We investigated the spawning sites and annual variability of the number of reproductive visiting pairs of the horseshoe crab Tachypleus tridentatus along the Tsuyazaki Coast in Fukuoka, Japan, from 2004 to 2008. We found 12 spawning sites of this endangered species. The silt-clay content of the sand fraction of sediment samples ranged from 0% to 6.1%. The median diameter and size-sorting of sediments ranged from -2.32 to 2.32 phi and 0.37 to 1.98 phi, respectively. The median diameter of sediments and the number of reproductive visiting pairs at each spawning site were significantly positively related. Our results also indicated that about 70% of reproductive females laid eggs at four sites around Tsuyazaki Bridge. Moreover, a continuous monitoring survey revealed a clear decrease in the number of reproductive visiting pairs in the threatened wild population. The factor most likely associated with this decline of horseshoe crabs is the recent coastal development around Tsuyazaki Bay. Therefore, we recommend continuing the citizen-based monitoring of the horseshoe crabs to contribute to the protection of the coastal ecosystem and biodiversity.

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In cases where invasive, exotic mammal control is conducted via trapping, spatial allocation of traps influences control results. In many cases, managers do not have sufficient information on the distribution of target species. Therefore, effective trap allocation methods based on capture results from prior years is useful for controlling target species. We examined effective trap allocation methods using a lattice model and considered two opposing situations in which population density dependence of catchability was either high or low. We used parameter values for the small Indian mongoose Herpestes javanicus found on Amami-oshima island in southern Japan. The results show that when population density dependence of catchability is low, eradication is achieved early if trap allocation is 2:1 in favor of areas where the target was previously captured, as compared to neighboring areas where the target was not captured. When density dependence of catchability is high, there is a trade-off between preventing further distribution expansion and reducing the remaining population. If many traps are allocated to an area where the target was captured in the vicinity, distribution expansion is slow. Reducing the remaining population requires allocation of the same amount of traps into both the surrounding areas and area where the target was captured.

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A method of fishing using live baitfish was developed as a part of ongoing measures to eradicate the largemouth bass, Micropterus salmoides. An 8-9 m-long rod was used in an open area with a small float, a small-sized hook and a 45cm snell attached to the end of the line. The Japanese dace, Tribolodon hakonensis, 5-9cm in standard length (SL), were used as baitfish. The hook was threaded through the anterior part of the dorsal section of the baitfish and the tip of the hook was extended from the body. Bass were struck and hooked 30-40 seconds after attacking and swallowing the baitfish. Investigations conducted in a pond showed that this fishing method was more effective for capturing bass than lure fishing, and the number of large-sized bass in the pond was effectively reduced using this method. The numbers of largemouth bass caught using three types of bait-live Japanese dace, live shrimps and worms-were also compared in nine ponds and lakes in the Nagano prefecture. Large-sized bass longer than 20cm SL were mostly caught using live Japanese dace, whereas live shrimp were more effective for catching smaller-sized bass than live worms and Japanese dace.

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To determine effects of anthropogenically-induced environmental changes on a sika deer (Cervus nippon) population, we measured food resource abundance and numbers of deer feeding scars at impacted and control sites. Study sites were set in cedar plantations and broadleaf secondary forests near Yakushima. Within each site, one-meter square plots were set along roadsides and in the forest interior. All grasses and seedlings within plots were harvested for dry weight measurements (food biomass). In addition, fixed transects were deployed near the harvested plots, and all feeding scars were counted along transect lengths. At both sites, there was more food biomass along roadsides than in forest interiors. There were also more food resources within the interior of forest plantations than within broadleaf secondary forest stands. Distributions of feeding scar numbers correlated closely with food biomass distributions. Hence, within our study area, road building and planting of artificial cedar stands have probably contributed to increased food biomass for the sika deer population.

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The sika deer population (Cervus nippon) in the Boso Peninsula of Chiba, central Japan, has expanded dramatically in recent decades, causing serious damage to rice crops. To predict the level of damage, we conducted approximately 350 interviews of paddy field owners and developed a regression model that included local deer density and landscape structure surrounding paddy fields as explanatory variables. Model selection using Akaike's information criterion (AIC) revealed that the level of damage was affected by landscape structure within a 400-m radius of a focal rice field as well as local deer density. This spatial scale was consistent with the home-range size of sika deer as well as the scale determining food quality and the reproductive rate of deer in the Boso Peninsula. The level of damage also increased with an increase in forested area but tended to decrease with increases in the surrounding forest-edge length in areas with higher deer densities. We also constructed a risk map for rice-crop damage to determine local deer densities that could keep damage at low levels using the above regression model. The estimated deer density at which this occurred was highly variable depending on landscape structure. Comparing such risk maps and current local deer density will help to facilitate the establishment of an objective management plan in a heterogeneous landscape.

