Study

Compensatory growth responses of Potamogeton pectinatus to foraging by migrating trumpeter swans in spring stop over areas

  • Published source details LaMontagne J.M., Jackson L.J. & Barclay R.M.R. (2003) Compensatory growth responses of Potamogeton pectinatus to foraging by migrating trumpeter swans in spring stop over areas. Aquatic Botany, 76, 235-244.

Summary

Action: Exclude wild vertebrates

A replicated, paired, controlled study in 1999 in two ponds in Alberta, Canada (LaMontagne et al. 2003) found that excluding migrating trumpeter swans Cygnus buccinator had no significant effect on the abundance of the dominant submerged macrophyte species. In two of two ponds, the abundance of sago pondweed Potamogeton pectinatus was statistically similar in both plots from which swans were excluded, and plots left open to swan grazing. This was true for both above-ground biomass (exclosures: 48–96 g/m2; open: 51–157 g/m2) and shoot density (exclosures: 22–284 shoots/m2; exclosures: 57–122 shoots/m2). In one pond, the density of small shoots (<1.0 g) was significantly greater in exclosures (18 shoots/0.09 m2) than open areas (7 shoots/0.09 m2). Methods: Five temporary swan exclosures (60 x 60 cm; 0.2 cm plastic mesh) were set up in each of two ponds. The exclosures were set up in spring 1999 before trumpeter swans migrated into the area, the removed in summer after the swans had moved out of the area. Macrophytes were cut from 30 x 30 cm quadrats in August 1999: 3–5 quadrats/pond in the (former) exclosures, and 5 quadrats/pond in adjacent macrophyte patches open to goose grazing. Biomass was dried before weighing.

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust