Grow-out culture of tropical abalone, Haliotis asinina (Linnaeus) in suspended mesh cages with different shelter surface areas

Thisstudy investigated the effects of shelter surface area (SSA) on the feeding,growth and survival of the donkey-ear abalone, Haliotisasinina reared in mesh cages (0.38×0.38×0.28m) suspended in flow-through tanks (water volume = 6m³). Cages had sections of polyvinylchloride (PVC) thatprovided shelters with surface area of 0.22 m², 0.44m² and 0.66 m².Hatchery-produced abalone with initial shell length of 32 ± 1mm and wet weight of 7.5 g were stocked at 50individuals cage^–1 that corresponded to stocking densities ofca. 227, 113 and 75 abalone m^–2 of SSA. The ratios of sheltersurface area to cage volume (SSA:CV) were 5.5, 11 and 16.5. Abalones wereprovided an excess red seaweed Gracilariopsis bailinae(= Gracilaria heteroclada) at weekly intervals overa 270-day culture period. Feeding rates (18–20% of wet weight), foodconversion ratio (26–27) and percent survival (88–92%) did notdiffer significantly among treatments (p > 0.05). Body size at harvest rangedfrom 56 to 59 mm SL and 52 to 57 g wet body weightwith significant differences between abalone reared at SSA 0.22m² and 0.66 m² (p < 0.05).Abalone reared in cages with 0.66 m² SSA grewsignificantly faster at average daily growth rates of 132 m and188 mg day^–1. Stocking densities of 75–113m^–2 SSA in mesh cages suspended in flow-throughtanks resulted in better growth of abalone fed red seaweed.     

Drivers of spontaneous and cultivated species diversity in the tropical city of Zhanjiang,China

Urban plant diversity influences the social functioning and well-being of urban dwellers. However, the patterns and drivers of plant diversity in tropical urban areas are still not entirely understood. In response to the knowledge deficiencies in this area, we investigated spontaneous and cultivated plant richness and their phylogenetic diversity and relatedness in 260 Urban Functional Units (UFUs), which represented nine different land use types according to anthropogenic function, in the tropical coastal city of Zhanjiang, China. Plant diversity was modelled as a function of UFU characteristics and human maintenance practices. Spontaneous species richness was highest in urban villages and vacant lands and lowest in transportation areas, while phylogenetic diversity was highest in utilities and lowest in parks. In comparison, cultivated species richness was highest in multi-family residential areas and lowest in vacant lands, while phylogenetic diversity of cultivated species was highest in commercial/industry areas and lowest in agriculture areas. The number of cultivated species and the degree of phylogenetic relatedness of spontaneous species were positively correlated with the human population density. The phylogenetic diversity of cultivated species within UFUs was generally higher than that of spontaneous species. Human maintenance of landscapes acted as an environmental filter for spontaneous species, but also promoted the number of cultivated plants. We conclude that appropriate investment in urban green areas may improve both plant species richness and phylogenetic diversity in urban environments.     

Climate shapes the novel plant communities that form after deforestation in Puerto Rico and the U.S. Virgin Islands

Environmental and past land use controls on tree species assemblages on the Commonwealth of Puerto Rico and the U.S. Virgin Islands were characterized to determine whether biophysical factors or land-use history has been more important in determining the species composition of secondary tropical forests after large-scale forest clearing for agriculture, widespread species introduction, and landscape-scale forest fragmentation. Post-deforestation, secondary forest assemblages are comprehensively described, both as broad general assemblages and island-specific variations by calculating species importance values from forest inventory data. Hierarchical clustering and indicator species analysis defined species assemblages, and then correlations between species assemblages and environmental variables were explored with non-metric multidimensional scaling, analysis of variance and χ² testing. These assemblages are arrayed along environmental gradients of decreasing spring moisture stress, decreasing maximum temperatures, and increasing minimum temperatures. Land-use history is not as important to determining variation in species composition across climatic zones, although several species assemblages are associated with certain geology types or land-use histories. Naturalized tree species are prominent in these secondary forests and contribute to the formation of some novel assemblages, but native late and early successional species also colonize former agricultural land, all influenced by the degree of disturbance. We conclude that environmental factors have an overarching effect on forest species composition across the broader range of climatic, geologic and topographic conditions and larger geographic scales, while land-use history influences subtropical secondary forest species assemblages within a specific climatic zone or set of relatively narrow environmental conditions.     

Effect of housing conditions (clean vs. dirty) on growth performance and feeding behavior in growing pigs in a tropical climate

The effect of bad sanitary conditions on growth performance and feeding behaviour were studied on a total of 48 Large White pigs between 95 and 130 d of age. This experiment carried out during the hot season in a tropical humid climate. Two groups of 12 pigs each were housed in a clean environment in which the pens were disinfected thoroughly prior to stocking and maintained in a clean state by daily washing the pens and by weekly emptying the manure stored beneath the partial concrete floor. The dirty environment was achieved by not cleaning the pens prior to stocking or throughout the experiment and by storing the manure beneath the floor slats throughout the experimental period. The microbial pressure was increased by introducing 5 additional non experimental pigs near each experimental dirty pen. Feeding behaviour parameters were measured using automatic feed dispensers. Pigs housed in a clean environment consumed more feed (2.283 vs. 1.953 kg/d; P < 0.001) and grew faster (871 vs. 780 g/d; P < 0.05) than those housed in the dirty environment. No significant effect on treatment was reported for the feed conversion efficiency (2.70 kg/kg on average). The reduced average daily feed intake in dirty pens was associated with a reduction of the meal size (334 vs. 282 g/meal; P = 0.10) whereas the meal frequency was not affected by treatment (7.5 meals/d on average). The rate of feed intake was significantly higher in the clean than in the dirty environment (34.0 vs. 29.9 g/min; P < 0.05).     

