The Lenfest Ocean Program supports scientific research aimed at forging solutions to the challenges facing the global marine environment. The program was established in 2004 by the Lenfest Foundation and is managed by the Pew Environment Group.

The University of Victoria, located in Victoria, British Columbia is a national and international leader in the study of the oceans, with expertise as far-ranging as ocean-climate interactions, ocean observation systems, physical and chemical oceanography, marine ecology, coastal resource management and ocean engineering.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Pew Environment Group, via EurekAlert!, a service of AAAS.

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Female fish flaunt fins to attract a mate

ScienceDaily (Oct. 8, 2010) — For the first time, biologists have described the evolution of the size of a female trait which males use to choose a partner. The research, published in the open access journal BMC Evolutionary Biology, shows that male cichlid fish prefer females with a larger pelvic fin and that this drives females to grow fins out of proportion with their body size.

Sebastian Baldauf from the University of Bonn, Germany, worked with a team of researchers to study the effects of female ornamentation in the African cichlid fish Pelvicachromis taeniatus. He said, "In contrast to the well-known phenomenon of sexual selection influencing male traits, the expression of female ornaments in relation to body size is almost completely unexplored."

Female P. taeniatus develop exceedingly large pelvic fins, which differ from male fins in shape and color. During courtship, females fan out their violet pelvic fin, suggesting that the fin is actively used during mate choice. The researchers found that males clearly preferred females with a larger pelvic fin and that pelvic fins grew in a more disproportionate way than other fins on female fish. According to Baldauf, "Our study is, to our knowledge, the first to show that male choice might scale the proportions of a female sexual trait, and therefore has implications for the understanding of the relationship of female traits with body size."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by BioMed Central, via EurekAlert!, a service of AAAS.

Journal Reference:

Sebastian A Baldauf, Theo CM Bakker, Fabian Herder, Harald Kullmann and Timo Thunken. Male mate choice scales female ornament allometry in a cichlid fish. BMC Evolutionary Biology, (in press) [link]

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Plants kick-started evolutionary drama of Earth's oxygenation

ScienceDaily (Oct. 9, 2010) — An international team of scientists, exploiting pioneering techniques at Arizona State University, has taken a significant step toward unlocking the secrets of oxygenation of the Earth's oceans and atmosphere.

Evolution of the Earth's multitude of organisms is intimately linked to the rise of oxygen in the oceans and atmosphere. The new research indicates that the appearance of large predatory fish as well as vascular plants approximately 400 million years ago coincided with an increase in oxygen, to levels comparable to those we experience today. If so, then animals from before that time appeared and evolved under markedly lower oxygen conditions than previously thought.

The researchers, including collaborators from Harvard, Denmark, Sweden and the United Kingdom, made use of a method developed at ASU by Ariel Anbar, a professor in the department of chemistry and biochemistry and the School of Earth and Space Exploration in the College of Liberal Arts and Sciences, and his research group. The method can be used to estimate global oxygen levels in ancient oceans from the chemical composition of ancient seafloor sediments.

Their important findings are presented in a paper published in the Proceedings of the National Academy of Sciences (PNAS), titled "Devonian rise in atmospheric oxygen correlated to radiations of terrestrial plants and large predatory fish."

"There has been a lot of speculation over the years about whether or not oxygen in the atmosphere was steady or variable over the last 500 million years," explained Anbar, who leads ASU's Astrobiology Program. "This is the era during which animals and land plants emerged and flourished. So it's a profound question in understanding the history of life. These new findings not only suggest that oxygen levels varied, but also that the variation had direct consequences for the evolution of complex life."

The Earth is 4,500 million years old. Microbial life has probably thrived in the oceans for most of that time. However, until about 2,300 million years ago, the atmosphere contained only traces of oxygen. During that time, some microbes in the oceans likely produced oxygen as a byproduct of photosynthesis. But the quantities they produced were insufficient to accumulate much in the atmosphere and oceans. The situation changed with the "Great Oxidation Event," 2,300 million years ago. Oxygen levels rose again around 550 million years ago. The first animals appear in the fossil record at this time, marking the beginning of an era that geologists call the "Phanerozoic" -- a Greek word meaning "evident animals." This new work explores how oxygen levels changed during the Phanerozoic.

