In the Wake of Hurricane Florence: How Genetic Tools Can Prevent Ecosystem Damage

https://www.acc.af.mil/News/Article-Display/Article/1638448/afcent-command-and-control-operations-weather-the-storm/

Hurricane Florence approaches the Carolinas

Hurricane Florence was devastating to much of the Carolinas. The flooding that ensued destroyed not only homes and livelihoods, but greatly affected animal agriculture. The effects of Florence resulted in the deaths of millions of animals and caused massive overflows or “overtopping” of animal waste, particularly from swine production facilities. North Carolina is the nation’s second largest producer of swine, and the 9.7 million pigs who call North Carolina home produce nearly 10 billion gallons of waste annually. The damages from Florence are disastrous not only from an economic perspective, but also from an environmental one.

In livestock production, lagoons are large basins primarily used for the treatment of animal wastes. Rather than simply being a collection site for waste, proper care of a lagoon involves “feeding” the lagoon with microbes that help degrade the waste into usable fertilizer. However, during massive flooding events the volume within these lagoons can quickly rise and overflow. This disrupts the waste treatment process and exposes the environment to large quantities of nitrogen, phosphorus, or even pathogenic material derived from animal wastes. According to the North Carolina Department of Environmental Quality, at least 32 lagoons have overtopped due to Florence, and another 61 lagoons have sustained structural damage or are close to overflowing.

An imbalance of nitrogen and phosphorus in any body of water contributes to a condition called eutrophication, in which excess nutrients allow for blooms of algae or plant matter. As these photosynthetic organisms flourish, they cause drastic changes to their environment. Algal blooms can be especially damaging, as many algae produce compounds which quickly reach toxic levels, algal overabundance clouds the water, and their rapid growth utilizes carbon leading to an increase in the pH of surrounding water. Eventually, algae change their own environment so extensively that they quickly die off, leading to subsequent microbial breakdown of the dead algae, which depletes oxygen. This rapid removal of oxygen then produces a “dead zone”, which is unsustainable for most life.

While nitrogen and phosphorus can be detrimental to the environment in large quantities, these are still very necessary components of any animal’s diet. Nitrogen and phosphorus are used as building blocks to produce DNA, proteins, and other compounds necessary for the growth. Therefore, agricultural production will need to find ways to provide these necessary building blocks while also preventing an excess of them in the environment. Thankfully, animal science research efforts have produced a unique potential fix!

Several years ago, researchers at the University of Guelph in Canada developed an animal designed with the world in mind: the Enviropig! The Enviropig is a transgenic animal, meaning its genome has been edited to contain a gene from a different species. In the case of the Enviropig, a bacterial-derived gene for the enzyme phytase is expressed in the pigs’ salivary glands, allowing the animal to break down more of the phosphorus in its diet. With more phosphorus broken down into a form the animal can digest, less phosphorus winds up in pigs’ waste, meaning less phosphorus contributes to eutrophication. A win for the pigs, now able to get better nutrition from their diet, and a win for humans and the environment, as we are able to produce and enjoy a more environmentally sustainable product. While the initial work on this project was put on hold in 2012 due to public scrutiny of genetically modified organisms (GMOs), a team of researchers in China developed their own version of an environmentally-conscious pig earlier this year. This new animal is able to break down greater amounts of both phosphorus and nitrogen from its diet, reducing their abundance in animal wastes.

Neither animal has been approved for use in the United States yet, but they both hold enormous potential to reduce the environmental impacts of animal agriculture. While the Enviropig and similar transgenic animals cannot yet solve every environmental issue, had they been mainstream prior to Hurricane Florence, perhaps there would be less concern with regard to ecosystem health after the flooding. Natural disasters are as unpredictable as they are unfortunate and dangerous; however, genetic tools such as these could provide one additional safeguard to protect the environment and public safety for the future.

https://www.publicdomainpictures.net/en/view-image.php?image=215663&picture=pigs

Livestock, such as pigs, can be genetically designed to help protect the environment!

Peer edited by Joanna Warren.

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Let’s Talk about Pets!

 Photo: Erin Spencer

Meet Marshmallow, an expert snuggler.

