Studies on the nutritional requirements of the larval stages of Penaeus japonicus using microencapsulated diets

Fatty acid biosynthesis in the larval stages of Penaeus japonicus Bate was examined by feeding microencapsulated diets containing (1-¹⁴C) palmitic acid, and fat-free diets supplemented with defined fatty acids. Highest larval growth rates were achieved on diets containing Tapes philippinarum lipid and, when defined fatty acids were substituted, on diets containing 20:63 fatty acid. The radioactive tracer experiments indicate that 16:17, 18:0 and 18:19 fatty acids may be synthesised from palmitic acid and that P. japonicus larvae may possess the ability to elongate 18:33 to 20:53 and 22:63, and 18:26 to 20:46. However, the rates of these reactions appear to be too slow to meet the larval requirements for essential fatty acids and the 3 series of polyunsaturated fatty acids must be provided in the diet.     

Correlated evolutionary changes in Drosophila female genitalia reduce the possible infection risk caused by male copulatory wounding

Male and female genitalia often show corresponding morphologies indicating coevolutionary processes, but ongoing debate exists as to the driving mechanisms of such coevolution between the sexes. Using interspecific matings between Drosophila santomea and Drosophila yakuba, this study provides evidence that micron-scale differences in male and female genital morphology and resultant mismatches between them during copulation cause wounding and infection risk to females. Male D. yakuba possesses a pair of sclerotized spikes (ventral branches of the basal processes) on the aedeagus, while these projections are much more rounded in D. santomea. D. yakuba females possess a pair of cavities with sclerotized platelets that receive the male genital spikes during copulation, whereas D. santomea females lack these cavities. The pointed genital spikes cause wounding in almost all females of D. santomea mating with male D. yakuba. Furthermore, when fluorescent-labeled microbeads were applied to male genitalia, they invaded the female hemocoel through the copulatory wounds significantly more frequently in heterospecific matings. Although the sclerotized platelets in the genital cavities prevented precise quantification of the extent of wounding in D. yakuba females, a similarly enhanced risk of microbial invasion was detected for the reciprocal heterospecific cross. All beads detected in the female hemocoel were immobilized by hemolymph clotting, indicating an effective immune response. The observed enhanced mating costs due to genital mismatch support the view that corresponding morphologies in female genitalia represent counteradaptations to harmful male behaviors, instead of being evolutionary adaptations to discriminate the species or genetic quality of male mates.     

Toward the Improvement of Trail Classification in National Parks Using the Recreation Opportunity Spectrum Approach

Trail settings in national parks are essential management tools for improving both ecological conservation efforts and the quality of visitor experiences. This study proposes a plan for the appropriate maintenance of trails in Chubusangaku National Park, Japan, based on the recreation opportunity spectrum (ROS) approach. First, we distributed 452 questionnaires to determine park visitors’ preferences for setting a trail (response rate = 68 %). Respondents’ preferences were then evaluated according to the following seven parameters: access, remoteness, naturalness, facilities and site management, social encounters, visitor impact, and visitor management. Using nonmetric multidimensional scaling and cluster analysis, the visitors were classified into seven groups. Last, we classified the actual trails according to the visitor questionnaire criteria to examine the discrepancy between visitors’ preferences and actual trail settings. The actual trail classification indicated that while most developed trails were located in accessible places, primitive trails were located in remote areas. However, interestingly, two visitor groups seemed to prefer a well-conserved natural environment and, simultaneously, easily accessible trails. This finding does not correspond to a premise of the ROS approach, which supposes that primitive trails should be located in remote areas without ready access. Based on this study’s results, we propose that creating trails, which afford visitors the opportunity to experience a well-conserved natural environment in accessible areas is a useful means to provide visitors with diverse recreation opportunities. The process of data collection and analysis in this study can be one approach to produce ROS maps for providing visitors with recreational opportunities of greater diversity and higher quality.     

Comparison of phenylpropanoid volatiles in male rectal pheromone gland after methyl eugenol consumption, and molecular phylogenetic relationship of four global pest fruit fly species: Bactrocera invadens, B. dorsalis, B. correcta and B. zonata

Males of many tephritid fruit fly species of the genus Bactrocera show a very strong affinity to methyl eugenol (ME). An attracted male compulsively ingests ME, which is then biotransformed before its metabolites are accumulated into the rectal gland. The glandular organ is known to serve as a reservoir for sex pheromone in some species. Upon ME-feeding, males of the oriental fruit fly, Bactrocera dorsalis, selectively accumulated two metabolites, 2-allyl-4,5-dimethoxyphenol (DMP) and (E)-coniferyl alcohol (E-CF), in the rectal pheromone gland. We compared the profiles of phenylpropanoid metabolites accumulated by three other species of very high economic and quarantine importance—Bactrocera invadens, Bactrocera zonata and Bactrocera correcta, with that of B. dorsalis. Males of each species were fed artificially on ME and the metabolites stored in the rectal glands were examined by means of chromatography and spectroscopy. Similar to B. dorsalis, males of laboratory-raised B. invadens accumulated DMP and E-CF, in almost equal quantities, in the rectal sac. The sum of DMP and E-CF increased gradually with time after ME consumption and reached as high as 150 μg/male 2 days post ME-feeding. Wild males of B. invadens captured in Kenya also possessed both the compounds in varying quantities. In contrast, males of B. zonata accumulated DMP and (Z)-coniferyl alcohol (Z-CF) in an approximate ratio of 1:1; whereas B. correcta is known to convert ME to (Z)-3,4-dimethoxycinnamyl alcohol (Z-DMC) and Z-CF also in an approximately 1:1 ratio. Thus, there are three types of binary combinations of rectal phenylpropanoid volatiles (i.e. DMP + E-CF; DMP + Z-CF; Z-CF + Z-DMC) utilized among the four Bactrocera species. Such differences in phenylpropanoid ingredients may play a critical role in differentiating these species if encountered in the natural habitat. In this context, the two putative sibling species—B. invadens and B. dorsalis, possess the identical subset of rectal volatiles (DMP and E-CF) in a similar proportion. Furthermore, the phylogenetic analyses of the four Bactrocera species by comparing nucleotide sequences in the mitochondrial genes showed that B. invadens clearly belonged to the same clade as B. dorsalis species. Therefore, we consider the two as the same biological species, and certainly not distinct.     