西双版纳热带雨林次生林的生物养分循环

本文获得了西双版纳热带雨林，砍伐后２块处于恢复演替阶段不同年代的次生林的生物量、生长量、年凋浇物量及它们的主要营养元素含量、对土壤养分状况的影响、以及土壤微生物状况和土壤生化活性等一系列资料。阐明了次生林生物物质和养分吸收、积累和归还的特点及对土壤养发状况的影响，研究了土壤微生物对凋落物的分解作用，从而对热带雨林次生林的生物养分循环作了一初步的探讨，为热带森林生态系统研究奠定了基础。研究表明：１．     

热带地区植物内生真菌生物多样性研究进展

植物内生真菌是指在其生活史的一定或全部阶段生活于健康植物体内部的真菌。内生真菌具有重要的生物学和生态学作用。简要介绍了热带地区植物内生真菌研究概况、资源多样性、寄主选择,并对热带内生真菌生物多样性的发展前景作了分析。     

Mineral Nutrition and Fertilization of Native Tree Species in Brazil

Abstract

In this review article, the progress of Brazilian research on mineral nutrition and fertilization of native tree species is discussed, taking as reference the scientific knowledge regarding the exotic species of the genera Eucalyptusand Pinus. There is a great knowledge gap in the theoretical base needed to develop technologies on nutritional management of native species. The high diversity of species, with variable or unknown responses to nutrient supply, makes difficult to set up a standardized and efficient fertilizer recommendation. Nevertheless, taking into account the successional groups and the growth rate of species, it is possible to discriminate the levels of nutritional requirements and to define differential management strategies of fertilization. Relevant aspects for future research on this line are also suggested.     

Nitrification and nitrifying potential of tropical and subtropical soils

Summary Nitrification was measured in five different soils (slate alluvial soil, sandstone shale alluvial soil, sandstone shale and slate alluvial soil, red soil, and Taiwan clay). In these soils different lag periods were recorded before the onset of nitrification. Nitrifying activity was highest in sandstone shale alluvial soil and the lowest in acidic red soil. A part from those in the red soil, the numbers of nitrifying bacteria detected were all higher than numbers reported in temperate soils. However, there were no clear relationships between the numbers of nitrifying bacteria and the rate of nitrification in these soils. When soil cores were incubated for 3 weeks, no NO _inf2 ^sup- or NO _inf3 ^sup- was defected in the slate alluvial soil. This was ascribed to denitrification.     

Nest predation in a fragmented Afrotropical forest: evidence from natural and artificial nests

Nest predation accounts for a substantial share of nest failure and low reproductive success in most tropical songbirds. Normally, forest fragmentation leads to an increase in nest predation pressure due to reduced cover, fewer (and poorer) nest sites and predator influxes from the surrounding habitats. To test this hypothesis, we studied natural nesting behaviour and nest success of the white-starred robin (Pogonocichla stellata) in seven Afrotropical forest fragments differing in size and level of habitat disturbance. Based on data from 12 nests, we estimate that 29% of all natural nests initiated by the robins survive to produce fledglings across all fragments. We also conducted an experiment using artificial (plasticine) model-eggs to reveal potential predators and compare relative predation rates amongst fragments. This experiment revealed that small mammals might be the major predators on robin nests at the egg-stage. In addition, it showed that the highest incidences of nest disturbance during this stage were in the most heavily disturbed fragment. This was presumably attributable to an influx of mammalian predators from the surrounding habitats as forest degradation created suitable habitats for them. Such an infiltration was recently reported in this study site. Both nest placement and microhabitat did not significantly affect depredation levels in our experiment. This suggests that depredation was predominantly incidental (i.e., predators mainly encountered nests fortuitously while foraging for other food items), where the likelihood of encountering a nest largely depended upon the prevalence of the principal potential predators - the small mammals.     

热带中西太平洋大眼金枪鱼的繁殖生物学特性

利用漂流金枪鱼延绳钓作业方式,于2018年6月~2019年3月对热带中西太平洋海域(WCPO,2°03''S~11°17''S,163°14''E~173°35''E)的大眼金枪鱼(Thunnus obesus)进行了取样,对其中886尾进行了繁殖生物学测定。使用广义线性模型(GLM)和有序多元Logistic回归模型,结合圆形统计方法,分析个体叉长等生物因素、渔获水深和月度等时空因素对繁殖生物学参数的影响。结果表明: 雄性和雌性平均叉长分别为132.2(±19.1) cm和125.4(±16.8) cm;取样群体中,雌雄比为0.54(±0.74),且叉长与雌雄比具有负相关关系(r=0.323, P =0.003),叉长大于140 cm后,雄性占主导;GLM模型结果显示,性腺指数(GSI)与叉长之间存在显著的二次方关系(P<0.001),即个体GSI随着叉长增加,当雄性和雌性叉长分别达到130~140 cm和140~150 cm后GSI随叉长下降;基于圆形统计发现,月度对个体GSI具有显著影响,其中雄性GSI上半年较下半年高(正弦显著,P<0.001),而雌性GSI年末和年初高于年中(余弦显著,P=0.021);有序多元Logistic模型结果显示,性腺成熟度随叉长显著增加(P<0.001),雄性性腺成熟度在5~7月较高(余弦显著,P=0.004);此外,栖息水层对雄性个体的性腺成熟度具有显著的影响(正相关,P<0.001);雄性和雌性个体50%性成熟叉长分别为96.13(?1.24) cm和104.93(?2.60) cm。研究结果为更好地了解热带WCPO大眼金枪鱼的繁殖生物学特征、科学养护热带WCPO大眼金枪鱼资源提供参考。