Spreading of the Australian yabby has led to decreases in other local species. But what happens when these species meet? (Image Credit: Daiju Azuma, CC BY-SA 2.5)
Insight into invasion: Interactions between a critically endangered and invasive cray fish (2018) Lopez et al., Austral Ecology, doi:10.1111/aec.12654
When we talk about invasive species, often the first thing that pops into our minds are things like feral cats, wild pigs, vicious newcomers that wipe out species or transform vast areas. But often what we focus on less are species which arrive and simply outcompete the locals.
The yabby (Cherax destructor) is one such invader. An Australian species, it has been introduced to new waterways through the country and is now threatening other species, including the Falls Spiny Crayfish (Euastacus dharawalus) in eastern New South Wales, Australia. The introduction of the yabby has resulted in a decreasing habitat range for the crayfish, but what sort of mechanisms are causing this? This experiment aimed to document interactions between the two species.
The Japanese skeleton shrimp is responsible for the reduction of many Norwegian local species who flee in terror because LOOK AT IT (Image Credit: Erling Svensen, CC BY 4.0)
Today’s creatures look horrific. Or they would, at least, if they weren’t so tiny. A long-range invader, the Japanese skeleton shrimp (Caprella mutica) is tiny, but their ability to colonise new areas quickly has made them a problem for other aquatic invertebrates since their first sighting in Norway 20 years ago.
The Lake Trout, the species which was almost driven to extinction by overfishing and Sea Lamprey invasion, has now been restored in the Great Lakes (Image Credit: Cory Goldsworthy, MDNR)
Back in June this year, I was fortunate enough to attend the 9th International Charr Symposium, a conference which takes place every three to four years focusing on fish in the genus Salvelinus. The conference took place on Lake Superior, a site where the local Lake Trout population had previously been greatly reduced by overfishing and the invasion of the Sea Lamprey in the first half of the 20th century.
Yet the concerted efforts of the State, Provincial and Federal governments’ Fisheries Departments from the U.S. and Canada worked to successfully control the invasive Sea Lamprey species, and the native Lake Trout population was restored. I spoke with Don Pereira, Don Schreiner and Cory Goldsworthy of the Minnesota Department of Natural Resources (MNDNR) and Minnesota Sea Grant (MNSG) about one of the rare success stories of invasion ecology.
In the series Norway’s Newcomers, we’ve looked extensively at not only Norway’s non-native species, but the genetics, definition and even the defense of alien species. So it made sense that we’d eventually find our way to interviewing an invasion biologist. I was in St. Paul, Minnesota earlier this year and was lucky enough to sit down with Professor Mark Davis.
Mark has been a strong opponent of the demonisation of invasive species for decades. Whilst many ecologists’ first reaction is to eradicate any non-native species, Mark has urged caution, and encouraged the community towards less pejorative terms. I spoke with Mark about the impact our work has on public opinion, how we should talk about non-natives, and living with the impact of invasive species going forward.