Schlacher Thomas A, Carracher Lucy K, Porch Nicholas, Connolly Rod M, Olds Andrew D, Gilby Ben L, Ekanayake Kasun B, Maslo Brooke, Weston Michael A
School of Science and Engineering, The University of the Sunshine Coast, Q-4558, Maroochydore, Australia.
Centre for Integrative Ecology, School of Life and Environmental, Deakin University, Geelong, Australia.
PLoS One. 2016 Aug 26;11(8):e0161905. doi: 10.1371/journal.pone.0161905. eCollection 2016.
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.
许多在海洋海滩和沿海沙丘繁殖的鸟类受到全球保护关注。这些物种大多依赖无脊椎动物（如昆虫、小型甲壳类动物）作为不可替代的食物来源，主要在沙丘附近海滩上部的滨线周围觅食。沙滩也是人类休闲的主要场所，这通过负面的践踏效应影响了这些食物资源。我们在澳大利亚维多利亚州一个温带海滩上进行了一项对照实验，量化了在一系列行人交通强度（每平方米高达56步）下急性践踏对上岸无脊椎动物群落的影响。践踏显著改变了群落结构（物种组成和密度），并与无脊椎动物丰度和物种丰富度的显著下降相关。践踏对稀有物种的影响最强。在重度踩踏的区域，沙滩跳虾（双足纲）的数量减半，而沙滩跳虾是在此海滩繁殖的濒危凤头鸻的主要猎物。与践踏持续产生的强烈影响形成对比的是，自然栖息地属性（如沉积物粒度、紧实度）作为预测因素的影响力要小得多。如果正如这里所表明的，践踏对无脊椎动物的急性抑制在海滩上更为普遍，那么这可能对依赖这些无脊椎动物的濒危脊椎动物构成重大威胁。这就需要重新思考保护行动，考虑对食物资源进行积极管理，可能通过增加漂浮植物或直接向繁殖领地补充猎物来实现。
