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. https://doi.org/10.1002/rra.3839
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.
Lake BESS research on the importance of water connectivity for healthy shallow lakes in the Upper Lough Erne, Northern Ireland and in the Broads, England, was presented to the Broads stakeholders yesterday. The event hosted by the Broads Authority.
This was an opportunity to discuss how our research will be translated into actions in the Broads where multiple major restoration projects are happening.
Carl Sayer gave an inspirational talk comparing the lake ecology and aquatic vegetation of the Upper Lough Erne region and The Broads.
We are organising two events in Northern Ireland to share our results with local stakeholders.
A workshop Tuesday November 24th 2015, from 6:45pm at Waterway Ireland HQ, Enniskillen, Co Fermanagh.
A lunch time seminar Wednesday November 25th 2015, 12.30 – 13.30, NIEA HQ, Belfast.
For both events there will be a presentation of our results and plenty of time for Q&As and discussion.
We would like to share our research findings with local stakeholders working on and around Upper Lough Erne’s satellite lakes so our research can be useful to those most concerned.
Please let us know if you would like to come by email: ambroise.baker [ at] ucl.ac.uk or with a message at the bottom of this page; and do not hesitate to forward this invitation to anyone you think could be interested.
Lake BESS is looking forward to going to the 100th Ecological Society of America (ESA) annual meeting in Baltimore! We have a talk scheduled Friday August 14th 2015 during the session “COS 142: Habitat Structure, Fragmentation, Connectivity”.
This is a very exciting opportunity to present our work asking the question: Does connectivity increase resilience of biodiversity against eutrophication in networks of shallow lakes? Our talk will be the only one focusing on freshwater in an collection of oral papers otherwise dedicated to ecological connectivity.
We will be using aquatic plant surveys conducted between 1983 and 2014 in our two study areas: The Broads, England, UK, and the Upper Lough Erne area, Northern Ireland, UK, and we will identify the relative importance of:
connectivity between lakes,
local water chemistry
and other factors
to explain the aquatic vegetation patters in the two lake districts during two time periods.
The comprehensive programme of the conference is available here online program and our abstract can be read there.
This post highlights another project Carl Sayer, Lake BESS’s principal investigator, is involved with: The Norfolk Pond Project. Ponds sustain a major share of freshwater diversity yet they have been subjected to near-systematic destruction, pollution or abandonment since WWII.
After years of neglect by conservation and research compared to other habitats, ponds are finally being incorporated into UK aquatic conservation approaches and the Norfolk Pond Project is an excellent example:
“Norfolk holds more ponds than any other English county with an estimated 23,000 ponds present. Most of these ponds are located in farmland, and have their origins as marl or clay pits and in some cases livestock-watering ponds dug in the 17th to 19th centuries. “
“In addition the Brecks, west Norfolk and sites north of Norwich are home to some of the most amazingly diverse ancient ponds in the UK, pingos – ponds that occupy ice depressions formed during the last great ice age. A great place to see pingos is at Norfolk Wildlife Trust’s nature reserve, Thompson Common.”
Last August, I was fortunate to be shown several ponds near Catcliffe and Treeton, East of Sheffield, UK, by Bob Croxton, form Sorby Natural History Society. The area is full of history and is a fascinating example of nature recovering following industrialisation.For instance, one of the ponds visited was formed in a lost piece of land amongst spoil heaps and three railway line! At this site Persicaria maculata and Nymphoides peltata were in full bloom (see picture) and two Potamogeton species were observed, now confirmed as P. pectinatus and P. pusillus. However only one shore was prospected and other nice aquatic plants are likely to be present in the rest of the pond.
On the whole, too many of the water bodies in the area were absolutely dominated by Elodea nuttallii, an invasive species that colonised the UK from the 1970s. It’s phenomenal spread in Britain and Ireland is summarised in a paper by Simpson that can be read from the BSBI archives. It remains unclear whether this spread has caused arm to aquatic biodiversity or whether it was simply facilitated by degraded habitats.
We’re just back from our very successful field work around the Upper Lough Erne, Co. Fermanagh, Northern Ireland. We managed to survey nearly 20 satellite loughs for aquatic plants, water chemistry and bryozoans (see this previous post).
The help we received from volunteers and project partners was absolutely tremendous! Over the two week we have been a dozen of us actively involved in this research campaign. We’d particularly like to thank Hannah, Robert, Tim and Stephen for joining our team at this occasion and also all the land owners who were kind enough to grant us access to the lakes we had targeted.
Battling through reed beds to get onto some of the lough with our boats was one of the striking aspects of this field work! But it was worth the effort and the diversity of aquatic plant observed over the two week is very impressive. For instance we have sightings for at least ten different Potamogeton species (see this previous post), an extremely good score!
We’ll post more picture and reports from this field work in the coming weeks.
The islands of Britain and Ireland have over 40 species or hybrids of pondweeds (genus Potamogeton). This diversity in pondweed is one of the highest in Europe with most European species being represented. Unfortunately local diversity and abundance of pondweeds have declined over the 20th Century, as a result of habitat destruction and pollution. The Upper Lough Erne region and The Broads are two areas of importance for the conservation of pondweed – but “what can we learn from these strongholds?” and “what measure could enhance their recovery nationally?” are questions we are trying to address part of the Lake BESS project. (Photo by Ambroise Baker: P. polygonifolius in full bloom).