The Summer of the Russian (Fish) invasion

Title Image Credit: Earl Steele, CC BY-NC-ND 2.0, Image Cropped
Title Image Credit: Earl Steele, CC BY-NC-ND 2.0, Image Cropped
Image Credit: mstk east, CC BY 2.0, Image Cropped
Image Credit: Maria Grist, CC BY-SA 4.0, Image Cropped
Platypus predation has differential effects on aquatic invertebrates in contrasting stream and lake ecosystems (2020) McLachlan-Troup, Scientific Reports, https://doi.org/10.1038/s41598-020-69957-1
A trophic cascade occurs when a predator’s effects of its prey goes on to affect ‘lower’ levels of that ecosystem. A great example is the effect that sea otters have on kelp: the sea otters prey extensively on sea urchins, which in turn increases the populations of kelp, which the sea urchins prey on. While this is a result of direct predation by otters, often this can occur through a prey species changing its behaviour to avoid the predators.
Yet most ecosystems are more complex than a simple three-level trophic system. Cascades are therefore more likely to occur when the ecosystem is less complex, or when there are well-defined relationships between species, as a result of a predator having preferred prey species or only a few groups of species making up an ecosystem.
This week’s authors investigated how the platypus (our recently-found-to-be-fluorescent friend) influences the abundance and species richness of invertebrates across both rivers and lakes, and whether it’s capable of affecting an ecosystems algae and sediments as well.
Read moreYet despite their role in our history, urban rivers today are often facing increasing levels of pollution as a result of human activity. As well as often being a huge tourist drawcard, and an ongoing resource for fishers, joggers and portable BBQ toters, freshwater ecosystems carry a disproportionate number of aquatic species, which makes this trend increasingly worrying.
After meeting at last year’s British Ecological Society Annual Meeting, I got in touch with Dr. Cecilia Medupin, a freshwater ecologist at the University of Manchester. Cecilia works to increase peoples understanding of rivers, including the project Our Rivers, Our City. I asked Cecilia abut our connection with rivers, the challenges they face, and how to inspire research and change in urban rivers.
Image Credit: Jacob Biewer, Sankey et al., 2015
Image Credit: Manfred Antranias Zimmer, Pixabay licence, Image Cropped
Invasion of freshwater ecosystems is promoted by network connectivity to hotspots of human activity (2019) Chapman et al., Global Ecology and Biogeography, https://doi.org/10.1111/geb.13051
The spread of invasive species throughout freshwater ecosystems is a topic we’ve looked at before on Ecology for the Masses. In a previous paper breakdown we talked about how recreational is heavily responsible for the presence of non-native fish at a European scale.
Our paper this week takes a more local approach. Can we predict the presence of non-native birds, invertebrates and fish by looking at the presence of human activity, and where that human activity is present?