Department of Biological Sciences, University of Essex, Colchester, UK.
Mar Pollut Bull. 2010;61(1-3):83-91. doi: 10.1016/j.marpolbul.2009.12.015. Epub 2010 Jan 13.
Information on the distribution of microphytobenthos (micro-algae forming biofilms on sediment surfaces) and phytoplankton in the Severn estuary is reviewed. Microphytobenthos (MPB) are widely distributed in salt marsh and mudflat environments, with biomass levels lower than in other estuaries (average 53 mg chl am(-2) on mud, 12 mg chl am(-2) on sand). Seasonal and spatial patterns occur in the species composition of biofilms. Large areas of the Severn have not been surveyed, but it is likely that MPB are abundant in these regions. Dissolved inorganic N, P and Si concentrations are high in the upper estuary (>400 microM nitrate, >10 microM phosphate, >140 microM silicate) and decrease seaward. Phytoplanktonic chl a concentrations are low in the main estuary (2.2 microg chl aL(-1)), but increase in the Bristol Channel and at the head of the estuary (>10 microg chl aL(-1)). High turbidity is the likely cause for low phytoplankton activity. Annual production of MPB was estimated at 33 g Cm(-2) of inter-tidal area y(-1) in the Severn estuary. This estimated benthic primary production would utilise 3.9% and 4.9% of the annual estuarine N and P loads. Construction of tidal energy barrages is estimated to significantly reduce annual estuarine MPB production (by 77% for the Cardiff-Weston barrage). It is unlikely that any potential increases in MPB biomass on remaining inter-tidal areas will be sufficient to compensate for these losses. In general, the data coverage for benthic and planktonic distribution, production and related nutrient cycles is extremely limited and significant new research work is needed to enable more definite predictions of the post-barrage situation to be made.
对塞文河口的微型底栖生物（在沉积物表面形成生物膜的微型藻类）和浮游植物的分布信息进行了综述。微型底栖生物（MPB）广泛分布于盐沼和泥滩环境中，生物量水平低于其他河口（泥滩平均为 53mgchl a m(-2)，沙滩为 12mgchl a m(-2)）。生物膜的物种组成存在季节性和空间性的变化。塞文河口的大部分区域尚未进行调查，但这些区域很可能存在丰富的 MPB。上河口的溶解无机氮、磷和硅浓度较高（硝酸盐>400μM，磷酸盐>10μM，硅酸盐>140μM），并随海水向外逐渐降低。主河口的浮游植物叶绿素 a 浓度较低（2.2μgchl a L(-1)），但在布里斯托尔海峡和河口头部增加（>10μgchl a L(-1)）。高浊度可能是浮游植物活动水平低的原因。塞文河口潮间带每年的微型底栖生物产量估计为 33gC m(-2) y(-1)。这一估计的底栖初级生产力将利用河口每年氮和磷负荷的 3.9%和 4.9%。潮汐能拦河坝的建设预计将显著降低河口每年的微型底栖生物产量（加的夫-韦斯顿拦河坝减少 77%）。在剩余的潮间带区域，微型底栖生物生物量可能会有所增加，但不太可能足以弥补这些损失。一般来说，底栖和浮游分布、生产力及相关养分循环的数据覆盖范围极其有限，需要开展大量新的研究工作，以便能够对拦河坝建成后的情况做出更明确的预测。
