Departure behaviour of juvenile southern bluefin tuna (Thunnus maccoyii) from southern Western Australia temperate waters in relation to the Leeuwin Current

The arrival of the warm tropical Leeuwin Current (LC) into southern Western Australia (SWA) may influence the movement timing and foraging habitat of juvenile southern bluefin tuna (SBT). Seasonal and interannual changes in the strength of the LC lead to thermal differences and potential changes in food availability between tropical and temperate waters in SWA. This phenomenon could influence the habitat utilization of SBT in these summer grounds. Movement characteristics determined from SBT tagged with acoustic transmitters (N = 244) using cross‐shelf lines of automated receivers for three summer‐autumn seasons (2004/2005, 2005/2006, 2006/2007) in SWA revealed interannual variability. Each year, the eastward movements of tagged fish increased as temperatures increased, and fish left the region when temperatures exceeded 20.0°C, a temperature indicative of the leading edge of the LC in SWA waters. Interannual fluctuations in the timing of movements were detected. When the LC was narrow and restricted to the shelf edge in 2004/2005, the distribution of SBT in shelf waters did not change before or after LC intrusion. In contrast, long distance eastward movements frequently occurred when the LC intrusion was spread wide over the continental shelf in 2005/2006 and 2006/2007. This suggests that, off SWA, juvenile SBT move quickly out of local foraging habitats defined by cool sub‐tropical temperate waters ahead of the tropical LC intrusion, despite these waters not being physiologically limiting. These results suggest that the behavioural response of SBT may be related to changes in prey availability as a result of changes in oceanographic conditions.     

日本知床半岛海域细鳞大马哈鱼和大马哈鱼的移动生态调查

在北海道知床半岛周边海域,用小型数据记录器监测细鳞大马哈鱼Oncorhyncus gorbuscha和大马哈鱼O.keta的回归游泳行为,探讨其与环境水温的关系。数据记录间隔时间为1 s,连续记录时间为226 h。于2008年8月至10月期间,在知床沿岸放流了带有数据记录器的洄游途中的大马哈鱼和细鳞大马哈鱼个体(分别为30尾和5尾),分别有13尾、3尾个体被捕获。研究表明:试验个体有一系列的上浮和下沉行为,并且频繁地回到表层水面,垂直移动中的深潜水是对表层高水温和暖流分层水中的一种适温调节行为。因此,尽管表层水温较高,性成熟后的大马哈鱼仍会回到表层水面寻找其产卵场所。     

Kinetics of the hydroxymethylation of phenol II: values of rate parameters and results of simulation experiments

The reaction course of the sodium hydroxidecatalyzed hydroxymethylation of phenol was analyzed by use of high-performance liquid chromatography (HPLC), and the rate constants for the seven reactions taking place consecutively and competitively were evaluated by means of a computer simulation technique. Calibration was done at the quantification of the six phenolic monomers from the peak areas in the HPLC chromatogram, taking the differences in molar ultraviolet absorption intensities of the six compounds into account. The values of the energies of activation for the seven reactions obtained differed greatly from those reported by Eapen and Yeddanapalli. Simulation experiments carried out by use of the newly obtained rate parameters showed that the amounts of phenol left unreacted and 2,4,6-trihydroxymethylphenol in the final reaction product increased as the reaction temperature was increased and the alkali/phenol molar ratio decreased. These phenomena can be attributed to the differences in the energies of activation for the seven reactions and differences in the acid strengths of the six phenolic monomers.Part of this paper was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998 and at the 1998 annual meeting of the Forest Products Society, Merida, Mexico, June 1998     

Influence of the melamine content in melamine-urea-formaldehyde resins on formaldehyde emission and cured resin structure

The effect of melamine content in melamine-urea-formaldehyde (MUF) resins on the formaldehyde emission and resin structure was investigated using six MUF resins synthesized with different F/(M + U) and M/U molar ratios. The formaldehyde emission from the plywood decreased as the F/(M + U) molar ratio decreased and the M/ U molar ratio increased. In addition, the bond performance was enhanced as the M/U molar ratio increased in the MUF resins with a fixed F/(M + U) molar ratio. Quantitative solution¹³C-NMR spectra of MUF resins revealed that the MUF resins with a high melamine content consisted of more highly branched crosslinkage structure and free melamine compared to the resins with low melamine contents. Furthermore, solid-state¹³C CP-MAS NMR spectra of cured MUF resins proved that more methylol groups, dimethylene ether, and branched methylene structures were present in the MUF resins with a higher F/(M + U) molar ratio, leading to increased bond strength and formaldehyde emission. There is no significant difference in the linkage structure of the cured resins with the same F/(M + U) and different M/U molar ratios except the ratios of carbonyl carbon of urea and triazine carbon of melamine. Therefore, the lower formaldehyde emission from cured MUF resins with a higher M/U molar ratio might be ascribed to the stronger linkages between triazine carbons of melamine than those of urea carbons. Consequently, the melamine contributed to strong crosslinking linkages in the cured resin structures, leading to lower formaldehyde emission and better bond performance.Part of this work was presented at the 48th Annual Meeting of the Japan Wood Research Society, Shizuoka, April 1998     

Influence of connectivity, habitat quality and invasive species on egg and larval distributions and local abundance of crucian carp in Japanese agricultural landscapes

