Lake Restoration by Fish Removal: Short- and Long-Term Effects in 36 Danish Lakes
Lake Restoration by Fish Removal: Short- and Long-Term Effects in 36 Danish Lakes
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DOI：
10.1007/s10021-008-9193-5
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发表时间：
2008-09
期刊：
影响因子：
3.7
通讯作者：
M. Søndergaard;Lone Liboriussen;A. Pedersen;E. Jeppesen
中科院分区：
文献类型：
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作者：
M. Søndergaard;Lone Liboriussen;A. Pedersen;E. Jeppesen
在过去的 10 至 15 年中，清除浮游生物和底栖鱼类（主要是蟑螂、Rutilus rutilus 和鳊鱼、Abramis brama）已被普遍用作改善丹麦湖泊生态质量的一种方法。在这里，我们研究了在 36 个主要是浅水和富营养化的湖泊中去除 41-1360 kg ha−1 鱼后获得的一般和长期影响。在 3 年内清除鱼量少于 200 kg ha−1 的湖泊中，仅观察到轻微影响，但清除率较高时，化学和生物变量都会受到显着影响。叶绿素 (Chla)、总磷 (TP)、总氮 (TN) 和悬浮固体 (SS) 的浓度下降至去除前水平的 50-70%。最显着和最持久的影响出现在 SS 和 Secchi 深度上，而最温和的影响出现在 Chla 上。这可能反映了鳊鱼种群的有效和持续减少，从而减少了再悬浮和SS，而蟑螂的生物量恢复到以前的水平，减少了浮游动物的吃草，而对Chla的控制较少。鱼类去除后，藻类总生物量也下降，特别是蓝藻的生物量，而隐植物的生物量增加，表明浮游动物的放牧压力增加。大多数湖泊沉水植物的丰度和物种数量有所增加。对于大多数变量而言，鱼类清除的影响在 6-10 年内都很显着，此后许多湖泊往往会恢复到恢复前的状况，这可能主要是因为外部和内部磷负荷持续较高。我们的结论是，充分广泛地清除浮游生物和底栖鱼类是创造清澈水体的有效工具；然而，要想在营养最丰富的湖泊中获得长期影响，可能需要反复清除鱼类。
During the past 10–15 years removal of plankti- and benthivorous fish (mainly roach,Rutilus rutilus, and bream,Abramis brama) has commonly been used as a method to improve the ecological quality of Danish lakes. Here, we examine the general and long-term effects obtained after the removal of 41–1360 kg fish ha−1in 36 mainly shallow and eutrophic lakes. In lakes in which less than 200 kg fish ha−1were removed within a 3-year period only minor effects were observed, but at higher removal rates both chemical and biological variables were markedly affected. The concentrations of chlorophylla(Chla), total phosphorus (TP), total nitrogen (TN), and suspended solids (SS) decreased to 50–70% of the level prior to removal. The most significant and long-lasting effects were found for SS and Secchi depth, whereas the most modest effects were seen for Chla. This probably reflects an efficient and persistent reduction of the bream stock which reduced resuspension and SS, while the biomass of roach returned to former levels, decreasing the zooplankton grazing with less control on Chla. Total algal biomass also declined after fish removal, particularly that of cyanobacteria, whereas the biomass of cryptophytes increased, indicating enhanced grazing pressure by zooplankton. The abundance and species number of submerged macrophytes increased in the majority of the lakes. For most variables the effects of the fish removal were significant for 6–10 years, after which many lakes tended to return to pre-restoration conditions, probably mainly because of consistently high external and internal phosphorus loading. We conclude that a sufficiently extensive removal of plankti- and benthivorous fish is an efficient tool to create clear water; however, repeated fish removal is presumably required to obtain long-term effects in the most nutrient rich lakes.