Abstract Biotic and abiotic factors affecting survival and growth of recently settled infaunal bivalves not only determine the strength of 0-year class populations, but the structure and function of benthic soft-bottom communities. At mudflats across north-central Casco Bay, a 517 km2 embayment in the western Gulf of Maine, USA, intertidal sediments are generally acidic (pore water pH range = 7.09–7.85), which can negatively affect settlement and subsequent recruitment success of infaunal bivalves due directly or indirectly to shell dissolution. In addition, predation on bivalves by invasive green crabs, Carcinus maenas, and native consumers is intense in this region. Two commercially important infaunal bivalve species occupy these sediments (softshell clams, Mya arenaria; hard clams, Mercenaria mercenaria). Fisheries managers, legislators, and others have suggested that adding crushed shells of M. arenaria to the surface of mudflats can ameliorate negative effects of acidic sediment pore water through chemical buffering. We investigated the interactive effects of modifying surface sediments using crushed and weathered shells of Mya and predator exclusion on abundance and size of 0-year class individuals of these two bivalve species in large-scale plots (9.3 m2) and small-scale experimental units (EU; 182.4 cm2). Field experiments were conducted over three years (170–204 days yr−1; each initiated prior to spawning and continuing well after settlement had ceased). Shell hash in large-scale plots (mean particle size = 19.3 mm) varied across three levels (0, 0.63, and 1.27 kg m−2), and between 0 and 1.27 kg m−2 in EU where shell size varied from 1.9–19.3 mm. Small-scale experiments also used granite chips that, like crushed shells, increased habitat heterogeneity but did not buffer sediments. Density and size of both bivalve species at the end of most field trials were significantly greater in predator-exclusion treatments vs. controls independent of shell treatment. In all trials, neither Mya nor Mercenaria responded positively to the presence of shell additions. Fisheries managers should focus attention on mitigating effects due to predators instead of spreading shell hash to buffer intertidal sediments.

中文翻译：

---

贝壳散列和捕食者排除对美国缅因州两种潮间带双壳类动物 0 年级新成员的交互影响

摘要 影响最近定居的双壳类动物生存和生长的生物和非生物因素不仅决定了0年级种群的强度，而且决定了底栖软底群落的结构和功能。在美国缅因湾西部 517 平方公里的海湾卡斯科湾中北部的泥滩上，潮间带沉积物通常呈酸性（孔隙水 pH 值范围 = 7.09-7.85），这会对底栖双壳类动物的沉降和随后的补充成功产生负面影响直接或间接由于壳溶解。此外，在该地区，入侵的绿蟹、Carcinus maenas 和本地消费者对双壳类动物的捕食非常频繁。两种商业上重要的双壳类动物物种占据这些沉积物（软壳蛤，Mya arenaria；硬壳蛤，Mercenaria mercenaria）。渔业管理者、立法者、和其他人提出，在泥滩表面添加沙棘碎壳可以通过化学缓冲来改善酸性沉积物孔隙水的负面影响。我们研究了使用 Mya 的压碎和风化壳改性表层沉积物和捕食者排除对大型地块（9.3 平方米）和小型实验单位中这两种双壳类物种的 0 年级个体的丰度和大小的交互影响（欧盟；182.4 平方厘米）。田间试验进行了三年（每年 170-204 天；每次在产卵前开始并在沉降停止后继续进行）。大规模图中的壳散列（平均粒径 = 19.3 毫米）在三个级别（0、0.63 和 1.27 kg m-2）中变化，并且在欧盟的 0 和 1.27 kg m-2 之间变化，其中壳尺寸从 1.9- 19.3 毫米。小规模的实验还使用了花岗岩碎片，这些碎片就像碎贝壳一样，增加了栖息地的异质性，但不会缓冲沉积物。在大多数田间试验结束时，两种双壳类物种的密度和大小在捕食者排除处理中显着高于独立于壳处理的对照。在所有试验中，Mya 和 Mercenaria 都没有对壳添加物的存在做出积极响应。渔业管理者应将注意力集中在减轻捕食者造成的影响上，而不是散布贝壳哈希来缓冲潮间带沉积物。Mya 和 Mercenaria 都没有对壳添加物的存在做出积极响应。渔业管理者应将注意力集中在减轻捕食者造成的影响上，而不是散布贝壳哈希来缓冲潮间带沉积物。Mya 和 Mercenaria 都没有对壳添加物的存在做出积极响应。渔业管理者应将注意力集中在减轻捕食者造成的影响上，而不是散布贝壳哈希来缓冲潮间带沉积物。