The early shorebird will catch fewer invertebrates on trampled sandy beaches

Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories

Steam unit and gas turbine power station reliable control for network black-start-up

The aim of the paper is the analysis of the dynamic behavior of a thermoelectric power plant equipped with a steam unit and a gas turbine during the early phases ofa black-start-up maneuver for the network restoration. Models of different detail level for two production units and the relevant regulators have been implemented into two simulation tools. The paper contains the description of the different models, identifies the cases in which the two simulation codes predict similar results and presents the main characteristics, as well as the fields of application of the two codes. As an example, the paper presents also an application of simulators developed for the planning and the preparation of island operation and start up field tests of a power station

Changes in abundance (left column) and species richness (right column) of surface-active invertebrates in relation to experimental trampling on the upper part of an ocean-exposed beach (statistics inside top panels are for linear regression analysis).

<p>Bottom row illustrates trampling effect sizes (indexed as the slope (+/- se) of linear regressions of abundance/species richness vs the number of steps) for logarithmic abundance classes of species.</p

Summary of similarity percentage analysis (SIMPER) listing species that cumulatively contributed 90% to the dissimilarity (Bray Curtis) in community structure between trampled and un-trampled plots.

<p>Summary of similarity percentage analysis (SIMPER) listing species that cumulatively contributed 90% to the dissimilarity (Bray Curtis) in community structure between trampled and un-trampled plots.</p

Contributions of variables in models relating three metrics of invertebrate assemblages (assemblage structure, total catch of individuals, species richness) to experimental trampling, key habitat attributes (wrack cover, sediment compactness, grain size) and the time pitfall traps were deployed during the experiments.

<p>Variable contributions are assessed in two complementary ways: i) a multi-model inference approach using cumulative weights, w+(j), and ii) the proportion of variance explained in distance-based linear models.</p

The Early Shorebird Will Catch Fewer Invertebrates on Trampled Sandy Beaches

<div><p>Many species of birds breeding on ocean beaches and in coastal dunes are of global conservation concern. Most of these species rely on invertebrates (e.g. insects, small crustaceans) as an irreplaceable food source, foraging primarily around the strandline on the upper beach near the dunes. Sandy beaches are also prime sites for human recreation, which impacts these food resources via negative trampling effects. We quantified acute trampling impacts on assemblages of upper shore invertebrates in a controlled experiment over a range of foot traffic intensities (up to 56 steps per square metre) on a temperate beach in Victoria, Australia. Trampling significantly altered assemblage structure (species composition and density) and was correlated with significant declines in invertebrate abundance and species richness. Trampling effects were strongest for rare species. In heavily trafficked plots the abundance of sand hoppers (Amphipoda), a principal prey item of threatened Hooded Plovers breeding on this beach, was halved. In contrast to the consistently strong effects of trampling, natural habitat attributes (e.g. sediment grain size, compactness) were much less influential predictors. If acute suppression of invertebrates caused by trampling, as demonstrated here, is more widespread on beaches it may constitute a significant threat to endangered vertebrates reliant on these invertebrates. This calls for a re-thinking of conservation actions by considering active management of food resources, possibly through enhancement of wrack or direct augmentation of prey items to breeding territories.</p></div