Karjalainen Miina, Engström-Ost Jonna, Korpinen Samuli, Peltonen Heikki, Pääkkönen Jari-Pekka, Rönkkönen Sanna, Suikkanen Sanna, Viitasalo Markku
Finnish Institute of Marine Research, Helsinki, Finland.
Ambio. 2007 Apr;36(2-3):195-202. doi: 10.1579/0044-7447(2007)36[195:ecocit]2.0.co;2.
Cyanobacteria of the Baltic Sea have multiple effects on organisms that influence the food chain dynamics on several trophic levels. Cyanobacteria contain several bioactive compounds, such as alkaloids, peptides, and lipopolysaccharides. A group of nonribosomally produced oligopeptides, namely microcystins and nodularin, are tumor promoters and cause oxidative stress in the affected cells. Zooplankton graze on cyanobacteria, and when ingested, the hepatotoxins (nodularin) decrease the egg production of, for example, copepods. However, the observed effects are very variable, because many crustaceans are tolerant to nodularin and because cyanobacteria may complement the diet of grazers in small amounts. Cyanobacterial toxins are transferred through the food web from one trophic level to another. The transfer rate is relatively low in the pelagic food web, but reduced feeding and growth rates of fish larvae have been observed. In the benthic food web, especially in blue mussels, nodularin concentrations are high, and benthic feeding juvenile flounders have been observed to disappear from bloom areas. In the littoral ecosystem, gammarids have shown increased mortality and weakening of reproductive success under cyanobacterial exposure. In contrast, mysid shrimps seem to be tolerant to cyanobacterial exposure. In fish larvae, detoxication of nodularin poses a metabolic cost that is reflected as decreased growth and condition, which may increase their susceptibility to predation. Cyanobacterial filaments and aggregates also interfere with both hydromechanical and visual feeding of planktivores. The feeding appendages of mysid shrimps may clog, and the filaments interfere with prey detection of pike larvae. On the other hand, a cyanobacterial bloom may provide a refuge for both zooplankton and small fish. As the decaying bloom also provides an ample source of organic carbon and nutrients for the organisms of the microbial loop, the zooplankton species capable of selective feeding may thrive in bloom conditions. Cyanobacteria also compete for nutrients with other primary producers and change the nitrogen (N): phosphorus (P) balance of their environment by their N-fixation. Further, the bioactive compounds of cyanobacteria directly influence other primary producers, favoring cyanobacteria, chlorophytes, dinoflagellates, and nanoflagellates and inhibiting cryptophytes. As the selective grazers also shift the grazing pressure on other species than cyanobacteria, changes in the structure and functioning of the Baltic Sea communities and ecosystems are likely to occur during the cyanobacterial bloom season.
波罗的海蓝藻细菌对生物具有多种影响，这些影响在多个营养级上影响着食物链动态。蓝藻细菌含有多种生物活性化合物，如生物碱、肽和脂多糖。一组非核糖体产生的寡肽，即微囊藻毒素和节球藻毒素，是肿瘤促进剂，会在受影响的细胞中引起氧化应激。浮游动物以蓝藻细菌为食，摄入时，肝毒素（节球藻毒素）会降低例如桡足类动物的产卵量。然而，观察到的影响差异很大，因为许多甲壳类动物对节球藻毒素具有耐受性，而且蓝藻细菌可能会少量补充食草动物的食物。蓝藻细菌毒素通过食物网从一个营养级转移到另一个营养级。在远洋食物网中转移率相对较低，但已观察到鱼类幼体的摄食和生长率降低。在底栖食物网中，尤其是在蓝贻贝中，节球藻毒素浓度很高，并且观察到底栖摄食的幼体比目鱼从水华区域消失。在沿岸生态系统中，已表明在蓝藻细菌暴露下，钩虾的死亡率增加且繁殖成功率下降。相比之下，糠虾似乎对蓝藻细菌暴露具有耐受性。在鱼类幼体中，节球藻毒素的解毒会带来代谢成本，这表现为生长和身体状况下降，这可能会增加它们被捕食的易感性。蓝藻细菌丝状体和聚集体还会干扰浮游动物的流体力学摄食和视觉摄食。糠虾的摄食附肢可能会堵塞，并且丝状体干扰梭子鱼幼体的猎物检测。另一方面，蓝藻细菌水华可能为浮游动物和小鱼提供避难所。由于腐烂的水华也为微生物环中的生物提供了丰富的有机碳和营养源，能够选择性摄食的浮游动物物种可能在水华条件下茁壮成长。蓝藻细菌还与其他初级生产者竞争营养，并通过固氮改变其环境中的氮（N）：磷（P）平衡。此外，蓝藻细菌的生物活性化合物直接影响其他初级生产者，有利于蓝藻细菌、绿藻、甲藻和纳米鞭毛虫，并抑制隐藻。由于选择性食草动物也会改变对除蓝藻细菌之外的其他物种的捕食压力，在蓝藻细菌水华季节，波罗的海群落和生态系统的结构和功能可能会发生变化。