The new study was led by Tais W. Dahl while he was a postdoctoral scholar at Harvard. Dahl spent several months in Anbar's lab at ASU during his graduate research learning how to make the necessary measurements from Gwyneth Gordon, Ph.D., who is also an author of this paper. Other authors include geochemist Don Canfield, Dahl's Ph.D. mentor at the University of Southern Denmark, and paleontologist Andrew Knoll, Dahl's postdoctoral mentor at Harvard.

Dahl returned to ASU to perform the measurements for this study, which involved measuring the relative amounts of different isotopes of the element molybdenum in rocks called "black shales." These rocks are formed from ancient ocean sediments.

Isotopes are atoms of an element, in this case molybdenum, that differ only in their mass and therefore can be easily distinguished from one another. Molybdenum has seven stable isotopes. Chemical reactions fractionate heavy from light isotopes. For example, carbon 12 is enriched by three percent in plants relative to the carbon in carbon dioxide in the atmosphere. Similarly, molybdenum isotopes are fractionated during their removal from seawater into ocean sediments. The magnitude of this fractionation is sensitive to the presence of oxygen.

The data Dahl obtained at ASU reveal that there were at least two stages of oxygenation during the Phanerozoic, separated by the oxygenation event 400 million years ago. This inference from molybdenum isotopes is corroborated by the appearance of large (up to 30 feet long) predatory fish in the fossil record 400 million years ago, coincident with the rise in oxygen. Animals of that size consume energy rapidly, requiring high levels of oxygen for their metabolism. "Tais's data indicate that early animals evolved in an environment with less oxygen than today," said Anbar. The newly discovered oxygenation event therefore explains the puzzling appearance of these fish in the fossil record. "It's always satisfying when we can demonstrate how an environmental change drove biological evolution," Anbar explained.

"But the real kicker is that these data also show us the reverse -- that biological innovation can drive environmental change" continued Anbar. He points to the fact that vascular plants also appear in the fossil record around 400 million years ago. The bodies of such plants decompose with difficulty, making it easier for organic carbon to be buried in sediments. When that happens, the organic carbon -- produced by photosynthesis -- is not available for reaction with oxygen. The consequence is a rise in the amount of oxygen in the environment.

"It's a push-me-pull-you situation," explained Anbar. The biological innovation of vascular plants led to more carbon burial, and therefore to more oxygen. Then, the rise in oxygen made it possible for larger animals to evolve. "This is a great example of what we call the "co evolution" of life and the environment," enthused Anbar "Geoscientists talk about this idea a lot, but we rarely find such nice examples."

This work was supported by the Danish National Research Foundation, Danish Council for Independent Research, the Swedish Research Council, the NASA Astrobiology Institute team at ASU and the NASA Exobiology Program.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Arizona State University, via EurekAlert!, a service of AAAS. The original article was written by Jenny Green.

Journal Reference:

T. W. Dahl, E. U. Hammarlund, A. D. Anbar, D. P. G. Bond, B. C. Gill, G. W. Gordon, A. H. Knoll, A. T. Nielsen, N. H. Schovsbo, D. E. Canfield. Devonian rise in atmospheric oxygen correlated to the radiations of terrestrial plants and large predatory fish. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1011287107

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Number of synapses shown to vary between night and day, zebrafish study finds

ScienceDaily (Oct. 7, 2010) — With the help of tiny, see-through fish, Stanford University School of Medicine researchers are homing in on what happens in the brain while you sleep. In a new study, they show how the circadian clock and sleep affect the scope of neuron-to-neuron connections in a particular region of the brain, and they identified a gene that appears to regulate the number of these connections, called synapses.

"This is the first time differences in the number of synapses between day and night and between wake and sleep have been shown in a living animal," said Lior Appelbaum, PhD, co-first author of the study, which will appear in the Oct. 6 issue of Neuron. He said further studies using the imaging method he and his colleagues developed could shed more light on how our brain activities vary according to time of day.

