虾池长竹蛏肥满度的研究   总被引：2，自引：0，他引：2  

王云  郑升阳 《台湾海峡》2001,20(Z1):57-59

本文作者于1997年4月至1998年3月期间，对幸福洋垦区虾池生长的长竹蛏进行了周年肥满度测定研究.结果表明长竹蛏5～9月份较肥，肥满度在60％～80％之间，11月至翌年4月份较瘦，肥满度在55％～47％之间；根据肥满度的测定，长竹蛏的繁殖期为6～8月份.  相似文献   

Episodic Mass Invasions of Juvenile Gadoids into the Wadden Sea and their Consequences for the Population Dynamics of Brown Shrimp (Crangon crangon)     

Rüdiger  Berghahn 《Marine Ecology》1996,17(1-3):251-260

Abstract. The brown shrimp Crangon crungon is considered to be a key species in the coastal waters of the North Sea and in particular in the Wadden Sea, since it occurs in masses and acts as both a highly efficient predator and important prey. The Wadden Sea is the nursery ground for brown shrimp. In 1990, a mass invasion of O-group whiting ( Merlangius merlangus ) reduced Crangon numbers to almost zero. Similar events, which had previously been reported in the 19th century, were observed in 1959 (whiting), 1970 (cod, Gadus morhua ), and 1983 (cod and whiting).
The 1990 invasion and the decline of the shrimp stock are documented on the basis of surveys that are compared with the years preceding and following. Consequences for the food web in the Wadden Sea and the reasons for the complete recovery of the shrimp stock in each case within one year after its collapse are discussed with regard to the Crangon crungon behaviour and reproductive potential. Sampling error and the impact of fisheries are also considered.  相似文献   

Preliminary Observations on the Feeding Activity of Fishes during Tidal and Diel Cycles in the Loire Estuary: The Bib Trisopterus luscus L. 1758     

J. P. ROBIN  J. MARCHAND 《Marine Ecology》1986,7(2):181-189

Abstract. .Series of experimental trawls repeated over the same area during both 12 and 24 h cycles coupled with an analysis of the stomach contents of the bib demonstrated quantitative and qualitative variations in the predator's diet. The population studied feeds continuously over 24 h, the coefficient of "fullness" is relatively constant, and freshly eaten prey can be observed both during the day and at night. The proportion of brown shrimp in the food increases after high tide, especially when this occurs at night, coinciding with the shrimp's period of maximum activity. However, the overall impact of the bib on the shrimp population depends more on the abundance of the former than on variations in their individual food intake.  相似文献   

Potential bioeconomic impact of reduced mortality of codend escapees of the shrimp fishery in the Davis Strait     

Christensen  Steen 《ICES Journal of Marine Science》1995,52(5):843-851

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浙江中南部外侧海区的虾类资源   总被引：4，自引：0，他引：4  

宋海棠  俞存根 《海洋学研究》1992,10(3):53-60

本文根据1986年8月至1987年11月浙江中南部海域(27°00′～29°30′N,125°00′E) 拖虾调查资料,分析了虾类资源的种类、组成,拖虾渔获量及主要种类的分布,提出进一步开发凹管鞭虾,假长缝拟对虾等新的虾类资源的建议,并讨论了合理利用的途径。  相似文献   

Changes in recruitment, growth, and stock size of northern shrimp (Pandalus borealis) at West Greenland: temperature and density-dependent effects at released predation pressure     

Wieland  Kai 《ICES Journal of Marine Science》2005,62(7):1454-1462

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对虾与鱼、贝类封闭式综合养殖的实验研究   总被引：11，自引：3，他引：11  

李德尚  董双林 《海洋与湖沼》2002,33(1):90-96

于1995－1999年采用陆基实验围隔法系统地研究了对虾与鱼、贝类封闭式综合养殖的基础问题，所选取的材料为中国对虾、台湾红罗非鱼、缢蛏与海湾扇贝，研究出了4种优化结构养殖模式。结果表明，4种模式的组成及各成分间生物量（收获前）的比值分别为：对虾的养殖效果都比同样条件下的对虾单养模式显著优越；其中最好的虾、鱼、贝三元综合养殖模式将产量提高了28％，投入氮的利用率提高了85％。同时采取封闭式的养殖方法，向浅海输出的氮只占养殖输入氮的6％－8％，从而显著降低了对浅海的污染。  相似文献   

