Geosiris is an early contender for Sexiest Plant of 2019

The Conversation/THawkes

Elizabeth Joyce, James Cook University

Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.

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It’s a pale rebel with a mysterious past, who doesn’t play by the family rules. You might not guess from looking at it, but Geosiris australiensis is my pick for the Sexiest Plant of 2019.

I might be biased though: my colleagues and I have just uncovered the amazing life, and evolutionary history of this mysterious herb. It was only found in Australia in 2017, so there’s plenty left to discover.

But here are five things we do know about this strange, alluring guy.

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You’re no sun of mine!

Geosiris (literally, “earth iris”) grow as small (5-12 cm high), pale, perennial herbs on the floor of the tropical rainforest. A single stem arises from an underground rhizome which produces a white or pale purple flower after every wet season.

Geosiris doesn’t photosynthesise. Most plants are autotrophic (auto = self, trophic = feeding) – that is, they make their own food using energy from the sun through photosynthesis. Plants photosynthesise by using green chlorophyll, stored in part of the cell known as a chloroplast.

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However Geosiris is mycoheterotrophic (myco = fungus, hetero = other, trophic = feeding). Instead of photosynthesising, it steals the food from autotrophic plants and uses fungi as the middle man. That is why Geosiris isn’t green: it doesn’t photosynthesise so there is no green chlorophyll.

So how does Geosiris get away with this? It’s unclear, but our best guess is that Geosiris has found a way to cheat an already well-established system.

More than 90% of all plants have a cooperative relationship with fungi in the soil, in which the fungus offers up soil nutrients (such as phosphorus) to the plant in exchange for carbon. However, when plants evolve mycoheterotrophy, they work out a way of hijacking this system: mycoheterotrophs take nutrients from the fungus as well as the carbon it harvested from the photosynthesising plant.

This relationship is thought to be very specialised, with specific mycoheterotroph, autotroph and fungus species involved in each interaction. We think this is what Geosiris does, but much more research is needed into how it gets away with such a scandal, what’s in it for the fungus, and what species of fungus is involved.

The sun feeds most plants, and Geosiris steals from them using fungal associations.
Author provided

They’re the family rebel…

Mycoheterotrophy is surprisingly common in plants. Occurring in more than 500 species of flowering plants, this stealthy feeding strategy has evolved at least 47 separate times in 36 plant families, one species of liverwort, and (possibly) one conifer.

However, Geosiris earns its rebel status by being the only mycoheterotrophic genus in its family, Iridaceae, which contains many popular garden genera such as Iris, Gladiolus, Freesia and Dietes.

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Geosiris split off from its autotrophic ancestors about 53 million years ago. During this time away from the family, Geosiris did away with photosynthesis and became mycoheterotrophic.

…with a sexy, slimmed-down genome

This loss of photosynthesis was accompanied by a major change in the genes of Geosiris. Genes responsible for photosynthesis are found in the chloroplast genome. The chloroplast genome mostly contains genes responsible for photosynthesis, however also contains a few genes important for processes like energy production.

Over the past 53 million years, the number of functional genes in the Geosiris chloroplast genome has roughly halved compared with its autotrophic relative Iris missouriensis. This reduction in number of genes is not random though. The genes lost were those responsible for photosynthesis, while the genes retained have vital functions like energy production that Geosiris still needs.

Think of it like a Fitbit. You buy one with the intention of seeing your New Year fitness resolutions through, but come March your exercise regime falls by the wayside. In the meantime your Fitbit stops working but you don’t mind: you’re not using it anymore so there is no need to get it fixed. Eventually that Fitbit ends up in the bottom of your drawer, lost forever along with sundry cables, batteries and the SoFresh Greatest Hits of 2010.

In the case of Geosiris, over time photosynthetic genes become mutated but the cell doesn’t bother to fix the mutated genes because they aren’t needed. These gene mutations are passed on to offspring, and over generations the genes are eventually lost forever.

