We surveyed the living condition of freshwater turtles and aquatic organisms with traps at eight ponds in the northeast region of Chiba Prefecture in the summer (Jul–Aug) and fall (Oct–Nov) of 2012. All ponds were invaded by exotic largemouth bass Micropterus salmoides and/or bluegill Lepomis macrochirus. Freshwater turtles were observed in five of six ponds with freshwater aquatic organisms (small fishes and/or crustacean), whereas no turtles were observed in two ponds with no aquatic organisms. Chinese pond turtles Mauremys reevesii were captured in both seasons. There was no significant correlation between the number of Chinese pond turtles captured and any environmental factors (water temperature, dissolved oxygen, pH, and electric conduct- ivity) in either season. The number of Chinese pond turtles captured positively correlated with the number of topmouth gudgeon Pseudorasbora parva and freshwater shrimps (Palaemonidae) in the summer, and the number of the Chinese pond turtles also positively correlated with the number of red swamp crayfish Procambarus clarkii in fall. The number of red-eared slider (Trachemys scripta elegans) captured also positively correlated with the number of freshwater shrimp in summer, suggesting that the two turtle species were competing for the same pray. Results of multiple regression analysis indicated that while aquatic macrophytes had positive effects on the number of small aquatic organisms observed, invasive largemouth bass had a negative effect on the organisms captured in the study. These findings suggesting negative impacts of invasive largemouth bass on a number of aquatic organisms which are potential pray for freshwater turtles in these pond ecosystems.

We investigated for an appropriate anaesthetic procedure with MS-222 to maintain anaesthesia for 1–3 minutes in three species of host fishes (Gymnogobius urotaenia, Rhinogobius spp. and Oryzias latipes) for unionid mussels, setting of which is useful in the experiment of glochidial infection to the specific body part of these fishes. Recovery time was prolonged with increasing MS-222 concentration, irrespective of the species. Under our protocol, use of 100 mg・l^-1 of MS-222 was appropriate in G. urotaenia and Rhinogobius spp. and 200 mg・l^-1 of MS-222 was appropriate in O. latipes to maintain anaesthesia for 1–3 min, respectively. We investigated for an appropriate anaesthetic procedure with MS-222 to maintain anaesthesia for 1–3 minutes in three species of host fishes (Gymnogobius urotaenia, Rhinogobius spp. and Oryzias latipes) for unionid mussels, setting of which is useful in the experiment of glochidial infection to the specific body part of these fishes.

Timing of migration in relation to environmental factors (weather conditions: temperature and snowfall, and artificial feeding) were investigated for swans wintering in Miyagi prefecture, northern Japan, during 15 years (2000/01–2014/15). The average numbers of swans were 3,870 in November, 13,057 in January and 3,230 in March, respectively. Results of GLMM (generalized linear mixed model) analysis indicated that increasing snowfall in December increased the number of swans in autumn migration (November to January). Decreasing snowfall in February, however, resulted in a decrease in the number in swans from January to March.

Recent research reports that harvest mice (Micromys minutus) are commonly found inhabiting wet areas with dense grass (Poaceae) and sedge (Cyperaceae) vegetation in low-lying grasslands, rice and other crop fields, fallow fields and marshland areas. On the other hand there are few studies reporting their frequent use of flood plains and embankments nationwide and only a very limited amount of research has been focused on how vegetation influences their nesting behavior in flood plains and embankments. Furthermore, no work has been conducted in urban areas to investigate the relationship between habitat use characteristics and covering vegetation types. This study aims to investigate the spherical nests of harvest mice in flood plains and embankments of Shonai River, which flows through western Nagoya, Aichi, Japan, and analyze the relation between the distribution of nests and the surrounding vegetation in order to reveal the habitat conditions of harvest mice in urban regions. The results show that the harvest mice were present in three main habitat categories within the 20-meter buffer zones surrounding nests. One of these categories was grassland covering 754.4– 860.9 m² (65.1–79.3%) of each buffer zone. These areas that were assumed to be suitable habitat were dominated by Johnson grass (Sorghum halepense) and Amur silvergrass (Miscanthus sacchariflorus). Another suitable habitat category contained areas where the buffer circles were dominated by artificially bare ground, urban parks and sports grounds containing grassland in only 114.2–297.8 m² (9.2–30.1%) of the circle. This research suggests that in flood plains under intense human influences in urban areas like Nagoya, harvest mice can make adaptive use of limited amounts of favored vegetation for nesting.

There are few reports of shrimp in the Toyo-gawa River in Higashi-Mikawa district, Aichi prefecture; therefore, basic data need to be collected to implement environmental protection activities. Shrimp fauna was collected with a hand net and surveyed from 13 sites in the lower and middle reaches of the Toyo-gawa River between 2010 and 2013. Sixteen shrimp species from seven families were identified. The largest shrimp population identified was Acetes japonicus, and the species with the widest distribution was Macrobrachium nipponense. Among the identified species, the only alien species was Procambarus clarkii. A cluster analysis divided the data into three groups: seawater species occurred in the lower part of the brackish water area, amphidromous species in the upper part of the brackish water area and lower part of the fresh water area, and freshwater species in the central to upper part of the freshwater area. Therefore, shrimp distribution is considered to be greatly affected by salinity.

137 Bewick’s Swans foraged seeds of Barnyardgrass Echinochloa crus-galli var. caudata in fallow fields of Echigo Plain, at 11 December, 2005. Using fallow fields by Bewick’s Swans is rare.

Species composition of the traditional boiled-dried fish and shrimp, Gota-niboshi, processed and sold around Lake Kasumigaura, Ibaraki Prefecture, eastern Japan were examined using samples purchased at 11 processing shops from August to September 2018. A total of 51,231 individuals representing six families and ten species were recorded throughout the study period. The most abundant species were the shrimp species Macrobrachium nipponense (43.4% of the total number of individuals collected during this study), the gobiid Tridentiger brevispinis (29.6%), the salangid Salangichthys microdon (25.3%), the osmerid Hypomesus nipponensis (0.8%) and the gobiid Acanthogobius lactipes (0.7%). A similarity index indicated differences in species composition of Gota-niboshi between shop groups. Such differences were not associated with any data regarding shop localities or purchase dates of Gota-niboshi samples.

We estimated the diet of carnivorous snakeheads Channa argus, native to China, Korea and Russia, using carbon and nitrogen stable isotopes in Lake Izunuma in 2006 and compared their diet with those of largemouth bass Micropterus salmoides. The relative contributions of potential prey to the diet of snakehead and largemouth bass were estimated using Bayesian mixing model (Stable Isotope Analysis in R). Largemouth bass smaller than 100 mm in total length (TL) foraged mainly on planktonic copepods and small fishes. In contrast, juvenile snakehead (56 to 69 mm TL) fed mostly on cladoceran zooplankton and rarely consumed fish. This result suggests that there was a scarcity of appropriately sized prey fish for juvenile snakehead in Lake Izunuma. Largemouth bass larger than 300 mm TL relied mostly on red swamp crayfish Procambarus clarkii. Adult snakehead (530 to 780 mm TL) also foraged mainly on red swamp crayfish as well as small fishes, though dietary contribution of crayfish to snakehead was smaller than that of largemouth bass. In the case where a population of red swamp crayfish increased after the extermination of largemouth bass, snakehead could add predation pressure on red swamp crayfish. Because snakehead could also consume native fishes, monitoring the population and diet of snakehead is required.