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The round crucian carp (Carassius auratus glandoculis) is an endemic species, which is categorized as endangered in Lake Biwa, Japan, by the Ministry of the Environment. The spawning behavior of the species has not been fully studied. We analyzed triggers for the spawning migration from Lake Biwa to the paddy field drainage area at Shimokasa of Kusatsu city, in Shiga Prefecture. Observations were conducted between May 14 and July 9, 2008. In the field, numbers of carp were surveyed daily, and statistical data on environmental factors were also collected and analyzed by canonical discriminant analysis. Results showed that spawning migration triggers included water level fluctuations in Lake Biwa and Chemical Oxygen Demand (COD). We discuss the implications of our findings in relation to conservation strategies for the species.

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Changes in species richness and species composition due to grazing by sika deer were examined in warm-temperate deciduous broad-leaved secondary forests in southeastern Hyogo Prefecture and northwestern Osaka Prefecture. The vegetation structure, species richness, and species composition of stands with apparent signs of deer grazing (grazed stands) were compared with those of ungrazed stands. The vegetation cover of the shrub layer (approximately 2m in height) and herb layer was lower in grazed stands than in ungrazed stands. A similar trend was observed for the number of deciduous plant species per 100m^2, even when deciduous plants were classified into four life forms (trees, shrubs, herbs, and climbers). Differences in the species richness of deciduous plants between ungrazed and grazed stands were larger for the shrub layer than for the herb layer, suggesting that the negative effect of deer grazing on species richness is greater in the shrub layer than in the herb layer. The species composition of the shrub and herb layers greatly differed between ungrazed and grazed stands; many species had lower frequencies of occurrence in grazed stands, whereas Illicium religiosum exhibited the opposite trend. Based on these results, we concluded that deer grazing considerably simplified the species composition of warm-temperate secondary deciduous broad-leaved forests.

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The effects of flooding and prescribed fire on the germination of black locust (Robinia pseudoacacia L.) seeds were investigated. We examined germination under several conditions, in which the seeds were either shaken together with sediment to simulate a flood, or sown/scattered over a field that was then burned. Seeds shaken together with gravel had a higher percentage of germination (80.0±11.2%, mean±sd) than seeds shaken with sand (19.2±8.3%), and seed germination was positively correlated with the amount (time) of shaking. The effect of fire on seed germination differed according to the depth of seed placement and the type of vegetation burned. Seeds placed at a depth of 3cm hardly germinated, because the ground temperature did not increase sufficiently during burning. At ground level, fire rapidly raised the surface temperature to>110℃ in a large gramineous community, but in a bed of Zoisia japonica the temperature increased to only 30-40℃. Accordingly, Robinia seeds placed in the Zoisia community showed the highest percentage of germination (25.8±20.5%), whereas seeds scattered on the surface in the large gramineous community showed high mortality (84.7±15.4%) and low germination (6.2±9.1%) due to the intense heat. The effects of fire on Robinia seed germination differed according to the biomass of the grass community: prescribed fires promote seed germination in short-grass communities but inhibit germination in long-grass communities.

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We constructed a butterfly database using records collected by citizen scientists during the period from 1923 to 2008 in the three westernmost wards of Tokyo, Japan. Using the database, we examined the temporal change in the butterfly fauna in the area and analyzed the contribution of nine ecological traits to the difference between two periods: 1923-1960 (past) and 1982-2008 (recent). Of the 66 species recorded in the past, 16 species had disappeared in the recent period. Logistic regression showed that the disappearance was significantly associated with three ecological traits: univoltine (P<0.01), feed plant specialist (P<0.05), and inability to utilize cultivated plant species as feed plants (P<0.01). By contrast, all six species newly recorded in the recent period were bivoltine or multivoltine, and four of these species utilized cultivated plant species. The newcomers were species that were known to have recently expanded their distributions in Japan, probably due to warming, the heat-island effect, and global climate change. Our results indicated that this type of database is useful for revealing temporal trends in rapid butterfly faunal change and for analyzing factors affecting the change.