They’re rare…

For more than 100 years, there was only one species of Geosiris known to science: Geosiris aphylla from the rainforests of Madagascar. It wasn’t until 2010 that a second species was discovered in the Comoro Islands, just north of Madagascar. But then, in 2017 botanists on an expedition discovered a new species_ – Geosiris australiensis – in the Daintree Rainforest of Queensland, Australia.

Author provided

So how did such a small, mycoheterotrophic herb find its way across the vast Indian Ocean?

…and glamorous globe-trotters

The Iridaceae family originated in Australia (back when Australia was still connected to Antarctica), but around 53 million years ago the ancestor of Geosiris travelled across the Indian Ocean to Madagascar. Then, around 30 million years ago, a lineage of Geosiris managed to travel back to Australia, splitting off into the newly discovered species Geosiris australiensis.

There are a few explanations as to how the ancestors of Geosiris did so much travelling in a time before Qantas frequent flyer points. One is that they did, literally, jump across the Indian Ocean, with seeds carried by wind between Madagascar and Australia. Geosiris has minuscule “dust seeds”, only about 0.2 millimetres wide. They’re so small they can be carried by wind for long distances. Records show that similar dust seeds from orchids have been carried thousands of kilometres by wind dispersal.

A second, more likely explanation, is that Geosiris travelled overland along the perimeter of the Indian Ocean. Geosiris jumped continents during periods when the global climate was especially hot and humid. During these times tropical rain forests extended from Africa, around the coast of the Indian Ocean, all the way to Southeast Asia.

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As a result, there was a lovely tract of suitable habitat for Geosiris to inhabit and travel through. If this is the case, perhaps there are even more species of the inconspicuous and mysterious Geosiris waiting to be discovered in the rainforests of Southeast Asia.

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Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.

Elizabeth Joyce, PhD candidate, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Here’s what happens to our plastic recycling when it goes offshore

Migrant workers break apart blocks of pressed plastic bottles at a recycling plant in Thailand.
EPA/DIEGO AZUBEL

Monique Retamal, University of Technology Sydney; Elsa Dominish, University of Technology Sydney; Le Xuan Thinh; Nguyen, Anh Tuan, and Samantha Sharpe, University of Technology Sydney

Last year many Australians were surprised to learn that around half of our plastic waste collected for recycling is exported, and up to 70% was going to China. So much of the world’s plastic was being sent to China that China imposed strict conditions on further imports. The decision sent ripples around the globe, leaving most advanced economies struggling to manage vast quantities of mixed plastics and mixed paper.

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China’s recycling ‘ban’ throws Australia into a very messy waste crisis

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By July 2018, which is when the most recent data was available, plastic waste exports from Australia to China and Hong Kong reduced by 90%. Since then Southeast Asia has become the new destination for Australia’s recycled plastics, with 80-87% going to Indonesia, Malaysia, Thailand and Vietnam. Other countries have also begun to accept Australia’s plastics, including the Philippines and Myanmar.

Destination of plastic exports from Australia between January 2017 and July 2018. Click image to zoom.
Source: UTS Institute for Sustainable Futures, based on Comtrade data

But it looks like these countries may no longer deal with Australia’s detritus.

In the middle of last year Thailand and Vietnam announced restrictions on imports. Vietnam announced it would stop issuing import licences for plastic imports, as well as paper and metals, and Thailand plans to stop all imports by 2021. Malaysia has revoked some import permits and Indonesia has begun inspecting 100% of scrap import shipments.

Why are these countries restricting plastic imports?

The reason these countries are restricting plastic imports is because of serious environmental and labour issues with the way the majority of plastics are recycled. For example, in Vietnam more than half of the plastic imported into the country is sold on to “craft villages”, where it is processed informally, mainly at a household scale.

Informal processing involves washing and melting the plastic, which uses a lot of water and energy and produces a lot of smoke. The untreated water is discharged to waterways and around 20% of the plastic is unusable so it is dumped and usually burnt, creating further litter and air quality problems. Burning plastic can produce harmful air pollutants such as dioxins, furans and polychlorinated biphenyls and the wash water contains a cocktail of chemical residues, in addition to detergents used for washing.

