Distribution of diatoms in the Northeast Water Polynya, Greenland

This study formed part of the Northeast Water project (NEW project) which dealt with physical, geophysical and biological processes in the Northeast Water Polynya off Northeast Greenland. This was part of the International Arctic Polynya Programme (IAPP). The diatom composition of the water masses, sea ice and melt ponds was analysed to show the relationship between ice and the water column near the ice with regard to the origin and fate of the cells in the ice and melt ponds. Fragilariopsis oceanica, Fragiliria sp. I and Chaetoceros socialis usually dominated the phytoplankton, while the ice and melt pond samples showed a wide range of assemblages, with different single-celled pennates and two undescribed species, Navicula sp. 1 and Nitzschia sp. 1 often dominant. Planktonic algae in sea ice can be released into the water column during ice break-up and melt, thus contributing to the spring bloom in the water column, if the timing of the release and the species composition are correct. The number of different ice algal assemblages supports the theory that cells originated from the water column, the benthos and freshwater. In addition, differential growth in the sea ice or melt ponds often altered the relative abundance of species in comparison with what is usually found in their original habitat. However, many of the cells in the ice and melt ponds were dead (empty frustules), making it difficult to determine whether the cells had actually lived in these habitats.     

Small scale retentive structures and Dinophysis

Despite its rarity, Dinophysis acuminata is in terms of economic impact, the first toxic algal species along the coasts of Western Europe. It is observed at low levels (< 20 cell l^− 1) all the year round but toxic events occur mainly in late spring and summer. D. acuminata ecophysiology is largely unknown due to the inability to culture it. Therefore, standard biomass models based on inorganic nutrition are largely inadequate. Presently, any progress in describing the conditions of population growth of this species will be a step forward to prediction of harmful events at the coast. This species has been observed at increased, albeit low cell densities in retentive eddies located in pycnocline layers. A concentration build-up of one species results from the balance between growth and loss processes, one of the latter being dispersal. The scales of interest for a D. acuminata population are of the order of 10 nautical miles on the horizontal and duration of 10 days, for a reported achievable growth rate of 0.6 day^− 1. A three dimensional (3D) hydrodynamical model of the Bay of Biscay has been elaborated to reproduce hydrological structures over the last decade. We attempt here to relate the existence of retentive structures revealed from simulations under realistic forcing conditions and the toxic coastal events recorded in the 10-year time series of the French plankton monitoring network database. The eddies in the coastal area appear to be directly related with the Dinophysis coastal events and they may be a potential effective tool to predict those.     

火花塞的种类及其应用分析

介绍13种类型的火花塞结构特点、性能;阐述火花塞既不“炽热”点火、又不“积炭”的热工作范围,以及火花塞选择的一般原则;分析火花塞选择不当的现象、原因;指出火花塞清洁、检查、调整的正确方法。     

解决船舶生物污损问题的国际统一方式

生物污损造成的环境生态破坏问题足近年来海洋环境保护工作者研究的热点问题,船舶的生物污损带来的外来物种入侵问题也引起了国际海事组织(International Maritime Organization,IMO)的高度关注.各成员国将在IMO的组织下为解决船舶生物污损问题制定国际统一的控制措施.通过对船舶牛物污损危害性的介绍,结合国外一些国家对生物污损问题的管理经验,并与压载水公约的立法过程进行对比,分析了IMO可能采取的立法措施,对我国航运业应采取的应对措施提出r意见和建议.     

基于生态种群理论的虚拟企业创新平台研究

为支持区域内企业的创新活动,方便企业之间的合作创新,构建虚拟企业创新平台是重要途径.在概括VEIP内涵与特征的基础上,针对VEIP与生态种群之间的相似性,分析了VEIP的种群特征,借鉴生态学中的Logistic增长模型,构建了单一创新群体的VEIP的成长模型.而对于有多个创新主体构成的VEIP,分析了不同创新主体之间的竞争和合作关系.研究发现,为实现VEIP的良性运转,VEIP要保持与外界的物质交流和信息交流,形成开放的生态系统;创新主体需要保持一定的差异性,形成功能完善的分工协作网络,使创新主体之间竞争与合作共存.     

