California is waging a war against some unwanted guests: invasive species. The state has spent over $3 million a year building an army of scientists and professionals to develop mitigation solutions. These unassuming critters have destroyed the Golden State’s ecology and are beginning to creep into the Bay Area. The Nutria, Shothole Borer Beetle, and Purple Sea Urchin pose serious threats to Northern California’s water supply, native flora and fauna, and public health.

Distinguished by its long orange teeth and white muzzle, the Nutria can be found in at least 20 states across America. These beaver-like rodents, discovered this year in the Bay Area, reproduce rapidly and can consume vegetation up to 25% of their body weight a day, causing damage to the environment around them. Native to South America, Nutria were intentionally bred in the Central Valley to supplement the fur trade and control aquatic vegetation. But, when the nutria fur trade collapsed, they were released en masse, quickly dispersing across the region. These semi-aquatic creatures live near water bodies, most commonly fresh and saltwater marshes, posing significant threats to these environments. Nutria create burrows that can result in water-retention and the destruction of banks, compromising the viability of species that rely on crucial wetlands.

But what does this mean for humans? The Nutria are hosts for several pathogens, including those that cause Tuberculosis and Septicemia. They carry rash-causing tapeworms in their feces and urine which can contaminate bodies of water. Their current occupation of the  Sacramento-San Joaquin Delta, a critical source of drinking water for residents in the Central Valley and Bay Area, puts the lives and health of humans, pets, and livestock at risk. Krysten Kellum is an information officer that works for the California Department of Fish and Wildlife (CDFW). She mentions that “Nutria feed on roots and tubers that hold soil together”, which could lead to erosion and agricultural damage. If left unchecked, this weak soil structure, combined with water contamination, could affect the crops produced in the region, and subsequently the Golden State’s economy and diet. The produce usually grown in the area — rice, grapes, and tomatoes among others — could drastically reduce in supply and increase in price. The Nutria are spreading across the Bay Area like wildfire and if they are not contained, our fragile ecosystems, farmlands, and water sources will be threatened. 

Mitigation measures, however, are not easy to implement. The 20 pound rodents can swim long distances underwater to evade capture and are often mistaken for beavers or muskrats, making them hard to recognize. Relocation isn’t a viable option as the Nutria will continue to wreak havoc in any new environment they are introduced to. Krysten points out that she and her department are “just doing our best to try and mitigate and eradicate the nutria infestation; there are a lot of boots on the ground out there.” In 2018, the California Department of Fish and Wildlife was allocated $10 million in state funds to tackle the problem of the elusive nutria. The Department launched the Nutria Eradication Program and has since assessed over 1.9 millions acres of land and deployed over 14,000 game trap sets. As of October 2024, more than five thousand Nutria have been humanely euthanized, but the population of the Nutria continues to grow. Krysten stresses “the importance of reporting suspected sightings to the CDFW site or calling the invasive species hotline.” The department has a nutria response team that follows up on these reports, and a combination of citizens and experts working together can help combat the Nutria infestation.

Contrary to the large Nutria, the shothole borer beetle is a minuscule black-brown insect, but its effects are not so small. As adult female beetles bore through trees to create tunnels, they introduce a fungus, Fusarium dieback, for their larvae to feed on when hatched. As the females lay eggs in the tunnels, the fungus grows and spreads throughout the tree. When the eggs hatch, the larvae consume the fungus, mate with males, and exit the tree through the tunnels to reinfect the host or find a different tree to bore through.

Initially detected in Southern California in the early twenty-first century, these tiny but destructive beetles were identified in San Jose in August 2024, but scientists think they may have gone undetected for years. These beetles are native to Southeast Asia and are believed to have arrived in the United States through packaging materials. As the fungus they depend on spreads, the tree’s interior structure and vascular system is weakened, preventing sufficient transport of water and nutrients. This process manifests in the foliage, which takes on a yellow tint, leading to a gradual death of the entire tree. Many of California’s beloved native trees are at risk of getting infected by the Shothole borers. More than 60 tree species, including the Avocado, Sycamore, and Castor Bean, are susceptible to suffering the dangerous effects of the Shothole Borer Beetles. In extreme cases, the beetles could threaten urban forests in areas of the Bay that cool cities, improve air quality, store carbon, and add to aesthetic.

The California Invasive Species Advisory Committee launched a strategic statewide initiative in 2019 to control the spread and effects of Fusarium Dieback. Identifying the invasive insect is one of the first steps to mitigating their spread. A key giveaway is the small, pen-tip sized, entry-holes indicating the presence of beetle tunnels. Examining the features of the trees themselves can reveal whether they are infected or not. Signs of infestation include staining, gumming, and secretions. For trees that have moderate infested branches, removing some tree-cover can prevent the fungus from spreading further. However, if the fungus has invaded a significant portion of the tree, the most successful way to control the spread is chopping the full tree into one-inch sized blocks in a process known as chipping.

Tree owners should prioritize using local firewood and keep their trees healthy by watching for signs of distress on native trees and reporting any suspected symptoms.

While Purple Sea Urchins’ nativity to California doesn’t fit the typical label of an invasive species, they are one of the largest threats to the state’s marine ecosystems. The spiny purple creatures have dominated the waters of the West Coast since the 1800s, when sea otters, one of their primary predators, were hunted to near extinction. Their population continues to flourish today for similar reasons. Starting in 2013, climate-change-induced marine heat waves and severe El Niño weather patterns led to a disease, called Star Wasting Syndrome, which drastically reduced sea star numbers, another key urchin-predator. This, combined with a toxic algal bloom, eradicated the sea stars that kept purple sea urchin populations in check.

These purple urchins pose a considerable threat to California’s kelp forest populations. They have completely inundated the sea floor, forming a purple carpet and created urchin barrens, taking over and attacking areas of kelp forests. These forests are integral to the stability of the region’s marine ecosystems; they provide shelter and food for organisms and help control seafloor erosion. However, 90% of the bull kelp, a type of kelp native to the Pacific, have disappeared in California, and the Purple Sea Urchins play a key role. Bull kelp disappearance could compromise the lives of other marine animals and consequently harm local fisheries and businesses. 

Scientists are hopeful that efficient population control methods could be put into place. One option is to remove the urchins manually until their natural predators can be reintroduced. The most appealing tactic, however, is to encourage the public to eat the urchins. Sea urchins are a Japanese delicacy, called uni, and selling these hand-harvested urchins to restaurants can provide funding for eradication efforts. However, there are several factors to consider that may affect the viability of this solution. Many coast-side restaurants feature urchins on their menus, but these are most commonly red sea urchins. Since the purple urchins are so populous, they are underfed and considerably smaller than their red counterparts.

Nonetheless, while visiting the Pacific Coast, sea urchin should definitely be on the list of foods to try. Restaurants in the region offer tasty dishes experimenting with the flavors of sea urchin and presenting it in a way that is appealing to all palates. Consider checking out these eateries that specialize in the delicacy:
- Swan Oyster Depot serves half-shell sea urchin with lemon and almost always has throngs of hungry visitors lining up to taste the store’s fresh seafood offerings.
- For sea urchin mixed into familiar dishes, visit SPQR in San Francisco for buttery sea-urchin pasta.
- Bar Crudo offers a twist on every Californian’s favorite, avocado toast, by layering uni on top.

Simple actions, like trying new seafood, can help keep these invasive species at bay. Although many are small in size, they induce large impacts on the Bay Area’s ecosystem which could permanently alter the region’s environment. For now, California places its hope in a few promising mitigation strategies for the nutria, shothole borer beetle, and purple sea urchin, hoping to experience a future not threatened by their dangerous overpopulations.