Fitness‐related consequences shed light on the mechanisms of covering and sheltering behaviors in the sea urchin Glyptocidaris crenularis          下载免费PDF全文

Chong Zhao  Zhenmin Bao  Yaqing Chang 《Marine Ecology》2016,37(5):998-1007

We know of no comparative assessment on the benefits and costs of long‐term covering and sheltering behaviors in sea urchins. The present study investigated the long‐term effects of conditions suitable for sheltering and covering behaviors on fitness‐related traits of sea urchins Glyptocidaris crenularis. In general, conditions suitable for covering and sheltering behaviors significantly affected the fitness‐related traits of G. crenularis in a long‐term laboratory study of 31 months. Glyptocidaris crenularis kept in conditions suitable for sheltering behavior (bricks with openings) showed significantly lower test size, body weight, organ (test, lantern, gonad and gut) weights, gonad index and slower gonad development than those kept in conditions suitable for covering behavior (presence of shells) and the control conditions (without conditions for covering and sheltering). However, the index of maximum pressure resistance of the test was significantly higher in G. crenularis kept in the sheltering conditions than those in the covering and control conditions. The present study provides new insight into the mechanisms of covering and sheltering behaviors and has implications for the conservation and aquaculture of sea urchins.  相似文献   

Community ecology of the metazoan parasites of snoek Thyrsites atun (Euphrasen, 1791) (Perciformes: Gempylidae) off South Africa     

MAI Nunkoo  CC Reed  SE Kerwath 《African Journal of Marine Science》2016,38(3):363-371

The parasite assemblage of snoek Thyrsites atun, a commercially important fish in the Benguela system, was examined over a one-year period. In all, 16 parasite taxa including eight new host records (Bolbosoma vasculosum, Caligus coryphaenae, Caligus dakari, Corynosoma australe, Hatschekia conifera, Nothobomolochus fradei, Rhadinorhynchus cadenati, Tentacularia coryphaenae) and four new locality records (B. vasculosum, C. dakari, Molicola uncinatus, Pseudoterranova sp.) were recovered from 210 specimens. The dominance of larval helminths in the component community suggests that T. atun occupies an intermediate position in the food web. The ‘nestedness metric based on overlap and decreasing fill’ (NODF) indicated that the parasite assemblage exhibited no nestedness (NODF = 73.3, p = 0.103). Generalised additive mixed modelling results indicated that host length is the main determinant of parasite species richness in T. atun. PERMANOVA and ANOSIM suggested that infracommunity structure varied little with respect to the sex, length, seasonality and capture region of the host. The stability and randomness in parasite acquisition, as indicated by the lack of nestedness of the parasite assemblage, can be ascribed to the opportunistic feeding behaviour and nomadic movement of T. atun in the southern Benguela. The homogeneity of the community structure of long-lived endoparasites suggests that a single T. atun stock occurs off South Africa.  相似文献   

Latent spatio-temporal activity structures: a new approach to inferring intra-urban functional regions via social media check-in data   总被引：1，自引：0，他引：1  

Ye Zhi  Haifeng Li  Dashan Wang  Min Deng  Shaowen Wang  Jing Gao 《地球空间信息科学学报》2016,19(2):94-105

Abstract

This article introduces a novel low rank approximation (LRA)-based model to detect the functional regions with the data from about 15 million social media check-in records during a year-long period in Shanghai, China. We identified a series of latent structures, named latent spatio-temporal activity structures. While interpreting these structures, we can obtain a series of underlying associations between the spatial and temporal activity patterns. Moreover, we can not only reproduce the observed data with a lower dimensional representative, but also project spatio-temporal activity patterns in the same coordinate system. With the K-means clustering algorithm, five significant types of clusters that are directly annotated with a combination of temporal activities can be obtained, providing a clear picture of the correlation between the groups of regions and different activities at different times during a day. Besides the commercial and transportation dominant areas, we also detected two kinds of residential areas, the developed residential areas and the developing residential areas. We further interpret the spatial distribution of these clusters using urban form analytics. The results are highly consistent with the government planning in the same periods, indicating that our model is applicable to infer the functional regions from social media check-in data and can benefit a wide range of fields, such as urban planning, public services, and location-based recommender systems.  相似文献   

氟利昂R12及其替代物的分子构型和特征光谱研究     

李静  刘玉柱  程启源  陈飞  林华  秦朝朝 《南京气象学院学报》2016,8(4):327-332

采用密度泛函理论对氟利昂R12及其替代物R134a在B3LYP/6-311G++（d,p）基组水平上进行结构优化和特征光谱计算.首次在该高精度基组下优化得到了R12和R134a的键长、键角和二面角等分子构型参数,且通过进一步的计算,得到了这两种分子的红外光谱和拉曼光谱.其中R12红外光谱的计算结果与美国国家标准局数据库（NIST）提供的实验结果基本吻合,说明了计算结果的准确性.另外通过从头算CIS方法对能量进行计算,得到了R12和R134a的紫外可见吸收光谱.计算结果可为进一步保护大气臭氧提供有用的数据参考.  相似文献   

A simple predator-prey model of exploited marine fish populations incorporating alternative prey     

Spencer  Paul D.; Collie  Jeremy S. 《ICES Journal of Marine Science》1996,53(3):615-628

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Seasonal Variation in Host Utilization of Epiphytic Lacuna Species in Mixed Algal and Surfgrass Stands in Japan     

