What is the optimal density of larval seeding in Acropora corals?

In situ larval seeding is a low-cost technique that is currently under development for the large-scale restoration of coral populations. One problem that still needs to be solved is the preparation of coral larvae for seeding, i.e., how many larvae are required to restore a certain area? In this study, we focused on the relationship between the numbers of larvae, settlers, and survivors for three?months post-settlement to determine the optimal larval seeding density. A comparison of three different larval densities (low, middle, and high) indicated that the number of settlers was proportional to the larval density, suggesting that settler density is determined by the number of larvae supplied. However, the survival rate of settlers on high-density plates was much lower than the corresponding rates on low- or middle-density plates during the first month after settlement. Moreover, most of the seeded corals had not survived on the low-density plates at three?months after settlement. Therefore, the middle larval density (i.e., 5000?larvae?m^?2) appears to be optimal for seeding on grid plates.     

Habitat management of little terns in Japan’s highly developed landscape

The little tern (Sterna albifrons) is a species of shorebird that nests in colonies on sandy beaches and riverbanks with little vegetation cover. In Japan, the natural breeding habitats of the terns have decreased drastically, and the species is listed under the category “vulnerable” in the Red List of the Government of Japan. To reduce the effects of habitat loss on the terns, conservationists are attempting to create and manage artificial colony sites in highly developed landscapes, such as reclaimed lands located in Tokyo Bay, central Japan. We present the factors that contribute to breeding success for this species and the habitat characteristics related to nest-site selection in the artificial colony sites along Tokyo Bay. Our data show that around 3 ha of a building rooftop without vegetation cover could sustain more than 2000 little tern nests. We found a strong positive relationship between colony size and hatching success, observing that a colony size of more than 100 lowered predation rates of eggs. On sites built upon white crushed-concrete, nest densities were high and predation rates of eggs were low. We also found that feeding rates were affected by foraging habitats, of which the best types were the shoreline of sandy beaches and mud flats. The 40 km dispersal range of the breeding terns, inferred from distribution data, should be considered when establishing a network of the multiple colony sites.     

Morpho‐demographic traits of two maërl‐forming algae in beds with different depths and fishing histories

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Effect of the lectin PHA on the feeding behavior of the grain aphid

The electrical penetration graph (EPG) method was used to quantify the effect of the lectin PHA (phytohemagglutinin) on the feeding behavior of the grain aphid Sitobion avenae F (Hemiptera: Aphididae). Addition of PHA to an artificial diet affected aphid probing behavior. In general, increasing concentrations of PHA in sucrose-agarose gels significantly reduced the number of aphid probes and extended their duration. Aphids feeding on the gels with lectin (without concentration 50 μg · cm⁻³) had a prolonged activity (EPG pattern C) that was corresponded to prolonged penetration of the epidermis and mesophyll for aphids feeding on plants. Such insects also showed a significant reduction in salivation and passive ingestion from gels and a reduction in the total number of gel penetrations. At concentrations ≤250 μg · cm⁻³, PHA reduced feeding behavior on gels, and the EPG data were interpreted to correspond with reduced salivation into phloem sieve elements (EPG pattern E1) and reduced ingestion of phloem sap (EPG pattern E2). PHA also delayed the onset of the first E1 and E2 patterns. At higher concentrations (≥500 μg · cm⁻³), PHA completely stopped salivation and passive ingestion from gels. Similarly, higher concentration of PHA strongly reduced activity on gels that corresponded to activity in xylem (EPG pattern G); high PHA delayed the onset of the first G pattern and reduced total time of pattern G activity.     

不同光质对嫁接砧木下胚轴生长的影响

近年随着蔬菜生产规模化、工厂化发展的不断扩大和蔬菜嫁接技术的广泛推广,研制蔬菜自动嫁接机已成为蔬菜工厂化生产发展的必然趋势.而要实现嫁接装备高效、精准完成蔬菜幼苗的自动化嫁接作业,首先必须克服蔬菜幼苗生长的不一致性,因此培育健壮、整齐、均匀一致的嫁接蔬菜用苗也是实现自动化嫁接作业的一个重要前提.蔬菜幼苗的生长发育是一个十分复杂的过程,而光源是影响植物生长的一个重要因素.为此,对不同光源(红、蓝、红蓝)照射对3种瓜科砧木幼苗下胚轴生长的影响进行了研究.研究结果表明,红光处理的幼苗下胚轴最高,茎较细;红蓝光处理的砧木幼苗下胚轴最高,茎较粗.对于嫁接砧木幼苗,红光处理具有光合活性,有利于砧木幼苗积累的能量,促进幼苗下胚轴的生长.     

Optimization of a spawning‑induction protocol for the prediction of natural coral spawning

Fisheries Science - Many scleractinian corals only spawn once a year, so opportunities for collecting their gametes are limited. Consequently, the induction of spawning in coral would be useful,...     

Estimating the spawning season of black sea bream Acanthopagrus schlegelii in Hiroshima Bay,Japan, from temporal variation in egg density

Fisheries Science - We aimed to determine the spawning period of black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan, based on the distribution of its eggs, to assist in the resource...     

Preliminary Study of the Optimum Dietary Riboflavin Level in Sea Cucumber,Apostichopus japonicus (Selenka)

A 14‐wk feeding trial was carried out to evaluate the optimum dietary riboflavin (vitamin B₂) level in juvenile sea cucumber, Apostichopus japonicus. A total of 360 sea cucumbers averaging 1.49 ± 0.07 g (mean ± SD) were randomly distributed into 18 rectangular plastic tanks, and each tank was then randomly assigned to one of three replicates of six diets containing 0.29 (B₂0), 4.22 (B₂4), 8.93 (B₂9), 17.9 (B₂18), 56.7 (B₂57), and 577 (B₂577) mg riboflavin/kg diet. At the end of 14 wk of feeding trial, average weight gain (WG) of sea cucumbers fed B₂9, B₂18, B₂57, and B₂577 diets were significantly (P < 0.05) higher than that of animals fed B₂0 diet. WG of sea cucumbers fed B₂18, B₂57, and B₂577 diets were significantly higher than those of animals fed B₂0 and B₂4 diets. Specific growth rate of sea cucumbers fed B₂9, B₂18, B₂57, and B₂577 diets were significantly higher than those of animals fed B₂0 and B₂4 diets. Feed efficiency of sea cucumbers fed B₂9, B₂57, and B₂577 diets were significantly higher than those of animals fed B₂0 and B₂4 diets. Although significant differences were recorded in proximate composition of sea cucumbers fed the experimental diets, no clear trends were observed. The ANOVA test suggested that the optimum dietary riboflavin level in sea cucumber could be 17.9 mg/kg diet but broken‐line analysis of WG indicated a level of 9.73 mg riboflavin/kg diet. Therefore, these results may indicate that the optimum dietary riboflavin level in sea cucumber could be higher than 9.73 mg/kg diet but lower than 17.9 mg/kg diet.