Self-organization and mechanical properties of mussel culture suspensions: A critical review

Published information on the spatial organization of mussel culture suspensions (collectors, socks, droppers and poles) is reviewed. Despite the several hundred studies on mussel culture this type of information is very scarce but suggests that mussels self-organize into phyllotatic patterns similar to those widely studied in cylindrical/tubular biological structures and mineral crystals. I demonstrate that space regulated self-thinning (SST) models developed for plane substrates are not applicable to mussel suspensions and propose a new SST model based on the packing geometry of mussel shells around a rope. The robustness of this model is assessed by its application to a wide range of cultured populations. This comparison suggests that the carrying capacity of individual suspensions for commercial-sized mussels is equivalent to a single layer of tightly packed mussels around the rope, independently of the species, type of suspension, presence/absence of pegs, site (growth rate) and stocking density and size. The emergent mechanical properties of these porous, extremely rough and heterogeneous bodies are reviewed. The proposed SST model provides insights into the biomechanical processes of self-thinning and sloughing.     

Water quality upstream and downstream of a commercial oyster aquaculture facility in Chesapeake Bay,USA

Oyster aquaculture is an expanding industry in the Chesapeake Bay. Oysters remove nitrogen (N) and phosphorus (P) from the water column through filtration and conversion of phytoplankton into shell and tissue, but also continuously excrete these same nutrients back into the water column as inorganic compounds readily available for plant or algal uptake. The objective of this study was to assess multiple water quality parameters upstream and downstream of a commercial oyster aquaculture facility in the mesohaline region of the Chesapeake Bay. Results of the study indicated a 78.4% average increase in total ammonia nitrogen (TAN) concentration and a 19.4% decrease in chlorophyll-a (Chl-a) concentration downstream of the facility. There was no significant change in the concentration of reactive phosphate (RP), nitrate–nitrogen (NO₃⁻–N), or nitrite–nitrogen (NO₂⁻–N) as water passed through the facility. It was determined that velocity of water through the facility had no influence on the change in TAN or Chl-a concentration from upstream to downstream of the facility. Increased reduction in Chl-a concentration from upstream to downstream was related to higher upstream concentrations of Chl-a. There was no correlation between increased rates of Chl-a removal and downstream TAN. Results of this study suggest that oyster aquaculture can significantly increase the amount of available inorganic nitrogen in the water column immediately downstream of a facility, independent of upstream availability of phytoplankton and flow velocity of water through the facility.     

水产养殖信息化关键技术研究现状与趋势

信息化技术已经成为现代渔业可持续发展的重要支撑技术之一。为了展现、引导与促进其在水产养殖环节的应用水平,按照信息的属性与尺度、养殖活动的流程与建模应用的层次,系统分析相关文献,对信息获取技术中知识挖掘、传感网络的辨识参数与其组织形式、遥感对区域水环境信息与养殖面积变化及其时空特征获取与监测的研究现状进行了整理;并对比分析了水质预测与预警模型、水产病害诊断中知识表示模式与推理方法、水产行为的量化与分析方法、饲料配方及投饲决策模型的建立、质量追溯中感知内容与平台的构建以及养殖中的控制策略与方法。综述结果表明,信息化技术正向水产养殖业深层次扩散,逐渐实现对水产养殖信息的全面感知与决策支持;信息获取技术由人工获取向依靠感知网络和遥感等数字化智能技术转变;信息处理向专家系统、管理系统、决策支持系统、追溯系统和精细化控制系统等依托人工智能、信息融合和建模处理的智能化信息系统发展;信息化应用使养殖活动更加强调和注重信息化思维和管理决策与其运作效率、效益的相互适应、促进与优化。     

生态综合养殖池塘氮磷沉积研究

通过使用沉积物捕获器获取沉积物,研究了一生态综合养殖池塘的沉积作用,并利用室内模拟实验研究了缢蛏（Sinonovacula constrzcta）的生物沉积作用,同时分析了池塘沉积物及其间隙水的营养盐;应用Fick第一定律对池塘沉积物-池水界面营养盐通量进行了估算.藻类池颗粒物质的日平均沉积速率为44.59 g/m^2,贝类池颗粒物质的日平均沉积速率为14.01 g/m^2;两个池塘试验期内（90 d）N、P的净沉积量分别为6061.5 g和3411 g（采样池塘面积各0.5 hm^2,水深50～60 cm）.结果显示实验期内生态综合养殖池塘沉积作用分别占N、P营养元素输出的2.2％和5.8％（质量分数）.     

