Balancing end-to-end budgets of the Georges Bank ecosystem

Oceanographic regimes on the continental shelf display a great range in the time scales of physical exchange, biochemical processes and trophic transfers. The close surface-to-seabed physical coupling at intermediate scales of weeks to months means that the open ocean simplification to a purely pelagic food web is inadequate. Top-down trophic depictions, starting from the fish populations, are insufficient to constrain a system involving extensive nutrient recycling at lower trophic levels and subject to physical forcing as well as fishing. These pelagic-benthic interactions are found on all continental shelves but are particularly important on the relatively shallow Georges Bank in the northwest Atlantic. We have generated budgets for the lower food web for three physical regimes (Well-mixed, Transitional and Stratified) and for three seasons (Spring, Summer and Fall/Winter). The calculations show that vertical mixing and lateral exchange between the three regimes are important for zooplankton production as well as for nutrient input. Benthic suspension feeders are an additional critical pathway for transfers to higher trophic levels. Estimates of production by mesozooplankton, benthic suspension feeders and deposit feeders, derived primarily from data collected during the GLOBEC years of 1995-1999, provide input to an upper food web. Diets of commercial fish populations are used to calculate food requirements in three fish categories, planktivores, benthivores and piscivores, for four decades, 1963-2002, between which there were major changes in the fish communities. Comparisons of inputs from the lower web with fish energetic requirements for plankton and benthos indicate that we obtained reasonable agreement for the last three decades, 1973-2002. However, for the first decade, the fish food requirements were significantly less than the inputs. This decade, 1963-1972, corresponds to a period characterized by a strong Labrador Current and lower nitrate levels at the shelf-edge, demonstrating how strong bottom-up physical forcing may determine overall fish yields.     

地理标签数据的获取与组织管理相关技术的研究

针对地理标签数据和地理标签数据平台的特点,采用主题爬虫技术与API接口技术相结合的方法进行地理标签数据的获取;利用谬值处理、重复事件处理,并构建基于主题和位置的层次结构等方法对地理标签数据进行处理;设计相应的存储模型。最后还通过相应的实验进行对比分析,以此来验证本文相关技术的优越性。     

崂山湾潮间带食物网结构的碳稳定同位素初步研究

通过对1993年8月和1994年2和5月在崂山湾潮间带采集的底栖生物碳稳定同位素组成(δ13C值)的分析,发现该区底栖动物的主要食物来源以δ13C值大致可划分为4类:水体中的颗粒有机质(POM)、底栖硅藻、大型底栖藻类和底泥中的有机物质(SOM).研究结果表明,底栖动物的碳稳定同位素组成与其所摄食的食物的碳稳定同位素组成有密切的关系,因此,底栖动物的碳稳定同位素组成可以用于研究其食物来源.碳稳定同位素数据证实,双壳类等滤食性动物的食物来源主要是POM;甲壳动物的δ13C值的范围较大,证明其食物来源的多样性;底栖硅藻是多数腹足类食物来源的相当重要组成部分.用碳稳定同位素示踪剂对该区底栖-水体耦合作用的初步研究表明,水体中的POM是底栖动物的重要食物来源,但底泥中有机质和底栖硅藻也是许多底栖动物食物来源的相当重要的组成部分.     

海洋信息资源目录服务系统设计初步研究

从目录服务的概念入手,针对海洋信息共享的特点,对基于元数据的海洋信息资源目录服务进行了初步研究。重点介绍了目录服务的体系结构、目录服务系统的功能设计和相关的关键技术,     

网络地理信息系统(WebGIS)的研究与应用

网络地理信息系统(WebGIS)是当前GIS技术热点,本文概述了WebGIS的基本特征和基本要求;分析了WebGIS的应用模型、客户端及服务器端的实现,最后引用了一个用Java实现的实例。     

广东省地籍数据库管理系统研究

将GIS技术、关系数据库技术、计算机及网络技术等信息技术引入地籍管理,旨在建立一个面向全广东省的城乡一体化的地籍数据库管理系统,实现地籍数据的多级联动、资源共享,形成标准统一、上下一致的无缝空间与属性地籍数据资源管理体系.