A Functional Analysis of the Benthic Macrofauna of the São Sebastião Channel (Southeastern Brazil)

Abstract.  The major problem in coastal areas of developing countries is disturbance caused by anthropogenic influence. This disturbance can be quantified by analysing the distribution and composition of marine communities using uni- and multivariate techniques and the biotic index. A study of benthic macrofauna was carried out along the São Sebastião Channel, northern coast of São Paulo State, Brazil, in an area with a submarine outfall, a petroleum terminal and a commercial harbour. Sampling was undertaken seasonally, by means of a van Veen grab (0.1 m²) at 15 oceanographic stations, from November 1993 to August 1994. A total of 392 species were identified (129 Polychaeta, 127 Mollusca, 98 Crustacea, 28 Echinodermata and 10 other phyla). The sedimentary pattern recorded for the São Sebastião Channel is very heterogeneous, influenced mainly by strong wind-driven currents, and differs from nearby shelf areas. The study area could be divided into three regions based on sediment texture and fauna: one region dominated by medium and coarse sand with low values of organic carbon; a second area where pelitic fractions were dominant with high values of organic carbon and nitrogen; and a third region characterised by fine and very fine sand, presenting intermediate organic carbon values. No temporal significant variation in abundance and species composition was found, except in autumn. The use of the 'marine Biotic Coefficient' showed the same ecological trend as the faunal abundance and demonstrated that the central continental region of the channel is affected by human activities.     

地史转折期的生态系

生态系的演变是地球各圈层系统耦合关系变化的直接标志。地史转折期的生态系具有复杂的生物内涵，在绝灭—残存—复苏过程中，各生物类别的演替遵循着一定的生存型式。大绝灭后生态系复苏的原动力是绝灭后迁入避难所的复活类型和大绝灭末期高压环境中产生的祖先类型的新生和辐射发展。全面了解绝灭后生态系的组成和结构，对于正确认识地史转折期，即圈层耦合结点处的地质作用型式和过程具有重要作用。     

中国晚泥盆世至早三叠世楔叶类植物多样性研究*

化石类群的分类单元多样性和形态多样性变化是生物宏演化的2个基本方面,而以往的研究对于后者的关注较少。晚古生代的楔叶类植物易于识别,化石记录丰富,但针对这一类群多样性演化的研究还较为缺乏。基于华北板块、华南板块晚泥盆世至早三叠世楔叶类植物属、种以及叶片形态编码数据库,对楔叶类植物宏演化历程进行详细研究。中国(华北板块和华南板块)楔叶类植物的属、种丰富度在晚古生代呈现出不稳定的持续增长,表现为晚泥盆世的初始兴盛、早石炭世杜内期至早二叠世萨克马尔期的缓慢上升、早二叠世萨克马尔期至晚二叠世吴家坪期的快速上升;晚二叠世长兴期,总体的属种多样性骤减;每百万年属种多样性在二叠纪—三叠纪之交亦有明显降低。华南板块楔叶类植物的属种多样性总体上小于华北板块,达到峰值的时间为卡匹敦期—吴家坪期,而华北楔叶类植物的属级多样性在空谷期—沃德期达到峰值。中国楔叶类植物叶片的形态多样性的剧烈变化与属种丰富度并不同步,表现为法门期至韦宪期较小,在宾夕法尼亚亚纪达到峰值,随后稍微下降并在二叠纪的大部分时段保持平稳。在晚古生代的叶片形态演化过程中,楔叶类植物的叶面积由小变大、叶片由深裂至不裂、叶尖形状由分裂变为圆形或钝圆、叶轮中的叶从大小相等到大小不等并出现叶镶嵌,这可能与当时植物群落中林下层光照强度的变化有关。     

Environmental limitations on recruitment from seed in invasive Spartina densiflora on a southern European salt marsh

The South American cordgrass, Spartina densiflora, has invaded a range of different habitats that can support different native species assemblages on salt marshes in the Gulf of Cadiz, Spain. Little is known about the mechanisms of invasion. We examined the potential for seed germination and recruitment in a field transplant experiment, representing a wide range of environments, on elevational gradients across marshes with muddy and sandy sediments. The biotic resistance of native, perennial vegetation (where present) to recruitment of the alien was also investigated. Spartina densiflora seeds were able to germinate over a greater than 2-m range of elevation in the tidal frame. Germination success on unvegetated muddy sediments was related to sediment redox potential, with poor germination at strongly negative redox potentials on the lower sites. On sandy, well-drained sediments, germination was apparently constrained by water availability at the highest elevations. Comparison of vegetated and cleared plots on the upper marsh showed that there was a negative relationship between the presence of Atriplex portulacoides and germination on the muddy sediments. Recruitment (survival of seedlings for 12 weeks) was seen only on unvegetated muddy sediments at the highest elevation. Hence the invasive success and wide elevational tolerance of S. densiflora on the marshes of the Gulf of Cadiz are not reflected in its short-term ability to become established from its prolific seed production. Colonization of sub-optimal habitats may be largely by vegetative propagules and clonal growth.     