Appelbaum, who is now a principal investigator in a lab at Bar-Ilan University in Israel, spent five years conducting the work while in the lab of Emmanuel Mignot, MD, PhD, professor of psychiatry and behavioral sciences. Mignot, who also directs the Stanford Center for Sleep Sciences and Medicine, is senior author of the paper; the other first author is Gordon Wang, PhD, a postdoctoral scholar in molecular and cellular physiology.

Why we need to sleep and how, exactly, sleep is restorative are two big, unanswered questions in biology. Knowing that brain performance changes throughout the day, researchers believe that daily cycles and sleep regulate "synaptic plasticity" -- the ability of synapses to change strength and even form and erase. And they theorize that nighttime changes in the number and strength of synapses help recharge the brain which, in turn, benefits memory, learning and other functions.

As the researchers note in their paper, daily cycle-related changes in the number of neuron-to-neuron connections hadn't previously been shown in a living vertebrate, and the "molecular mechanisms of this type of synaptic plasticity are poorly understood." So they turned to the zebrafish, a small aquarium pet, for help.

Like humans, zebrafish are active during the day and sleep at night -- something that researchers in Mignot's lab discovered in previous research. Larvae of the handy little fish also happen to be transparent, enabling researchers to look directly at the animal's neuronal network. "This can't be done in any other vertebrate animal," said Mignot, who is also the Craig Reynolds Professor of Sleep Medicine, adding that his group was aided by the imaging expertise of co-author Stephen Smith, PhD, professor of molecular and cellular physiology, and his lab.

For this study, the researchers used a fluorescence-imaging technique to monitor neural activity in the specific region of the brain that regulates sleeping and waking. With their technique, they were able to watch synapses within individual hypocretin neurons, and they showed that the number of these connections fluctuated between day and night.

Appelbaum noted this is the first time rhythmic changes in synapse numbers have been observed in the brain of a living vertebrate. The work also, Mignot said, further demonstrates the brain's ability to reorganize and adapt to changes. "It gets ready for new activity by telling the neurons they have to shut down synapses during this time of day but increase them at other times of the day," he said.

The researchers determined that the differing number of synapses between day and night was primarily regulated by the body's internal clock but was also affected by behavior -- for instance, how much sleep the fish got. They also identified a gene, NPTX2b, that appears to be involved in regulating the rhythmic changes in synapses. "It's one actor in an unknown mechanism," said Appelbaum, explaining it's unlikely that only one gene is involved, but its identification gets researchers that much closer to understanding the process.

Appelbaum said he considers the imaging method itself one of the strongest points of the paper, and by using the technique developed in this study, investigators can image synaptic plasticity in other neuronal systems -- circuits -- of the zebrafish to expand on these findings. "With these techniques, we can look at other areas of the brain, such as the one in charge of memory, to see how sleep cycles affect synapses," he said, adding that he doesn't expect to see the same results in every part of the brain.

"Those changes are likely circuit-dependent," he explained, saying that synaptic plasticity in memory circuits might prove to be more affected by behavior, such as sleep, than by the circadian clock (the opposite of what was found in hypocretin neurons). Knowing this, he said, could help identify which regions of brain are most affected by waking and sleeping and further uncover what happens when we slumber.

Other study authors are Tohei Yokogawa, PhD, then a graduate student in Mignot's lab; research assistant Gemini Skariah; and Philippe Mourrain, PhD, a senior research scientist in psychiatry and behavioral sciences, who co-directed the work.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford University Medical Center. The original article was written by Michelle Brandt.

Journal Reference:

Lior Appelbaum, Gordon Wang, Tohei Yokogawa, Gemini M. Skariah, Stephen J. Smith, Philippe Mourrain, Emmanuel Mignot. Circadian and Homeostatic Regulation of Structural Synaptic Plasticity in Hypocretin Neurons. Neuron, 2010; 68 (1): 87-98 DOI: 10.1016/j.neuron.2010.09.006

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Nature and humans leaving indelible mark on rivers, harming the intricate food webs they support

ScienceDaily (Oct. 14, 2010) — Rivers and streams supply the lifeblood of ecosystems across the globe, providing water for drinking and irrigation for humans as well as a wide array of life forms in rivers and streams from single-celled organisms all the way up to the fish humans eat. But humans and nature itself are making it tough on rivers to continue in their central role to support fish species, according to new research by a team of scientists including one from Arizona State University.

