A Comparison of the Effects of Two Prey Enrichment Media on Growth and Survival of Pacific Bluefin Tuna,Thunnus orientalis,Larvae

Three experiments were conducted to investigate the growth, survival, and standardized cohort biomass of Pacific bluefin tuna, Thunnus orientalis, larvae fed nutritionally enhanced prey during the first week of feeding using two commonly used, commercially available enrichment media, AlgaMac Enrich and Marine Glos. T. orientalis larvae exhibited exponential growth in standard length and dry weight. The daily specific growth rates in length and weight are the first reported for T. orientalis larvae and the averages ranged from 3.8 to 4.1% and 27.5%, respectively, for larvae in the AlgaMac treatment and from 4.1 to 6.1% and 31.5%, respectively, in the Marine Glos treatment. Average daily growth rates in length ranged from 0.16 to 0.23 mm/d for larvae in the AlgaMac treatment and from 0.17 to 0.27 mm/d for those in the Marine Glos treatment. Daily growth rates in length were similar to those reported for other tuna larvae reared in the laboratory but slower than most published estimates for larval tunas in situ at similar water temperatures. Mean prey number per gut was positively associated with mean prey level in the tank. Both enrichment media appear to be good sources of nutritional improvement of planktonic prey for T. orientalis larvae.     

Winter monsoon promotes the transport of Japanese temperate bass Lateolabrax japonicus eggs and larvae toward the innermost part of Tango Bay,the Sea of Japan

Northwesterly cold winds characteristic of the East Asian Winter Monsoon (EAWM) dictate winter climatic conditions over the Japanese Archipelago. Japanese temperate bass Lateolabrax japonicus is a commercially important coastal fish that spawns offshore in winter and uses shallow waters as nursery habitats. To investigate the effects of EAWM on the planktonic period of L. japonicus, eggs, larvae, and juveniles were quantitatively collected in Tango Bay on the Sea of Japan side in winter and spring from 2007 to 2017. Although eggs occurred close to the mouth of the bay, planktonic larvae occurred further inside as they developed. The horizontal distribution of planktonic larvae, combined with water velocity data obtained from mooring observations, indicated that planktonic larvae are transported south‐ to westward through Ekman current and an anticyclonic circulation, which are driven by northwesterly winds. To evaluate survival during the planktonic period in each year class, the abundance of benthic larvae/juveniles was divided by winter total landings of Lateolabrax spp. (proxy of the spawning stock size). This survival index exhibited a positive correlation with the northwesterly component of winter winds, and a negative correlation with winter air temperature (average from December to February, Spearman's correlation, p < .05). There was, however, no significant correlation with winter water temperature or winter freshwater discharge in the bay. We conclude that northwesterly cold winds of EAWM play a critical role in transporting L. japonicus eggs and larvae toward nursery habitats, specifically beaches and estuaries fringing the innermost part of Tango Bay.     

Variations in the morphology of Rhizomucor pusillus in granulomatous lesions of a Magellanic penguin (Spheniscus magellanicus)

This report presents a new case of mucormycosis encountered in penguin characterized by morphological variation of hyphae and presence of sporangia with numerous sporangiospores. A 4.5-year-old Magellanic penguin (Spheniscus magellanicus) died after exhibiting anorexia, poor nutritional condition and dyspnea. Multiple nodular lesions were observed in the thoracic and abdominal regions. Histopathologically, hyphae of various sizes were seen in the lungs, air sac and nodular lesions. Myriad sporangiospores and several sporangia were observed in/around the bronchi or parabronchi. The very narrow and short hyphae in the nodules were not consistent with the characteristics of Mucorales. However, for most hyphae, including those in the nodules, sporangiospores and sporangia, immunohistochemistry revealed Mucorales-positive reactions. In addition, these fungi were identified as Rhizomucor pusillus by gene analysis.     

Leak detection by monitoring pressure to preserve integrity of agricultural pipe

Paddy and Water Environment - Leakage of agricultural pipes has been increasingly frequent problems due to corrosion, loosening of joints, and cracks, which result in the subsidence of peripheral...     