I love my pets. Growing up, I always had animals: fish, hamsters, hermit crabs, and even rats (my mom was particularly happy when those were out of the house). The current menagerie includes two cats, two fish, a bearded dragon, and a horse, and two fish.

Pets provide us joy (how many cat videos have you watched today?) and can even help us live longer. And they’re popular: 63% of American households have pets, resulting in more than 360 million pets in the United States alone. Consequently, pets and pet products account for over $40 billion in spending in the United States every year.

If you’re pet-obsessed (like me!), that probably doesn’t come as a surprise. But what might surprise you is that pets can pose a massive threat to our native ecosystems.

Even when people buy animals with the best intentions, a lot of things can change throughout the course of pet ownership. Maybe they realize their hubby is allergic to cats, or that teeny baby turtle outgrew his aquarium. Regardless of the reason, many pet owners will ultimately face a difficult decision: what do you do with a pet you can no longer care for?

Releasing pets into the wild may be considered a “humane” response by unknowing owners (thanks a lot Finding Nemo), but this is problematic for a number of reasons. First, a significant change in environment will likely be stressful for the pet and could lead to death. Second, they might be carrying diseases or pathogens that could spread to native wildlife, which is why even seemingly innocuous actions like flushing a dead fish could be dangerous. Lastly, in the right climate, released pets could establish breeding populations and become invasive.

Photo: Erin Spencer

The lionfish is an invasive species introduced in the Western Atlantic through aquarium releases.

This is more common than you might think. Here are a few examples of released pets becoming invasive pests in the United States:

  • Lionfish: Originally from the Indo-Pacific, these venomous fish are wreaking havoc on native fish populations in the Western Atlantic, Caribbean, and Gulf of Mexico. Considered the “Hoover vacuums of the sea”, lionfish will eat anything up to half their size. Despite being highly invasive, they are still a popular aquarium fish are are sold in the United States.
  • Cats: Your cuddly kittens have a deadly side. Domestic outdoor and feral cats kill a median of 2.4 billion birds and 12.3 billion mammals every year, leading cats to be considered one of the largest human-linked threats to wildlife in the country.
  • Giant African Land Snail: These massive mollusks are one of the world’s largest snails and consume more than 500 types of plants. To top it off, they can damage plaster and stucco structures and can carry a parasitic nematode that causes meningitis in humans.
  • Burmese python:  Reaching up to 23 ft in length, Burmese pythons are some of the largest snakes in the world. Now an invasive species established throughout South Florida, Burmese pythons pose a serious risk to native wildlife and domestic pets. More than 2,000 pythons have been removed from the Everglades National Park since 2002, a figure that likely represents a small fraction of the population.

And the list goes on (check out this site if you want to read more). Thankfully, there are definitive steps that we can take as pet owners to make sure we aren’t contributing to this massive problem.

  1. First and foremost: never, ever release your pets into the wild.
  2. Keep your pet in appropriate housing to minimize chances of escaping.
  3. Properly dispose of materials in your pet’s habitat, including bedding, tank water, terrarium plants, and anything that might carry pathogens or “hitchhikers” from your pet.
  4. Never release live pet food like crickets or feeder fish. Always make sure these animals are kept in secure containers so they cannot escape.
  5. Thoroughly do your research before buying a pet. Ask how care will change as the pet gets older to make sure you’re equipped to take care of the animal throughout its lifetime.
  6. Ask your pet store about their return policy — some stores will take animals back past the normal 30 day return period.

Invasive species are a massive threat to ecosystems and economies worldwide, costing $120 billion in damages each year in the United States alone. We all need to do our part to prevent the next big species invasion by practicing responsible pet ownership.

The environment (and your pets!) will thank you.

Photo: Erin Spencer

Dracarys is perfectly happy in his aquarium, thank you very much.

Peer edited by James Custer.

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Little Farmers in the Animal Kingdom

Think of a farmer. Chances are, an image of an overall-wearing, pitchfork-wielding man just popped into your head. But humans are only one of a surprisingly large group of animals that cultivate their own food.