Pesticide use in rice and rice–fish farms in the Mekong Delta, Vietnam

Pest management practices among rice and rice–fish farmers and their perception of problems related to pests and pesticides were surveyed in the Mekong Delta. A total number of 64 different pesticides were identified during the survey. Approximately 50% were insecticides, 25% were fungicides and 25% were herbicides. The main insecticides used were pyrethroids (42%) carbamates (23%) and cartap (19%). Non-IPM farmers used twice as many pesticides as IPM farmers. Their application frequency and the amount of active ingredient used were 2–3 times higher per crop, as compared to IPM farmers. During the last three years IPM farmers estimated that they had decreased the amount of pesticides used by approximately 65%, while non-IPM farmers said that they had increased the amount of pesticide used by 40%. Also, farmers growing fish in their rice fields used less pesticide than farmers growing only rice, as pesticides adversely affect cultures of fish. Taking a long-term perspective integrated rice–fish farming with IPM practices provides a sustainable alternative to intensive rice mono-cropping, both from an economic as well as an ecological point of view.     

一种新的池塘溶解氧预测模型

池塘溶解氧的精确预测一直是池塘人工养殖生产中的瓶颈问题。该文建立了基于神经网络的池塘溶解氧智能预测模型，并对预测模型进行了验证，其预测结果与实测数据拟合良好。     

养殖水体氮的生物转化及其相关微生物研究进展

综述了国内外养殖水体N的生物转化及其相关微生物研究进展,指出养殖水体中N循环主要起源于所加入的配合饲料及有机或无机肥料,在生物和非生物共同作用下含氮化合物不断迁移转化,构成复杂的动态平衡,其中微生物起着关键作用,泥水界面层是有机物矿化和营养物质再生的重要场所。并提出渔业生产调控措施。     

不同养殖模式下对虾早期死亡综合症致病菌的动态变化

[目的]为指导南美白对虾高位池的科学养殖提供理论依据。[方法]选取2种养殖模式的南美白对虾高位池塘为试验对象,通过周期性的水样采集研究了虾池水体细菌数量、弧菌数量以及弧菌中非副溶血弧菌和副溶血弧菌比例变化规律与早期死亡综合症发生的相关性。[结果]试验虾池在养殖初期弧菌数量较低,养殖过程中弧菌数量与细菌总数的消长趋势基本一致。当虾池中细菌总数高于2.5×104cfu/ml,弧菌数量高于1.5×103cfu/ml,非副溶血弧菌与副溶血弧菌的比例超过10∶1,虾池内极易发生早期死亡综合症。[结论]该研究结果可用于进行对虾健康养殖的风险评估。     

高效液相色谱法测定养殖水体中的亚甲基蓝

[目的]探讨一种高效液相色谱法测定水产养殖水体环境中亚甲基蓝含量的分析方法,为亚甲基蓝测定方法的建立提供参考。[方法]将水样经预处理后利用二氯甲烷萃取,经旋转蒸发仪抽真空浓缩净化后高效液相色谱-紫外检测器检测,采用外标法定量分析。[结果]亚甲基蓝在0.05~1.00 mg/L质量浓度范围内线性相关系数均大于0.999;在0.06~0.80 mg/L添加范围内的平均回收率为75.2%~86.0%,相对标准偏差均小于12.0%;方法定量限为0.05 mg/L。[结论]该方法的重现性较好,操作方便,定性准确且回收率较高,能够用于快速分析水产养殖水体环境中亚甲基蓝含量。     

我国鱼病生态防治研究情况简述

本文从水产养殖结构调整、鱼类种质改良、养殖水平控制和病原生物量控制四个概述了我国鱼病生态防治研究的状况。