This research investigates the influence of environmental parameters that are known to affect bdelloid rotifer species richness and composition in temperate zones on the genus Rotaria in tropical zone. Our study analysed species richness and composition of the genus Rotaria from 390 samples collected from several types of aquatic habitats in Thailand. Coordinates, elevation, limnological parameters such as water temperature, conductivity, total dissolved solids, salinity, dissolved oxygen and pH were measured. A total of nine species was recorded. Of these, one species, Rotaria macrura (Ehrenberg, 1832), was a new record for Thailand and new to the oriental region, and was a yet undescribed species, Rotaria sp. The species diversity of this genus increased from eight to 10 species. The presence or absence of the genus Rotaria was significantly influenced by dissolved oxygen and habitat type. For the samples where the genus occurred, species richness was not affected by any of the limnological or bioclimatic variables. Differences in species composition were affected only by habitat type. The results support former suggestions that common abiotic parameters do not seem to strongly influence diversity in bdelloids, whereas major ecological differences between habitats influence bdelloid occurrence.

Integrated crop–livestock systems in the tropical region are diverse and not well characterized. To better understand the conditions and potential of these systems, we characterized the spatial and social arrangement of integrated systems within a landscape context. Integrated systems are defined by biomass and nutrient flows, linking crop, livestock and human components of agriculture. The landscape is defined within a spatial framework of these flows. To understand the diversity of integrated systems in the tropics, we characterized three case study areas: Southern Mali, Brazilian Cerrados and Amazon frontier. Methodology was based on historical and descriptive approaches of these cases, mobilizing interdisciplinary knowledge of a large research team. This provided a retrospective view to discuss four key points about the future of integrated systems in the tropics: (i) importance of landscape structure for conception and adaptation of the integrated systems; (ii) key role of local institutions in managing such integrated systems; (iii) trade-offs between external and internal resources; and (iv) role of nitrogen to improve system efficiency. This paper concludes with the relevance of social sciences in the further development of integrated systems.

The assemblage structure of harpacticoid copepods inhabiting the soft sediments of littoral and sublittoral areas of Cat Ba archipelago (South China Sea) is analysed. Three basic types of harpacticoid taxocenes were observed in the upper sublittoral. Main dominant species of taxocenes were Amphiascoides sp., Stenhelia latioperculata, Paramphiascella sp., Phyllopodopsyllus sp., Tisbe sp.1 and Amphiascoides sp. In addition, the main characteristics of harpacticoid species composition in littoral rock pools are described. A comparative analysis of shallow-water harpacticoid communities from different biotopes of the tropical region is presented, and shows that harpacticoid diversity and abundance are lowest in muddy sediments. Highest diversity and abundance are found in washed sands and silty sands with detritus. In general, the structure of muddy bottom communities is the most homogeneous throughout the tropics. Mangrove forests have no significant influence on harpacticoid taxocene structure. Harpacticoid associations of washed sands and silty sands with detritus demonstrate greater diversity and are region-specific.