You might already know about leaf-cutter ants–some 47 species of ants in the New World that meticulously cut fresh vegetation into fragments that look far too big for them to hold. But they somehow manage to carry those leaf and flower cuttings back to their nests. This plant material is then used to feed the fungus that these ants depend on for food. Just like human farmers, the ants regularly plant, cultivate, and harvest their crop. However, rather than wheat or soybeans, the crop is a specific species of fungus. In fact, the relationship between the ant farmers and fungus is so complete that neither can survive without the other: the fungus can no longer  propagate itself without help from the ants, and the ants need the fungus for nutrition. Leaf-cutter ants are an extreme group of farming ants because they are so dependent on their fungal crop for survival, but about 240 ant species (collectively known as the attine ants) practice some form of fungus farming.

https://commons.wikimedia.org/wiki/File:Hitchiking_leafcutter_ant.jpg

A leaf-cutter ant carrying a leaf back to its nest, where the leaf will be used to grow fungi. Image from Wikimedia.

Farming isn’t limited to ants: some species of termites and ambrosia beetles (a type of weevil) are also known to grow fungus for food. These groups demonstrate some of what we think of as the most ‘advanced’ farming. They’re ‘advanced’ because they have evolved many adaptations specific to farming, such as specialized organs or behaviors, and they often can’t survive without farming. Because of this, and because scientists have long-known about the farming practices of these animals, these three groups are the most heavily studied non-human farmers. But focusing on just ants, termites, and beetles overlooks the fact that farming is likely evolutionarily beneficial for many organisms: when food is in short supply, being able to generate your own can be life saving.

Unsurprisingly then, once scientists started looking for evidence of farming in different organisms, they found it in snails, amoebas, and fish, among others. For example, the dusky farmerfish cultivates a specific species of algae. They do so in little ‘gardens,’ which they aggressively defend from other fish. When the farmerfish are experimentally removed from their gardens, all the algae is quickly eaten by other fish. The algae don’t seem to grow outside of these gardens, and the fish rely on this algae as a staple food, making this another relationship where both players need each other to survive.

But not all farming works this way: a different type of farming relationship was described in 2011 between an amoeba and a bacterium. The social amoeba, Dictyostelium discoideum, lives as single-celled organisms that spend their time eating bacteria. When environmental conditions get tough, the individual cells aggregate to form a ‘slug’ that crawls elsewhere more rapidly than the individual amoeba cells could have. Once in a better environment, the slug changes shape again. This time, it turns into a stalked fruiting body that releases spores. Each spore becomes a new single-celled amoeba. Some strains of this amoeba farm their bacteria: instead of eating all the available bacteria, they take some up and incorporate them into their fruiting bodies. When spores are released, the new amoebas are already carrying the bacteria with them, which they then use to seed their new environment with food–just like humans sowing their fields.

https://commons.wikimedia.org/wiki/File:Dictyostelium_discoideum_01.jpg

D. dictyostelium in its stalked form, before releasing spores. These spores may or may not contain bacteria for farming, depending on the D. dictyostelium strain. Image from Wikimedia.

Not all Dictyostelium discoideum individuals demonstrate this farming behavior, which suggests that there could be downsides to farming. In this case, farming may be disadvantageous if the amoebas find themselves in a new environment that is already full of food. If this happens, the farming amoebas would have paid a cost by not eating all of the available food (and growing and reproducing) in their prior environment. In comparison, the non-farming amoebas wouldn’t have paid this same cost because they always eat all the food available to them. Because research on non-human farming has often focused on species that must farm to survive, the costly aspects of this behavior have not been extensively considered.

As scientists continue to explore the diversity of life on Earth, finding and characterizing new farming relationships can continue to give us insight into what this unique behavior can look like, and how it might vary in its evolution.

 

Additional readings:

Ants, termites, beetles: Mueller et al. 2005. The evolution of agriculture in insects. Annual Review of Ecology, Evolution, and Systematics 36:563-95.

Fish and algae: Hata H, Koto M. 2006. A novel obligate cultivation mutualism between damselfish and Polysiphonia algae. Biology Letters 2:593-6.

Amoebas: Brock et al. 2011. Primitive agriculture in a social amoeba. Nature 469:393-8. Brock et al. 2013. Social amoeba farmers carry defensive symbionts to protect and privatize their crops. Nature Communications 4:2385.

Peer edited by Paige Bommarito.

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