Nutrient and microbial dynamics in high-intensity, zero-exchange shrimp ponds in Belize
Nutrient and microbial dynamics in high-intensity, zero-exchange shrimp ponds in Belize
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DOI：
10.1016/s0044-8486(02)00575-6
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发表时间：
2003-04-02
期刊：
影响因子：
4.5
通讯作者：
Pearson, DC
中科院分区：
文献类型：
--
作者：
Burford, MA;Thompson, PJ;Pearson, DC
在中美洲伯利兹水产养殖有限公司（BAL）的5个不同作物年龄的高强度（120只米(2)）对虾（凡纳滨对虾）池塘中，对微生物和浮游植物过程及其对水质的影响进行了为期3周的研究。这些池塘的特点是整个作物的零水交换，塑料衬里和高曝气率。以鱼粉基饲料、收获基饲料和糖蜜的形式输入的氮(N)和有机碳(C)导致了高浓度的溶解有机氮和无机氮（分别为2.29-5.56和0.17-10.66 mg l(-1)）和溶解有机碳（14.20-48.10 mg l(-1)）。磷酸盐水平也很高，在0.07到1.17毫克/升（-1）之间。高营养物浓度促进了细菌、浮游植物（主要是自养鞭毛虫）和原生动物的生长。高达40%的细菌与絮凝物有关。然而，水柱中的细菌数量和氧（O-2）消耗量并没有随着作物年龄的增长而增加。这可能是由于碳氮比降低到细菌生长的最佳水平以下。高达22%的O-2消耗是由于硝化作用，并且有一些迹象表明，老作物的总氨态氮（TAN）浓度降低，亚硝酸盐和硝酸盐水平增加。浮游植物和细菌都是高铵吸收速率的原因。在高硝酸盐浓度的池塘中，硝酸盐的吸收率也很高。与作物年龄无关，浮游植物的生产力仍然很高，池塘在净O-2产量（自养）和净O-2消耗（异养）之间波动，与作物年龄无关。这反映了细菌和浮游植物种群的高度动态性质，浮游植物个体物种的频繁繁殖和崩溃。高混合率导致浮游植物和其他碎屑悬浮在水柱中。然而，一小部分污泥（<池塘面积的2%）确实积累了高氮、高碳含量和高孔隙水TAN。本研究表明，尽管通常认为池塘的水质较差，即营养物浓度高，浮游植物数量高且不稳定，细菌数量多，但虾的产量相对于传统池塘来说是高的。在这些系统中，通过提高C/N比，从而提高细菌生长的C可利用性，似乎有增加细菌产量的余地。然而，哪些微生物过程可能被促进，以及这样做的好处是否大于成本，这仍有待确定。爱思唯尔科学有限公司版权所有
Microbial and phytoplankton processes, and their effect on water quality were examined over a 3-week period in five high-intensity (120 animals m(-2)) shrimp (Litopenaeus vannamei) ponds of varying crop ages at Belize Aquaculture Ltd., (BAL) in Central America. These ponds were characterized by zero water exchange throughout the crop, plastic lining and high aeration rates. Nitrogen (N) and organic carbon (C) inputs, in the form of fishmeal-based feed, gain-based feed and molasses, resulted in high concentrations of dissolved organic and inorganic N (2.29-5.56 and 0.17-10.66 mg l(-1), respectively) and dissolved organic C (14.20-48.10 mg l(-1)). Phosphate levels were also high, ranging from 0.07 to 1.17 mg l(-1). The high nutrient concentrations promoted the growth of bacteria, phytoplankton (mostly autotrophic flagellates) and protozoa. Up to 40% of the bacteria were associated with flocculated matter. However, bacterial numbers and oxygen (O-2) consumption in the water column did not appear to increase with crop age. This may be due to a reduction in the C/N ratio below the optimum for bacterial growth. Up to 22% of the O-2 consumption was due to nitrification and there was some indication of lowering of total ammoniacal N (TAN) concentrations and an increase in nitrite and nitrate levels in older crops. Both phytoplankton and bacteria were responsible for high rates of ammonium uptake. In ponds with high nitrate concentrations, nitrate uptake rates were also high. Phytoplankton productivity remained high irrespective of crop age and ponds fluctuated between net O-2 production (autotrophy) and net O-2 consumption (heterotrophy) irrespective of crop age. This reflected the highly dynamic nature of the bacterial and phytoplankton populations with frequent blooms and crashes of individual phytoplankton species. The high mixing rates resulted in phytoplankton and other detritus remaining suspended in the water column. However, a small area of sludge (< 2% of pond area) did accumulate containing a high N and C content, and high pore water TAN. This study showed that despite what is generally considered as poor water quality in the ponds, i.e. high nutrient concentrations, high and unstable phytoplankton numbers, and high bacterial numbers, shrimp production was high relative to conventional ponds. There appeared to be scope for increasing bacterial production in these systems by increasing the C/N ratio, and hence C availability for bacterial growth. However, it remains to be established which microbial processes are likely to be promoted, and if the benefits of this outweigh the costs. Crown Copyright (C) 2003 Published by Elsevier Science B.V. All rights reserved.