Marine

Jun

26

2008
 
 

Six billion dollar answer



No-take marine reserves help species recover faster than expected

coral trout/grouper/cod fish!The world’s largest network of no-take marine reserves is a success. Relieved readers of Current Biology this week can see how the controversial closing down to all fishing on more than a third of Australia’s Great Barrier Reef Marine Park has allowed significant recovery of target species densities in just two years. A team of scientists led by Hugh Sweatman of the Australian Institute of Marine Science found that populations of coral trout (Plectropomus spp.) — the main target for reef line fisheries — within protected areas had bounced up by around two thirds compared with those where fishing was still allowed. Big, bold initiatives might not be popular with the people they affect most but, in this case at least, they work. Source: Russ GR, Cheal AJ, Dolman AM, Emslie MJ, Evans RD, Miller I, Sweatman H & Williamson DH (2008) Rapid increase in fish numbers follows creation of World’s largest marine reserve network. Curr. Biol. DOI: tba

Image: © Timothey Kosachev

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Jun

18

2008
 
 

There’s a catch, after all



Offsetting marine bycatch could do more harm than good, study finds

Trawling for solutionsCan fisheries bycatch impacts be offset by making efforts to protect afflicted species elsewhere? Not according to a study published today in PLoS ONE, which claims that the “compensatory mitigation for marine bycatch” approach is a non-starter. A baker’s dozen of international scientists, led by University of California Santa Cruz researcher Myra Finkelstein, found that diverting attention to other conservation measures – such as removing non-native predators from breeding grounds – could potentially spell disaster. The problem is that such an approach requires action for each individual bycatch species, thereby spreading conservation resources too thinly. The focus should remain on finding ways to reduce bycatch, Finkelstein’s team concludes. Source: Finkelstein M, Bakker V, Doak DF, Sullivan B, Lewison R, Satterthwaite WH, McIntyre PB, Wolf S, Priddel D, Arnold JM, Henry RW, Sievert P & Croxall J (2008) Evaluating the potential effectiveness of compensatory mitigation strategies for marine bycatch. PLoS ONE DOI: 10.1371/journal.pone.0002480

Image: © Thomas Shortell

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Jun

12

2008
 
 

Jets and sharks



Large predatory sharks are about to leave the Mediterranean

Do we still need a bigger boat?The Mediterranean sea is pretty much a big pond, so many European holiday makers would probably breathe a quiet sigh of relief to read in Conservation Biology that the number of big, fierce sharks swimming among them has plummeted in recent years. An international team, led by Dalhousie University’s Francesco Ferretti, fearlessly waded through public and private archives, searching for evidence of population trends among the twenty largest species known to prowl the Med. In the five species for which there were sufficient data – a paucity all too telling of our scientific neglect of these top oceanic predators – precipitous declines were clear. Hammerhead sharks Sphyrna spp. were worst hit: none have been seen in coastal waters since 1963, and no records of the sharks anywhere in the Mediterranean exist after 1995. Nervous bathers should note that only the thresher shark Alopias vulpinus has been recorded in coastal waters in recent years. If looks like it is safe to be in the water after all. Just as long as you’re not a shark. Source: Ferretti F, Myers RA, Serena F & Lotze HK (2008) Loss of large predatory sharks from the Mediterranean Sea. Cons. Biol. DOI: 10.1111/j.1523-1739.2008.00938.x

Image: © Bart Coenders

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Jun

4

2008
 
 

A fish called… what?



Overfished species sold mislabeled, hindering consumer choice

What's your fish?Mmmm, red snapper. But hang on, is that really what you’re eating? A group of Stanford University scientists, led by Cheryl Logan, have used DNA forensics to uncover fishy goings on in the seafood marketplace. Taking 77 “Pacific red snapper” whole fish or fillets from a range of sources in California and Washington, including grocers, fish markets and sushi restaurants, they found a total of eleven species, only one of which was true red snapper Lutjanus campechanus. Between 60% and 63% of the samples were from fish not on the FDA Seafood list. Writing in Biological Conservation, Logan’s team say that although around 80% of all fish landed are identified to species level, that picture changes somewhat by the time they reach our plates. This “institutionalized mislabeling” is preventing customers from making informed, conservation-minded choices about what fish to eat and what to avoid. Source: Logan CA, Alter SE, Haupt AJ, Tomalty K & Palumbi SR (2008) An impediment to consumer choice: overfished species are sold as Pacific red snapper. Biol. Conserv. DOI: 10.1016/j.biocon.2008.04.007

Image: © Jill Chen

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May

14

2008
 
 

Our fault? Sure is



Comprehensive analysis links global ecological changes to human activity

melting glaciers are down to usThirty five years’ worth of data covering hundreds of independent studies put beyond reasonable doubt the impact of human activity on the planet, according to a paper published today in Nature. NASA scientist Cynthia Rosenzweig and colleagues collated a diverse array of findings, allowing them to pin down the causes of physical (glacier shrinkage, warmer oceans and so on) and biological (early leaf burst, breeding seasons and algal blooms) changes that have been documented in recent decades. More than 95 percent of some 829 physical, and 90 percent of the nearly 29,000 biological changes they examined were in a direction consistent with a warming climate. If there’s any comfort to be drawn from the findings, it’s that climate warming is overwhelmingly the most important factor influencing changes in the natural world: habitat destruction, overfishing and pollution are mere trifles by comparison, so at least we know which problem to tackle first! Source: Rosenzweig C, Karoly D, Vicarelli M, Neofotis P, Wu Q, Casassa G, Menzel A, Root TL, Estrella N, Seguin B, Tryjanowski P, Liu C, Rawlins S& Imeson A (2008) Attributing physical and biological impacts to anthropogenic climate change. Nature DOI: 10.1038/nature06937