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Deer-proof fences have been used to protect and restore endangered perennial herbs in some areas of Japan where the forest floor vegetation has been diminished by browsing sika deer (Cervus nippon Temminck). However, little work has been done to evaluate the optimal timing for installing such deer-proof fences. Thus, I surveyed the occurrence, number of individuals, and number of mature individuals of 12 perennial species inside seven deer-proof fences over 5 years post-establishment, three of which were installed in 1997 (1997 fences), and the other four in 2003 (2003 fences). The occurrence of six species was equal between the 1997 fences and the 2003 fences, while that of the remaining six species was higher within the 1997 fences than the 2003 fences. Past records indicated that three of these latter six species were distributed equally between the areas of the 1997 and 2003 fences. These results suggest that the potential distribution of nine species found within the 1997 fences was equal to that of the 2003 fences. The number of individuals of four of these nine species was greater in the 1997 fences than in the 2003 fences, or showed differing relative rankings. These findings suggest that these four species have difficulty recovering, given the assumption that the fences were constructed in regions where the forest floor was subjected to the continual sika deer browsing. In contrast, the remaining five species did not show significantly different numbers of individuals between the 1997 and 2003 fences. Thus, these five species appear to be unaffected by 10 or 16 years, respectively, of sika deer browsing. These findings demonstrate that some species have difficulty recovering once the forest floor has been diminished by browsing sika deer. Thus, the early establishment of deer-proof fences is suggested to enable the best recovery of perennial herbs.

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Fish fauna and host utilization of freshwater unionoid mussels were investigated in the riverside pools (called 'wando') along the Yodogawa River, Osaka, to assess the influence of the domination of exotic fishes (e.g. bluegill sunfish Lepomis macrochirus and largemouth bass Micropterus salmoides) on the reproduction of mussels. Total population ratios of bluegill and largemouth bass ranged from 10-64% at the study sites. Thirty-nine to 67% of Unio douglasiae nipponensis larvae and 18-96% those of Anodonta spp. parasitized both fishes. About 99% of U. douglasiae nipponensis larvae found on both were not encysted. About 97% of Anodonta spp. larvae on both were encysted or had metamorphosed successfully. Artificial infection experiments also certified the unsuitability of both fish to U. douglasiae nipponensis, as the ratio of successful metamorphosis was ca. 0.5% and more than ca. 80% of larvae were dead on both hosts. Innate rather than acquired immunity would induce these unsuitabilities. These results would indicate that the dominance of bluegill and largemouth bass negatively influence the reproduction of U. douglasiae nipponensis. We need to monitor the population of U. douglasiae nipponensis in the Yodogawa river, and pay attention to other inland waters where such a problem might arise.

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Myoginohana Marsh is a lowland reed marsh with high indigenous species richness, including 19 endangered species. However, the area dominated by Ischaemum aristatum var. glaucum, which once occupied most of the area of the marsh, has been declining since the late 1990s. We hypothesized that I. aristatum var. glaucum is an indicator of indigenous species richness in the marsh, due to its tussocks, which provide suitable habitat for other species. The marsh vegetation was classified into three distinct types: type C, where Carex deispalata dominates in the middle layer beneath Phragmites australis, which is dominant in the grass canopy; I^+, where I. aristatum var. glaucum dominates in the middle layer, with a patchy moss-layer on the soil surface; and type I^-, where I. aristatum var. glaucum dominates in the middle layer, without moss. The average species density within a 1-m^2 quadrat was highest in type I^+. A whole-marsh-scale survey revealed that the distribution of four endangered species was significantly associated with type I^+. A microsite-scale survey revealed that species density was significantly higher in tussock microsites than in microsites with tussocks. Type I^+ vegetation was characterized by specific environmental conditions: a lower density of P. australis in the high vegetation layer; greater light availability above the middle and low layers of vegetation; and higher frequency of winter mowing or burning than the other vegetation types. These results suggested the importance of I. aristatum var. glaucum as an indicator of plant species richness in the marsh. The ongoing loss of the area dominated by the species may cause a rapid decline in species richness and local extinctions of some endangered plants.

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We investigated the presence/absence of common carp (Cyprinus carpio) and coverage of aquatic plants including endangered species in 74 small agricultural ponds in hilly regions of Iwate Prefecture, Japan. Our results revealed that the presence of common carp has significant negative effects on the coverage of floating-leaved plants and submerged plants, but not on emergent plants. This indicates that the introduction of common carp to small agricultural ponds can modify habitat conditions for many aquatic organisms by reducing the coverage of aquatic plants.

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Biodiversity was mapped by citizens in Chigasaki City (36km^2), a suburb of Tokyo. The participants identified the traditional rural landscape (a mixture of forest, grassland, and wetland) and a coastal dune ecotone (a mixture of maritime forest and dunes) as important for regional biodiversity and for the identity of the city. In total, 163 species (plants and animals) were chosen as indicator species for forest, grassland, freshwater wetland, and coast habitats. The indicator species were mapped at a 25-m spatial resolution. The city was divided into 76 areas, and the number of indicator species in each environment was used as a measure of ecosystem integrity. The integrity of the traditional rural landscape was calculated as the sum of values of forest, grassland, and freshwater wetland. The results were used to determine core areas to protect. Further applications for city planning are under discussion.

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