In the build up to our SCI Agri-Food Early Career Committee’s 2019 #agrifoodbecause Twitter competition, we are looking back over the best photos of the 2018 competition. Entrants were asked to take photos and explain why they loved their work, using the hashtag #agrifoodbecause on Twitter.
Our 2018 winner, Claire Dumenil from Rothamsted Research, won first prize for her visually striking image of a fruit fly on a raspberry. She received a free SCI student membership and an Amazon voucher.
#agrifoodbecause invasive pests threaten food production and food security, worldwide! #SWD #drosophilasuzukii #Rothamsted #cardiffuni – Claire Dumenil (@CnfDumenil)
#agrifoodbecause I work on reducing aphid infestations on wheat. From the lab to the field – Amma Simon (@amma_simon)
With their fluffy body bumblebees are fantastic pollinators! Work with them can improve crop pollination !! #agrifoodbecause – Sandrine Chaillout (@100chillout)
#agrifoodbecause I can develop drought tolerant wheat varieties – Samer Mohamed (@samer313)
#agrifoodbecause My Research looks at wild pollinators and how we can build a sustainable farming future with them and us in mind! – Laura James (@JamJamLaura)
#agrifoodbecause our improving understanding of the devastating pest, whitefly Bemisia tabaci s.l., will help farmers to increase yields and feed their children <3 – Sona Vyskocilova (@VyskocilovaS)
The IHNV virus has spread worldwide and is fatal to salmon and rainbow trout – costing millions in sales of lost farmed fish. The current vaccination approach requires needle injection of fish, one by one. Now, however, Seattle-based Lumen Bioscience has come up with a new technology to make recombinant vaccines in a type of blue-green algae called Spirulina that costs pennies to produce and can be fed to fish in their feed.
To be effective, oral vaccines have not only to survive the gut environment intact but must also target the appropriate gut-associated immune cells. The approach developed by Lumen overcomes many of the problems with complex and expensive encapsulation strategies attempted in the past, according to CEO Brian Finrow.
‘[It] focuses on a new oral-vaccine platform [using] engineered Spirulina to express high amounts of target antigen in a form that is both provocative to the immune system – ie generates a desirable immune response that protects against future infection – and can be ingested orally without purification, in an organism that has been used as a safe food source for both humans and fish for decades.’
To produce the new oral vaccine, the Lumen researchers first developed a strain of Spirulina that manufactures recombinant proteins in its cell walls that the salmon immune system recognises as IHNV viruses. They then rapidly grew the strain in a large-scale indoor production system – requiring only light, water, salt and trace nutrients – and harvested and dried all the raw Spirulina biomass. This dried powder can then be fed to the fish.
Images of turtles trapped in plastic packaging or a fish nibbling on microfibres pull on the heartstrings, yet many scientists studying plastics in the oceans remain open-minded on the long-term effects.
While plastics shouldn’t be in our oceans, they say there is still insufficient evidence to determine whether microplastics – the very tiniest plastic particles, usually defined as being less than 1mm in diameter – are actually harmful.
It is estimated that over 1,000 turtles die each year from plastic waste. Image: NOAA Marine Debris Program
On top of this, there is debate over how much plastic is actually in the sea and why so much of it remains hidden from view. Much of the research carried out to date is in its early stages – and has so far produced no definitive answers.
‘My concern is that we have to provide the authorities with good data, so they can make good decisions,’ says Torkel Gissel Nielsen, Technical University of Denmark (DTU). ‘We need strong data – not just emotions.’
Searching the sea
Plastic shopping bags can be degraded into microplastics that litter the oceans. Image: Wikimedia Commons
Gissel Nielsen leads a team of researchers who discovered that levels of microplastics in the Baltic Sea have remained constant over the past three decades, despite rising levels of plastics production and use.
The study – by researchers at DTU Aqua, the University of Copenhagen, Denmark, and Geomar, Germany – analysed levels of microplastics in fish and water samples from the Baltic Sea, taken between 1987 and 2015.
‘The result is surprising,’ says Nielsen. ‘There is the same amount of plastic in both the water and the fish when you go back 30 years.’ He claims that previous studies of microplastics levels were ‘snapshots’, while this is the first time levels have been studied over a longer period.
The UK introduced a ban in January this year of the sale and manufacture of products containing microbeads. Image: MPCA Photos
‘The study raises a number of questions, such as where the plastic has gone,’ he says. ‘Does it sink to the bottom, are there organisms that break it down, or is it carried away by currents? Some is in the sediment, some is in the fish, but we need to find out exactly how much plastic is there.’
In the study, more than 800 historical samples of fish were dissected and researchers found microplastics in around 20% of them. This laborious process involved diluting the stomach contents in order to remove ‘organic’ materials, then checking the filtered contents under a microscope to determine the size and concentration of plastics. It illustrates the difficulty of quantifying plastics in any sample, says Gissel Nielsen.
‘You must remove the biology to get a clear view of the plastics,’ he says.
Just as rivers supply the sea with water, they also act as a source of pollution. Researchers at the Helmholtz Centre for Environmental Research (UFZ), Germany, found that 10 large rivers are responsible for transporting 90% of plastic waste into the sea.
The team collected pre-published data on plastics in rivers and collated it with upstream sites of ‘mismanaged’ plastics waste – municipal waste that is uncollected.
‘The more mismanaged plastic waste there was, the more you found in the river,’ says Christian Schmidt, UFZ. ‘There was an empirical relationship between the two.’
The Yangtze river (pictured in Shanghai, China) is the main polluter of plastic in the ocean in the world. Image: Pedro Szekely/Flickr
Eight of these 10 rivers are in Asia, while the other two are in Africa. All of them flow through areas of high population.
