Dec 14, 2018
The best in science communication tells a compelling story, and this week we have a great one! Gabriel Montejo-Kovacevich joins us to talk about her research in Central and South America studying butterflies of the genus Heliconius, also known as longwings. She shares her story of the hard work and the gratifying rewards of field research in challenging conditions. Gabriela is at the front line of science, and we are grateful to her for sharing her adventure and her research with us.
“Houston, I’m out of here” is probably what Voyager 2 said when it officially left the Solar System and is now roaming in the deep space between stars.
The craft was launched before Voyager 1. It may seem counter-intuitive, but it was set on a different trajectory that Voyager 1, so it left our star space 6 years after Voyager 1 did, hence it was already originally planned as Voyager 2.
Why is this a big deal? For many reasons:
Next up for the twins is a minefield of comets loosely gravitationally bound to our Sun. Hopefully they won’t meet their demise there, but even if they do - they’ve done so much more than anyone expected from them that it’d be a well deserved rest.
If they survive that hurdle, they will be orbiting the center of our galaxy for billions of years and it will take Voyager 1 another 40,000 years to reach another star system despite its looming speed of 61,000 kilometres per hour.
We’ve spoken at length about the horrific bleaching happening on the GBR, the world’s largest coral reef. Coral reefs are vast colonies of hard coral, an organism which extracts calcium carbonate from seawater to construct a limestone structure for protection. The tiny animals in coral are clear. They get their bright reds and vivid purples from colourful algae called zooxanthellae that live in their cells, providing the oxygen that the corals need to grow — albeit slowly. Coral reefs, which by some estimates support a quarter of all ocean life, are harmed by warming oceans. Bleaching occurs when the ocean temperature rises. If prolonged, bleaching causes coral to die. And this was the case last year and the year before last. The 2,300 kilometre long reef was severely bleached by back-to-back heatwaves in early 2016 and early 2017, causing half the coral to die.
Aerial surveys led by researcher Terry Hughes at James Cook University show that the Great Barrier Reef survived last year’s extreme summer better than the previous year’s, hinting that it is becoming more resilient. However, some coral species are faring better than others, meaning the reef is likely to look very different in years to come.
“Despite the fact that 2017 was hotter, we saw less bleaching over all across the whole reef,” Dr. Hughes said. The reason, he said, was a novel concept scientists call ecological memory: the idea that the past experience of a biological community can influence its ecological response today or in the future.
This sounds good news for the Reef, but doesn’t change the fact that in order to recover as much as possible from a bleaching event a reef needs 10 years. With rising ocean temperatures becoming more common, the world’s coral is set for more bleaching and death in years to come, which doesn’t only represent an avoidable human tragedy, but an ecological disaster.
This research is published in Nature Climate Change.
I’ve been congested for three weeks now and I can tell you it’s super annoying! So I truly commiserate with the poor seals who keep getting something far worse stuck up their noses - eels! That’s right they are figuratively snorting unagi-sushi!
The Hawaiian Monk Seal Research Program informs via the website Live Science that a live eel getting stuck up a seal nose is not a unique case.
The monk seals feed on or near the bottom of the ocean. So, they go for the food, for example eels, whose strategy is to hide at the bottom of the ocean.
Scientists don’t know how the eel got up its nose - it could have, rammed itself into the nostril and maybe got stuck in the heat of an attempt to escape. Or may be the seal brought the eel out to the surface to eat the prey, and the eel could have whipped around and got into the nose…
It can be also a case of “not knowing better” since this phenomenon has been observed only in young seals, who might just be inexperienced at hunting.
Or the seal might have sneezed or regurgitated the eel through the wrong pipe.
Not to worry though - the seal’s day turned for the better as researchers managed to remove it from its nose. The eel however did not have the same luck as it died. Maybe it got a fatal scare of how dark the nose of the seal was?
After my hideously pessimistic take on the last story it is time for some optimism.
Freed from two large dams, a small river in Washington state USA has efficiently flushed vast amounts of mud, sand and gravel towards the sea.
This is the world’s largest dam-removal project so far. Two barriers on the Elwha River (32 and 64 metres high respectively) were dismantled between 2011 and 2014 to restore the river’s flow. Amy East at the US Geological Survey in Santa Cruz, California, and her team monitored river flow and topography before, during and after the dams’ removal.
The release of 20 million tonnes of sediment that had been trapped in the reservoirs behind the dams substantially altered the shape of the river, filling pools and creating new sandbanks. But five months later most of the change had settled down and the 20 million tons of debris had in the main reached the Strait of Juan de Fuca.
Rivers of sufficient stream power seem to be able to cope with large dam removals without serious harm, the authors conclude. I assume this is good news for recovery of various ecosystems and species supported by the river. I looked into how dams affect rivers.
The dam wall itself blocks fish migrations, which in some cases and with some species completely separate spawning habitats from rearing habitats. The dam also traps sediments, which are critical for maintaining physical processes and habitats downstream of the dam (include the maintenance of productive deltas, barrier islands, fertile floodplains and coastal wetlands).
Another significant and obvious impact is the transformation upstream of the dam from a free-flowing river ecosystem to an artificial slack-water reservoir habitat. Changes in temperature, chemical composition, dissolved oxygen levels and the physical properties of a reservoir are often not suitable to the aquatic plants and animals that evolved with a given river system. Indeed, reservoirs often host non-native and invasive species (e.g. snails, algae, predatory fish) that further undermine the river's natural communities of plants and animals.
The alteration of a river's flow and sediment transport downstream of a dam often causes the greatest sustained environmental impacts. Life in and around a river evolves and is conditioned on the timing and quantities of river flow. Disrupted and altered water flows can be as severe as completely de-watering river reaches and the life they contain. Yet even subtle changes in the quantity and timing of water flows impact aquatic and riparian life, which can unravel the ecological web of a river system.
A dam also holds back sediments that would naturally replenish downstream ecosystems. When a river is deprived of its sediment load, it seeks to recapture it by eroding the downstream river bed and banks (which can undermine bridges and other riverbank structures, as well as riverside woodlands). Riverbeds downstream of dams are typically eroded by several meters within the decade of first closing a dam; the damage can extend for tens or even hundreds of kilometers below a dam.
IN SUMMARY Large dams have led to the extinction of many fish and other aquatic species, the disappearance of birds in floodplains, huge losses of forest, wetland and farmland, erosion of coastal deltas, and many other unmitigable impacts.
I realise we use dams to prevent floods, hence reduce the occurrence of natural disasters affecting human life. (Although the 3 Gorges Dam on the Yangtze river led to the displacement 1.3 million people and led to the loss of many cultural sites.) Another great benefit of dams is the hydroelectric power they can generate, providing cleaner energy than fossil fuels.
A PhD candidate in Zoology at the University of Cambridge. Gabriela's work is on the ecology, physiology and genomics of thermal adaptation to altitude in Heliconius butterflies. More information on her study system can be found at http://www.heliconius
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That concludes this episode of the Blue Streak Science Podcast.
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