Animals often shape environmental microbial communities, which can in turn influence animal gut microbiomes. Invasive species in critical habitats may reduce grazing pressure from native species and shift microbial communities. The landlocked coastal ponds, pools, and caves that make up the Hawaiian anchialine ecosystem support an endemic shrimp (Halocaridina rubra) that grazes on diverse benthic microbial communities, including orange cyanobacterial-bacterial crusts and green algal mats. Here, we asked how shrimp: (1) shape the abundance and composition of microbial communities, (2) respond to invasive fishes, and (3) whether their gut microbiomes are affected by environmental microbial communities. We demonstrate that ecologically relevant levels of shrimp grazing significantly reduce epilithon biomass. Shrimp grazed readily and grew well on both orange crusts and green mat communities. However, individuals from orange crusts were larger, despite crusts having reduced concentrations of key fatty acids. DNA profiling revealed shrimp harbor a resident gut microbiome distinct from the environment, which is relatively simple and stable across space (including habitats with different microbial communities) and time (between wild-caught individuals and those maintained in the laboratory for >2 yr). DNA profiling also suggests shrimp grazing alters environmental microbial community composition, possibly through selective consumption and/or physical interactions. While this work suggests grazing by endemic shrimp plays a key role in shaping microbial communities in the Hawaiian anchialine ecosystem, the hypothesized drastic ecological shifts resulting from invasive fishes may be an oversimplification as shrimp may largely avoid predation. Moreover, environmental microbial communities may have little influence on shrimp gut microbiomes.

中文翻译：

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一种地方性的 atyid 虾放牧控制夏威夷 anchialine 生态系统中的微生物群落

动物经常塑造环境微生物群落，进而影响动物肠道微生物群落。关键栖息地的入侵物种可能会减少本地物种的放牧压力并改变微生物群落。构成夏威夷 anchialine 生态系统的内陆沿​​海池塘、水池和洞穴支持着一种特有的虾（Halocaridina rubra) 以不同的底栖微生物群落为食，包括橙色蓝藻细菌外壳和绿藻垫。在这里，我们询问虾如何：（1）塑造微生物群落的丰度和组成，（2）对入侵鱼类作出反应，以及（3）它们的肠道微生物群落是否受到环境微生物群落的影响。我们证明了生态相关水平的虾放牧显着降低了表皮生生物量。虾很容易吃草，在橙色外壳和绿色垫子群落上生长良好。然而，来自橙色结壳的个体更大，尽管结壳的关键脂肪酸浓度降低。DNA 分析显示虾拥有与环境不同的常驻肠道微生物组，这在空间（包括具有不同微生物群落的栖息地）和时间（在野生捕获的个体和在实验室中维持 > 2 年的个体之间）相对简单和稳定。DNA 分析还表明，虾放牧改变了环境微生物群落组成，可能通过选择性消耗和/或物理相互作用。虽然这项工作表明，地方性虾的放牧在塑造夏威夷 anchialine 生态系统中的微生物群落中起着关键作用，但假设的由入侵鱼类引起的剧烈生态变化可能过于简单化，因为虾可能在很大程度上避免了捕食。此外，环境微生物群落可能对虾肠道微生物群落影响不大。DNA 分析还表明，虾放牧改变了环境微生物群落组成，可能通过选择性消耗和/或物理相互作用。虽然这项工作表明，地方性虾的放牧在塑造夏威夷 anchialine 生态系统中的微生物群落中起着关键作用，但假设的由入侵鱼类引起的剧烈生态变化可能过于简单化，因为虾可能在很大程度上避免了捕食。此外，环境微生物群落可能对虾肠道微生物群落影响不大。DNA 分析还表明，虾放牧改变了环境微生物群落组成，可能通过选择性消耗和/或物理相互作用。虽然这项工作表明，地方性虾的放牧在塑造夏威夷 anchialine 生态系统中的微生物群落中起着关键作用，但假设的由入侵鱼类引起的剧烈生态变化可能过于简单化，因为虾可能在很大程度上避免了捕食。此外，环境微生物群落可能对虾肠道微生物群落影响不大。由入侵鱼类导致的假设的剧烈生态变化可能过于简单化，因为虾可能在很大程度上避免捕食。此外，环境微生物群落可能对虾肠道微生物群落影响不大。由入侵鱼类导致的假设的剧烈生态变化可能过于简单化，因为虾可能在很大程度上避免捕食。此外，环境微生物群落可能对虾肠道微生物群落影响不大。