Lowland streams are often provided with concrete lined beds and banks. However, no studies have compared invertebrate assemblages between concrete and natural streambeds in lowland streams. In this study, we conducted a survey on stream invertebrates in study sites with concrete and natural streambeds in 6 streams flowing the Dogo Plain in Ehime Prefecture, southwestern Japan. We aimed to clarify the characteristics of invertebrate assemblages and habitat features on concrete beds by comparing with those on natural beds in lowland streams. Analyses using generalized linear mixed model (GLMM) revealed that current velocity was higher and water depth and the amount of benthic organic matter (BOM) were smaller in concrete sites than in natural sites. Invertebrate taxon richness was lower in concrete sites, but the difference was not large (concrete: 17.5, natural: 21.7). Analyses using generalized linear model (GLM) exhibited positive relationships between taxon richness and BOM, particularly in concrete sites. The biplot of non-metric dimensional scaling (NMDS) did not show distinctive difference in the community structure of invertebrates between two bed types. Our results imply that the habitat alteration with concrete beds has weaker impact on stream invertebrates in lowland streams than in mountain streams. The weak impact can be attributed to the overwhelming effect of water quality degradation and low current velocity in lowland streams, and periphyton bloom on concrete beds. Although the conversion of concrete-lined substrate to natural substrate is an important measure to restore lowland streams, we suggest that it should be promoted together with other measures such as water quality improvement.

Artificial night lighting has various negative effects on wildlife; therefore, it is thought that the rare nocturnal Hynobius tokyoensis has be adversely affected in some way. In this study, a laboratory experiment was conducted to clarify the effects of artificial lighting at night on the moving distance and time spent active of this nocturnal species. The experiment was conducted in a thermostatic room with an experimental apparatus for obser vation. The lighting conditions were 0 (no-light), 0.01 to 0.03, 1 to 3, and 30 to 50 lux, and nocturnal behavior was observed using an infrared video camera. The moving distance and the time spent active of the observed individuals were calculated from the video recordings, and the body weight of the individuals was also recorded. In the likelihood ratio test results for moving distance, all variables were significant: interaction, illuminance, and body weight. Therefore, it is clear that the moving distance is affected by illuminance and body weight, although the effect of illuminance differs depending on body weight. On the other hand, only illuminance was significant in the test for time spent active. Moving distance was suppressed by 32 to 42％ at an illuminance of 0.01 to 0.03 lux, by 59 to 78％ at 1 to 3 lux and by 77 to 100％ at 30 to 50 lux compared to the no-light condition. Time spent active was suppressed by 32 to 46％, 61 to 87％, and 79 to 100％, respectively.

To clarify the environmental factors affecting the distribution of the endangered Nagoya Daruma Pond Frog （Pelophylax porosus brevipodus） in paddy levees and fallow paddy fields, we conducted field surveys at 23 study stations in Kurashiki, Okayama, western Japan. Based on the agricultural calendar in the study site, we set five investigation periods of ʻbefore midsummer drainageʼ, ʻduring midsummer drainageʼ, ʻafter midsummer drainageʼ, ʻbefore harvestʼ and ʻafter harvestʼ between July and November 2017. In the paddy levees during the investigation periods between ʻduring midsummer drainageʼ and ʻbefore harvestʼ, the effects of physical environmental factors on the number of frog individuals collected were analyzed with generalized linear models （GLM）. The total number of individuals of P. p. brevipodus collected in the paddy levees during all the investigation periods was maximum before midsummer drainage, and decreased until after harvest. On the other hand, in the fallow paddy fields, the total number of frog individuals was maximum before midsummer drainage and then decreased until after midsummer drainage, but increased before harvest and then decreased after harvest. The results of GLM indicate that the coverage of plant stems, leaves and litter and coverage of prostrate plants have positive effects on the habitat preference of P. p. brevipodus. These results indicate that P. p. brevipodus utilizes not only paddy levees, but also fallow paddy fields as a habitat and that the habitat utilization is different between paddy levees and fallow paddy fields in relation to the agricultural calendar. Our results also indicate that coverage of vegetation in paddy levees should be more than 60% for conservation of populations of P. p. brevipodus.

If the spatial characteristics of rice paddies and waterways in relation to water management—specifically, water-depth—can be grasped in an areal and timely manner, then an important environmental consideration for aquatic organism habitat analysis can hence be used. This study verifies whether the water-depths of paddy fields and waterways can be successfully predicted using water indices calculated using a low-altitude-remote- sensing (LARS) approach. A DJI Matrice 300 system equipped with a MicaSense Altum was attached to an unmanned aerial vehicle (UAV) and used to capture images of paddy fields in Sogabe, Kameoka City, Kyoto Prefecture. The resulting images were processed using photogrammetry to produce orthomosaic representations. A normalized difference water index (NDWI) was calculated from near-infrared and green wavelengths, with water-depths of subject paddy fields and waterways then accordingly measured within 1h immediately after the capturing the image using the UAV. The NDWIʼs of the water-depth measurement points were extracted using geographic-information-system technology, with a linear regression equation and coefficient of determination between water-depth and NDWI ultimately calculated. NDWI values were relatively high for flooded paddy fields and there were NDWI differences even for paddy fields with only a single section. Moreover, NDWI values were relatively high for waterways, indicating that NDWIʼs can be used to help understand the heterogeneity of water-depths within paddy fields and evacuated water areas, such as waterways. Although predicting the water depth by generalizing one regression equation and collectively predicting water-depths during an entire irrigation season through the methods used in this study is difficult, accurately assessing individual-case water-depths depending on paddy field conditions within a discrete study area, especially during the frog breeding season and the start of mid-drying season is possible. Such determinations will ultimately provide critical data in support of new aquatic habitat evaluations for a variety of Kyoto Prefecture wetland settings.

