How can scientists detect potentially invasive species at low densities before they become a serious issue? As Science Daily reports, University of Illinois aquatic ecologist Eric Larson and colleagues from Notre Dame recently used environmental DNA (eDNA) to detect the presence of rusty crayfish in two lakes the invasive species has never before called "home." This methodology is promising as an early warning system because of how sensitive it is to detecting species within an aquatic community. In fact, eDNA is so sensitive that Larson concedes he may have found false positives; traces of rusty crayfish DNA may have been deposited in the lakes by water currents or a predator. While the eDNA technology is not refined enough to estimate the number of individuals of a given species within a community, it is a promising tool for testing for presence or absence before a known invasive species burgeons to a troublesome population size. At the very least, it gives managers a good idea of where to focus their search efforts. As for determining whether Larson was indeed reading a false positive…let the crayfish surveys begin! The original study was published in the Journal of Applied Ecology (Dougherty et al. 2016).
Henry Fandel, Ph.D. student in Biology
A new study by Bradshaw et al. in Nature Communications estimates that invasive insects cause at least $77 billion USD in damage per year. The authors warn that this is a gross underestimate due to lack of research outside Europe and North America. Insects cause widespread damage through the spread of infectious diseases, destruction of crops, damage to infrastructure, and disturbance to ecosystems. The rapid spread of invasive insect species is causing massive economic costs and global warming is likely to increase their spread towards the poles. According to one of the authors, Frank Courchamp, more pesticides or genetic manipulation to combat invasive insects is not the best solution. Instead, he recommends improving bio-security in international trade.
Sheila Moore, Master’s student in Biology
Bigger isn’t always better, especially when it comes to nonnative species invading new areas. A recent article published in Nature Communications by Early et al. (2016) found that most of the world is exposed to invasions due to travel and commerce, and that developing countries comprise some of the most vulnerable areas across the globe. Additionally, because developing countries don’t often have the resources to respond to invasion events, things like the invasive 440 pound Nile perch are likely able to eat over 200 native fish into extinction. Article by Natalie Jacewicz for NPR.
Vanessa Wuerthner, Ph.D. student in Biology
"Want to get rid of invasive species? Eat them.” A recent article in The Week highlights a growing movement to include invasive species on the menu at home and in restaurants. Coined "Culinary Conservation," multiple organizations (Eat the Invaders, Invasivore.org and Eradication by Mastication) have provided recipes and hosted events centered around invasive-oriented cuisine. The movement has found a home in multiple restaurants serving up species like the Asian carp and lionfish, which pose serious ecological and economic harm to their invaded ranges. Critics of the movement warn against the dangers of creating a demand for species we hope to eradicate, but for species like the Asian Carp, which have become perhaps irreversibly established, including them in our diet may be a good way to put their persistence to use.
Devin Digiacopo, Ph.D. student in Biology
Eradicating Invasive Species One Sushi Roll at a Time (New York Times). Chef Bun Lai is doing his part in helping to curb the threat of invasive species the only way he knows how – through making them what’s for dinner! For the past several years, Bun Lai has been serving his guests at his New Haven, CT restaurant local invasive species such as lionfish, Asian carp, and Asian shore crabs. According to the article, The Truth is in the Muck, In Popular Mechanics, "Bun [Lai] discovered that the crabs could be pan fried in olive oil and seasoned, creating a taste that is an uncanny imitation of a Dorito." Mr. Lai has more recently opened up shop in Miami FL and has his sights set on the many invaders in the Sunshine State, such as feral pigs, and invasive seaweed, which are becoming all too common within the Everglades. Through Mr. Lai’s example, hopefully others will follow suite with this sustainable initiative - and start to enjoy bags of Asian shore crabs as a snack!
Nick Buss, Ph.D. student in Biology
Samantha Klein, Junior in Environmental Science
Try to name the tiny orange-googly-eyed critter swimming around in a bowl on the stand in the living room or on a desk in a bedroom – perhaps with a little castle that has a picture of a mermaid on it? If goldfish came to mind – your thought process was correct. These aquatic inhabitants are very different in the wild however – which is where they have been found in three countries now – the US, Canada, and Australia. In the wild, goldfish retract back to their original colors, yellow and brown after just a few breeding cycles and they increase in weight to about the size of a 2L bottle of soda. This happens because in nature the fish are not being bred by people to be orange and because goldfish in nature have a wide diet. Female goldfish in the wild can lay upwards of 40,000 eggs every year, and survivorship is high due to a lack of natural predators. Goldfish are long distance swimmers (seems unlikely from keeping them in a bowl) so they can migrate effectively and efficiently to new areas to spawn and to live. These fish have large ecological effects – they swim near the bottom of the lakes/ponds/rivers and uproot the vegetation, leading to nutrient leaching, algal blooms, and eutrophication. So how are these cute little fellows getting out of their bowls and into nature? Human introductions are the leading cause, setting them free, and likely unaware of the severe ecological impacts that they can have. Goldfish are now listed as an invasive aquatic species. The best way to manage these fish is prevention – don’t want your fish? Don’t let it go or flush it! Donate them to recommend local pet stores or other owners – whatever you do, just don’t let them free! Article: In the Wild, Goldfish Turn from Pet to Pest (The New York Times).
Brooke Florio, Senior in Biology
When we think about invasive species, we commonly think of species that have been transported over long distances and impact ecosystems within which they are completely novel. However, we also move species short distances, or introduce novel populations of species into areas in which native populations of the species already occur – “native invaders.” Given the increasing appreciation for how variation within species can influence ecosystems – we should wonder what the ecological impacts of native invaders and altering intraspecific (within species) diversity are? For example, captive breeding programs for conservation, or breeding species for aquaculture or agriculture (including transgenic alteration) alter species “traits” (e.g., faster growth rates, or increased ability to resist disease). These “populations” of species can be intentionally re-introduced back into their native environment (i.e., where wild populations occur) – fish such as rainbow or brown trout raised in hatcheries are stocked into water bodies to enhance commercial or recreational fishing. Populations can also be unintentionally released – 2 million Atlantic salmon escape aquaculture in North America every year. Buoro et al. in Ecology Letters conducted a meta-analysis (an analysis of studies) to compare the ecological impacts of native salmonids (salmon and trout) invaders to non-native invaders that have been introduced to locations that have native salmon species or no native salmon species, respectively. They found that “native invaders” at least rivaled or possibly exceed the impacts of non-native invaders. However, impacts of native invaders were only documented at the lowest level of ecological organization (impacts on behavior or fitness of native salmon). We currently know little about the effects of native invaders on other species in communities or in ecosystems. This study highlights that what we know about the impact of invasive species is likely only the tip of the iceburg, and that we need to think about invasive species more broadly than species that are moved over long distances.
Kirsten Prior, Assistant Professor in Biology