Farm ponds have high conservation value because they contribute significantly to regional biodiversity and ecosystem services. In Japan pond draining is a traditional management method that is widely believed to improve water quality and eradicate invasive fish. In addition, fishing by means of pond draining has significant cultural value for local people, serving as a social event. However, there is a widespread belief that pond draining reduces freshwater biodiversity through the extirpation of aquatic animals, but scientific evaluation of the effectiveness of pond draining is lacking. We conducted a large-scale field study to evaluate the effects of pond draining on invasive animal control, water quality, and aquatic biodiversity relative to different pond-management practices, pond physicochemistry, and surrounding land use. The results of boosted regression-tree models and analyses of similarity showed that pond draining had little effect on invasive fish control, water quality, or aquatic biodiversity. Draining even facilitated the colonization of farm ponds by invasive red swamp crayfish (Procambarus clarkii), which in turn may have detrimental effects on the biodiversity and water quality of farm ponds. Our results highlight the need for reconsidering current pond management and developing management plans with respect to multifunctionality of such ponds. Efectos del Drenado de Estanques sobre la Biodiversidad y la Calidad del Agua en Estanques de Cultivo.

山田 佳裕 1) ，井桁 明丈 2) ，中島 沙知 3) ，三戸 勇吾 3) ，小笠原貴子 4) ， 和田 彩香 4) ，大野 智彦 5) ，上田 篤史 2)，8) ，兵藤不二夫 2) ，今田 美穂 2) ， 谷内 茂雄 2) ，陀安 一郎 6) ，福原 昭一 7) ，田中 拓弥 2) ，和田英太郎 2)，9)The runoff of suspended substances，nitrogen，and phosphorus by enforced draining during the ploughing season Experiments in paddy fieldsThe runoff of suspended substances (SS)，nitrogen，and phosphorus by enforced draining during the ploughing season was calculated from experiments in two paddy fields．The area of a paddy field was 3000m 2 ．The total fluxes were 33 kg (SS)， 85 g (total-N)， and 46 g (total-P) in Field A， with a small decrease in water levels (8mm)， 110kg (SS)，589 g (total-N)，and146 g (total-P) in Field B with a major decrease in water levels (72mm)． Furthermore， the nitrogen/phosphorus ratios (mol ratios) of the waste water by the enforced draining were 4.1 (Field A) and 8.8 (Field B)．In comparison with N/P of the phytoplankton (16)，it was found that the phosphorus flowed out efficiently with the enforced draining．Increasing the supply of the phosphorus to Lake Biwa is not desirable in view of the current problems of eutrophication．The careless water management of paddy fields was a crucial factor in any plan to improve the water quality of Lake Biwa．

The aim of this study is to evaluate the effect of visual biofeedback therapy in acquiring supraglottic swallow (SGS) in a randomized-controlled trial with healthy individuals. Eighteen individuals (mean age, 26 years) who could not close or keep closed the vocal folds before and during the swallow in SGS were allocated randomly to either a visual biofeedback group (eight individuals) or a nonbiofeedback group (10 individuals). A videoendoscope was inserted intranasally and an SGS exercise, using 4 ml of green-colored water, was performed 30 times per day up to 5 days. When the participant failed to perform SGS, the result was provided only to the participants in the visual biofeedback group. The median length of time until acquiring SGS was 1.5 days in the visual biofeedback group and 3.5 days in the nonbiofeedback group (P=0.040). We concluded that visual biofeedback effectively enabled participants to acquire SGS earlier.

Biological invasion is one of the major threats to farm pond biodiversity. Farm ponds may serve as biodiversity hot spots because they provide refuge sites for a variety of animals and plants inhabiting floodplain marshes.Developing effective management methods with regard to the multifunctionality of farm ponds is one of the major concerns among environmental managers. Here, we investigated through a field survey and interviews the effects of pond management on the presence/absence of alien species in 64 farm ponds in Hyogo Prefecture, Japan. The result of the field survey indicated that bluegill sunfish (Lepomis macrochirus) and red swamp crayfish (Procambarus clarkii) are the most widespread and abundant aquatic invaders in the study region. Although it is generally believed that pond draining is effective in eradicating alien fish, pond draining showed no effect on the presence/absence of bluegill sunfish, but influenced the occurrence of red swamp crayfish, with crayfish generally found in drained ponds. The presence/absence of bluegill sunfish was generally high where dam water or agriculture draining is used as the major water supply. Thus, the alien bluegill sunfish probably immigrate into farm ponds from dams or irrigation systems even though they may temporarily disappear following pond draining. If the (mutually exclusive) distributions of bluegill sunfish and red swamp crayfish are determined at least in part by interspecific interactions between the two species, eradication of one species may lead to an increased density of the other.

No abstract