We investigated the species composition and distribution of aquatic bryophytes in the riffles of upper and middle reaches of the Yahagi River, Japan, by longitudinal and cross-sectional observation. Ten species of Bryopsida (mosses) and one species of Hepaticopsida (liverworts) were recorded in this study. A rich flora of bryophytes was observed at the water edges and in the splash zones of large boulders, comparable to previous studies, whereas Ectropothecium obtusulum and Rhynchostegium riparioides were found to dominate in channels where water flows throughout the year. They were commonly found on the submerged riverbed of the Yahagi River, and these two species were more abundant in many study stations below dams.

Sandy beach ecosystem is an ecotone receiving a variety of organic matter subsidized from both ocean and terrestrial areas. These organic materials should be trophic bases sustaining the beach communities composed of invertebrates such as crustaceans and insects. However, little is known about how much these communities relied on subsidized organic matter from the ocean and terrigenous organic matter. In this study, therefore, we examined the relative importance of marine and terrestrial organic matter as the trophic base of the beach communities on the Shinhama and Yuriage beaches of Sendai Bay, Japan, using the stable isotope ratios of carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur. (δ³⁴S) with a Bayesian statistical isotope mixing model. Using these data, we also assessed the effects of seawalls constructed on the sandy beaches 120～200 m away from the shoreline. The stable isotope analysis showed that arthropods on both Shinhama and Yuriage beaches exhibited a range of stable isotope ratios between terrestrial plants and seaweeds. The trophic contribution of the mixed isotope analysis revealed that the contribution of marine organic matter was high for beach hoppers, tenebrionid beetles and ghost crabs. The contribution of organic matter produced by the beach plants was also high for the arthropods collected on the beach but not so for those collected on the land side of the sea walls, where the arthropods mainly relied on organic matters produced by non-beach plants. These results indicate that the arthropods inhabiting sandy beaches strongly depend on, directly and indirectly, the organic matter subsidized from the ocean as a trophic base and suggest that seawalls act to block the spatial flow of such marine organic matter.

Using aerial photographs taken by a drone, i.e., unmanned aerial vehicles (UAV), we examined the seasonal and spatial variations of debris stranding on the sandy beaches of Sendai South Bay, which was damaged by the tsunamis caused by the Great East Japan Earthquake, 2011, We classified the debris into ten types, enumerated seasonally these from the shoreline to the embankment at two beach areas and described the seasonal changes in the abundance and spatial distribution patterns of the debris. Throughout the study period, the most abundant debris was driftwood, which was probably discharged from the rivers flowing into Sendai South Bay and accounted for 70％ of the total debris enumerated. Among the debris of anthropogenetic origin, i.e., marine garbage, plastic caps and bottles were the most abundant, followed by processed timbers, styrene forms and plastic bags. Most of the garbage was generally found within 30 to 60 m from the shoreline and increased in summer, while the driftwood was often found even near the embarkments and tended to accumulate on the beaches. The principal component analysis revealed that among the garbage, spatial and temporal variations of the plastic caps and bottles were somewhat related to those of the driftwood, suggesting the likelihood that the latter entraps the formers on the beaches. These results also indicate that aerial images taken by a UAV are useful for examining and quantifying the spatial and temporal variations of the marine debris drifting on beaches.

This report describes the progress of biodiversity conservation projects and initiatives in the reconstruction of coastal protection facilities after the Great East Japan Earthquake in Miyagi Prefecture, Japan, as well as the research and evaluation conducted there. Biodiversity conservation projects and efforts in the reconstruction of coastal protection facilities in Miyagi Prefecture include the unconstruction or downsizing, setting back, laying coastal sand for seawalls, and the designating conservation areas without mounding or laying coastal sand on mounds for coastal protection forests. It is considered to be a characteristic of coastal protection facility reconstruction projects in Miyagi Prefecture that such diverse biodiversity conservation projects and efforts were carried out in many locations. In addition, many residents and NPOs are included in the requestors and proponents of biodiversity conservation (including sandy beach conservation). The involvement of many experts in various fields of expertise in biodiversity conservation projects and efforts, and the fact that there are locations where multiple biodiversity conservation projects and efforts were conducted are also considered to be characteristics of the projects in the prefecture. Since the effects of many of these biodiversity conservation projects and efforts have not been verified, there is an urgent need to investigate and verify the effects of them. Miyagi Prefecture has a wide variety of biodiversity conservation projects and efforts, and seems to be a suitable region for the verification and evaluation of various types of projects. In addition, since some of the projects were implemented in close proximity to each other, it is considered to be a valuable site for investigating synergistic effects of them or the effects of ensuring continuity between different environments.