不同养殖模式虾池弧菌对抗菌药物的耐药性与虾池水质评价     

张瑜斌  章虹  柯盛  章洁香 《广东海洋大学学报》2007,27(1):42-47

研究了湛江东海岛3种不同养殖模式虾池弧菌对抗菌药物的耐药性,并对虾池水域环境的水温、盐度、DO、pH、叶绿素a、DOC、无机氮、无机磷、硅酸盐、细菌总数和弧菌数量变化进行了监测和评价。结果表明,调查的三个虾池的弧菌对万古霉素产生耐药性,高位新池和传统精养池的弧菌对利福平产生耐药性,对其他抗菌药尚未形成耐性,3个虾池的弧菌对恩诺沙星和氯霉素高度敏感,传统精养池和天然虾池的弧菌对复方新诺明、庆大霉素、TMP和环丙沙星高度敏感;在水平差异上,高位新池的弧菌比传统精养池和天然虾池对12种抗菌药更具耐药性,同时多重耐药菌株在高位新池中出现,可能与虾苗来源和配合饲料中添加了抗菌药物有关。水质监测结果表明,养殖过程中,虾池水域环境逐渐富营养化,无机氮和Chla超过富营养化阈值,细菌总数增加;两个精养池的水体富营养化程度高于天然虾池;调查期间的弧菌数量在对虾发病的感染剂量阈值范围之内,尚无弧菌病害发生的潜在危险。  相似文献   

基于Google Earth Engine的红树林年际变化监测研究   总被引：1，自引：0，他引：1  

刘凯  彭力恒  李想  谭敏  王树功 《地球信息科学学报》2019,21(5):731-739

遥感技术已广泛应用于红树林资源调查与动态监测中,但仍然存在遥感数据获取困难、数据预处理工作量大、监测时间长而周期过大等问题,影响了学者对红树林演变过程的精细刻画与理解。本文基于Google Earth Engine（GEE）云遥感数据处理平台,选取Landsat系列卫星数据,生成长时间序列年际极少云影像集（云量少于5%）,利用3个红外波段反射率（NIR、SWIR1、SWIR2）和3个特征指数（NDVI、NDWI、NDMI）建立阈值规则集,实现对实验区越南玉显县红树林、红树林-虾塘、不透水面-裸地、水体4种目标地物的专家知识决策树分类和土地覆盖的制图,并基于分类结果监测该区域1993-2017年的红树林年际动态变化。结果表明：GEE平台可满足多云多雨地区红树林的长时间序列年际变化监测需求;本文阈值分类方法可以有效提取红树林及红树林-虾塘,实验区有86%年份的影像分类精度达到80%以上;年际变化监测可精细刻画实验区红树林面积先增后减再增的变化过程,也能准确反映红树林与红树林-虾塘养殖系统面积之间的负相关关系。红树林年际动态监测结果可以降低红树林演变分析的不确定性,并能更精细地量化红树林与其他土地覆盖类型的转化过程,从而评估经济发展、政策等因素对红树林演变的影响。  相似文献   

Can start-up motives influence social-ecological resilience in community-based entrepreneurship setting? Case of coastal shrimp farmers in Sri Lanka     

《Marine Policy》2017

The aim of this paper is to understand the extent to which the start-up motives can influence social-ecological resilience in community-based entrepreneurship setting. The case study approach was used to study five coastal communities in northwestern Sri Lanka. Shrimp farmers’ start-up motives include both the desire to capitalize on opportunities to utilize their resources and skills (opportunity-driven) and the need to establish satisfactory sources of income (necessity-driven). They have come up with diverse entrepreneurial responses to face various stressors and shocks by using their existing capital types and their willingness for collaboration. Farmers’ coping capacity is demonstrated through their individual responses whereas adaptive and transformative capacities are demonstrated mostly through their community cooperative work. Findings also reveal that the start-up motives of small-scale shrimp farmers are less influential on their social-ecological resilience in the community setting. Instead, the key to social-ecological resilience lies with the understanding of the nature of stressors and their commitment for collective action.  相似文献