Globally, rivers and streams are being drained due to human use and climate change. These and other human impacts alter the natural variability of river flows. Some impacted rivers have dried and no longer run, while still others have actually seen increases in the variability of flows due to storm floods. The end result is that these two forces are conspiring to shorten food chains, particularly by eliminating top predators like many large-bodied fish.

"Floods and droughts shorten the food chain but they accomplish this in different ways," said John Sabo, an Arizona State University associate professor in the School of Life Sciences. Sabo is the lead author of the paper, "The Role of Discharge Variation in Scaling of Drainage Area and Food Chain Length in Rivers," which appeared Oct. 15, 2010, in Science Express, the online, early publication venue for the journal Science.

"High flows take out the middle men in the food web making fish (the top predator) feed lower in the food chain; droughts completely knock out the top predator. The end result in either case is a simpler food web, but the effects we see for low flows are more catastrophic for fish, and much more long lasting," said Sabo, who studies ecology, evolution and environmental sciences.

Sabo and his co-authors -- Jacques Finlay, University of Minnesota, St. Paul; Theodore Kennedy, U.S. Geological Survey, Southwest Biological Science Center, Flagstaff, Ariz.; and David Post, Yale University, New Haven, Conn. -- suggest that the fate of large bodied fishes should be more carefully factored into the management of water use, especially as growing human populations and climate change increasingly affect water availability.

The researchers studied the food webs that live in and depend on rivers for their survival. They studied 36 rivers and streams in the U.S. ranging in size from the Mississippi and Colorado Rivers, down to and their small tributaries. The rivers included in the study provide water for drinking to large cities like New York City, Minneapolis, Phoenix, Las Vegas and Los Angeles.

At the top of these food webs were large bodied fish, which appear the most vulnerable to variations in river flows. The researchers found that even though the mechanics were different, the end result of floods and droughts on the food webs were similar and the effects appear to be long lasting.

The study employed naturally occurring stable isotopes of the element nitrogen to measure how high top-predators were in the food chain. Nitrogen provides an indicator for how high a consumer is in the food chain because it bioaccumulates increasing by 3.4 parts per million with each link in the chain.

"Floods simplify the food web by taking out some of the intermediate players in it so that the big fish begin to eat lower on the food chain than they would if the food web were not exposed to high flows," Sabo said. "That makes them lower on the food chain themselves. Predators that eat lower on the food chain are having a dinner that has essentially missed a meal in itself. Imagine a lion eating grass, instead of eating gazelles that eat grass."

"With droughts, it's completely different, they just eliminate the top predator altogether because many fish just can't tolerate the low oxygen and high temperatures that follow when a stream starts drying out," said Sabo, who specializes in river and riparian ecosystems. "Even if it doesn't go completely dry, the conditions get so bad that the fish just can't handle it, and it takes them much longer to come back."

Sabo added that climate change is going to have a hand in frequency and intensity of the floods and droughts of coming years.

"Climate is giving us a new set of operating terms to work with," Sabo said. "We will experience overall drying and great weather variability, both of which will further shorten river food chains.

"There will be drying in some regions, particularly along the equators and increased flow in some rivers, primarily at higher latitudes," Sabo explained. "We will see more variability because there will be change in the seasonality of storms, ocean currents are changing and the way the ocean blows storms to us is going to be different. Drying and more variable flows are coming."

"In some places, like the Southwest U.S., we will get a double punch," he added. "As the streams dry, they also will become more variable in that as rain falls it will race over the parched ground, causing flooding"

Human toll

The human effect on rivers and streams and the food chain they support are closely tied to land use change, such as water diversion and regulation of flows due to dams.

Sabo outlined a classic scenario that humans face during drought years. As drought takes hold, the need for water for irrigation and other agricultural purposes increases and leads to a draw down of natural river flow. The effects downstream can be devastating. Natural drying through drought is not a human effect, but withdrawal of river water during a drought is, and it can have long-term consequences.

"We would not have guessed that infrequent drought would have had a big effect on the stream, but our results shows that it does," Sabo said. "River and stream water draw-down has a lasting effect."