‘Countries like India and China have seen huge economic growth – and now use large amounts of plastic food packaging and bottles – but have limited waste collection systems,’ he says. The data include both microplastic and ‘macro’ plastics – but microplastics data dominate ‘because scientists are more interested in that’, says Schmidt.
Plastic Ocean. Video: United Nations
While it is important to measure how much plastic is in the environment, Schmidt believes that the next step of his research will be more important – understanding the journey the plastics make from the river to the sea.
For all the uncertainty and debate over how much plastic is in the sea – and what harm it can do – one thing is clear. Future research is likely to focus more on the plastics that we can’t see, rather than the items we can.
It’s well known that the oceans are becoming more acidic as they absorb increasing amounts of CO2 from the atmosphere. Now, German researchers say they have found the first evidence that this is happening in freshwaters, too, with potentially widespread effects on ecosystems.
‘Many current investigations describe tremendous effects of rising CO2 levels on marine ecosystems,’ says Linda Weiss at Ruhr-University Bochum: acidic oceans can have major impacts on marine food webs, nutrient cycles, overall productivity and biodiversity. ‘However, freshwater ecosystems have been largely overlooked,’ she adds.
Waters with high acidity have reduced biodiversity.
Weiss and colleagues looked at four freshwater reservoirs in Germany. Their analysis of data over 35 years – from 1981 to 2015 – confirmed a continuous increase in CO2, measured as the partial pressure or pCO2, and an associated decrease in pH of about 0.3, suggesting that freshwaters may acidify at a faster rate than the oceans.
In lab studies, the team also investigated the effects of higher acidity on two species of freshwater crustaceans called Daphnia, or water fleas. Daphnia found in lakes, ponds and reservoirs are an important primary food source for many larger animals.
Daphnia are an essential part of the freshwater food chain. Image: Faculty of Natural Sciences at Norwegian University of Science and Technology/Flickr
When Daphnia sense that predators are around, they respond by producing ‘helmets’ and spikes that make them harder to eat. Weiss found that high levels of CO2 reduce Daphnia’s ability to detect predators. ‘This reduces the expression of morphological defences, rendering them more vulnerable,’ she says.
The team suggest that CO2 alters chemical communication between species, which could have knock-on effects throughout the whole ecosystem. Many fish learn to use chemical cues from injured species to detect predatory threats and move away from danger, for example.
Ocean acidification - the evil twin of climate change | Triona McGrath | TEDxFulbrightDublin. Video: TEDx Talks
Cory Suski, an ecologist at the University of Illinois at Urbana-Champaign, US, says he is not aware of many other data sets showing trends in CO2 abundance in freshwater over an extended time. Also, he notes: ‘A lot of the work to date in this area has revolved around behavioural or physiological responses to elevated CO2, so a morphological change is novel.’
But he points out that it is difficult to predict how this change could impact aquatic ecosystems, or whether this may be a global phenomenon, simply because of the complex nature of CO2 in freshwater. The amount of CO2 in freshwater is driven by a number of factors including geology, land use, water chemistry, precipitation patterns and aquatic respiration.
In May 2018, the first full-scale mobile marine plastics collection system, developed by The Ocean Cleanup, will leave San Francisco, California, bound for the ‘Great Pacific Garbage Patch,’ also known as the Pacific trash vortex. The plan, ultimately, is to use 60 of these $5m systems to clean up half of the debris in the Pacific Garbage Patch within five years, according to Boyan Slat, CEO of Netherlands foundation The Ocean Cleanup, speaking at the Cefic Chemical Congress held in Vienna, Austria, at the end of October 2017.
Each collection system comprises a 1km U-shaped barrier, which floats on the surface of the ocean and supports a 4m deep screen to channel floating plastic debris to a central collection point, for future recycling. A 100m prototype system has already been tested in the North Sea.
The system will leave from the San Francisco bay area. Image: Giuseppe Milo
The environmental cost of the Pacific’s plastic waste currently stands at roughly $13bn/year, while an estimated 600 wildlife species are threatened with extinction partly as a result of ingesting it. Plastic microbeads and particles only represent 5% of the plastics in the oceans, ‘but the remaining 95% will break down into small particles and chemicals that are already in the tuna we eat,’ Slat said. The larger plastics debris are all found in the top 4m of the oceans, the same depth as the system’s screens.
Plastic debris can end up in the food we eat. Image: Pixabay
Also speaking in Vienna, Emily Woglom, executive VP, Ocean Conservancy, said that 8m t/year of plastics goes into the oceans – ‘one city dump truck every minute’; between 2010 and 2025 the amount in the oceans will double. As much as ‘30% of fish on sale have plastics in them,’ she said. Most of the plastics now come from the developing economies, mainly in Asia, she added, noting that the Trash Free Seas Alliance, founded by the Ocean Conservancy and supported by the American Chemistry Council, Dow Chemical, P&G and the World Plastics Council as well as several big-name food and beverage companies have recently adopted the goal of launching a $150m fund for waste management in South East Asia.
How we roll. Video: The Ocean Cleanup
Meanwhile, Slat says that the mobile collection systems can also be used to trap plastic pollution closer to the source, for example in rivers and estuaries. Researchers at The Ocean Cleanup estimate that rivers transport between 115 and 241 m t/years of plastic waste into the oceans, with two-thirds coming from just 20 rivers, mostly in Asia.
The Pacific trash vortex forms as a result of circular ocean currents created by wind patterns and the forces created by the Earth’s rotation. Similar gyres are found in the South Pacific, Indian Ocean, and North and South Atlantic.