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    Earthworm Jim – Hero?
    By Robert H Olley | March 2nd 2012 07:16 AM | 6 comments | Print | E-mail | Track Comments
    About Robert H

    Until recently, I worked in the Polymer Physics Group of the Physics Department at the University of Reading.

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    Ever since the publication of The Formation of Vegetable Mould through the Action of Worms with Observations of Their Habits by Charles Darwin, the European Earthworm Lumbricus terrestris has had a pretty good press. 

    Darwin may not have been the first to appreciate their value: Aristotle called them “the intestines of the soil” [1].  And very valuable they are, this side of the Pond.  Though they are not getting it all their own way.  According to Wikipedia:

    In parts of Europe, notably the Atlantic fringe of northwestern Europe, they are now locally endangered due to predation by the accidentally introduced New Zealand flatworm and the Australian flatworm.  These predators are very efficient earthworm eaters, being able to survive for lengthy periods with no food, so still persist even when their prey has dropped to unsustainably low populations. In some areas, this is having a seriously adverse effect on the soil structure and quality. The soil aeration and organic material mixing previously done by the earthworms has ceased in some areas.

    However, their reputation has suffered a bit of a bashing in parts of North America, where they are found not to do so well in agricultural land.

    L. terrestris is considered invasive in the north central United States. It does not do well in tilled fields because of a lack of nutrients, pesticide exposure, and physical injuries from farm equipment.

    and are harming forest ecosytems:

    The species, however, thrives in fence rows and woodlots and can lead to reductions in native herbaceous and tree regrowth. 

    Now another charge is laid at its door.  The Smithsonian Migratory Bird Center tells us:

    Earthworms to blame for decline of Ovenbirds in northern Midwest forests, study reveals


    Minnesota and Wisconsin appear to have lost any worms they may have had during the prolonged and severe glaciations which affected North America.  Since then, fungal systems have developed in the maple-and-basswood forests which slowly decompose the thick layers of leaf litter.  These have provided good soil for a variety of herbaceous plants, among which the nests of the Ovenbird can be well hidden.

    Along comes the earthworm, brought to those remote forests by loggers and fishermen, and rapidly eats and digests that leaf litter.  And now the forest floor is largely bare soil, and the few plants that grow there do little to hide the nest.  Also, the number of insects declines, so the bird requires a larger territory, leading to smaller populations. 

    (from the Smithsonian article)

    However:

    The researchers found no decline in three other species of ground-nesting birds included in their survey – the Hermit Thrush, Black-and-White Warbler and Veery – nor did they find a correlation between Ovenbird decline and invasive worms in other forest types, such as red oak, paper birch and aspen.

    So I ask  – why is the combination of ovenbird, maple-basswood and earthworm so problematic?

    [1] http://www.naturenorth.com/fall/ncrawler/ncrawler2.html


     

    Comments

    Bonny Bonobo alias Brat
    Interesting article and links Robert, except that I really wish that I hadn't read that :-
    Night crawlers are the biggest worms around here, but they pale in comparison to Australia's giant earth worm that may exceed 3 metres in length! 
    Definitely no more walking across the lawn to my swimming pool barefoot at night! I knew that worms often surfaced when it rained but I didn't know that sexually mature worms surfaced every night and the idea of a 3 metre long, sexually mature worm surfacing at any time doesn't even bear thinking about!
    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine
    Thor Russell
    Haha have you read "Dune"? Hope you're not planning in going to the Aus desert anytime soon then.
    Thor Russell
    Bonny Bonobo alias Brat
    Australia is full of scary creatures most of which I have gradually come to terms with, deadly snakes and spiders, even 3 metre long sexually mature worms surfacing on my lawn at night but I don't think I could cope with the scariest creature of all, Dr SSSSSSSSSascha Vongehr who just said that he is planning to retire in nearby Nimbin unless there are already too many Germans in Australia, which of course there could never be! Time to return to England maybe?
    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine
    A vision of 3 meter long sexually mature Sascha surfacing on your lawn every night and shaking the air with accusations of crackpottery just had me in stitches!.. No, seriously, Sascha is brilliant... One just has to learn to appreciate him...
    Also, I'm wondering whether them 3 meter sexually mature worms are any good as fishbait? Do fishermen have to chop them up? Or are they just plain useless?

    The Giant Gippsland worm is listed as 'vulnerable' and is not used as fishbait (even though the idea is rather appealing). They are usually found to be 1-2 meters in length, although a few three meter long specimens have been found.

    Bonny Bonobo alias Brat
    Probably great fish bait for a great white shark which is another rather scary creature often found in Australia. Before we emigrated to Australia I remember opening an encyclopedia that listed the world's most dangerous creatures and half of them resided in or around Australia.
    My latest forum article 'Australian Researchers Discover Potential Blue Green Algae Cause & Treatment of Motor Neuron Disease (MND)&(ALS)' Parkinsons's and Alzheimer's can be found at http://www.science20.com/forums/medicine