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Capelin is a planktivorous key fish species in many subarctic ecosystems representing the link between lower trophic levels and apex predators. Little is known, however, of capelin in Greenland waters, but it has been suggested that size and growth increases due to difference in food availability and temperature conditions along a 1,500 km south-north gradient on the west coast. It is presently unknown how the qualitative state of capelin energy content is affected along this gradient. Based on 2007 and 2008 samples, we show that energy content increases with capelin length in both spawning and non-spawning fish and that it varies with latitude in spawning fish along West Greenland (60-71°N). Combining our results on energy content with information on capelin growth along the same latitudinal climate gradient demonstrates that less and lower-quality food is available to capelin predators in the south than in the north., Author(s): R. Hedeholm [sup.1] [sup.2] [sup.3] , P. Grønkjær [sup.1] , S. Rysgaard [sup.2] Author Affiliations: (1) grid.7048.b, 0000000119562722, Marine Ecology, Department of Biological Sciences, Aarhus University, , Building 1135, [...]

A several centimeter thick, [H.sub.2]S-oxidizing microbial mat was encountered in a high-latitude Arctic fjord. Microscopic investigations revealed that the mat contained numerous filamentous bacteria, and fluorescence in situ hybridization showed that the vast majority of these belonged to [gamma]-Proteobacteria and that Abstract Thiothrix spp. was present. The mat grew on a layer of accumulated decaying macroalgae and was characterized by a complex three-dimensional structure consisting of numerous holes, voids and chimney-like structures. Microsensor measurements performed in situ and in a laboratory-established mesocosm showed a highly dynamic [O.sub.2], pH and [H.sub.2]S distribution, especially around protruding structures of the mat. Detailed microsensor investigations documented that anoxic sulfidic water emerged trough the chimneys and indicated a microcirculation, replenishing the emerging water with oxygenated water in areas were the mat was absent. This governed an efficient advective exchange of solutes and presumably allowed the mat to grow to the extensive thickness of several centimeters.

A highly-precise method for determining the nitrogen-15 isotope content of urea using as little as 10 nmol sample was developed. The procedure works by combining cation exchange and enzymatic hydrolysis of urea with microdiffusion-hypobromite oxidation method. The procedure is applicable to both freshwater and marine samples while interference was found only from volatile methyl amines.

A several centimeter thick, H2S-oxidizing microbial mat was encountered in a high-latitude Arctic fjord. Microscopic investigations revealed that the mat contained numerous filamentous bacteria, and fluorescence in situ hybridization showed that the vast majority of these belonged to γ-Proteobacteria and that Thiothrix spp. was present. The mat grew on a layer of accumulated decaying macroalgae and was characterized by a complex three-dimensional structure consisting of numerous holes, voids and chimney-like structures. Microsensor measurements performed in situ and in a laboratory-established mesocosm showed a highly dynamic O2, pH and H2S distribution, especially around protruding structures of the mat. Detailed microsensor investigations documented that anoxic sulfidic water emerged trough the chimneys and indicated a microcirculation, replenishing the emerging water with oxygenated water in areas were the mat was absent. This governed an efficient advective exchange of solutes and presumably allowed the mat to grow to the extensive thickness of several centimeters. [ABSTRACT FROM AUTHOR]

Examines a method for determining nitrogen-15 isotope in urea. Details on the materials and methods used in this study; How the nitrogen-15 isotope can be determined; Information on the use of the hypobromite oxidation method.