Working conditions at these informal processors are also hazardous, with burners operating at 260-400℃. Workers have little or no protective equipment. The discharge from a whole village of household processors concentrates the air and water pollution in the local area.

Before Vietnam’s ban on imports, craft villages such as Minh Khai, outside Hanoi, had more than 900 households recycling plastic scraps, processing 650 tonnes of plastics per day. Of this, 25-30% was discarded, and 7 million litres of wastewater from washing was discharged each day without proper treatment.

Author provided

These plastic recycling villages existed before the China ban, but during 2018 the flow of plastics increased so much that households started running their operations 24 hours a day.

The rapid increase in household-level plastic recycling has been a great concern to local authorities, due to the hazardous nature of emissions to air and water. In addition, this new industry contributes to an already significant plastic litter problem in Vietnam.

Green growth or self-preservation?

A debate is now being waged in Vietnam, over whether a “green” recycling industry can be developed with better technology and regulations, or whether they must simply protect themselves from this flow of “waste”. Creating environmentally friendly plastic recycling in Vietnam will mean investment in new processing technology, enhancing supply chains, and improving the skills and training for workers in this industry.

Engineers at the Vietnam Cleaner Production Centre (which one of us, Thinh, is the director of) have been working on improving plastic processing systems to recycle water in the process, improve energy efficiency, switch to bio-based detergents and reduce impacts on workers. However, there is a long way to go to improve the vast number of these informal treatment systems.

What can we do in Australia?

While Australia’s contribution to the flow of plastics in Southeast Asia is small compared to that arriving from the United States, Japan and Europe, we estimate it still represents 50-60% of plastics collected for recycling in Australia.

Should we be sending our recyclables to countries that lack capacity to safely process it, and are already struggling to manage their own domestic waste? Should we participate in improving their industrial capacity? Or should we increase our own domestic capacity for recycling?

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While there may be times it makes sense to export our plastics overseas where they are used for manufacturing, the plastics should be clean and uncontaminated. Processes should be in place to make sure they are recycled without causing added harm to communities and local environments.

Australia and other advanced economies need to think seriously about the future of exports, our own collection systems and our “waste” relationships with our neighbours.

Monique Retamal, Research Principal, Institute for Sustainable Futures, University of Technology Sydney; Elsa Dominish, Senior Research Consultant, Institute for Sustainable Futures, University of Technology Sydney; Le Xuan Thinh, Director, VNCPC; Nguyen, Anh Tuan, Senior researcher, Environment Science Institute, and Samantha Sharpe, Research Director, Institute for Sustainable Futures, University of Technology Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Flash photography doesn’t harm seahorses – but don’t touch

Maarten De Brauwer, Curtin University; Benjamin John Saunders, Curtin University, and Tanika Cian Shalders, Curtin University

We all enjoy watching animals, whether they’re our own pets, birds in the garden, or elephants on a safari during our holidays. People take pictures during many of these wildlife encounters, but not all of these photographic episodes are harmless.

There is no shortage of stories where the quest for the perfect animal picture results in wildlife harassment. Just taking photos is believed to cause harm in some cases – flash photography is banned in many aquariums as a result.

But it’s not always clear how bright camera flashes affect eyes that are so different from our own. Our latest research, published in Nature Scientific Reports, shows that flash photography does not damage the eyes of seahorses, but touching seahorses and other fish can alter their behaviour.

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Look but don’t touch

In the ocean it is often easier to get close to your subject than on land. Slow-moving species such as seahorses rely on camouflage rather than flight responses. This makes it very easy for divers to approach within touching distance of the animals.

Previous research has shown that many divers cannot resist touching animals to encourage them to move so as to get a better shot. Additionally, the high-powered strobes used by keen underwater photographers frequently raise questions about the welfare of the animal being photographed. Do they cause eye damage or even blindness?

A researcher photographing a ghost pipefish.
© Luke Gordon

Aquariums all around the world have taken well-meaning precautionary action. Most of us will have seen the signs that prohibit the use of flash photography.

