First record of Craspedacusta sowerbii Lankester, 1880 (Hydrozoa, Limnomedusae) in a natural freshwater lagoon of Uruguay, with notes on polyp stage in captivity

Abstract The freshwater cnidarian Craspedacusta sowerbii Lankester 1880, has invaded lakes and ponds as well as artificial water bodies throughout the world. The first record in Uruguay corresponding to the jellyfish was made in 1961 in two artificial fountains, with no mention of the polyp form. Although local reports of other related polyp species have been made, information on the benthic form of C. sowerbii is lacking. Here we report the finding of live frustules, solitary individuals, medusae and colonies from a natural lagoon in August 2010, allowing us to observe the morphology and behavior of the polyp stage in captivity. In addition, molecular identification and remarks on the potencial path of introduction are presented. This is the first record in Uruguay of both polyp and medusa stages of C. sowerbii in a natural water body, Del Medio Lagoon (Dpto. de Florida), Uruguay

PRELIMINARY TESTING OF A SELENIUM-BASED SYSTEMIC DEER BROWSE REPELLENT

Silviculturists use a variety of techniques, including repellents, to reduce browse damage by white-tailed deer (Odocoileus virginianus) to valuable eastern hardwood seedlings. Systemic selenium, sodium selenite, was evaluated with captive white-tailed deer for its repellency in white ash (Fraxinus americana) and black cherry (Prunus serotina) seedlings. Selenium had no effect in reducing browsing of black cherry. However, there was a reduction (p\u3c0.05) in the white ash browsing level

Brown trout fry move inshore at night: a choice of water depth or velocity?

The instream positions of brown trout fry differ between daylight and darkness. According to field and laboratory observations, recently emerged 0+ brown trout use shallow and slow-flowing areas close to the bank at night and tend to move off-shore during daylight. In laboratory channels, we tested whether the use of habitats close to the river bank could be attributed to a choice of either water depth or velocity. In two complementary experiments, emerging brown trout alevins were given the choice of using shallow-slow or deep-swift habitats (experiment 1), and deep-slow or shallow-swift habitats (experiment 2). At night, a persistent preference for the shallow habitats was displayed, regardless of velocity. It was concluded that swim-up brown trout fry respond to shallowness rather than ambient low water velocity when selecting habitats close to the bank at night. The behavioural significance of this result and implications for river management are discussed