Detrital shadows: estuarine food web connectivity depends on fluvial influence and consumer feeding mode

We measured the influence of landscape setting on estuarine food web connectivity in five macrotidal Pacific Northwest estuaries across a gradient of freshwater influence. We used stable isotopes (δ13C, δ15N, δ34S) in combination with a Bayesian mixing model to trace primary producer contributions to suspension- and deposit-feeding bivalve consumers (Mytilus trossulus and Macoma nasuta) transplanted into three estuarine vegetation zones: emergent marsh, mudflat, Japanese eelgrass (Zostera japonica), and native eelgrass (Zostera marina). Fluvial discharge and consumer feeding mode strongly influenced the strength and spatial scale of observed food web linkages, while season played a secondary role. Mussels displayed strong cross-ecosystem connectivity in all estuaries, with decreasing marine influence in the more fluvial estuaries. Mussel diets indicated homogenization of detrital sources within the water column of each estuary. In contrast, the diets of benthic deposit-feeding clams ind...

本研究针对太平洋西北岸五大大潮差河口，沿淡水影响梯度探究了景观背景对河口食物网连通性的调控效应。研究采用稳定同位素（stable isotopes，δ¹³C、δ¹⁵N、δ³⁴S）结合贝叶斯混合模型（Bayesian mixing model），追踪了初级生产者（primary producer）对移植至三类河口植被带——挺水沼泽、潮间带泥滩、日本鳗草（Zostera japonica）与本土大叶藻（Zostera marina）——的滤食性与沉积食性双壳类（bivalve）消费者（褐贻贝Mytilus trossulus与鼻蛤Macoma nasuta）的营养贡献。河流径流量与消费者摄食模式对观测到的食物网关联强度与空间尺度具有显著影响，而季节仅发挥次要作用。褐贻贝在所有受试河口均表现出较强的跨生态系统连通性，且在淡水影响更强的河口，其受海洋影响的程度呈下降趋势；褐贻贝的食性特征表明，各河口水柱内的碎屑源趋于均质化。与之相反，底栖沉积食性蛤类的食性……