Epiphytic seaweeds and invertebrates associated with South African populations of the rocky shore seagrass Thalassodendron leptocaule — a hidden wealth of biodiversity     

《African Journal of Marine Science》2013,35(4):523-531

Seagrasses support a great diversity of epiphytic organisms. There are no detailed published accounts of algae and animals growing on seagrasses in South Africa. The seagrass Thalassodendron leptocaule (previously known as Thalassodendron ciliatum) is unique among southern African seagrasses in that it occurs on exposed rocky outcrops along the Mozambican and north-eastern South African coasts; most other seagrasses are restricted to sheltered bays and estuaries. Here we present accounts of species of flora and fauna identified growing epiphytically on this seagrass in northern KwaZulu-Natal. A total of 52 taxa of macroalgae and 204 species of macroinvertebrates were identified as epiphytic on South African T. leptocaule. The most frequently observed macroalgal epiphytes were predominantly Rhodophyta and were common among periodically exposed, intertidal and subtidal habitats. The crustose red coralline algae Pneophyllum amplexifrons and Hydrolithon farinosum were frequently observed, primarily on stems and leaves of the seagrass respectively. The most diverse groups of epiphytic invertebrates were Arthropoda, Annelida and Mollusca, which together comprised 76% of the macroinvertebrate species recorded. This seagrass species is evidently an important substratum and ecosystem that supports a hidden wealth of biodiversity.  相似文献   

Diversity of decapod crustaceans at the interface of unconsolidated seabed areas and rocky shores in tropical/subtropical Brazil     

《African Journal of Marine Science》2013,35(3):361-371

The decapod crustacean assemblages from unconsolidated seabed areas located near rocky shores in the Ubatuba region on the south-east coast of Brazil were analysed by investigating the abundance, richness, diversity and dominance of species. The relationships of the sediment and bottom-water temperature to total species abundance, richness and diversity were also evaluated. Monthly samples were taken from January 1998 through December 1999 at sites in Ubatumirim and Mar Virado. At each locality, three areas were defined as either ‘exposed’, ‘sheltered’ or ‘island’. The highest species abundance was found in the sheltered area of Ubatumirim and the exposed area of Mar Virado, and during autumn. At Ubatumirim, the highest richness occurred in the exposed area and the highest diversity near the island. At Mar Virado, the highest richness and diversity were found near the island. Autumn and winter collections yielded the highest richness but the lowest diversity. The higher diversities, which were measured near the islands and during spring and summer, were consequences of the greater evenness of the data. The areas with the highest diversity also had the most heterogeneous sediment composition, thus reinforcing the hypothesis that areas with more complex substrata support more diverse faunas.  相似文献   

Towards quantitative ecological risk assessment of elevated carbon dioxide levels in the marine environment     

Pepijn de Vries  Jacqueline E. Tamis  Edwin M. Foekema  Chris Klok  Albertinka J. Murk 《Marine pollution bulletin》2013

The environmental impact of elevated carbon dioxide (CO₂) levels has become of more interest in recent years. This, in relation to globally rising CO₂ levels and related considerations of geological CO₂ storage as a mitigating measure. In the present study effect data from literature were collected in order to conduct a marine ecological risk assessment of elevated CO₂ levels, using a Species Sensitivity Distribution (SSD). It became evident that information currently available from the literature is mostly insufficient for such a quantitative approach. Most studies focus on effects of expected future CO₂ levels, testing only one or two elevated concentrations. A full dose-response relationship, a uniform measure of exposure, and standardized test protocols are essential for conducting a proper quantitative risk assessment of elevated CO₂ levels. Improvements are proposed to make future tests more valuable and usable for quantitative risk assessment.  相似文献   

The projected impact of climate and land use change on plant diversity: An example from West Africa     

《Journal of Arid Environments》2013

In West Africa, plant diversity is threatened by future climate and land use change, however, synergistic forecasts for this area are lacking to date. We investigated the impact and the interplay of future (2050) climate and land use change on plant diversity in Burkina Faso, which covers the major bioclimatic gradient in West Africa. Thus, regions with different levels of species richness can be investigated. The LandSHIFT model was adapted for this study to derive novel future (2050) land use simulations. One-class support vector machines (SVMs) were performed with these land use simulations together with current and future (2050) climate projections at a 0.1° resolution. Our modeling results show that the flora of Burkina Faso will be primarily negatively impacted by future climate and land use changes. However, we found contrasting latitudinal patterns. The more humid regions in Southern Burkina Faso would be more affected in terms of species loss than the Sahel. Climate change is more important than land use change under the assumption of technological stagnation in the agricultural sector. Our results suggest that, in general, the plant diversity in dry and humid regions of the tropics might respond differently to climate and land use change.  相似文献   

The taxonomical and functional diversity of three groups of aquatic insects in rheocrene karst springs are affected by different environmental factors     

