WTT Blog - Tagged with invasive non native species

Plant invasions and trout rations: the sequel

Posted on January 07, 2019

Plant invasions and trout rations: the sequel

It's a great pleasure to welcome back Alex Seeney to the WTT Blog. Just over 18 months ago, he was one of the first of the early career researchers to contribute a post (The riparian invasion: salmonid friend or foe?) about their ongoing science. Well, Alex is now Dr Alex (congratulations) and has returned with an update which I have been eager to see. I well remember some work by Sally Hladyz on how invasive rhododendron can severely impair stream functioning; her work demonstrated that the plant supplied poor leaf litter quality and blocked out the sun, subsequently depressing decomposition rates and algal production rates meaning less food for inverts. Do balsam and knotweed exert similar influences? Over to (Dr) Alex.....

Invasions by non-native species are reported as one of the greatest threats to global biodiversity, and the invasion of riparian ecosystems by invasive non-native plants (INNP hereafter) presents a common and difficult challenge for river and fishery managers.

Stocked fish or native invader?

Posted on August 17, 2017

Anyone with an interest in rivers or lakes and the life within them, be it from a conservation, management, or angling perspective (and of course those three are not mutually exclusive) will be aware of invasive non-native species (INNS), the impacts they may cause in certain situations, and the importance of biosecurity. Ecologists with a particular interest in invaders differentiate between non-native (i.e. those species introduced beyond their original distribution range, a pertinent example being pink salmon) and native invaders (referring to species that add to existing or establish new populations within their native range). The artificial stocking of salmonids into waterbodies is one such example of the deliberate introduction of native invaders, to allegedly enhance commercial and recreational fisheries, as well as for conservation purposes in some instances. The evidence accruing as to the benefits of this approach makes interesting reading.

In 2016, Buoro and colleagues used the global-scale introductions of salmon and trout as a robust biological model (i.e. lots of studies with plenty of data to analyse) to investigate the ecological effects of changing intraspecific (within species; e.g. stocking farmed brown trout in to rivers containing wild brown trout populations) and interspecific (between species; e.g. stocking rainbow trout into lakes with Arctic char) diversity. The enormity of the dataset collated from the literature allowed them to look at various levels of organisation which introduces a lot of complexity. However, the take home message was that, overall, introduction of native invaders resulted in stronger ecological effects than those associated with changes in interspecific diversity caused by non-native species.

The riparian invasion: salmonid friend or foe?

Posted on May 23, 2017

The riparian invasion: salmonid friend or foe?

'Tis the season to bash balsam - if you don't know how to, check out the definitive guide from WTT chum, Theo Pike, for guidance! Timely then for a new blog focussing on invasive plants. Alex Seeney from the Centre for River Ecosystem Science (CRESS) at the University of Stirling, is battling with balsam and knotweed from a more academic angle, and below gives an overview of some his research to date. This valuable work is supported by Scottish Natural Heritage.

Some of the most diverse and complex habitat types in aquatic systems are found at the interface between terrestrial and aquatic communities – the riparian zone. These diverse, dynamic systems provide an ecologically important buffer between land and water, and as such they are of particular importance to the health and quality of the waterways they border.