Image © Sburel

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May

3

2008
 
 

Nor any drop to breathe



Oxygen disappears from the world’s tropical oceans, consequences ahead

open waterParts of the world’s oceans contain little oxygen, and those areas are getting bigger, according to findings published this week in Science. Lothar Stramma, a marine scientist at Universität Kiel, Germany, and colleagues constructed a 50-year time line of dissolved oxygen concentrations at depths of up to 2000 metres. The found that parts of the eastern tropical Atlantic and equatorial Pacific oceans have been becoming increasingly oxygen poor, a phenomenon most likely linked to climate change – atmospheric carbon dioxide levels in particular. Of course, that’s a problem for organisms that inhabit those regions, and it will probably impact on our fisheries. Source: Stramma L, Johnson GC, Sprintall J & Mohrholz V (2008) Expanding oxygen-minimum zones in the tropical oceans. Science USA DOI: 10.1126/science.1153847

Image © Alessia Giangrande

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Apr

1

2008
 
 

Floating ideas



Ballast-free ship could prove a cheaper way to prevent invasive species

A better way to transport cargoWouldn’t it be great to stop transporting alien species around the planet in ships’ ballast water? Current regulations force operators to install expensive filtration systems, which combine with UV and/or chemical treatment to weed out the array of unwelcome stowaways. An alternative, the ballast-free ship, replaces traditional ballast tanks with “trunks” that can be opened or closed to the outside as required. The forward movement of the ship creates a constant flow of water through the trunks, ensuring that the ship is only ever using local seawater. And there’s an unexpected benefit, according to a model study – using a physical model, rather than a mathematical one – carried out by Miltiadis Kotinis and Mike Parsons at the University of Michigan Marine Hydrodynamics Laboratory. Writing in the Transactions of the Society of Naval Architects and Marine Engineers, the U-M researchers suggest their design can also deliver fuel savings because of its greater efficiency. At anything up to 7.3 percent, that could mean a 650-foot bulk carrier hauling 32000 metric tons of cargo from the Great Lakes to Europe and back would pocket an extra $150000. And that’s no April Fool’s joke, unlike this one… Source: Kotinis M & Parsons MG (2008) Hydrodynamic investigation of the ballast-free ship concept. Transactions of the Society of Naval Architects and Marine Engineers DOI: tba

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Mar

20

2008
 
 

Fish in a pickle



Overexploitation destabilizes population sizes, meta-analysis finds

Ooooh, but they look so tasty!The trouble with rare things – like many of the fish species we’ve driven to near extinction – is that their numbers become prone to extreme swings, rendering them vulnerable to hitting that final zero. That’s the message from a paper published this week in Nature. Dalhousie University biologist Coilín Minto and colleagues analyzed fisheries data from 147 wild populations of fish, comprising a total of 39 species. Historically overexploited species, such as North Sea herring, showed the highest levels of year-on-year variation in numbers. Understanding how variability is affected by population size could help conservationists estimate more accurately the time needed for overfished stocks to recover. Source: Minto C, Myers RA & Blanchard W (2008) Survival variability and population density in fish populations. Nature DOI: 10.1038/nature06605

Image © esemelwe

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Mar

6

2008
 
 

Something fishy in the water



Chemical plays key role in climate regulation… and helps fish find food

OK, so where's all the food?Dimethylsulfoniopropionate – let’s just call it DMSP – signals feeding time at the reef, according to a brief paper published this week in Science. Scientists have known for some time that fish are attracted to something in the water that helps them to locate food, but an experiment carried out by Gabrielle Nevitt and colleagues shows that DMSP, a compound produced by phytoplankton and marine algae, is the guiding cue. DMSP has a known link with ocean productivity and its breakdown product – plain ol’ dimethylsulfide – is also thought to exert a major influence on global climate regulation. This dual role, says Nevitt’s team, could help us understand the effects of climate change on the marine ecosystem. Source: DeBose JL, Lema SC & Nevitt GA (2008) Dimethylsulfoniopropionate as a foraging clue for reef fishes. Science DOI: 10.1126/science.1151109

Image © Sean Lema

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Mar

1

2008
 
 

Hitting the buffers



Empirical evidence finally matches what theorists have long suspected

Life on the rocksBig old marine reserves are best, according to Joachim Claudet and colleagues in their recent Ecology Letters paper. Using original data spanning 33 years of European marine conservation effort, the University of Perpignan researcher’s team found that the reasons why some reserves enhance fish density and biodiversity, but others don’t, largely rests on two simple factors: how large the protected areas is and how long it’s been protected for. Conversely, the study suggested that a large buffer zone, where limited fishing is allowed, reduces the effectiveness of the reserve it surrounds. Much of the artisanal fishing goes on in the buffer zone, and their presence is linked to a complex set of social, ecological and economic influences. One way to hang onto them would be to increase the size of the protected area: a win-win situation perhaps? Source: Claudet J, Osenberg CW, Benedetti-Cecchi L, Domenici P, García-Charton J-A, Pérez-Ruzafa A, Badalamenti F, Bayle-Sempere J, Brito A, Bulleri F, Culioli J-M, Dimech M, Falcón JM, Guala I, Milazzo M, Sánchez-Meca J, Somerfield PJ, Stobart B, Vandeperre F, Valle C & Planes S (2008) Marine reserves: size and age do matter. Ecology Letters DOI: 10.1111/j.1461-0248.2008.01166.x

Image © Christina Deridder

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