Microplastics are getting into mosquitoes and contaminating new food chains



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khlungcenter/Shutterstock

Amanda Callaghan, University of Reading and Rana Al-jaibachi, University of Reading

There is no doubt that plastic pollution in oceans is a growing worldwide problem. The internet is full of images of seabirds and other marine animals entangled in plastic waste, and animals starve because their guts are blocked with plastic bags.

But the problem goes much deeper than this. Much plastic pollution is in the form of microplastics, tiny fragments less than five micrometres in size and invisible to the naked eye. Our new research shows that these microplastics are even getting into tiny flying insects such as mosquitoes. And this means the plastic can eventually contaminate animals in a more unlikely environment: the air.

Microplastics can come from larger plastic items as they break down, but are also released directly into waste water in their millions in the form of tiny beads found in many cosmetic products including face wash and toothpaste (though these are now banned in many countries). Many tiny animals can’t tell the difference between their food and microplastics so end up eating them. Once inside an animal, the plastic can transfer via the food chain into fish and other creatures and eventually become a potential health problem for humans.

Mosquitoes leave the water and take microplastics with them.
Shaun Wilkinson/Shutterstock

By studying mosquitoes, we have found a previously unknown way for plastic to pollute the environment and contaminate the food chain. Our new paper, published in Biology Letters, shows for the first time that microplastics can be kept inside a water-dwelling animal as they grow from one life stage to another.

Although most microplastic research has focused on the sea, plastic pollution is also a serious problem in freshwater, including rivers and lakes. Much of the freshwater research has concentrated on animals that live in the water throughout their life. But freshwater insects such as mosquitoes start their lives (as eggs) in water and, after several stages, eventually fly away when they grow up.

Testing the mosquitoes

It occurred to us that aquatic insects might carry plastics out of the water if they were able to keep the plastics in their body through their development. We tested this possibility by feeding microplastics to mosquito larvae in a laboratory setting. We fed the aquatic young in their third larvae stage food with or without microplastic beads.

We then took samples of the animals when the larvae shed their skin to become larger fourth-stage larvae, when they transformed into a non-feeding stage called a pupa, and when they emerged from the water as a flying adult. We found the beads in all the life stages, although the numbers went down as the animals developed.

Plastics were retained as the mosquitoes went through different life stages.
Blue Ring Media/Shutterstock

We were able to locate and count the microplastic beads because they were fluorescent. We found beads in the gut and in the mosquito version of the kidney, an organ that we know survives the development process intact. This shows that not only do aquatic insects such as mosquitoes eat both sizes of microplastics, they can keep them in their gut and kidney as they develop from a feeding juvenile larva up to a flying adult.

In this way, any flying insect that spends part of its life in water can become a carrier of plastic pollution. And flying insects are eaten in their thousands by predatory insects in the air such as dragonflies as well as by birds and bats.

Our results have important implications since any aquatic insect that can eat microplastics in the water could potentially carry them in their body to their flying stage where they can move the plastics into new food chains. As a result, freshwater plastic pollution is a problem that has implications far beyond those of water quality and eventual marine pollution.

Clearly these results raise a number of questions, including what effect microplastics have on the survival and development of mosquitoes through their life stages. And we still need to examine the effect of different types and sizes of plastics on more species to see how widespread an issue this could become.The Conversation

Amanda Callaghan, Associate Professor of Zoology, University of Reading and Rana Al-jaibachi, PhD researcher, University of Reading

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

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Human-caused climate change severely exposes the US national parks



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Trees have died in Rocky Mountain National Park, Colo., as climate change has intensified bark beetle infestations and drought.
Patrick Gonzalez, CC BY-ND

Patrick Gonzalez, University of California, Berkeley

Human-caused climate change is disrupting ecosystems and people’s lives around the world. It is melting glaciers, increasing wildfires, and shifting vegetation across vast landscapes. These impacts have reached national parks around the world and in the United States. Until now, however, no analysis had examined climate change trends across all 417 U.S. national parks.

