Dynamics of Iron Oxides in Two Benchmark Inland Valley Soils and Rice Grain Yields in Nigeria

An investigation was conducted on two contrasting inland valley soils (Fluvauents and Tropaquents) over two cropping seasons (1993, 1994, and 1995) in two benchmark wetlands in Nigeria, and the contents and dynamics of iron (Fe) forms (active and organic) were examined when two different rice (Oryza sativa L) cultivars (‘ITA 212’ and ‘Suakoko 8’) were planted. Results showed that active Fe ranged between 0.96 and 3.16% on Fluvaquents and between 1.57 and 4.73% on Tropaquents; organic Fe, on the other hand, ranged between 0.05 and 2.84% (Fluvaquent) and between 0.60 and 2.38% (Tropaquents). Dynamics of the two Fe forms did not follow any clear pattern in the two cropping seasons on both soil types. On Fluvaquents, grain yields (GY) ranged between 2.40 and 3.46 t/ha (‘ITA 212’) and between 2.35 and 3.15t/ha (‘Suakoko 8’). Similarly, on Tropaquents, the GY ranged between 0.68 and 2.13 t/ha (‘ITA 212’) and between 0.61 and 2.11 t/ha (‘Suakoko 8’). Generally, the GY on Fluvaquents was higher than on Tropaquents and declined in the second cropping seasons. Results further showed that active Fe is significantly negatively correlated with GYs of rice. Critical active Fe and organic Fe contents for lowland rice on these soils were 2.90 and 1.80%, respectively.     

植物激素与木材形成

综述了植物激素在树木维管组织分化中的作用．生长素是调节木质部细胞分化的主要因子；细胞分裂素在诱导分生组织发端和分生细胞分化上起重要作用；赤霉素促进纤维的形成，赤霉素和生长素结合使用，可有效地促进次生木质部中纤维分化；乙烯能促进树木韧皮部和木质部分化。还讨沦了木材形成过程中的三个主要问题：生长素含量的多少直接控制了沿树轴木质部导管、管胞的大小和密度；外界环境因子影响木质部细胞分化；温带落叶阔叶树环孔材和散孔材形成的机理，生长素控制环孔材树种早材宽导管的形成以及晚材窄导管和纤维形成的假说。对今后改善树木木材的质和量上有一定参考价值。     

梨树和桃树新梢次生木质部细胞解离的比较研究

采用Joffrey氏离析法[1]对梨和桃各3个品种新梢次生木质部细胞解离,在扫描电镜下,清晰观察到梨各品种新梢次生木质部导管细胞为孔纹导管类型,而桃为螺纹导管类型;在光镜下观察了供试各品种的导管、管胞、纤维细胞的长度和直径。结果表明:梨的导管细胞长度为429.9～440.4μm,直径为29.9～31.6μm,而桃则为303.1～316.7μm和26.2～35.1μm。梨与桃表现了极显著差异;管胞和纤维细胞长度和直径也表现了显著和极显著差异。     

The influence of food availability on breeding success of African penguins Spheniscus demersus at Robben Island, South Africa

From 1989 to 2004, the breeding success of African penguins Spheniscus demersus at Robben Island, South Africa was significantly related to estimates of the abundance of both their main prey species, anchovy Engraulis encrasicolus and sardine Sardinops sagax, and to the combined biomass of these species. When the combined spawner biomass of fish prey was less than 2 million ton, pairs fledged an average of 0.46 chicks annually. When it was above 2 million ton, annual breeding success had a mean value of 0.73 chicks per pair. Given previously estimated values of survival and age at first breeding, these levels of breeding success are inadequate to sustain the African penguin population. With the higher level of breeding success, an equilibrium situation might be attained if adult survival could be increased by 6-7% per annum. Attempts to reduce mortality of penguins have included the collection, cleaning and return to the wild of oiled birds, culling of Cape fur seals Arctocephalus pusillus pusillus seen preying on penguins around breeding localities and control of the spread of disease. Management of the purse-seine fishery should ensure adequate escapement of fish to maintain the combined biomass of anchovy and sardine above 2 million ton. The maintenance of suitable breeding habitat and removal of feral predators from breeding localities will also be important in improving breeding success.     

Effects of human activities on migratory waterbirds at Lashihai Lake, China

Surveys on migratory waterbirds and their habitats at Lashihai Lake, China, were conducted from October 1999 to April 2000. Five fixed points, representing different degrees of habitat disturbance and quality, were selected around the lake. We used counts (n=30) to compare diversity and abundance of waterbirds at each point and evaluate the effects of habitat disturbance. The distribution of waterbirds was affected by disturbance, with more than one-third of the total species and nearly half of the total individuals occurring at the least disturbed point. Species richness was weakly and abundance was strongly correlated to habitat disturbance, but not to habitat quality. Habitat destruction and use of canoes were prominent at the lake. Naxi ethnic fishermen (n=37) were interviewed. They caught 570 waterbirds between October 1999 and March 2000 in fishing nets. An estimation of the total number of waterbirds been trapped on the lake is 6164. Diving species were most susceptible. Conservation measures that should implement immediately include the cessation of habitat destruction, better plan for the development of tourism, a reduction in the number of canoes and zoning of the non-fishing area.     

