Hairs in old books isotopically reconstruct the eating habits of early modern Japan.

To complement literature-based historical knowledge of the eating habits of 17th- and 18th-century Japan, we analysed carbon and nitrogen isotope ratios (δ13C and δ15N, respectively) of human hairs embedded in cover paper of Japanese books printed during 1690s-1890s, taking regional and temporal variations into consideration. We purchased 24 book sets from second-hand book markets. Twenty-three sets contained enough human hairs, which were non-destructively extracted from the thick, recycled paper of the book covers and used to measure the δ13C and δ15N values, found to be identical within each book set. Relatively low δ13C values and high δ15N values suggested that people depended on rice, C3 vegetables, and fish, more exclusively than contemporary Japanese people. The relatively high δ13C values found in Edo (Tokyo) might be associated with the preference for C4 millets by Edo people as a measure against beriberi (locally recognised as the Edo affliction). The δ15N values gradually increased over 200 years, indicating an increase in the contribution of marine fish both as food and fertiliser for rice fields as suggested by literature-based studies. Further collection of hairs from books will enable a thorough examination of regional and temporal variations to better understand the pre-globalised food culture.

Using food network unfolding to evaluate food-web complexity in terms of biodiversity: theory and applications.

Food-web complexity often hinders disentangling functionally relevant aspects of food-web structure and its relationships to biodiversity. Here, we present a theoretical framework to evaluate food-web complexity in terms of biodiversity. Food network unfolding is a theoretical method to transform a complex food web into a linear food chain based on ecosystem processes. Based on this method, we can define three biodiversity indices, horizontal diversity (DH ), vertical diversity (DV ) and range diversity (DR ), which are associated with the species diversity within each trophic level, diversity of trophic levels, and diversity in resource use, respectively. These indices are related to Shannon's diversity index (H'), where H' = DH  + DV  - DR . Application of the framework to three riverine macroinvertebrate communities revealed that D indices, calculated from biomass and stable isotope features, captured well the anthropogenic, seasonal, or other within-site changes in food-web structures that could not be captured with H' alone.

Terrestrial-aquatic linkage in stream food webs along a forest chronosequence: multi-isotopic evidence.

Long-term monitoring of ecosystem succession provides baseline data for conservation and management, as well as for understanding the dynamics of underlying biogeochemical processes. We examined the effects of deforestation and subsequent afforestation of a riparian forest of Japanese cedar (Cryptomeria japonica) on stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹5N) and natural abundances of radiocarbon (Δ¹4C) in stream biota in the Mt. Gomadan Experimental Forest and the Wakayama Forest Research Station, Kyoto University, central Japan. Macroinvertebrates, periphytic algae attached to rock surfaces (periphyton), and leaf litter of terrestrial plants were collected from six headwater streams with similar climate, topography, and bedrock geology, except for the stand ages of riparian forests (from 3 to 49 yr old in five stands and > 90 yr old in one reference stand). Light intensity and δ¹³C values of both periphyton and macroinvertebrates decreased synchronously with forest age in winter. A Bayesian mixing model indicates that periphyton contributions to the stream food webs are maximized in 23-yr-old forests. Except for grazers, most macroinvertebrates showed Δ¹4C values similar to those of terrestrial leaf litter, reflecting the influence of modern atmospheric CO2 Δ¹4C values. On the other hand, the Δ¹4C values of both periphyton and grazers (i.e., aquatic primary consumers) were significantly lower than that of modern atmospheric CO2, and were lowest in 23-yr-old forest stands. Previous studies show that root biomass of C. japonica peaks at 15-30 yr after planting. These evidences suggest that soil CO2 released by root respiration and dispersed by groundwater weathers carbonate substrata, and that dissolved inorganic carbon (DIC) with low Δ¹4C is incorporated into stream periphyton and some macroinvertebrates. The ecological response in the studied streams to clear-cutting and replanting of Japanese cedar is much slower (~20 yr) than the chemical response (< 5 yr). More than 50 yr is required for the food web structure to completely recover from clear-cutting. The ecological delay is attributed to several biogeochemical factors, the understanding of which is critical to integrated management of forest-stream continuum and the prediction of ecosystem resilience in response to environmental change.

Different chemical cues originating from a shared predator induce common defense responses in two prey species.

