• How mountain streams signal climate chan

    From ScienceDaily@1:317/3 to All on Thu Apr 7 22:30:40 2022
    How mountain streams signal climate change
    Invertebrates as indicators of ecosystem health

    Date:
    April 7, 2022
    Source:
    University of California - Riverside
    Summary:
    A new tool can better assess an important but overlooked indicator
    of global warming: the variety of bugs, worms, and snails living
    in high mountain streams.



    FULL STORY ==========================================================================
    A new tool can better assess an important but overlooked indicator of
    global warming: the variety of bugs, worms, and snails living in high
    mountain streams.


    ========================================================================== Water-based invertebrates are especially vulnerable when the climate
    swings from historic droughts to massive floods. Because they serve as
    food for other forms of alpine life, such as birds, bats, frogs and fish, ecologists worry about the insects' ability to thrive.

    Understanding how these small creatures are affected by climate change
    requires understanding where we ought to find them. Yet, classic
    ecological theories did not account for what a team of UC Riverside
    ecologists and their UC collaborators found on a recent survey of aquatic
    life in California's Sierra Nevada.

    As a step toward protecting them, the team applied a new theory for
    predicting biodiversity to high mountain streams. That theory, and the
    results of the field survey that gave rise to it, are now detailed in
    an article in the journal Ecological Monographs.

    "We've come up with new ways of thinking about biodiversity in high
    mountain Sierra streams, because the old ways weren't successful for
    us," said Kurt Anderson, associate professor of evolution and ecology,
    and article co-author.

    "Classic theories of stream ecology weren't developed in the Sierras,
    so we are adapting a new set of ideas to better explain what we're seeing
    up there," Anderson said.



    ==========================================================================
    One such classic theory is the River Continuum Concept, which discusses
    how stream ecosystems function as they move from the stream sources down
    to bigger, more open rivers. According to the continuum concept, there
    should be a smooth gradient of change from high to low elevations. The
    team surveyed for stream biodiversity along a gradient, to test concepts
    like this one.

    "We saw a change, but only partially and not for the reasons the theory
    said we should," Anderson said. "For example, we found that lakes tended
    to interrupt the smooth change we were supposed to have seen." The UCR
    team observed that diversity of invertebrates generally increased in
    waters headed down and was lowest in steams situated immediately below
    lakes.

    "We believe the lakes may have a disconnecting effect and are causing the downstream waterways to have to start over again in building diversity,"
    said Matthew Green, UCR ecologist and first author on the new paper.

    The team also found a great variety of life forms in cold, isolated
    streams high up in the headwaters. Despite the general trend toward
    an increase of diversity moving downstream, sometimes, differences in
    species among isolated headwaters could be as great as those between
    upstream and downstream.

    "These are the aquatic life forms that are at the edge of the precipice of climate change," said Dave Herbst, a researcher from the Sierra Nevada
    Aquatic Research Laboratory, a UC Natural Reserve, and co-author on
    the paper.

    The areas just below lakes were dominated by only a few species of invertebrates and insects with the ability to filter food particles. Other sites with mixed food sources had more species present.

    The team recommends that interconnected systems of flowing water be
    protected from diversions, and from habitat damage caused by unrestrained
    land development. When waters are allowed to flow as they should, the
    number of resources available to creatures that live in them support
    higher diversity.

    "That is what will permit these small, but crucially important life forms
    to thrive," Anderson said. "Where intact habitats have been compromised, restoration efforts may be key to providing the entire ecosystem with resilience to the coming adversities of climate change."

    ========================================================================== Story Source: Materials provided by
    University_of_California_-_Riverside. Original written by Jules
    Bernstein. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Matthew D. Green, Kurt E. Anderson, David B. Herbst, Marko
    Spasojevic.

    Rethinking biodiversity patterns and processes in stream ecosystems.

    Ecological Monographs, 2022; DOI: 10.1002/ecm.1520 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220407101015.htm

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