广西的红树林资源及其开发利用

广西的红树林植物种类计有10科14属14种,现有红树林面积5654hm~2。红树林是广西的优势海洋资源之一,其动植物资源潜力大,生态景观旅游价值高,同时,是良好的生态养殖场所。受沿海经济发展和人口增加等因素的影响,红树林资源的破坏日益严重,如何合理利用红树林资源是一个必须认真研究的课题。     

渔业资源开发的生态经济系统分析

渔业生产的对象是渔业资源,渔业的动力即是社会对物质的需求和利润。渔业资源处在自然水体当中,它与环境之间不断地进行物质的交换,形成了自然生态系统。生物的再生产使系统在不断更新,同时也为人类的持续利用提供了条件。人类对渔业资源的开发利用,尽管最初以社会对物质的需求开始,但某     

基于克里格插值的绿华-三横海域渔业资源量空间分布的初步探讨

基于2007年5、9月,2008年7月,2009年3、5、7、10、12月渔业资源拖网调查数据,应用克里格插值法对绿华-三横海域的渔业资源量的空间分布进行了初步分析,得到如下结果:东库鱼礁区和三横鱼礁区聚集生物的作用是显而易见的;三横鱼礁区聚集生物的效果要相对强于东库鱼礁区聚集生物的效果;岛礁周围的渔业资源量分布特征是符合实际情况的。结果表明,应用克里格插值对绿华-三横海域的渔业资源空间分布的分析是可行的。     

An initial assessment of mangrove resources and human activities at Mahout Island,Arabian Sea,Oman

This study was initiated to provide information on mangrove structure, communities, wildlife, socio-economics and human impacts on one of the most important areas of mangroves in Oman at Mahout Island, located on the Arabian Sea coast. The island is fringed with a luxuriant vegetation of mangroves formed by Avicennia marina (Forsk.) Vierh. Tree height, diameter at breast-height (dbh) and basal area (m²) show progressive increases from the upper to the lower level of the shore. Density (number of stems/0.1 ha) is variable, showing three peaks in transects across western and southern mangroves. The northern mangroves are the most developed, characterized by muddy substrate, followed by the western on a sandy bottom, and the southern surrounded by rock-flat. The mangroves support a large number of fishes, shrimps, crabs and molluscs. Wildlife are represented by shorebirds, waterfowls, turtles and dolphins.The Mahout population consists of bedouins, mostly supported by fishing. It is semi-settled with seasonal migration in summer to large towns. Fishing activities are usually between September and May. Shrimps and fish are the main natural resources. Human impacts were identified and qualitatively assessed: overutilization of mangroves by woodcutting or livestock grazing; litter and pollution; killing of turtle and other wildlife; removal of benthic marine organisms; the proposed construction of a fishery harbor; and the potential of mariculture and tourism. Management, based on sustainable development, should be undertaken to protect Mahout resources.     

Diversity and distribution of the mangrove forests in Taiwan

In a survey of 1992 to 1994, mangrove forests withfour species of true mangroves, Kandelia candel(L.) Druce, Avicennia marina(Forsk.) Vierh.,Rhizophora stylosaGriff., and Lumnitzera racemosaWilld., were found at 22locations in the west coast of Taiwan. The northernrange of their distribution was at Tanshui Estuary(Latitude 25^°11N) and the southern range atTapen Bay (22^°28N). The total area wasestimated to be 286.95 ha. There was an obvious changein species composition and a decrease in speciesnumber of true mangroves from south to north: the fourspecies dominated by A. marinain thesouth and K. candelas thesole species in the north. Air temperature associatedwith sea surface temperature and oceanic currents inwinter, but not soil property, was found to be theprimary environmental factor, affecting the diversityand distribution of true mangroves in Taiwan as wellas in the northeast region of Asia.     

Porewater nutrient profiles and nutrient sediment–water exchange in a tropical mangrove waterway, Mapopwe Creek, Chwaka Bay, Zanzibar

Sediments were examined in the Mapopwe Creek, a tidally dominated mangrove waterway in the Chwaka Bay mangrove forest, Zanzibar, to assess their significance in the nutrient dynamics of the mangrove forest and the adjacent bay. Porewater concentrations of dissolved ammonium and that of soluble reactive phosphorus (SRP) were generally higher during the dry season than during the wet season. NO₃^? plus NO₂^? concentration averaged 1 µm and did not vary much between the two periods. Fluxes of ammonium ranged from ?575 to 523 µm m^?2 h^?1 and those of SRP from ?55.7 to 69.5 µm m^?2 h^?1. Measurements of NO_x did not show any consistent fluxes of this dissolved nitrogen species. Variations of flux rates between the two seasons were not significant even though there were small variations in the flux direction in both nutrients. Results imply that Mapopwe sediments are a source of NH₄⁺ but act as a sink for SRP.     

