Aquatic Ecology Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom.
Water Res. 2013 Sep 1;47(13):4357-69. doi: 10.1016/j.watres.2013.04.043. Epub 2013 May 7.
Algal and cyanobacterial blooms in reservoirs are driven by nutrient enrichment and may present economic and conservation challenges for water managers. Current approaches such as suppression of algal growth with barley straw, ferric dosing or manipulation of fish stocks have not yielded long term successes. A possibility that has sparked growing interest is the encouragement and cultivation of natural filter feeders, such as mussels, which remove suspended matter from the water and reduce nutrient levels through biodeposition and assimilation. This review focusses on the zebra mussel (Dreissena polymorpha) as a tool for enhancement of water quality in reservoirs. Native to the Ponto-Caspian region, this species has invaded many lakes and reservoirs across North America and Western Europe, where it occurs in very high densities. While purposeful introduction of a non-native species into new sites is socially unacceptable, we investigate the possible benefits of encouraging increased abundance of zebra mussels in sites where the species is already established. We estimate that the annual nitrogen and phosphorus input into a large UK reservoir (Grafham Water) could be assimilated into zebra mussel biomass by encouraging settlement onto 3075 m and 1400 m of commercial mussel ropes, respectively. While zebra mussel cultivation has an incredible capacity to push eutrophic systems towards a clear water state, there are many risks associated with encouraging an invasive species, even within sites where it has already established. The zebra mussel is a prominent biofouler of native unionid mussels and raw water pipes, it changes the physical characteristics of the places it inhabits, in sites low in phosphorus it can be responsible for toxic cyanobacterial blooms, it alters nutrient cycling and community structure and it can have negative impacts on amenity value. Increased propagule pressure from elevated numbers of veliger larvae in the water column may increase the risk of spread to other locations. This may render some reservoir systems, such as dammed rivers which have outflows to downstream watercourses, unsuitable for cultivation. Such reservoirs are especially common in North America. We consider the practicalities of putting a zebra mussel cultivation system into place and identify gaps in knowledge. We conclude that zebra mussel cultivation offers an attractive tool for managing nutrient-enriched reservoirs, but that the benefits and costs must be balanced on a site-by-site basis.
水库中的藻类和蓝藻水华是由营养物质富化引起的，这可能给水资源管理者带来经济和保护方面的挑战。目前的方法，如利用大麦秸秆抑制藻类生长、投加铁盐或操纵鱼类种群，都没有取得长期成功。一种越来越受到关注的可能性是鼓励和培育天然滤食者，如贻贝，它们可以从水中去除悬浮物，并通过生物沉积和同化作用降低营养水平。本综述重点介绍了斑马贻贝（Dreissena polymorpha）作为改善水库水质的工具。该物种原产于里海-黑海地区，现已入侵北美的许多湖泊和水库以及西欧的许多湖泊和水库，在这些地区，其密度非常高。虽然将非本地物种有目的地引入新的地点在社会上是不可接受的，但我们调查了在已经建立该物种的地点鼓励增加斑马贻贝丰度的可能好处。我们估计，在英国的一个大型水库（Grafham Water）中，每年进入系统的氮和磷可以通过鼓励在 3075 米和 1400 米的商业贻贝绳索上定居，从而被斑马贻贝生物量同化。虽然斑马贻贝养殖具有将富营养化系统推向清水状态的巨大能力，但即使在已经建立该物种的地点，鼓励入侵物种也存在许多风险。斑马贻贝是本地贻贝和原水管道的主要生物污损生物，它改变了它栖息的地方的物理特性，在磷含量低的地方，它可能会导致有毒蓝藻水华，它改变了营养循环和群落结构，并对舒适价值产生负面影响。水柱中幼虫数量增加导致繁殖体压力增加，可能会增加传播到其他地点的风险。这可能会使一些水库系统（如大坝河流，这些河流有向下游水道的流出物）不适合养殖。这种水库在美国尤其常见。我们考虑了实施斑马贻贝养殖系统的实际情况，并确定了知识上的差距。我们的结论是，斑马贻贝养殖为管理富营养化水库提供了一种有吸引力的工具，但必须在站点基础上权衡收益和成本。