海船压载水处理设备研发的重要性分析

通过对海洋污染及我国航运及造船业发展状况的分析,结合将要实施的相关公约,说明研发海船压载水处理设备的必要性,并介绍研发海船压载水处理设备的关键技术。对了解海船压载水处理设备原理有一定的借鉴作用。     

Topological constraints on the dynamics of wasp-waist ecosystems

Small pelagic fish species like anchovy or sardines are of high ecological and economical importance. As marine food webs are fished down, these small pelagics tend to be more exploited and overfished. It is not yet very well known what the possible effects of their collapse can be, therefore there is an urgent need to outline a theoretical framework for understanding their dynamics. These fish occupy very special position in food webs, ensuring energy transfer between species lower and higher levels, while forming narrow “wasp-waists” poor in number of species (but very abundant). Our purpose was to quantify the interaction structure of model food webs of equal complexity but different levels of “wasp-waistedness”. We analysed the topological properties of the webs by characterising every direct and indirect interactions between individual species, as well as by assessing the relative positional importance of each species in each web. We found that (1) the shorter the interaction pathways considered, the weaker the predictive power of node degree for positional importance, (2) the importance of species varies more in wasp-waist food webs, (3) if longer indirect chain effects are considered, indirect effects can well be stronger than direct ones, (4) interactions between coexisting wasp-waist species are stronger than the average, and (5) the “self-regulatory” looping effects are also stronger for wasp-waist species. Based on the topological properties of the networks, our results describe constraints acting on the dynamical behaviour of wasp-waist ecosystems. We give explanations, from this viewpoint, for regime shifts in which one WW species replaces another, and for the unpredictable dynamics of these fish stocks. From a marine conservation viewpoint, we illustrate that as the abundance of wasp-waist species decreases, the architecture of energy flows becomes highly vulnerable and unreliable. We provide an approach for quantifying these structural changes.     

International trade in marine species: Is CITES a useful control mechanism?

Abstract

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was created to prevent species becoming threatened through international trade. It generally prohibits international commercial trade in seriously threatened species but permits trade in a regulated manner in species vulnerable to exploitation but not yet at risk of extinction. CITES covers comparatively few marine taxa, reflecting the fact that most marine species have much greater ranges and fecundity than terrestrial species and so are more resilient to exploitation. Exceptions are to be found in the higher vertebrates. Several marine mammals may have benefited from CITES controls, although their popular appeal, commercial importance, and extreme vulnerability have meant that other treaties and conservation activities have been adopted to control their exploitation. Marine turtles Cheloniidae and the estuarine crocodile (Crocodylus porosus) certainly have benefited from CITES controls. Many commercially important fishes and invertebrates are covered by international and regional fishery agreements; a few, with life histories making them particularly vulnerable to exploitation, are subject to CITES controls. The structure of CITES limits its utility as a conservation tool for marine species, but where other mechanisms fail or are absent, it plays a useful role, and it is particularly valuable as an international trade monitoring mechanism.     

船舶压载水防治措施探讨

船舶压载水是外来海洋生物入侵的重要途径,严重危害水域生态平衡,破坏生物多样性,危害环境,造成严重的经济损失。本文针对压载水污染问题,从压载水的管理、处理技术、无压载舱船舶设计等方面,探讨压载水的预防途径和防治方法。     

Seasonal changes in the positional importance of components in the trophic flow network of the Chesapeake Bay

Community-level processes may shape food web structure. In this paper, a graph theoretical study of the weighted trophic flow network of the Chesapeake Bay ecosystem shows how important are positions in the energy (carbon) transport system. The positional importance of components is compared to the quantity of energy flowing through them. We suggest that the congruence between important network positions and large flows refers to the larger role of trophic interactions in community control. A seasonal dynamical analysis of the network has led us to the conclusion that winter is the season when the importance of predation is the highest.