Biotransformation of halogenated benzenes in anaerobic sediments

The transformation kinetics of halogen substituted benzenes was examined in estuarine sediment. The sediment was sulfidogenic with sulfate concentration of 20 mmole/l. All compounds transformed without any lag period, with rate constants between 0.0016 and 0.0342 day^-1 or half-lives of 20 and 433 days. For the compounds with different halogen substituents on the aromatic ring, the transformation rate of the compound decreased in the order: I s> Br s> Cl s> F.     

Correction to: Design considerations of constructed wetlands to reduce landfill leachate contamination in tropical regions

Journal of Material Cycles and Waste Management - In the original publication of the article, Eq. 5 was published incorrectly. The correct equation is given below.     

Effects of ocean acidification on the early developmental stages of the horned turban,Turbo cornutus

To estimate the impact of CO₂-driven ocean acidification on the early life stages of gastropods, the effects of increased partial pressure of seawater carbon dioxide (pCO₂) (800–2,000 μatm) on the early developmental stages and larval shell length of the commercially important gastropod, the horned turban snail, Turbo cornutus were investigated. Increase in experimental seawater pCO₂ had an increasingly negative impact on the early developmental rate; the proportion of embryos or larvae displaying retarded development increased at higher pCO₂. The proportion of embryos that developed to the 4-cell stage at 2 h after fertilization decreased linearly with increasing pCO₂. At ~1,000 μatm pCO₂, retarded development was observed in ~50 % of larvae. No embryos developed to the 4-cell stage at 2,000 μatm pCO₂ within 2 h of fertilization. A similar trend continued until 24–26 h after fertilization; the proportion of larvae attaining veliger stage by 24–26 h also decreased with increasing pCO₂. The shell length of T. cornutus veligers decreased gradually as seawater pCO₂ increased, but markedly decreased in seawater under nearly unsaturated and unsaturated conditions (≤1.04) of the aragonite saturation state (Ω _aragonite). The results indicate that increased pCO₂ seawater has a progressive and acute effect on embryonic and larval T. cornutus, and imply that the extended early developmental period and/or the downsized larval shell produced by ocean acidification will have a negative impact on survival, settlement and recruitment well into the future.     

Pilot-scale studies of domestic wastewater treatment by typical constructed wetlands and their greenhouse gas emissions

Three typical constructed wetlands (CWs) including Vertical Flow (VF), Free Water Surface (FWS), and Subsurface Flow (SF), and combined VF-SF-FWS constructed wetlands were investigated for the treatment of domestic wastewater with low C/N ratio. The performance of nutrient removal and the characteristics of greenhouse gas emissions, such as CH₄ and N₂O, from these CWs were compared. The results indicated that the four types of CWs had high removal efficiencies for organic matter and suspended solid (SS). The combined wetland also showed a comparatively good performance for nitrogen and phosphorus removal, and the removal efficiencies for total nitrogen (TN) and total phosphorus (TP) were 81.3% and 84.5%, respectively. The combined CWs had a comparative lower global warming potential. The FWS CW had the highest tendency to emit CH₄ and led to a higher global warming potential among the four types of CWs, which was about 586 mg CO₂/m²·h.     

Design considerations of constructed wetlands to reduce landfill leachate contamination in tropical regions

In tropical regions, landfill leachate contamination at municipal solid waste disposal sites is a critical issue because of the large volume of highly contaminated leachate formed during the rainy season. We evaluated the efficacy of constructed wetlands (CWs) with the ability to reduce the water volume and pollutant levels to reduce leachate contamination compared to the most commonly used treatment system, stabilization ponds, based on parameters obtained in a field experiment in Thailand. The simulation indicated that CWs had a higher potential to reduce the water volume than stabilization ponds over the course of a year. Scenario evaluations under varying initial water depths, system depths, and area sizes indicated that the CWs could reduce the treatment area to prevent overflow and leachate pollution. In addition, the CWs were estimated to reduce the leachate amount and pollution by 83–100% and 92–99%, respectively. When there is limited land available, deeper CWs can be used to sustainably prevent contamination from leachate overflow. Effectively designed CW systems may be valuable for both reducing the required area and the contamination; therefore, CWs are a promising option for sustainable landfill leachate treatment systems in developing tropical regions.