ABSTRACT: Black mangroves Avicennia germinans are becoming increasingly common in coastal wetlands in the Gulf of Mexico (USA). As mangroves displace salt marsh vegetation, there may be consequences for associated wetland fauna. In a series of field studies, we compared prey refuge values between marsh and mangrove vegetation for a vertically migrating gastropod, the marsh periwinkle Littoraria irrorata. Littoraria were tethered to marsh grasses (Spartina alterniflora) or the aerial roots (pneumatophores) of Avicennia in arrays that fully crossed vegetation type (Spartina vs. Avicennia), tether height (base vs. canopy), and wetland location (edge vs. interior marsh platform). After 1 d, acute predation rates were twice as high on Littoraria tethered to the base of Spartina stems than on those tethered to pneumatophores, suggesting that mangroves provided superior refuge from benthic predators like blue crabs. In the canopy, Spartina reduced acute predation rates by 75%, indicating that marsh grasses may provide superior refuge from aerial predators (possibly wetland birds). After 7 d, the effect of vegetation type diminished, but Littoraria mortality was 2 times higher on the benthos than in the canopy. Links between vegetation type and predation intensity on this important basal consumer may have broader consequences for trophic dynamics in coastal wetlands that are experiencing mangrove encroachment.

中文翻译：

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沼泽和红树林植被对沼泽长春花 Littoraria irrorata 的捕食避难价值

摘要：黑色红树林Avicennia Germinans在墨西哥湾（美国）的沿海湿地中变得越来越普遍。随着红树林取代盐沼植被，可能会对相关的湿地动物群产生影响。在一系列实地研究中，我们比较了沼泽和红树林植被之间垂直迁移的腹足动物（沼泽长春花Littoraria irrorata）的猎物避难价值。Littoraria被拴在沼泽草（Spartina alterniflora）或Avicennia的气生根（pneumatophores）上，排列成完全交叉的植被类型（Spartina vs. Avicennia)、系绳高度（底座与树冠）和湿地位置（边缘与内部沼泽平台）。1 d 后，拴在Spartina茎基部的 Littoraria 的急性捕食率是拴在 pneumatophores 的那些的两倍，这表明红树林为蓝蟹等底栖捕食者提供了优越的避难所。在树冠中，Spartina将急性捕食率降低了 75%，这表明沼泽草可以为空中捕食者（可能是湿地鸟类）提供更好的避难所。7 d后，植被类型的影响减弱，但Littoraria底栖生物的死亡率是冠层的 2 倍。植被类型与这一重要基础消费者的捕食强度之间的联系可能对正在遭受红树林侵占的沿海湿地的营养动态产生更广泛的影响。