Alien invaders threaten native wildlife

I'd like to echo the warning given in this piece. For a number of years I've been attempting to control both crassula and myriophyllum in a small pond; the latter had completely filled the pond from side-to-side and top-to-bottom. We tried chemicals, black plastic and finally dredging, which removed most of the vegetative mass. We are now having to hand-pull both species on a monthly basis with no long-term hope of success.

I`ve just had a walk round Oldham market,I could have easily been in Calcutta, alien invaders eh, I think we are fighting a losing battle there. I believe scorpions are now thriving in Hull docks, grey squirrels have all but wiped out the indiginous red, signal crayfish are on a rampage, mitten crab are eating away the Thames embankment, Himalayan Balsa and Giant Hogweed all over the show, rodedendrums flourishing in all our parklands and now the Eastern Europeans looking for housing and work.

Easy solution .....

get the Eastern Europeans out to Hull docks picking up scorpions!

Some of the invaders Monk mentioned have been around so long that we've forgotten that they are "introduced" species and now regard them as native. How far do we go have to go back to decide what is native and what is not? 100 years? 200? 500?

Is it not all just part of what's gone on for many thousands of years all over the world? Species introduced. Species extinct. Survival of the fittest? Man has conquered, gone to all the farthest flung corners of our world, and each time has made changes to their environment. Some good, some bad, but nature adapts. Nature will always find a balance, if we give it a chance.

Can any country really say what their true indingenous species are and which are alien invaders?

I agree with The Monk - hogweed, balsam, mitten crabs, scorpions, squirrels, carp. All introduced - all should be eradicated ;>)

introduced" species and now regard them as native. How far do we go have to go back to decide what is native and what is not? 100 years? 200? 500?

Theres a little bit more to it than that Janet, in the UK we have indiginous species, endemic species and introduced species, time, death, birth, migration and immigration are of course part of the ecological societal equation, the mechanistic forces that drive life if you like. By survival of the fittest you will be referring to the ecological niche which all species fit into in order that they can compete and survive, although survival of the fittest also applies to the genetic fitness (part of the same thing really), its ability to radiate and produce fit gene pools which can adapt over time whitin that particular environment. It all a bit too complicated to explain fully here of course, but introduced species can be a problem because they havent had time to naturalise and may have no natural preditors, they may also suddenly complete for the same ecological nitch as endemic and indiginous species, this can create many problems of ecological inbalance, ecological disasters in many cases (rabbits in Western Australia). time scales for genetic gene pools is far greater than 500 years, we are talking geological time scales for evolutionary adaption, or at least certainly in the upper reaches of the pyramid.



Can any country really say what their true indingenous species are and which are alien invaders?

It is sciences wording which designates what is indiginous and what is endemic, we know what has been introduced, we put time periods and taxonic names on flora and fauna to help us understand the world and how we consider these things developed under our present understanding. The best way I can answer your last question is by asking you another question Janet

what is a weed?

My answer would be its a plant in the wrong place!

NO that's just your opinion,wrong place for who or what?.

Most people don't like nettles in their garden, that doesn't mean to say that they're not indigenous(sp?) does it?

No Nettles in my jungle,i mean garden,maybe they can't compete with the Dandelions,Bindweed and Brambles. That reminds me,i'm sure i've got a boat down there somewhere.

Only good use I've known for nettles is in the wrapping of Yarg cheese down in sunny Cornwall, and their nettle cordial! I was half-expecting to have a tingly mouth (I'm a big fan of chilli!) but, it was quite refreshing!

NO that's just your opinion,wrong place for who or what?.

yes thats quite right Trish and thats what I was saying you see, its man who determines these things, we have not taxonic name for weed, its not science and has no latin name of course


Most people don't like nettles in their garden, that doesn't mean to say that they're not indigenous(sp?) does it?

no, not at all Milo, the problem from the gardeners point of view though is nettles complete with his garden environment sps and wipe out his own introduced species, this of course only effects his garden, the problem occurred when we look at the bigger picture though, an introduced specie effecting an island as large as ours, effects the ecological balance and ultimately the food chain, its realatively easy to control a small garden, much more difficult to control a country the size of the UK. Examples of this are evident in the more recently introduced carp, they are the same specie as our original introduced carp, but the longer termed stocking has become naturalised over time and space and as such have developed certain bacterial resistances peculiar to this environemnt, semi endemic if its better to understand that way, then we introduce non-naturalised varieties and the immunity of the naturalised sps conflicts and in many cases deteriorates. A classic example in humans was on one of the Scottish Westerm Isle, islanders lived for many years on this particulalr island and then suddenlyt had to move to the mainland to live, many of them died within months of migrating through catching simple viruses which their immunical system has simply no had time to evolve against.

No Nettles in my jungle,i mean garden,maybe they can't compete with the Dandelions,Bindweed and Brambles. That reminds me,i'm sure i've got a boat down there somewhere.

yes, mines pretty much the same Trish, nettles like all plants need the right environment (haha so do boats), you provide the right soil profile and lack of predatory sps, the nettle will thrive and they are pretty resiliant plants, the other sps in your garden will be dominant at the moment, but this will be a constant battle, arms race if you like, and your garden will be changing all the time until one dominant specie takes over, once another more dominant specie is introduced, change will occurr again.

Only good use I've known for nettles is in the wrapping of Yarg cheese down in sunny Cornwall, and their nettle cordial! I was half-expecting to have a tingly mouth (I'm a big fan of chilli!) but, it was quite refreshing!

I`ve seen them do that Milo, I find it quite amazing, nettles though contain nutritious and medicineral minerals of course.

Just out of interest has anyone studied island biogeography and the separation of species by space and time?

An island of course can be something separated by a change in environemantal conditions, or isolated from surrounding environments, which has no usable corridors to allow fauna and flora to move,ie a peice of land surrounded by water, an oasis in the middle of a desert, a garden in the middle of a concrete jungle, once flora and fauna becomes isolated from its original niche it can evolve differently to suit its new environment, this is one way speciation can occur, Darwens finches are a classic example of this, one specie radiating and adapting to suit a limited enviroment in order that all available niches can be utilised.

Yes. lake Victoria chiclids (Haplochromis sp) being another classic example.

yes I read about those Stuart, chiclids adapt very well to new environments, we had some introduced into the St Helens canal which survied and proliferated extremely well for many years.

If anyone has a genuine interest in ecology I can fully recommend "Ecology, Individuals, populations and communities" by Begon, Harper and Townsend (1986)Blackwell Scientific Publications, regularly updated

"If anyone has a genuine interest in ecology I can fully recommend "Ecology, Individuals, populations and communities" by Begon, Harper and Townsend (1986)Blackwell Scientific Publications, regularly updated"


Along with "Shredding For Beginners" ??

Shredding For Beginners, now your talking Ed, you know I learned today that many jazz players play loads of fancy 9ths, 11ths sus plus whatever ect and then rip the back out of pentatonic riffs over the top and call it fusion. interesting eh mate

I don't think there's any point getting bogged down in defining what's alien and what isn't. The plant species in question have the ability to out-compete all other spp. and so ruin a fishery.

Whilst we're on the topic perhaps we should look at our own house, after all anglers have long been introducing fish species into places they shouldn't be. One of the other ponds I manage used to be crystal clear and rich in aquatic plants and insects - and then someone put in some small carp. Now it's just a turbed puddle full of stunted carp. In this case I'd welcome a little human predation for the pot.

Ane here was me thinking the topic was about Eastern Europeans...........