New paper: Heterogeneity enables coexistence of native and invasive aquatic plants

Salgado, J., Sayer, C. D., Willby, N., Baker, A. G., Goldsmith, B., McGowan, S., Davidson, T. A., Bexell, P., Patmore, I. R. & Okamura, B. (2021) Habitat heterogeneity enables spatial and temporal coexistence of native and invasive macrophytes in shallow lake landscapes. River Research and Applications.

First published: 15 July 2021
Macrophyte invasive alien species (IAS) fitness is often hypothesised to be associated with beneficial environmental conditions (environmental matching) or species-poor communities. However, positive correlations between macrophyte IAS abundance and native plant richness can also arise, due to habitat heterogeneity (defined here as variation in abiotic and native biotic conditions over space and time). We analysed survey and palaeoecological data for macrophytes in satellite lakes along the Upper Lough Erne (ULE) system (Northern Ireland, UK), covering a gradient of eutrophication and connectivity to partition how environmental conditions, macrophyte diversity and habitat heterogeneity explained the abundance of Elodea canadensis, a widely distributed non-native macrophyte in Europe. E. canadensis abundance positively correlated with macrophyte richness at both the within- and between-lake scales indicating coexistence of native and invasive species over time. E. canadensis was also more prolific in highly connected and macrophyte-rich lakes, but sparser in the more eutrophic-isolated ones. Partial boosted regression trees revealed that in eutrophic-isolated lakes, E. canadensis abundances correlated with water clarity (negatively), plant diversity (positively), and plant cover (negatively) whereas in diverse-connected lakes, beta diversity (both positively and negatively) related to most greatly E. canadensis abundance. Dense macrophyte cover and unfavourable environmental conditions thus appear to confer invasibility resistance and sufficient habitat heterogeneity to mask any single effect of native biodiversity or environmental matching in controlling E. canadensis abundance. Therefore, in shallow lake landscapes, habitat heterogeneity variously enables the coexistence of native macrophytes and E. canadensis, reducing the often-described homogenisation effects of invasive macrophytes.

Workshop and Seminar about Upper Lough Erne’s satellite lakes

Following the previous post, this is just to let you know that our trip to Northern Ireland was very successful. It gave us a chance to discuss our research results with many partners, stakeholders and members of the public. The interest we met makes us hope that our research will find direct applications on the ground.

We would like to thank the many people who made this trip possible at the Fermanagh and Omagh District Council, Waterways Ireland, the Northern Ireland Environmental Agency and Queen’s University Belfast.

Fermanagh is the happiest place in the UK!

The BBC reported today that Fermanagh is the happiest place in the UK according to a recent survey by the ONS. Is there a link with the exceptional freshwater biodiversity levels we found during our work in the Upper Lough Erne region, part of Co. Fermanagh? Our Lake BESS work is only a preliminary step towards answering such fundamental question: a whole new research agenda lies ahead of us to better understand the value of nature and ecosystems in what is often referred to as coupled human-environment systems.