"We found that some streams affected by drying 5 to 10 years ago, are still missing large-bodied fishes compared to same sized streams that never dried. That is the major difference," Sabo explained. "Our data show that food webs can recover sooner after a flood, in roughly a year, but it takes far longer to recover in the case of drying or drought."

The study hints that competing users of the river water -- agricultural production and recreational uses like fishing -- need to work out amenable use of rivers and streams that not only look to the immediate future, but also project long term effects of their use.

"The question becomes can you have fish and tomatoes on the same table," Sabo said. "They compete for the same resource and society depends on both -- agriculture for grain, fruits, vegetables and river-caught fish for protein, particularly in the developing world."

"Humans may need to make some really hard decisions about how to allocate water so that we grow the right food but still leave enough in the rivers to sustain fish populations," he said. "Some river fish, like salmon in the U.S., are very important commercially."

Sabo added that scientists appear to be on the cusp of major advances in understanding how climate and human use of rivers affects biodiversity and global water security. This paper fits into this bigger picture because it suggests that some aspects of climate and human effects on biodiversity are mediated by the variability in freshwater supplies and thus, could have feedbacks on food security in regions of the world where freshwater fisheries are a significant source of protein for growing populations.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Arizona State University.

Journal Reference:

John L. Sabo, Jacques. C. Finlay, Theodore Kennedy, and David M. Post. The Role of Discharge Variation in Scaling of Drainage Area and Food Chain Length in Rivers. Science, 2010; DOI: 10.1126/science.1196005

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Poor start in life need not spell doom in adulthood

ScienceDaily (Oct. 21, 2010) — Does the environment encountered early in life have permanent and predictable long-term effects in adulthood? Such effects have been reported in numerous organisms, including humans.

But now a biology graduate student at the University of California, Riverside reports that how individuals fare as adults is not simply a passive consequence of the limits that early conditions may impose on them. Studying how adult Trinidadian guppies (small freshwater fish) responded to their early food conditions, Sonya Auer found that the guppies had compensated for a poor start to life in unexpected, and potentially adaptive, ways.

"Adult guppies were able to mitigate the potential negative effects of early setbacks, such as poor conditions during early stages of growth and development, by being flexible in their growth and reproductive strategies," said Auer, who works in the laboratory of David Reznick, a professor of biology.

Study results appear in the December 2010 issue of The American Naturalist.

To study how adult guppies responded to early food conditions, Auer raised two batches of juvenile guppies separately on low and high food levels in the lab. Once they reached sexual maturity, she switched half of the females from each juvenile food level to the opposite adult food level and kept the other half on the same ration trajectory received during the juvenile stage.

She then measured adult responses in somatic growth, reproductive rate, reproductive investment, number of offspring, offspring size and female body condition to juvenile growth history, how these responses changed with age and how they affected overall reproductive success under low and high adult food conditions.

She found that, as predicted, females reared as juveniles on low food matured at a later age, at a smaller size and with less energy reserves than females reared on high food as juveniles.

"Entering adulthood, they were subsequently limited in the amount of time they had to produce babies, the number of babies they could carry at one time, and the amount of energy they could invest in reproduction," she said. "However, females reared on low food were able to replenish their fat reserves, increase their growth rate to make up for their small body size, and produce more babies to compensate for their delayed maturity. The end result was that they were able to achieve the same reproductive success as females reared on high food, regardless of the quality of the adult environment."

Next, Auer plans to study how guppy growth and reproductive strategies respond to seasonal variation in food availability in the wild.

Female guppies used in the experiment were the offspring of first generation descendents of fish collected in 2008 from a downstream, high predation site on the Aripo River in the Northern Range Mountains of Trinidad.

The research was supported by a University of California Dissertation Research grant and a National Science Foundation Graduate Research Fellowship to Auer, and a National Science Foundation grant to Reznick.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California -- Riverside.