In freshwater ecosystems, inducible defenses that involve behavioral or morphological changes in response to chemical cue detection are key phenomena in prey-predator interactions. Many species with different phylogenetic and ecological traits (e.g., general activity patterns and microhabitats) use chemical cues to avoid predators. We hypothesized that prey species with a shared predator, but having different ecological traits, would be adapted to detect different chemical cues from the predator. However, the proximate mechanisms by which prey use chemical cues to avoid predation remain little known. Here, we tested our hypothesis by using fractionated chemical components from predatory dragonfly nymphs (Lesser Emperor, Anax parthenope julius) to trigger anti-predator behavioral responses in two anuran tadpoles, the wrinkled frog Glandirana (Rana) rugosa and the Japanese tree frog Hyla japonica. Glandirana rugosa detected chemical cues that had either high or low hydrophobic properties, but H. japonica responded only to chemical cues with hydrophilic properties. During the normal behaviors of these tadpole species, G. rugosa remains immobile in benthic habitats, whereas H. japonica exhibits active swimming at the surface or in the middle of the water column. As we had hypothesized, these tadpole species, which have different general activity levels and microhabitats, detected different chemical cues that were exuded by their shared predator and responded by changing their activities to avoid predation. The specific chemical cues detected by each tadpole species are likely to have characteristics that optimize effective predator detection and encounter avoidance of the shared dragonfly predator.

Quantification of cyprinid herpesvirus 3 in environmental water by using an external standard virus.

Cyprinid herpesvirus 3 (CyHV-3), a lethal DNA virus that spreads in natural lakes and rivers, infects common carp and koi. We established a quantification method for CyHV-3 that includes a viral concentration method and quantitative PCR combined with an external standard virus. Viral concentration methods were compared using the cation-coated filter and ultrafiltration methods. The recovery of virus-like particles was similar for the two methods (cation-coated filter method, 44%+/-19%, n=3; ultrafiltration method, 50%+/-3%, n=3); however, the former method was faster and more suitable for routine determinations. The recovery of seeded CyHV-3 based on the cation-coated filter method varied by more than 3 orders of magnitude among the water samples. The recovery yield of CyHV-3 was significantly correlated with that of the seeded lambda phage, and the average ratio of lambda to the CyHV-3 recovery yield was 1.4, indicating that lambda is useful as an external standard virus for determining the recovery yield of CyHV-3. Therefore, to quantify CyHV-3 in environmental water, a known amount of lambda was added as an external standard virus to each water sample. Using this method, CyHV-3 DNA was detected in 6 of the 10 (60%) types of environmental water tested; the highest concentration of CyHV-3 DNA was 2x10(5) copies liter(-1). The lowest recovery limit of CyHV-3 DNA was 60 copies liter(-1). This method is practical for monitoring CyHV-3 abundance in environmental water.

Detection of cyprinid herpesvirus 3 DNA in river water during and after an outbreak.

The disease caused by cyprinid herpesvirus 3 (CyHV-3) brings catastrophic damages to cultivated carp and koi and to natural carp populations; however, the dynamics of the virus in environmental waters are unclear. In July 2007, CyHV-3 DNA was detected in a dead common carp collected from the Yura River in Kyoto Prefecture, Japan, and this was followed by mass mortality. We collected water samples at eight sites along the Yura River for 3 months immediately after confirmation of the disease outbreak and attempted to detect and quantify CyHV-3 DNA in the water samples using molecular biological methods. The virus concentration was carried out by the cation-coated filter method, while the purification of DNA from the samples was achieved using phenol-chloroform extraction and a commercial DNA extraction kit. CyHV-3 was detected by PCR using six sets of conditions, three sets of primers (SphI-5, AP, and B22Rh exon 1), and two volumes of template DNA, and was quantified using real-time PCR. Our results indicate broader distribution of CyHV-3, even though dead fish were found only in a limited area; moreover, the virus was present at high levels in the river not only during the mass mortality caused by the disease but also for at least 3 months after the end of mass mortality. Our results suggest the possibility of infection by CyHV-3 via environmental water. The sequences of CyHV-3 collected from the Yura River matched perfectly with that of the CyHV-3 Japanese strain, suggesting that they share the same origin.