The quality of habitat at and around a spawning site, and the availability of movement between spawning and nonspawning habitats are likely to be important determinants for population persistence in a degraded and fragmented landscape. We assessed the influence of habitat connectivity, habitat quality and invasive species for distributions and local abundance of eggs and larvae of crucian carp (Crassius auratus complex, which is listed as “data deficient” on the Japanese Red List) in agricultural landscapes surrounding Lake Mikata, Japan, where drainage ditches and paddy fields are extensively utilised for spawning (lake or river shores are also used). We investigated the presence and abundance of eggs and larvae of crucian carp and habitat components at 146 sites across a range of presumed spawning habitats. Egg presence was affected strongly by connectivity to the lake (watercourse distance from the lake), and egg abundance was significantly influenced by both connectivity and habitat quality. In contrast, larval presence was primarily related to habitat quality. Larval abundance was influenced by connectivity and habitat quality, but the effect of connectivity was relatively low. Furthermore, larval abundance was negatively related to the presence of the invasive species red swamp crayfish (Procambarus craki) and bullfrog (Rana catesbeiana). Our findings indicate that connectivity, habitat quality and the presences of invasive species are crucial in determining suitable spawning and nursery habitats, but their relative importance may vary depending on egg and larval life stages. We suggest that restoring connectivity, improving habitat quality and removal of invasive species could be effective conservation strategies for the declining populations of crucian carp in agricultural landscapes.     

PCR-based species-specific amplification of ITS of Mecistocirrus digitatus and its application in identification of GI nematode eggs in bovine faeces

Differential diagnosis of Mecistocirrus digitatus infection relies on morphological examination of either eggs in faecal samples or L3 larvae developed in vitro. Technical limitations hinder the practicability of these approaches. Hence, in order to develop a specific diagnostic measure for M. digitatus infection, we determined the sequence of the internal transcribed spacer (ITS) of its ribosomal DNA (rDNA) and designed primers for PCR-based species-specific amplification of the ITS to differentiate between M. digitatus and other common gastrointestinal (GI) nematode species. The newly designed primers amplified a single specific 520 base pair (bp) fragment from the M. digitatus ITS, and its detection limit was as low as 0.001 ng. Further, this sensitivity suggested that the specific fragment could be amplified even from a unicellular egg that collected directly from uteri of an adult M. digitatus female. In fact, we designed a method that employs a small piece of a cover slip and a filter paper by which we could differentially amplify a PCR fragment from a unicellular egg. The reliability of the specific PCR assay was also demonstrated with 10 oval samples that collected from bovine faeces by using sugar flotation method. These data suggested that the specific PCR assay of the ITS region of M. digitatus rDNA could be useful for the identification of GI nematodes.     

Larval growth rates differ in response to seasonal temperature variations among clupeoid species inhabiting the Pacific coastal waters of Japan

Growth rates of round herring Etrumeus teres, Japanese anchovy Engraulis japonicus, and Japanese sardine Sardinops melanostictus larvae respond differently to seasonal temperature variations in Sagami Bay on the Pacific coast of central Japan. Larvae of these three clupeoid species were collected from small seine net catches between February 2008 and April 2009. Correlations between otolith growth increment widths and ambient temperatures were examined at five body sizes and indexed to otolith radii of 50–175 μm, which corresponded to notochord lengths of 15–24 mm. Round herring larvae showed positive correlations between growth rate and habitat temperature at all five body sizes. In contrast, Japanese sardine larvae did not show significant correlations between growth rate and ambient temperature at any of the five body sizes. Japanese anchovy larvae showed significant but weaker correlations between growth rate and temperature than round herring. Although these three species share habitats with some differences in seasonal occurrence in the bay, they showed different species-specific responses to seasonal habitat temperature variations. These differences in response to temperature variations may constitute an ecological basis for different migration patterns among the three species.     

Ectomycorrhizal fungal community of naturally regenerated Pinus thunbergii seedlings in a coastal pine forest

To add to knowledge of ectomycorrhizal (ECM) community structure on the roots of Pinus thunbergii seedlings in a Japanese coastal forest, we sampled naturally regenerated current-year and 1- to 5-year-old seedlings. We classified the 667 root tips on current-year seedlings and the 1,927 root tips on older seedlings into 13 phylotypes based on morphological and genetic analyses. Cenococcum geophilum, members of the families Clavulinaceae, Russulaceae, or Thelephoraceae or the genus Trichophaea, were indicated to be fungi forming P. thunbergii ectomycorrhizas. Among them, C. geophilum and Clavulinaceae sp. 1 were the most or second most dominant species. A species accumulation curve based on the number of samples nearly reached a plateau, with observed species richness equal to 11 species and the Jackknife2 and Chao2 richness estimators indicating 14 and 12 species, respectively. In addition, Simpson’s 1/D was 3.89 and Shannon–Wiener’s H′ was 1.71, indicating a relatively low taxonomic diversity. There was no significant difference in the ectomycorrhizal formation rate, or the occurrence frequency and the number of ECM phylotypes between current-year and older seedlings. These results indicated that less diverse fungi were involved in ectomycorrhizal formation on coastal pine seedlings compared with those in comparable inland forests in the study area.     

不同添加剂对全株玉米和青玉米秸青贮饲料质量的影响

为了探讨不同添加剂对全株玉米和青玉米秸青贮饲料质量的影响,利用乳酸菌制剂和酶制剂单独或联合使用对原料进行青贮调制，并对开封后的青贮饲料进行了现场评定、实验室评定、生物评定和二次发酵试验。结果表明：不同添加剂处理后得到的全株玉米、青玉米秸青贮饲料的感官评定均优于对照组；在降低青贮饲料的NDF、ADF含量，提高动物的消化率上，乳酸菌制剂和酶制剂混合作用时的效果最显著；另外，乳酸菌1和乳酸菌1＋酶制剂1能够有效地抑制青贮饲料的二次发酵。