先秦时期珠江三角洲蛋人与西樵山文化关系初探

珠江三角洲蛋人是岭南最古老、最原始且沿续时间最长的土著族群之一。"西樵山文化"是先秦珠江三角洲蛋人创造的一种原始文化,他们从距今6000年前出现在珠江三角洲地区以来,一直过着渔猎、捕捞生活,固守着他们传统的生产、生活方式。文章认为,西樵山文化细石器主要是用于狩猎和纹身的工具,双肩斧、锛等石器是蛋人先民用于砍伐林木,建造船只、竹木筏及窝棚等的工具,较小型双肩斧、锛等石器是蛋人先民的生活用具,贝丘、沙丘遗址是蛋人先民临时性、季节性的陆上宿营地。     

Food organisms and feeding habits of larval and juvenile Japanese flounder Paralichthys olivaceus at Ohama Beach in Hiuchi-Nada, the central Seto Inland Sea, Japan

ABSTRACT:   The abundance of food organisms and feeding habits of larval and juvenile Japanese flounder were examined during the period from May to August in 1999, 2000 and 2001 at the sandy Ohama beach, the central Seto Inland Sea. The food organisms collected with a sledge net consisted of 40 families from 18 orders, dominated by mysids, crangonids and gammarids. The mean densities of mysids, crangonid shrimp ( Crangon spp.), gammarids and fish were 2.74, 6.74, 2.91 and 0.15 individuals/m², respectively. The main prey of the flounder ( n  = 202; range of total length 9.80–75.95 mm) was mysids and small crangonid shrimp (<14 mm in body length). Prey fish availability was low, as the density of fish was low. The small crangonid shrimp was abundant, and the large crangonid shrimp, which could prey on larval flounder, was not abundant. The crangonid shrimp was important not as a predator for the flounder but as prey. The flounder preferred epifaunal mysids, Nipponomysis ornata and Anisomysis ijimai , to sand-burrowing mysids, Iiella oshimai , and avoided crangonid shrimp.     

试论内陆河流域水资源费的构成与确定

内陆河流域水资源的分布特征与利用条件在不同地区间的显著差异性，以及生态环境体系的极度脆弱等特点，决定了其水价政策不仅要具有经济杠杆作用，体现所有者的经济利益，而且要能有效地调节水资源在上、中、下游，在经济发展和生态环境维护之间的合理分配，同时还应具有在时空及水质方面的可伸缩性。     

Effect of varying dietary protein levels on growth and production of Chanos chanos (Forsskal) in inland saline groundwater: laboratory and field studies

Two experiments were conducted to investigate the effects of varying dietary protein (35–45%) and energy levels (17.34–19.44 kJ g⁻¹) on the growth performance of milkfish (Chanos chanos) maintained under laboratory (experiment 1) and field conditions (Experiment 2) in inland saline groundwater. The results of experiment 1 (initial weight of fish: 0.25 g) revealed that, irrespective of the protein source (fish meal or processed full fat soybean), fish fed a diet containing 40% protein showed significantly (p<0.05) higher growth in terms of live weight gain and specific growth rate, low feed conversion ratio [1.71 (fish meal) and 1.58 (soybean)], high nutrient retention (gross protein retention: 28.59 and 31.05%; gross energy retention: 24.23 and 26.04%), apparent protein digestibility (81.74 and 85.91%) and digestive enzyme activity (specific protease and amylase). An observation on the postprandial excretion of metabolites (N–NH₄ and o–PO₄) indicated significantly (p<0.05) low levels of these metabolites in aquaria where the fish were fed 40% dietary protein irrespective of the protein source. The results of experiment 2 also indicate (initial weight of fish: 4.43 g) a significantly (p<0.05) higher growth performance (weight gain, biomass, specific growth rate, growth day⁻¹ and fish production) in ponds where the fish were fed 40% dietary protein. Irrespective of the experimental conditions (laboratory/field), feeding the fish higher dietary protein levels (beyond 40%) not only repressed growth performance but also affected proximate composition by lowering protein accumulation and energy assimilation. An investigation on the effects of feeds on water quality parameters revealed that values for total alkalinity, NH₄–N, NO₃–N, turbidity, total dissolved solids and parameters indicative of productivity (chlorophyll a, net primary productivity and plankton population) increased significantly (p<0.05) from treatments 1–3 (35–40% protein) and declined thereafter, in treatment 4 (42% dietary protein), indicating that water quality characteristics correlated well with fish growth. The results suggest that in order to obtain a high-yield in milkfish culture system the fish should be fed supplementary diets containing appropriate (40%) protein levels, especially when the stocking rates are high.