Similarly, a variety of guidelines and laws exist in the scuba-diving community. In the United Kingdom, flash photography is prohibited around seahorses. Dive centres around the world have guidelines that include prohibiting flash or limiting the number of flashes per fish.

While all these guidelines are well-intended, none are based on scientific research. Proof of any damage is lacking. Our research investigated the effects of flash photography on slow-moving fish using three different experiments.

What our research found

During the first experiment we tested how different fish react to the typical behaviour of scuba-diving photographers. The results showed very clearly that touching has a very strong effect on seahorses, frogfishes and ghost pipefishes. The fish moved much more, either by turning away from the diver, or by swimming away to escape the poorly behaving divers. Flash photography, on the other hand, had no more effect than the presence of a diver simply watching the fishes.

For slow-moving fishes, every extra movement they make means a huge expense of energy. In the wild, seahorses need to hunt almost non-stop due to their primitive digestive system, so frequent interruptions by divers could lead to chronic stress or malnutrition.

Researchers tested the effect of high-strobe flashes on frogfish.
Author provided

The goal of the second experiment was to test how seahorses react to flash without humans present. To do this we kept 36 West Australian seahorses (Hippocampus subelongatus) in the aquarium facility at Curtin University. During the experiment we fed the seahorses with artemia (“sea monkeys”) and tested for changes in their behaviour, including how successful seahorses were at catching their prey while being flashed with underwater camera strobes.

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An important caveat to this experiment: the underwater strobes we used were much stronger than the flashes of normal cameras or phones. The strobes were used at maximum strength, which is not usually done while photographing small animals at close range. So our results represent a worst-case scenario that is unlikely to happen in the real world.

The conclusive, yet somewhat surprising, result of this experiment was that even the highest flash treatment did not affect the feeding success of the seahorses. “Unflashed” seahorses spent just as much time hunting and catching prey as the flashed seahorses. These results are important, as they show that flashing a seahorse is not likely to change the short-term hunting success (or food intake) of seahorses.

Scuba divers should always avoid touching animals.
sanc0460/Flickr, CC BY

We only observed a difference in the highest flash treatment (four flashes per minute, for ten minutes). Seahorses in this group spent less time resting and sometimes showed “startled” reactions. These reactions looked like the start of an escape reaction, but since the seahorses were in an aquarium, escape was impossible. In the ocean or a large aquarium seahorses would simply move away, which would end the disturbance.

Our last experiment tested if seahorses indeed “go blind” by being exposed to strong flashes. In scientific lingo: we tested if flash photography caused any “pathomorphological” impacts. To do this we euthanised (following strict ethical protocols) some of the unflashed and highly flashed seahorses from the previous experiments. The eyes of the seahorses were then investigated to look for any potential damage.

The results? We found no effects in any of the variables we tested. After more than 4,600 flashes, we can confidently say that the seahorses in our experiments suffered no negative consequences to their visual system.

What this means for scuba divers

A potential explanation as to why flash has no negative impact is the ripple effect caused by sunlight focusing through waves or wavelets on a sunny day. These bands of light are of a very short duration, but very high intensity (up to 100 times stronger than without the ripple effect). Fish living in such conditions would have evolved to deal with such rapidly changing light conditions.

This of course raises the question: would our results be the same for deep-water species? That’s a question for another study, perhaps.

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So what does this mean for aquariums and scuba diving? We really should focus on not touching animals, rather than worrying about the flash.

Flash photography does not make seahorses blind or stop them from catching their prey. The strobes we used had a higher intensity than those usually used by aquarium visitors or divers, so it is highly unlikely that normal flashes will cause any damage. Touching, on the other hand, has a big effect on the well-being of marine life, so scuba divers should always keep their hands to themselves.

Maarten De Brauwer, PhD-candidate in Marine Ecology, Curtin University; Benjamin John Saunders, Lecturer / Research fellow in Marine Ecology, Curtin University, and Tanika Cian Shalders, Marine Scientist, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.