The United States established the first national park in the world, Yellowstone National Park, in 1872. U.S. national parks today protect some of the most irreplaceable natural areas and cultural sites in the world. Colleagues and I aimed to uncover the magnitude of human-caused climate change on these special places. We conducted the first spatial analysis of historical and projected temperature and precipitation trends across all U.S. national parks and compared them with national trends.

Our newly published results reveal that climate change has exposed the national parks to conditions hotter and drier than the country as a whole. This occurs because extensive parts of the parks are in extreme environments – the Arctic, high mountains, and the arid southwestern United States.

Many national parks are located in regions with the fastest rates of warming in the United States.
Patrick Gonzalez, CC BY

Rapid warming and drying

National parks conserve the most intact natural places in the country. They harbor endangered plants and animals and unique ecosystems. They also help assure human well-being by protecting watersheds that provide drinking water to people and by storing carbon, which naturally reduces climate change.

Our findings show that temperatures in the national park area increased at double the national rate from 1895 to 2010. At the same time, precipitation decreased across a greater fraction of the national park area than across the United States as a whole.

Our analysis of climate trends starting in 1895 showed that temperatures increased most in Denali National Preserve, Alaska, and rainfall declined most in Honouliuli National Monument, Hawaii. Hotter temperatures from human-caused climate change have intensified droughts caused by low precipitation in California and the southwestern United States.

Many national parks in the southwestern U.S. have experienced intense drought.
Patrick Gonzalez, CC BY

Human-caused climate change has caused historical impacts in places where we found significant past temperature increases. These impacts include melting of glaciers in Glacier Bay National Park, Alaska, tree death from bark beetles in Yellowstone National Park, upslope vegetation shifts in Yosemite National Park, California, and northward vegetation shifts in Noatak National Preserve, Alaska.

To quantify potential future changes, we analyzed all available climate model projections from the Intergovernmental Panel on Climate Change. Continued greenhouse gas emissions under the highest emissions scenario could increase U.S. temperatures in the 21st century six times faster than occurred in the 20th century.

This could increase temperatures in national parks up to 9 degrees Celsius by 2100, with the most extreme increases in Alaska, and reduce precipitation by as much as 28 percent, in the national parks of the U.S. Virgin Islands. Heating could outpace the ability of many plant and animal species to move and stay in suitable climate spaces.

In places where models project high temperature increases, research has found high vulnerabilities of ecosystems. These vulnerabilities include severely increased wildfire in Yellowstone National Park, extensive death of Joshua trees in Joshua Tree National Park, California, and possible disappearance of American pika, a small alpine mammal, from Lassen Volcanic National Park, California.

Human-caused climate change has doubled wildfire in the western U.S. Here, the Rim Fire burns west of Yosemite National Park, Calif., in 2013.
USDA/Mike McMillan, CC BY

Our research provides climate data to analyze vulnerabilities of plants, animals and ecosystems. The data can also help park managers develop adaptation measures for fire management, invasive species control and other ways to protect parks in the future.

For example, based on analyses of the vulnerability of ecosystems to increased wildfire under climate change, parks can target prescribed burning and wildland fire in the short term to reduce the unnatural buildup of fuels that can cause catastrophic wildfires in the long term.

A solar panel on the roof of a building in Lassen Volcanic National Park, Calif., reduces greenhouse gas emissions and electricity costs for the park.
Patrick Gonzalez, CC BY-ND

Reducing emissions can help parks

Ultimately, our results indicate that reducing greenhouse gas emissions from cars, power plants and other human sources can save parks from the most extreme heat. Compared to the highest emissions scenario, reduced emissions would lower the rate of temperature increase in the national parks by one-half to two-thirds by 2100.

Cutting greenhouse gas emissions through energy conservation, improved efficiency, renewable energy, public transit and other actions would reduce the magnitude of human-caused climate change, helping save the U.S. national parks for future generations.The Conversation

Patrick Gonzalez, Associate Adjunct Professor, University of California, Berkeley

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