Gaiser E E, Scinto L J, Richards J H, Jayachandran K, Childers D L, Trexler J C, Jones R D
Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA.
Water Res. 2004 Feb;38(3):507-16. doi: 10.1016/j.watres.2003.10.020.
Growing concern over the ecological consequence of phosphorus (P) enrichment in freshwater wetlands has elicited considerable debate over the concentration of water column P associated with eutrophication. In the oligotrophic Everglades, the displacement of native communities by enriched ones is widespread and has occurred at sites experiencing only minimal elevations in P input. To help define regulatory criteria for P inputs to the Everglades, we constructed an experiment that mimics P input to the natural system by continuously delivering P at concentrations elevated 5, 15 and 30 microgl(-1) above ambient to 100-m long flow-through channels. We compared patterns of P accumulation in the water, periphyton, detritus and soils among the channel treatments and also along a 16 km transect from an enriched canal that inflows to the interior of the same marsh. Water column TP and SRP were unrelated to input TP concentration in both the experiment and the marsh transect. However, concentrations of TP in periphyton mats were significantly elevated at all levels of experimental enrichment and as far as 2 km downstream from water inputs into the marsh. Elevated periphyton TP was associated with significant loss of periphyton biomass. In oligotrophic wetlands, traditional measures of water column SRP and TP will substantially underestimate P loading because biotically incorporated P is displaced from the water column to benthic surfaces. Using periphyton TP as a metric of P enrichment is uncomplicated and analogous to pelagic TP assessments in lakes where most P is sequestered in phytoplankton.
对淡水湿地磷（P）富集所产生的生态后果的日益关注，引发了关于与富营养化相关的水柱磷浓度的大量争论。在贫营养的大沼泽地，富营养群落取代本地群落的现象很普遍，并且在磷输入仅略有增加的地点就已发生。为了帮助确定大沼泽地磷输入的监管标准，我们构建了一个实验，通过向100米长的流通渠道持续输送浓度比环境浓度高5、15和30微克/升的磷，来模拟向自然系统输入磷的情况。我们比较了渠道处理之间以及沿着一条从流入同一沼泽内部的富营养化运河延伸16公里的样带中，水、周丛生物、碎屑和土壤中磷的积累模式。在实验和沼泽样带中，水柱总磷（TP）和溶解性反应磷（SRP）与输入的总磷浓度均无关。然而，在所有实验性富营养化水平下以及在水流入沼泽下游达2公里处，周丛生物垫中的总磷浓度均显著升高。周丛生物总磷升高与周丛生物量的显著损失有关。在贫营养湿地中，传统的水柱溶解性反应磷和总磷测量方法将大大低估磷负荷，因为生物结合的磷从水柱转移到底栖表面。使用周丛生物总磷作为磷富集的指标很简单，类似于湖泊中浮游总磷评估，在湖泊中大多数磷被隔离在浮游植物中。