Makoto Kanamori  Seiji Goshima  & Hiroshi Mukai 《Marine Ecology》2004,25(1):51-69

Abstract.  On the subtidal rocky shore of Akkeshi Bay, Hokkaido, Japan, the congeneric phytal gastropods, Lacuna uchidai and L. decorata , inhabit the multispecific vegetation consisting of the surfgrass, Phyllospadix iwatensis and the brown alga, Cystoseira hakodatensis . We studied the phenologies of Phyllospadix and Cystoseira , host utilization patterns and life histories of Lacuna spp. to examine how these gastropods accommodate the seasonal fluctuations of the habitat. The preferences for macrophyte by Lacuna spp. were examined by laboratory experiments. The phenologies of macrophytes, the seasonal and between-substrata variations of Lacuna spp. were examined by monthly sampling from Phyllospadix and Cystoseira beds between May 1999 and May 2000. Lacuna uchidai showed significant preference for Phyllospadix , whereas L. decorata had no preference for a particular substratum. Most L. uchidai were collected from the Phyllospadix bed, however L. decorata appeared in both Phyllospadix and Cystoseira beds. The peak of new recruit of L. uchidai coincided with that of Phyllospadix biomass. The synchronization of life cycle with the phenology of the host may be adaptive for using the limited habitat. Seasonal variation in density of L. decorata coincided with neither patterns for Phyllospadix nor Cystoseira . Seasonal variation in density and size frequency distribution suggested L. decorata migrated among adjacent macrophytes. Although it was a little vague, this hypothesis was probably the best explanation of our results. Our study shows that two co-occurring Lacuna species utilize the macrophytes as habitats by the different life histories and utilization patterns and, may be alternatively accommodated to the seasonal fluctuations of their habitats.  相似文献   

浙江乐清湾海岸带功能区划分与海洋产业发展   总被引：7，自引：0，他引：7  

李春平  张灵杰  董丽晶 《海洋通报》2003,22(5):38-43

乐清湾为浙江省重点海湾之，资源的多宜性与不同行业开发利用的矛盾冲突是当前海湾可持续发展面I临的主要障碍。本文从乐清湾海岸带地区的自然环境与社会经济条件出发，探讨了开展海岸带功能区划的必要性，提出了区划的基本方案。在分析乐清湾海岸带地区海洋产业发展现状与问题的基础上，运用层次分析法研究了该湾近期海洋产业的发展方向与主导产业。最后，讨论了实现海洋产业协调发展的若干对策与建议。  相似文献   

Quantitative traits correlative analysis and growth comparison among different populations of bay scallop,Argopecten irradians   总被引：5，自引：0，他引：5  

LIU Baozhong  LIANG Yubo  LIU Xiaolin  DONG Bo  XIANG Jianhai 《海洋学报(英文版)》2004,23(3):533-540

The shell traits and weight traits are measured in cultured populations of bay scallop, Argopecten irradians. The results of regression analysis show that the regression relationships for all the traits are significant (P<0.01). The correlative coefficients between body weight, as well as tissue weight with shell length, shell height and shell width are significant (P<0.05). But the correlative coefficients between the anterior and posterior auricle length with body weight as well as tissue weight are not significant (P>0.05). The multiple regression equation is obtained to estimate live body weight and tissue weight. The above traits except anterior and posterior auricle length are used for the growth and production comparison among three cultured populations, Duncan's new multiple range procedure analysis shows that all the traits in the Lingshuiqiao (LSQ) population are much more significant than those of the other two populations (P<0.01), and there is no significant difference between the Qipanmo (  相似文献   

Limiting similarity, niche filtering and functional diversity in coastal lagoon fish communities     

David Mouillot  Olivier Dumay  Jean Antoine Tomasini 《Estuarine, Coastal and Shelf Science》2007,71(3-4):443-456

The fundamental idea behind the study of biodiversity patterns is the presumed connection between the shape of species assemblages and the functional ways in which they are organized, this functional organization referring to how species are related to one another, as competitors or members of a web of interactions and to how species are facing similar environmental constraints. Amongst the different facets of biodiversity, functional diversity is certainly a key for ecosystem processes in coastal areas. However, surprisingly, patterns of functional diversity have received little attention until now. After presenting a common framework linking functional diversity patterns to species coexistence theories, the aim of our study was twofold: (1) to seek assembly rules in brackish lagoon fish communities drove by functional traits. To this aim we used null models to examine the influence of two opposing forces acting on community structure: interspecific competition that might prevent the coexistence of the most similar species, and environmental filters that might result in the most similar species to coexist. (2) To seek relationships between fish functional diversity and environmental gradients, if any. Fish sampling was carried out in two coastal lagoons where stations differ considerably in terms of physicochemical parameters. Using morphological functional traits, functional diversity of fish communities was estimated using two recently published indices as well as a new proposed index. Firstly our study was not able to demonstrate a limitation of similarity in coexisting lagoon fishes due to interspecific competition. Conversely our results support the niche filtering hypothesis preventing species too dissimilar from one another to co-occur at the same station. Secondly, salinity was positively related to the functional diversity of fishes in both lagoons suggesting that within species assemblages near the channel species are less redundant than at stations far from the channel where species tend to be functionally similar (benthic and eating zooplankton).  相似文献   

N阶中立型泛函微分方程新的振动准则     

夏青 《中国海洋大学学报(自然科学版)》2001,31(3):448-454

作者对一类N阶中立型泛函微分方程给出了新的区间振动准则。文中的结果推广和改进了由Lalli等人得到的广义Kamenev型准则及其它已知结果。  相似文献