Ecosystem response to bivalve density reduction: Management implications
Ecosystem response to bivalve density reduction: Management implications
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DOI：
10.1023/a:1013354807515
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发表时间：
2002-01-01
期刊：
影响因子：
1.8
通讯作者：
Gregory, Leah
中科院分区：
文献类型：
--
作者：
Dame, Richard;Bushek, David;Gregory, Leah
沿海生态系统很容易被过度开发，并因物理和生物因素而改变。在本文中，我们讨论了目前的想法和论点，沿海生态系统管理的重点系统，有大型双壳类过滤器馈线组件。几个世纪以来，物种或种群方法一直用于渔业管理。随着对具体环境影响和关系的了解越来越多，越来越明显的是，对这些系统的渔业管理采取广泛或全面的办法通常更合适。一个正在进行的生态系统规模的实验中，牡蛎是完全从潮沟被描述和作为一个案例研究。实验设计考虑了系统承载能力的估计。使用人口或物种的方法来监测牡蛎，实验操作后，唯一可观察到的变化是夏季体细胞生长略有增加，并提高招聘牡蛎与牡蛎礁删除小溪。这些数据被解释为一个迹象表明，与牡蛎目前的小溪低于或接近承载能力。然而，当游泳生物，浮游生物和水化学数据也检查了一个更复杂的画面出现。在夏季生长季节，游泳生物的生物量在所有小溪往往大于牡蛎生物量。此外，我们的计算表明，牡蛎不产生足够的铵，以满足浮游植物的生产力，但游泳动物，水柱矿化和沉积物可以占大部分的赤字。最后，微鞭毛虫是牡蛎的首选食物，在夏季生长季节占浮游植物的主导地位，而硅藻则在寒冷的月份占主导地位。浮游植物优势相的变化的时间似乎反映了游泳动物在小溪的季节性到达和离开时间。我们认为，密集的双壳类珊瑚礁和床是强烈的正反馈回路，使其生态系统容易受到结构的巨大变化的指示。在自然系统中没有报告过这种变化，但在受过度捕捞、营养负荷和污染影响的系统中发现了这种变化。因此，沿海生态系统可持续渔业管理需要了解生态系统科学，并认识到以双壳类为主的系统表现出复杂的反应，不容易用线性动力学来解释。
Coastal ecosystems are easily overexploited and changed by physical and biological factors. In this paper, we discuss current ideas and arguments for coastal ecosystem management with an emphasis on systems that have large bivalve filter feeder components. For centuries the species or population approach has been utilized in fisheries management. With the growing knowledge base on specific environmental effects and relationships, it has become increasingly evident that a broad or holistic approach to fisheries management in these systems is usually more appropriate. An ongoing ecosystem scale experiment in which oysters are completely removed from tidal creeks is described and used as a case study. The experimental design takes estimates of the systems carrying capacity into account. Using the population or species approach to monitor the oysters, the only observable change after the experimental manipulation was a slight increase in summer somatic growth and elevated recruitment of oysters in creeks with oyster reefs removed. These data are interpreted as an indication that the creeks with oysters present are below or near carrying capacity. However, when nekton, plankton and water chemistry data are also examined a much more complicated picture emerges. During the summer growing season, nekton biomass in all creeks is often greater than oyster biomass. Also, our calculations show that oysters do not produce enough ammonium to satisfy phytoplankton productivity, but nekton, water column remineralization and sediments can account for most of the deficit. Finally, microflagellates, which are a preferred food for the oysters, dominate the phytoplankton during the summer growing season and diatoms dominate the colder months. The timing of the change in phase of phytoplankton dominance seems to mirror the seasonal arrival and departure times of nekton in the creeks. We argue that dense bivalve reefs and beds are indicative of intense positive feedback loops that make their ecosystems susceptible to dramatic changes in structure. Such changes have not been reported for natural systems, but are found in systems influenced by over-fishing, nutrient loading and pollution. Thus, the management of sustainable fisheries in coastal ecosystems requires an understanding of the ecosystem science and the realization that systems dominated by bivalves exhibit complex responses that are not easily explained by linear dynamics.