Floods are extreme weather events that can rapidly change water quality in receiving estuaries. The delivery of nutrients to the coastal zone via floods may stimulate productivity; however, in urban areas, the degradation of water quality and influx of contaminants can negatively affect inhabiting biota. Determining flood effects on inhabiting biota is important for informing catchment management practices. We investigated the body condition response of a commercially important prawn species, the brown tiger prawn Penaeus esculentus, to a large cyclone-driven flood in an urbanized subtropical coastal bay. Prawns were caught 10 days before the flood, 11 days after the flood, and 53 days after the flood in bare substrate areas of central Moreton Bay in Australia. Stable isotopes (δ¹⁵N and δ¹³C) were determined for prawn muscle tissue, and lipid content and a length-weight (Fulton’s K) index were used to assess prawn body condition. There were two distinct isotope signatures of tiger prawns living in either riverine or marine influenced areas, suggesting different residency areas within the bay. A flood signal (lower δ¹³C values post-flood) was detected in prawns in the southern area closest to the Logan River. Condition indices showed a short-term increase in condition of prawns in these southern sites, with no apparent condition change in prawns at other sites. A concurrent pulse in benthic primary productivity (chlorophyll a biomass) was measured in this southern area. Our results suggest that nutrients from the flood stimulated benthic primary production that was transferred through the food web, with positive impacts on prawn nutrition at southern sites. With an expected increase in unpredictable weather, including floods, under a changing climate, understanding short- and long-term ecosystem responses in modified catchments is important for mitigating sediment erosion and estuarine and coastal infilling effects, while maintaining productivity benefits to fisheries in receiving estuaries.

洪水是极端天气事件，可以迅速改变入海口的水质。通过洪水将营养物输送到沿海地区可能会提高生产力；然而，在城市地区，水质的下降和污染物的涌入会对居住区的生物群产生负面影响。确定洪水对栖息地生物区系的影响对于告知集水区管理实践很重要。我们调查了商业上重要的对虾物种棕虎虾对虾Penaeus esculentus的身体状况对城市化亚热带沿海海湾中大型旋风驱动洪水的响应。在洪水发生前10天，洪水发生11天以及洪水发生53天之后，在澳大利亚摩顿湾中部裸露的基底区域捕捞了大虾。稳定同位素（δ ¹⁵N和δ ¹³ C）进行了测定对虾肌肉组织，和脂质含量和长度为重量（富尔顿K）索引被用来评估虾体的条件。居住在河流或海洋影响地区的虎虾有两种不同的同位素特征，表明海湾内有不同的居民区。洪水信号（降低δ ^13个在最靠近洛根河南部地区虾中检测到C值后的洪水）。状况指数显示这些南部地点的虾的状况短期增加，而其他地点的虾的状况没有明显变化。底栖初级生产力的并发脉冲（叶绿素a生物量）在该南部地区进行了测量。我们的结果表明，洪水中的营养物刺激了底栖初级产品的生产，这些初级产品通过食物网转移，对南部地区的虾营养产生了积极影响。在气候变化的情况下，包括洪水在内的不可预测的天气预计会增加，因此，了解改良集水区的短期和长期生态系统响应对于减轻沉积物侵蚀和河口和沿海填充效应，同时保持接收河口的渔业的生产力效益非常重要。