Journal Reference:

Sonya Auer. Phenotypic Plasticity in Adult Life History Strategies Compensates for a Poor Start in Life in Trinidadian Guppies (Poecilia reticulata). he American Naturalist, December 2010

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Alternative fish feeds use less fishmeal and fish oils

ScienceDaily (Oct. 18, 2010) — As consumers eat more fish as part of a healthy diet, U.S. Department of Agriculture (USDA) scientists are helping producers meet this demand by developing new feeds that support sustainable aquaculture production.

Commercial fish farms have traditionally fed feeds that include high levels of fishmeal and fish oil, according to fish physiologist Rick Barrows with USDA's Agricultural Research Service (ARS). But the fishmeal in these feeds comes from small, bony fish species like menhaden, herring and capelin, which are in short supply.

Also, more people around the globe are turning to fish as a source of lean protein, driving the growth of aquaculture worldwide. Aquaculture now supplies half of the seafood produced for human consumption.

To satisfy these demands, Barrows and his colleagues at the ARS Small Grains and Potato Germplasm Research Unit in Hagerman, Idaho, are developing alternative fish feeds made from concentrated plant proteins.

Barrows produces the feed himself using a piece of food manufacturing equipment called a "cooking extruder." Barrows is formulating and manufacturing feeds for several fish species, including trout, salmon, white sea bass and yellowtail.

At the ARS National Cold Water Marine Aquaculture Center in Franklin, Maine, research leader William Wolters works with Barrows to develop diets for Atlantic salmon, using concentrated plant proteins. Protein levels in most grain and oilseed sources are low and need to be concentrated to reach the high protein requirements of fish.

Wolters is currently evaluating six experimental diets which contain combinations of alternative proteins, plus a fishmeal diet being fed to fish for comparison. According to Wolters, the ongoing studies seem to indicate that the modern alternative diets work better for the fish than previous alternative diets.

Feeds for warm-water fish are being developed at the Harry K. Dupree Stuttgart National Aquaculture Research Center's facility in Fort Pierce, Fla. ARS fish biologist Marty Riche is working with Barrows to develop feed for pompano, one of Florida's highest valued fish. Riche uses ingredients such as corn, gluten meal, and soy proteins to develop feeds that contain less fishmeal.

Read more about this and other aquaculture-related research in the October 2010 issue of Agricultural Research magazine, available online at: http://www.ars.usda.gov/is/AR/archive/oct10/feeds1010.htm.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by USDA/Agricultural Research Service. The original article was written by Sharon Durham.

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Better synchronization helps fish deal with predator threat

ScienceDaily (Oct. 11, 2010) — Fish alter their movements when under threat from predators to keep closer together and to help them to blend into the crowd, according to new research headed by scientists at the University of York.

Researchers in the York Centre for Complex Systems Analysis (YCCSA), based in the University's Department of Biology, used a combined computer simulation and experimental study of group behaviour to discover that shoaling fish co-ordinate their movements more frequently when under threat.

They 'update' their behaviour more often because by moving in a more coherent fashion with shoal members, individual fish are able to reduce the risk of being targeted by predators as the 'odd one out'.

The model predicts that higher updating frequency, caused by threat, leads to more synchronized group movement with both speed and nearest neighbour distributions becoming more uniform.

The research is published in the latest issue of Proceedings of the Royal Society B. The study is supported by the Natural Environment Research Council.

The scientists suggest that the so-called 'oddity effect' could be the driving force for the behavioural changes. The computer model measures speed and distance distributions and provides a method of assessing stress levels of collectively grouping animals in a remotely collectable and non-obtrusive way.

Dr Jamie Wood, of YCCSA, said: "We find that as grouping animals feel more threatened, they monitor their fellows more frequently which results in better synchronization.

"Closely coordinated movement has the advantage that predators find it more difficult to single out a single target for their prey. Our work may help to explain how tightly bound fish shoals emerge and determine how agitated animals moving in groups are at any given moment."

The research also involved scientists at the Institute of Integrative and Comparative Biology at the University of Leeds and the Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin,

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of York.

Journal Reference:

N. W. F. Bode, J. J. Faria, D. W. Franks, J. Krause, A. J. Wood. How perceived threat increases synchronization in collectively moving animal groups. Proceedings of the Royal Society B: Biological Sciences, 2010; 277 (1697): 3065 DOI: 10.1098/rspb.2010.0855

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View the original article here