中国海洋渔业水域环境研究现状及展望

渔业水域环境是水生生物赖以生存、繁衍的最基本条件,优良的渔业水域环境是海洋渔业持续发展的物质载体与必然条件。近年来中国海洋渔业水域环境状况日趋严峻,依据海洋渔业水域监测数据,分析了中国海洋渔业水域环境的现状;概括了中国海洋渔业水域环境面临的主要问题及破坏原因;综述了海洋渔业水域环境保护及修复对策的研究现状,并对今后的研究工作提出了方向与内容上的展望。     

Origins of mangrove ecosystems and the mangrove biodiversity anomaly

1. Mangrove species richness declines dramatically from a maximum in the Indo-West Pacific (IWP) to a minimum in the Caribbean and Western Atlantic. Explaining this ‘anomalous’ biogeographic pattern has been a focus of discussion for most of this century. 2. Two hypotheses have been put forward to explain the mangrove biodiversity anomaly. The ‘centre-of-origin hypothesis’ asserts that all mangrove taxa originated in the IWP and subsequently dispersed to other parts of the world. The ‘vicariance hypothesis’ asserts that mangrove taxa evolved around the Tethys Sea during the Late Cretaceous, and regional species diversity resulted from in situ diversification after continental drift. 3. Five lines of evidence are used to test between these two hypotheses. First, we review the mangrove fossil record. Second, we compare modern and fossil distributions of mangroves and eight genera of gastropods that show high fidelity to the mangrove environment. Third, we describe species-area relationships of mangroves and associated gastropods with respect to area of available habitat. Fourth, we analyse patterns of nestedness of individual plant and gastropod communities in mangrove forests. Fifth, we analyse patterns of nestedness of individual plant and gastropod species. 4. All five lines of evidence support the vicariance hypothesis. The first occurrences in the fossil record of most mangrove genera and many genera of gastropods associated with mangrove forests appear around the Tethys Sea from the Late Cretaceous through the Early Tertiary. Globally, species richness in any given mangrove forest is tightly correlated with available area. Patterns of nestedness at the community and species-level both point towards three independent regions of diversification of mangrove ecosystems: South-east Asia, the Caribbean and Eastern Pacific, and the Indian Ocean region.     

东北地区药用苔藓植物资源及其开发利用前景

东北地区苔藓植物资源丰富 ,种类多 ,蕴藏量大 ,本文共记述了 4 6种药用苔藓植物 ,包括 6种苔类和 4 0种藓类 ,并对其生境、地理分布、药用功效等进行了初步讨论 ,认为东北地区药用苔藓植物资源具有巨大的潜在利用价值 ,而现有应用较为原始 ,应进行合理的开发与利用。     

Measurement of the diffusion coefficient for salt in salt flat and mangrove soils

Excluded salt accumulated at mangrove roots must be transported away from the root zone by diffusive processes, due to the low permeability of most mangrove soils. The diffusion coefficient for salt in mangrove soils determines the rate of this diffusive transport but has not been determined experimentally before. In this work we used a 12-month long-time series of salt concentration profiles measured in a sediment core over which fresh water was continuously circulated, to determine the diffusion coefficient for salt in the soil. Salt concentrations were measured using an electrical conductivity probe that was developed for use in hypersaline (salt concentration up to and in excess of 120g/l) conditions. A modified formula was experimentally determined to relate electrical conductivity to salt concentration and temperature, applicable up to a salt concentration of 200g/l. This was done because standard formulae relating these variables do not apply in the hypersaline conditions often encountered in salt flat sediments. The salt concentration profiles were used in a simple mathematical model to determine a sediment diffusion coefficient for salt in a salt flat sediment. This value of D=(4.6±0.2) ×10^–5m²/day was approximately half that calculated theoretically.     

Gelidium commercial exploitation: natural resources and cultivation

The state of the Gelidium agarophyte resource was last reviewed in 1990 during the First International Workshop on Gelidium. The main objective of the present study was to gather and analyse the new information made available since then, with emphasis on the G. sesquipedale resource from the Iberian Peninsula and Morocco. Other Gelidium-based resources world-wide are also reviewed, as well as new attempts to cultivate Gelidium species in the sea. In general, since the late 1980s, G. sesquipedale yields have decreased in Portugal, and increased in Spain and Morocco. Current reported values, in dry weights, are ca. 670 t yr-1 for Portugal (average 1995–1997), 5200 t yr-1 in Spain, and 6950 t yr-1 for Morocco (average 1994–1996). Efforts to develop cultivation of G. sesquipedale in the sea in Spain have yet to progress beyond the demonstration scale. Other important Gelidium-based agarophyte resources are located in: (i) South Africa where, in addition to G. pristoides, new species are being harvested, with total agarophyte landings of 140 t yr-1 in 1996; (ii) Mexico, where G. robustum harvest averaged 750 t yr-1 in 1987–1996; (iii) and Chile where harvest of Gelidium species yielded ca. 460 t yr-1 in 1990–1992. Preliminary research on new techniques for commercial cultivation of Gelidium species is also reported from these countries. This revised version was published online in June 2006 with corrections to the Cover Date.     