Ecological quality of some Tunisian coast and lagoon locations,by using benthic community parameters and biotic indices

Three Tunisian coastal and lagoon sites, variously affected by human activities, and differing according to their degree of communication with the sea, were studied. The total organic matter content and the granulometry of the sediment were measured and the macro-invertebrates were sampled and identified. Currently due to the lack of an efficient single biotic index for quality assessment, indications from these measurements can contribute to enrich our knowledge of the southern Mediterranean areas. Several biotic indices (AMBI, BENTIX, BOPA, BOPA modified, I2EC, ITI), most of which have been used in the context of the European Water Framework Directive, and some other structural parameters were used. The results show that the Bizerte lagoon, an almost closed area characterized mainly by extreme salinity/temperature and with a strong fluctuation of nutrients, appears biologically more impoverished. The Dkhila coast, which is more open to the sea, however, appears to be less dominated by the principal species. Biotic indices showed that the most polluted areas included the region exposed to urban inputs of Bizerte, the mouth of Hamdoun wadi and the harbour areas. In these locations, benthic macrofauna is dominated by opportunistic species like Capitella capitata, Scolelepis fuliginosa, Prionospio malmgreni, Polydora sp., Cirratulus cirratus and Cirriformia tentaculata. Other stations, which are farther from the sources of disturbance such as the mouths of the principal Wadis, the south of the Bizerte ship canal and the south of the Tunis bay, appear to be in good ecological condition and hosted a variety of sensitive species, Other stations were classified differently by the biotic indices used mainly because of the lack of a real inter-calibration of the various classification methodologies used by these indices.     

Response of BITS (a benthic index based on taxonomic sufficiency) to water and sedimentary variables and comparison with other indices in three Adriatic lagoons

The European Water Framework Directive (WFD, 2000/60/EC) recommends the development of biotic indices for assessing the ecological quality status of water bodies. The Benthic Index based on Taxonomic Sufficiency (BITS) was specifically developed for lagoonal systems, according to the tolerant/opportunistic approach. Macrobenthic data, variables indicative of eutrophication and variables indicative of sedimentary organic matter quality were collected during 18 surveys carried out between 2004 and 2005 in three Adriatic coastal lagoons (Venice Lagoon, Sacca di Goro, Lesina Lagoon). The relationship between environmental variables and biotic indices (AMBI, BENTIX, BITS, BOPA and FINE) was tested using multivariate analyses. Indices based on species classification level appeared to relate better with the variables describing organic matter quality, whereas BITS, which is based on family classification level, seemed related to eutrophication indicative variables, such as sulphide, ammonium, dissolved oxygen and orthophosphate concentrations. The BITS approach reduces the costs associated with sorting and identification of organisms. Providing a rapid assessment of ecological quality, and producing an ecologically relevant classification, BITS seems a promising tool for monitoring programs of Adriatic lagoonal ecosystems. Its sensitivity in reflecting the field conditions elsewhere, however, remains to be assessed.     

海洋生态系统健康评价的底栖生物指数法研究进展

海洋大型底栖无脊椎动物能对自然和人为活动导致的水和沉积物质量变化做出可预测的响应,因此利用底栖生物作为海洋生态环境监测的生物指标和进行系统健康度量的生物指数已经得到了广泛的认可.本文比较分析了几种常用的和正在发展的海洋生态系统健康和生态环境质量状况评估的底栖生物指数,包括指示生物法、Shannon-Wiener多样性指数、BI指数、AMBI指数和Bentix指数,总结了这几种生物指数的应用和特性,探讨了底栖生物指数在实际应用中可能存在的问题和解决的办法,以期为我国海洋生态系统健康评估工作提供参考.     

赤潮影响因素研究进展

通过对赤潮发生的生物、化学、物理等影响因素研究现状的分析,认为赤潮生物是引发赤潮的内在因素,化学因素是赤潮发生的物质基础,而物理因素则是提供赤潮发生的环境条件。在赤潮生物存在的前提下,化学和物理因素都可以限制赤潮的发生,所以,将生物学、化学与物理海洋学耦合仍旧是赤潮研究需要解决的问题。在分析了现有研究状况的基础上,从不同角度提出了赤潮的研究方向。     

Biological structures as a source of habitat heterogeneity and biodiversity on the deep ocean margins

Biological structures exert a major influence on species diversity at both local and regional scales on deep continental margins. Some organisms use other species as substrates for attachment, shelter, feeding or parasitism, but there may also be mutual benefits from the association. Here, we highlight the structural attributes and biotic effects of the habitats that corals, sea pens, sponges and xenophyophores offer other organisms. The environmental setting of the biological structures influences their species composition. The importance of benthic species as substrates seems to increase with depth as the complexity of the surrounding geological substrate and food supply decline. There are marked differences in the degree of mutualistic relationships between habitat-forming taxa. This is especially evident for scleractinian corals, which have high numbers of facultative associates (commensals) and few obligate associates (mutualists), and gorgonians, with their few commensals and many obligate associates. Size, flexibility and architectural complexity of the habitat-forming organism are positively related to species diversity for both sessile and mobile species. This is mainly evident for commensal species sharing a facultative relationship with their host. Habitat complexity is enhanced by the architecture of biological structures, as well as by biological interactions. Colony morphology has a great influence on feeding efficiency for suspension feeders. Suspension feeding, habitat-forming organisms modify the environment to optimize their food uptake. This environmental advantage is also passed on to associated filter-feeding species. These effects are poorly understood but represent key points for understanding ecosystems and biodiversity on continental margins. In this paper we explore the contributions of organisms and the biotic structures they create (rather than physical modifications) to habitat heterogeneity and diversity on the deep continental margins.