USC Dana and David Dornsife College of Letters, Arts & Sciences > Blog

September 19, 2014

No More Waste! Closing the Loop in Our Urban Food System

Filed under: Wrigley Institute — Jessica Dutton @ 8:18 am

USC Wrigley Institute

By: Ryan Lesniewski

Last summer I was enjoying the cool ocean breeze while doing my graduate research on Catalina Island, but now the air conditioning in my car will have to suffice. This summer I’m a WIES Sonosky Fellow, and I drive 20 miles east of LA to a research facility in Irwindale, CA for my research.

It’s quite a different environment here in the urban jungle compared to a more natural setting like Catalina, but lately I’ve been focusing on how biological processes might be able to help Los Angeles become more sustainable. At the Irwindale facility that is part of Dr. Ken Nealson’s lab, we are developing technologies that can potentially reclaim value from our city’s enormous amount of uneaten food. Some of our projects include preventing food waste spoilage, extracting valuable organic compounds, cultivating insect larvae from food waste, and producing organic fertilizers.

We use microbes and insects to do most of the heavy lifting. Given the right conditions, specific types of microorganisms help convert the organics in food waste into compounds that help prevent further breakdown. This is actually a good thing, since we feed it to a hungry insect called the black soldier fly (BSF). The BSF larvae are able to live and grow quite happily off of this food waste.

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The black soldier fly, adult and larvae

My specific project has been to track nutrients through this process and determine which products would make a good fertilizer. After some testing and modifications, I grow lettuce using the experimental fertilizer treatments to evaluate its performance. Together, these technologies are able to create value out of things that were once destined for the landfill.

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Ryan in his research greenhouse

This is one part of the solution. Teaching people how to be more sustainable in their everyday lives is the other part.

Aside from my research, this summer I’ve helped install two aquaponic systems at a local high school and a women’s shelter. Aquaponics uses fish waste and microbial communities to grow fruits and vegetables. This method uses less water and is more space-efficient compared to conventional farming. The school I am working with is on track to open one of the first student-run farmers markets from food grown on the high school campus!

ryan teaching

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Aquaponics system: grow beds on top and fish tanks on bottom

Providing these systems exposes kids, teachers, and the community to methods for growing healthy food in small spaces with less water. If we really want to change the way our city works, we have to educate all ages on why it’s important, and what they can do to help. We have a lot of brilliant and open minds here in LA, and I think we have what it takes to close the loop in our food system. I’m really happy to do my part to help get it started.

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September 9, 2014

Taking a Closer Look at Marine Pollution Monitoring with Mussels

Filed under: Graduate,Wrigley Institute — Jessica Dutton @ 8:54 am

USC Wrigley Institute

By: Megan Hall

Hi, my name is Megan, and I’m entering my fourth year as a PhD student in the Marine Environmental Biology program at the University of Southern California (USC). I’ve been on Catalina Island at the Wrigley Marine Science Center for a large part of the summer as a 2014 WIES Summer Fellow, doing experiments with baby mussels and metals.

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Megan in the lab

Copper—did you know…?

When I tell people that I study copper pollution, a common reaction is, “I didn’t even know copper was a pollutant!” But believe it or not, copper is a major contaminant in coastal waters. Numerous bays and harbors exhibit copper concentrations that exceed the safe limits for at least some portion of the year.

Where does this copper come from, you may ask? Copper is washed into the sea with urban runoff, which occurs in Southern California during our infrequent rainfall events. Copper is also the predominant chemical used in antifouling paint: a special paint that covers the hulls of almost all boats to prevent “pests” like barnacles, tunicates, and mussels from growing there. These animals can be pesky for boat owners, who incur high costs in scraping and cleaning their hulls to get rid of them. But they are also important members of coastal ecosystems, and when copper dissolves from the antifouling paint into surrounding waters, it can be very harmful for the local marine populations.

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Mussel larvae under the microscope

Monitoring with mussels

The Environmental Protection Agency (EPA) requires that coastal waters and effluent be tested for copper toxicity to ensure that ecosystems are not being damaged by human inputs.

Copper is toxic to many marine organisms, but to varying degrees. So to protect all organisms in coastal waters, regulators set the copper limits low enough to protect the most sensitive organism in the system. In most U.S. marine waters, that organism is the bay mussel Mytilus.

Safe concentrations of copper are determined by exposing mussel embryos to copper-contaminated water samples for 48 hours, and then counting the number of animals that survive and normally develop to the early larval stage.

In theory, this information should tell us how many animals make it through a copper exposure at a given concentration, and will thus make it into adulthood and possibly reproduce. However, toxicologists are increasingly questioning this approach for understanding the effects of pollutants on an animal’s chances of surviving, reproducing, and contributing to the next generation of the species.

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Problems, and solutions?

Although toxicity tests that are currently used provide good baseline data, they don’t provide some important information that could be very useful in determining safe pollutant levels. For example, if an animal is still alive and well after 48 hours of copper exposure, does that mean it got out scot free and will be okay for the rest of its life?

Prior evidence suggests that this might not be the case. Recent findings from my own summer research also indicate that after 48 hours of copper exposure, some animals that survive will still go on to display reduced growth rate, delayed development, and increased mortality.

Additionally, I am curious about what is happening below the surface in these toxicity tests. The physical analysis that is currently used does not consider anything about the animals’ molecular physiology inside. Imagine if a doctor were to just look at you without any blood tests or scans, and say, “You’re fine!” Doesn’t seem thorough, right?

For that reason, I’m analyzing the animals’ gene expression: a good basic way to determine what is happening inside the animal, and an indicator of physiological stress that may not be evident at the whole organism level. So far, I’ve found that gene expression in mussel larvae changes significantly with increasing copper concentrations, and that expression also changes in animals that appear abnormal when compared to those that appear normal.

Gene expression measurements are already telling us a ton about the effects of copper on the development of mussels, and it will be very exciting to see what we uncover next! Together, longer-term monitoring of these physical and molecular measurements can provide more detailed information on safe copper limits in coastal waters, and hopefully allow us to better protect mussels and other sensitive marine organisms.

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Megan is a Wrigley Institute 2014 Summer Fellow, and a PhD student in the lab of Dr. Andrew Gracey in the Department of Biological Sciences at USC.

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