中国优势肥用植物资源潜力与利用

将中国优势肥用植物初步划分为富氮型、富钾型、富硅型、富硼型、高腐殖化型和综合型,并对其资源潜力进行分析。简要总结了中国肥用植物的利用现状,提出开发该类植物资源的意义、原则和有效途径,认为从稻草硅素生物有效性、肥用植物加工提取技术和优质商品肥方面加强研究,可实现优势肥用植物的高效利用,促进我国持续农业的发展。     

Demersal fish resources in the east china and yellow seas

Demersal fish resources in the East China and Yellow Seas were reviewed. A current and historical survey of the fishery was made. The distribution and migration of demersal fish were characterized, and an assessment of fishery resources was provided. The standardization of fishing efforts and resources management were also examined.     

The decomposition of mangrove litter in a subtropical mangrove forest

Decomposition of Avicennia marina (Forsk.) Vierh. leaf and woody litter (twigs) was studied using litter bag experiments in a subtropical mangrove forest at two tidal levels (high and low) with different inundation regimes and during two seasons (summer and winter). Losses in dry weight were best described by a single exponential model which showed loss rates of both leaves and twigs were significantly higher low down on the shoreline (greater inundation) and in summer. The time (days) required for the loss of half of the initial dry weight (t ₅₀) was summer: high 59, low 44; winter: high 98, low 78. For twigs the values (days) were summer: high 383, low 179; winter; high 1327, low 1207. There is an exponential relationship between leaf litter t ₅₀'s and latitude which indicates the importance of temperature and therefore season, to the dynamics of organic cycling and export in mangrove systems.     

Developing management plans for the mangrove forest reserves of mainland Tanzania

The mangroves of Tanzania are currently not being managed although they are legally gazetted as forest reserves. The management of this overexploited and under estimated natural resource rests with the Forest and Beekeeping Division in the Ministry of Natural Resources and Tourism. It is the Division's intention to conserve the mangroves of Tanzania, therefore steps are being taken to reach that goal. So far the Division, through its established mangrove project, has done an inventory of all the mangroves of mainland Tanzania with the assistance of NORAD. Aerial photography and ground checks were used to assess the state of all the mangrove reserves in the country. Literature search and a socio-economic study was also undertaken.The inventory revealed that the area covered by mangrove vegetation is 115 901 ha while the previous records indicate about 80 000 ha. If the bare saline areas, water bodies, and salt pans which are part of the mangrove reserves are included, the area amounts to 172 879 ha for the Tanzania mainland. The mangrove reserves have already been mapped in 30 sheets. Some sheets are mapped using a scale of 1:25 000 while others are mapped in 1:50 000 scale. The maps show the vegetation types, the area of each vegetation type, and the stand density and height of each compartment.The paper therefore presents the current status of the mangroves of Tanzania in respect to area, distribution and vegetation types. Included are the strategies being used to develop the mangrove management plans for Tanzania.     

The role of bacteria in nutrient recycling in tropical mangrove and other coastal benthic ecosystems

Sedimentary bacteria have generally been recognized as an essential food for protists and invertebrates, forming the base of benthic food webs. This trophic role has been well documented, but bacteria play an equally important role as mineralizers of organic detritus and recyclers of essential nutrients. Recent evidence suggests that this latter role is more important than their trophic function in tropical mangrove and coastal sediments. Bacteria in these systems are, on average, more abundant and productive than their counterparts in higher-latitude systems. They account for a disproportionate share of nutrient uptake to the extent that bacterial communities act as a sink for carbon, processing most of the energy and nutrients in tropical aquatic systems. Most bacteria remain unconsumed in tropical deposits, dying naturally and lysing, with the next generation of cells consuming, mineralizing and recycling this material either into new biomass or dissolved material. Bacteria in tropical aquatic sediments are ultimately controlled by inputs of dissolved and particulate detritus, natural mortality and recycling. To replenish damaged ecosystems in the tropics, restoration of the natural geochemical profile in the sediments is necessary to re-initiate the growth of bacteria in order to restore the essential recycling processes which assist in the conservation of nutrients.