Responses of leaf photosynthesis and plant growth to altered source–sink balance in a Japanese and a Dutch tomato cultivar

We investigated the effects of altered source/sink ratio by leaf or fruit pruning on leaf photosynthetic characteristics and whole-plant growth of ‘Momotaro York’, a Japanese cultivar, and ‘Dundee’, a Dutch cultivar and verified a hypothesis for sink-limitation of plant growth proposed by Tanaka and Fujita (1974). Plants were grown hydroponically with a high-wire system in a greenhouse for 11 weeks. Light-saturated photosynthesis of young, fully expanded leaves measured at atmospheric CO₂ partial pressure of 37 Pa and at an intercellular CO₂ partial pressure of 20 Pa was not influenced by alteration of source/sink ratio for either cultivar. Although soluble sugars were accumulated in leaves under high source/sink conditions, the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase, a rate-limiting factor for CO₂-limited photosynthesis, was not affected by the altered source–sink balance. Net assimilation rate of a whole plant increased with decreasing source/sink ratio, but this can be accounted for by the changes in light interception per unit leaf area, without taking the source–sink relationship into consideration. It was concluded that the altered source/sink ratio did not change leaf photosynthetic capacity and the sink-limitation hypothesis cannot be applied to either cultivar under the conditions of the present study.     

Growth characteristic and sink strength of fruit at different CO2 concentrations in a Japanese and a Dutch tomato cultivar

The aim of the present study was to elucidate how fruit growth was limited by the source and sink capacities in a Japanese (‘Momotaro York’) and a Dutch (‘Dundee’) tomato cultivar. The two cultivars were grown hydroponically with a high-wire system in greenhouses for 25 weeks, and the growth characteristics and sink strength of fruit were determined. Fruits were pruned to four (4F) or one (1F) per truss. The latter were used to determine potential fruit growth, an indicator of fruit sink strength. Growth was also determined under normal (LC) and enriched (HC, 700 μmol mol⁻¹) CO₂ concentrations to examine the effect of source enhancement on fruit production. In both cultivars under normal CO₂, the growth rate of fruit pruned to 4F per truss was lower than that in 1F, indicating that maximum potential fruit growth was not achieved. Under HC conditions, fruit growth rate of ‘Dundee’ achieved in 4F trusses was lower than that in 1F. In ‘Momotaro York’ in HC, fruit growth in 4F trusses was close to potential. This implies that fruit growth was source-limited irrespective of CO₂ concentrations in ‘Dundee’ cultivar while fruit growth in ‘Momotaro York’ under normal and enriched CO₂ conditions was limited by source and sink strengths, respectively. Adjustments of cultural practices including increasing fruit number per truss and/or genetic approaches to enhancing fruit sink strength by breeding may improve fruit yields of Japanese cultivars under high source/sink conditions.     

Novel plasmodesmata association of dehydrin-like proteins in cold- acclimated Red-osier dogwood (Cornus sericea)

Dehydrins are proteins associated with conditions affecting the water status of plant cells, such as drought, salinity, freezing and seed maturation. Although the function of dehydrins remains unknown, it is hypothesized that they stabilize membranes and macromolecules during cellular dehydration. Red-osier dogwood (Cornus sericea L.), an extremely freeze-tolerant woody plant, accumulates dehydrin-like proteins during cold acclimation and the presence of these proteins is correlated with increased freeze tolerance (Karlson 2001, Sarnighausen et al. 2002, Karlson et al. 2003). Our objective was to determine the location of dehydrins in cold-acclimated C. sericea stems in an effort to provide insight into their potential role in the freeze tolerance of this extremely cold hardy species. Abundant labeling was observed in the nucleus and cytoplasm of cold-acclimated C. sericea stem cells. In addition, labeling was observed in association with plasmodesmata of cold-acclimated vascular cambium cells. The unique association of dehydrin-like proteins with plasmodesmata has not been reported previously.