Shifts in shredder communities and leaf breakdown along a disrupted stream continuum

AbstractStream ecosystem functions are predicted to vary longitudinally along a stream network as a result of changes in physical and biotic processes. Conversion by headwater communities of allochthonous materials, such as leaves, into readily available sources of energy is an essential process for maintenance of downstream communities. We investigated how location along a stream continuum, the presence of a dam, and leaf type affected leaf breakdown. We placed yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), and white oak (Quercus alba) leaf packs in Sims Creek (North Carolina, USA), at a 1st-order site, a 2nd-order site above a dam, and a 2nd-order site immediately below this dam. Leaf breakdown rates of all species were slower at the above-dam than at the headwater site, and breakdown rates for birch and maple were lower at the below- than the above-dam site. Detritivore composition and abundance differed among sites. Leaf packs had lower detritivore abundance at the below- than the...