Abstract: During the winter, from September 2012 to April 2013, 243 sea turtles were found along the Japanese coast of the Sea of Japan. Of these, 196 had been washed ashore, 44 were obtained as bycatch, and the remaining three came from an unknown source. The most notable finding was 119 post-hatchling loggerhead turtles, Caretta caretta, with carapace lengths of approximately 10 cm. Using mixed stock analysis, their natal regions were determined to be mainly areas in southern Japan, including the Okinawa Islands, Okinoerabu Island, and Yakushima Island. Furthermore, the post-hatchlings appear to have entered the Sea of Japan via the Tsushima Current from October to November 2012, which is when the post-hatchling bycatch increased, and 90 of the 107 post-hatchlings that washed ashore were found between December 2012 and January 2013. Small sea turtles, especially post-hatchlings, do not survive the low winter water temperatures in the Sea of Japan. However, two post-hatchlings were found in Mutsu Bay and eastern Hokkaido, indicating that post-hatchlings can exit the Sea of Japan to the Pacific Ocean via the Tsugaru Strait. Therefore, the dispersal of loggerhead post-hatchlings might not be entirely unsuccessful.
Abstract: Adult caddisflies were collected using light traps to investigate invertebrate habitat features in the Seta-Uji River, the outlet of Lake Biwa. Four hydropsychid and two psychomiid species were dominant in frequency and number, whereas many species common to Japanese rivers were absent. Based on the number of species in each caddisfly family, filter-feeders, which feed on lake-derived plankton, and net-spinners, which prefer stable substrates, were more dominant. Shredders/collectors that feed on deposited detritus, and case-holders, which require sand, were less dominant. The plankton supply, stable lake-outlet flow, and scarcity of lentic habitat were reflected in the caddisfly community. Occurrence differed among species, even within the same genus. Species that were abundant in the Seta-Uji River tended to be the same as those distributed mainly in the middle and lower sections of river continua, whereas the absent species tended to be the same as those distributed mainly in the upper or all longitudinal sections. As Lake Biwa separates the outlet of the Seta-Uji River from its upper reaches, some species may be unable to maintain their populations in the Seta-Uji River without an upper source of individuals. The location of the lake may explain the differences in the caddisfly community between the Seta-Uji River and other lake-outlet rivers.
Abstract: Castanea crenata is a duodichogamous tree in which individual flowering phenology progresses in the order male → female → male. Differences in flowering patterns between individuals and the adaptive significance of duodichogamy in C. crenata have not been previously explored in natural populations. In this study, we monitored the phenology of individual male and female flowers from eight C. crenata trees in a natural forest using tree towers. In five of the eight trees, flowering occurred in the order male → female → male. For the other three trees, either type of flowers (i.e., first male, second male or female) started to bloom at the same time. Within individual trees, male and female phases overlapped. In addition, the flowering period of the first and second male phases was assessed for 49 trees. At this population level, we observed a greater overlap in male and female flowering periods after pooling the first and second male phases. This overlap in flowering periods among individuals was also evident when we included our eight study trees in the population data. Our results suggest that duodichogamous flowering phenology may promote outcrossing of the self-incompatible tree species C. crenata, rather than prevent self-pollination.
Abstract: Sunlight is a mixture of electromagnetic radiation at wavelengths ranging from 300 to 2500 nm at the surface of the earth. Interactions between electromagnetic waves and matter change with the wavelength. Ultraviolet and visible light (330−760 nm) is absorbed by photoreceptor proteins in the eyes of animals, providing them with ‘visible’ information. Photosynthetically active radiation (400−700 nm) is essential for many plants, while near-infrared light (700–2500 nm) is absorbed by water and organic compounds. Therefore, measurements of the features of these reflection spectra can be useful for studying both the vision of animals and physiological functions of plants. Spectrometers are used to measure the electromagnetic spectrum and conventionally most have been large instruments installed indoors. Recent technological developments have produced handheld spectrometers that can measure the spectrum at a pinpoint anywhere. Moreover, imaging spectrometers, which spectrally disperse the incident light at each pixel, continue to be improved and can provide spectroscopic images at any scale. This review explains spectrometry and introduces ecological studies using the latest spectrometers. The recent application of spectrometry to field studies should reveal new relationships between organisms and light.
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