《Limnologica》2021

Karst springs represent valuable and often the most threatened habitats in the riverine landscape. Unlike other stream habitats, they have several specifics that determine their insularity in the river continuum, e.g., high seasonal thermal and chemical stability. The presented study aimed to find out the taxonomical and functional richness of three groups of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) in the Western Carpathians karst springs, as well as uncover the mechanism of the EPT community assembly. Low within-site species richness was generally found, however, there was high between-site diversity and thus high total diversity of the studied groups of benthic invertebrates as well. Species richness of the EPT community was higher in larger and colder springs: those with lower concentrations of CO₂ and Fe, as well as higher concentrations of SO₄²⁻. Analysis of functional richness, as well as functional dispersion, did not reveal any clear assembly mechanism in the spring EPT community; however, both analyses indicated a higher proportion of environmental filtering there. Unlike the taxonomic richness, the functional richness of the EPT community was significantly higher in small and medium springs with higher water temperatures, as well as in springs with the presence of deadwood. Between-site dissimilarities in the functional composition of EPT were significantly correlated with environmental differences of springs, which determined variables such as spring size and temperature, as well as the concentration of CO₂ and SiO₂.  相似文献   

北固山湿地植物群落特征及其物种多样性研究   总被引：15，自引：4，他引：15  

付为国  李萍萍  吴沿友  卞新民  陈歆 《湿地科学》2006,4(1):42-47

北固山湿地位于镇江市东北,由长江携带泥沙长期沉积形成,植被属原生裸地演替,植物种类丰富。但近年由于污染排放及渔民围网捕鱼,植被受到破坏,生态功能被削弱。采用样方法调查了镇江北固山湿地植物群落的组成,种类和外貌,并分析了其物种的多样性差异,从而为湿地的生态修复提供理论和技术依据。试验结果表明:群落物种组成较为丰富,有15科28属33种,但仅限于草本植物,生活型以地面芽植物和一年生植物占优势,物种出现频度上以D、C两个级别为主,表明群落内物种的分布较为均匀。从季相动态上看,季相明显,群落的优势种2~4月前是虉草(Phalarisarundinacea)单优种群,4~6月是虉草-芦苇(Phargnitescommunis)共优种群,6~11月是芦苇-酸模叶蓼(Polygonumlapathifolium)共优种群。随着基底高程的变化,植物呈现明显的平行于堤岸的带状分布,并形成区别明显的三个区域。其中,物种的丰度、多样性指数、群落的均匀度以及生物量均随基底高程的增加而增加,而生态优势度却随基底高程的增加减小。物种多样性指数受立地环境和人为因素的共同影响。其中,一定程度的人为干扰虽降低物种丰度,但由于其对优势种芦苇破坏较为严重,降低了群落的生态优势度而相应提高了群落的均匀度,最终对物种多样性指数有增加效应。在以上研究的基础上,提出了禁止污染排放及围网捕鱼等措施,并在裸露或物种稀少区域人工栽培土著物种以增加湿地生态系统物种的多样性和稳定性。  相似文献   

Pedodiversity: a controversial concept   总被引：8，自引：1，他引：8  

CHEN Jie  ZHANG Xue-lei  GONG Zi-tong  WANG Jun 《地理学报(英文版)》2001,11(1):110-116

1 Conceptual introductionSpatial soil variation is a fundamental notion of pedology, formally expressed in the hierarchical system of soil taxonomy and soil associations[1,2]. Since the 1990s, a Spanish research team led by Ibá?ez has been presenting a possible approach to systematically analyze taxonomic diversity of pedosphere by methods employed in ecological studies, drawing a parallel with the concept of biodiversity in ecology. According to Ibá?ez et al., it would be quite reasonable …  相似文献   

The community structure of a tropical intertidal mudflat under human exploitation   总被引：1，自引：0，他引：1  

de Boer  W. F.; Prins  H. H. T. 《ICES Journal of Marine Science》2002,59(6):1237-1247

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Predictability of Functional Diversity Depends on the Number of Traits     

ZHANG Zihao  HOU Jihua  HE Nianpeng 《资源与生态学报(英文版)》2021,12(3):332-345

Analysis of functional diversity, based on plant traits and community structure, provides a promising approach for exploration of the adaptive strategies of plants and the relationship between plant traits and ecosystem functioning. However, it is unclear how the number of plant traits included influences functional diversity, and whether or not there are quantitatively dependent traits. This information is fundamental to the correct use of functional diversity metrics. Here, we measured 34 traits of 366 plant species in nine forests from the tropical to boreal zones in China. These traits were used to calculate seven functional diversity metrics: functional richness (functional attribute diversity (FAD), modified FAD (MFAD), convex hull hypervolume (FRic)), functional evenness (FEve), and functional divergence (functional divergence (FDiv), functional dispersion (FDis), quadratic entropy (RaoQ)). Functional richness metrics increased with an increase in trait number, whereas the relationships between the trait divergence indexes (FDiv and FDis) and trait number were inconsistent. Four of the seven functional diversity indexes (FAD, MFAD, FRic, and RaoQ) were comparable with those in previous studies, showing predictable trends with a change in trait number. We verified our hypothesis that the number of traits strongly influences functional diversity. The relationships between these predictable functional diversity metrics and the number of traits facilitated the development of a standard protocol to enhance comparability across different studies. These findings can support integration of functional diversity index data from different studies at the site to the regional scale, and they focus attention on the influence of quantitative selection of traits on functional diversity analysis.  相似文献   

绿辉石角闪石玉——缅甸非翡翠玉新品种     

施加辛 《云南地质》2008,27(4):430-433

绿辉石角闪石玉是近来缅甸发现的一个非翡翠玉类的新品种。矿物成分主要为高压带的角闪石,不均匀分布少量绿辉石及蓝闪石。  相似文献