Kalifornische Austern, australische Frösche und britische Flusskrebse kommen mit dem Klimawandel besser zurecht als gedacht

Die University of California in Davis versuchte am 10. Oktober 2016 mit einer typischen Klimawandelgeschichte zu punkten. In einer Studie fanden Brian Cheng und Kollegen heraus, dass die kalifornischen Austern offenbar besser mit dem Klimawandel zurechtkommen können als erwartet. Dieses unerhört positive Ergebnis konnte man den Leuten aber offenbar nicht zumuten. Deshalb fokussierte man auf Bohrschnecken (“Oyster drills”), die angeblich in Zukunft noch viel aktiver werden und die Austern bei lebendigem Leibe aussaugen. In der folgende Pressemitteilung geht der erste Preis an den Doktoranden Brian Cheng, der das Horrorszenario in bester Hollywoodmanier detailliert schildert:

Climate change may benefit native oysters, but there’s a catch:
Oysters Can Tolerate Extremes Better Than Predatory Snails Can — If the Snails Don’t Get Them First

Amid efforts to restore native oyster populations on the West Coast, how are oysters expected to fare under climate change in the decades and centuries to come? Not too badly, according to a study from the University of California, Davis. But there’s a big “if” involved.

In the study, published Oct. 10 in the journal Functional Ecology, researchers investigated oysters in the lab and in oyster beds at California’s Tomales Bay and San Francisco Bay. They found that certain components of climate change may actually benefit oysters in California in the long term, provided they have enough food, because they tend to grow faster at warmer temperatures. Good news? Not so fast.

Meet oyster drills, two species of predatory snails introduced to California from the East Coast and Asia. While oysters are more tolerant of extreme temperatures and low salinity, such as can occur during floods, warming over the next few decades first benefits the oyster drills, increasing the rate at which they eat the oysters.

Oyster drills ‘the worst way to go’

“To me, it’s the worst way to go,” said lead author Brian Cheng, a doctoral candidate at UC Davis Bodega Marine Laboratory at the time of the study and currently a postdoctoral fellow at the Smithsonian Environmental Research Center. “Imagine you’re an oyster. You have a suit of armor you wear and that you cannot move. Imagine there was something that could crawl onto you and begin blasting away on your shell of armor. Imagine they could secrete acid and use a file-like tongue to bore tiny little holes into the shell. Then they insert their tongue and tear away bits of flesh, eating you alive. Once the hole is made, the oyster is basically done.”

The silver lining is that oyster drills are relatively easy to find, identify and remove. Cheng said this makes them a good candidate for eradication.

The last native oyster

Oysters are an iconic California seafood, and while the Olympia oyster is the only native oyster on the West Coast, it is no longer fished in California. Most oysters slurped down by consumers are farmed Pacific oysters native to Asia.

But wild oysters hold benefits beyond the gustatory: Their complex shell formations harbor other animals and plants, serving as habitat. Researchers are also investigating how they may help buffer the effects of sea level rise, contributing to a “living shoreline” that reduces rates of erosion.

In addition to holding management implications for native oyster populations, the study is also relevant for oyster farms, though they were not the focus of the research. Oyster farmers are well aware of oyster drill issues, Cheng said, but the study points out that the drill problem is expected to get worse before it gets better, and that management will be key to the survival of both oysters and oyster farms.

“Oysters are expected to do better if provided with unlimited resources, but we don’t know if that will be the case in the wild under climate change,” Cheng said. “So while there’s evidence they could do better, by no means is it a slam dunk. Other aspects of climate change, such as ocean acidification, may continue to be detrimental to oysters.”

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Unerwarteterweise ist auch die Bedrohung australischer Frösche durch den Klimawandel offenbar geringer als gedacht, wie die University of Adelaide am 12. Oktober 2016 meldete:

Temporary extinction reprieve for some frogs

Australian scientists have good news for frog conservation ─ there may be longer than expected time to intervene before climate change causes extinction of some species. The scientists used new methods for modelling the threat of climate change on frogs in tropical north-eastern Australia and showed that, at least for some species, there is likely to be more time than earlier thought before expected climate shifts and associated habitat loss drive them to extinction.

The study, published today in the scientific journal Biology Letters, shows that as many as four species of frogs in the protected Wet Tropics of Queensland UNESCO World Heritage Area face extinction by 2080 due to human-induced climate change. However, the research also shows that for at least three species, there might be sufficient time for conservation managers to intervene successfully. The researchers, from the University of Adelaide, the University of Tasmania and James Cook University, used the latest biodiversity modelling techniques to show that extinctions from climate change can occur after substantial time lags.

Lead author Dr Damien Fordham, ARC Future Fellow with the University of Adelaide’s Environment Institute, says: “This is a rare example of good news for conservation because it means that for some frog species there is likely to be more time than expected for on-ground management intervention. “For example, our research shows that the window of time between impact and extinction might be adequate for successful translocation programs to be established.” Co-author Professor Barry Brook, Professor of Environmental Sustainability at the University of Tasmania, says this may also mean good news for other flora and fauna. “By showing that extinction delays can exceed decades for short-lived animals such as frogs, it follows that the time lags for extinction might be even larger for long-lived species, such as large vertebrates and trees,” Professor Brook says.

This study also has important implications for ‘triage’-based conservation prioritisation, which is the idea that conservation managers should actively decide on which species have a reasonable prospect of being saved, and then direct precious conservation resources accordingly. “If long time scales for extinction lags exist for some species, the likelihood that these extinctions can be averted through active on-ground management increases,” says Dr Fordham. “Furthermore, it means that other species in more immediate need could be targeted for early conservation intervention.”

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Und auch Flusskrebse in Großbritannien können auftamen. Der Klimawandel wird für sie verbeserte Lebensbedingungen bringen, wie The Telegraph am 4. Oktober 2016 meldete:

Climate change could be a boon for crayfish and other freshwater creatures
British rivers could be set for an explosion of crayfish and other crustaceans as global warming pushes up inland water temperatures, new research predicts. While similar sea-based species are set to suffer from climate change, their freshwater counterparts are likely to benefit from a warmer habitat. Previous research involving land-based vertebrae has found that the diversity of a species tends to increase with warming and that this is a general trend across habitats.

Weiterlesen in The Telegraph