and Nesterova, V. N. 2005. The relationship between plankton, capelin, and cod under different temperature conditions e ICES Journal of Marine Science, 62: 1281e1292.On the basis of data from cold (1982 and 1987) and warm summers (1983, 1984, 1990, and 1992), we explore the relationship between the phytoplankton bloom and the timing and intensity of the zooplankton bloom. In warm years, there is more overlap in the time between the zooplankton and the phytoplankton bloom. In northern areas (76e78(N) with seasonal ice, the phytoplankton bloom and reproductive processes in Calanus finmarchicus and Calanus glacialis continue well into August, evidenced by the presence of an abundance of nauplii and younger copepodites. We analyse feeding intensity of capelin and its distribution relative to food availability and capelin abundance. The extent to which feeding areas of cod and capelin, its major prey, overlap is subject to the abundance of these species, distribution of zooplankton, and sea temperature in a given year.
Using cod feeding data, this paper considers the distribution and abundance of macroplankton from different ecological groups (euphausiids and hyperiids) and the variability in their consumption by cod over a period of years during which different water mass temperatures were observed. These years were also characterized by variable abundance of capelin, cod's main food source. Differences in intensity and duration of cod consumption of euphausiids and hyperiids species are shown, depending on their abundance, temperature conditions, cod distribution, and the supply of capelin for cod. This paper discusses the energetics of consuming different types of prey and the role euphausiids play in the energy balance of cod. The low fat content of cod is sometimes associated with feeding on postspawning euphausiids in summer and autumn.
Zooplankton in the Barents Sea has been monitored in a joint program by Norway and Russia using Juday (37 cm) and WP2 (56 cm) vertical plankton nets. We have compared the nets in two studies (2007 and 2013) with the Juday and WP2 nets mounted side by side on a common frame. WP2 collected consistently more zooplankton biomass than Juday, by 15–20% for both studies. Higher catch for small and medium size fractions as well as total biomass suggest that the difference was not due to extrusion or escape of organisms through the meshes, but rather that the amounts of flow and filtration of water through the two nets were different from the estimated volumes. Results for two hauling speeds (0.5 and 1.0 m s−1) in the 2013 study were not conclusive due to apparent changes in plankton composition at the sampling station during the study. The Juday and WP2 biomasses were highly correlated and the two nets showed very similar species composition with the pairwise design. The two nets would therefore give comparable spatial and temporal patterns of zooplankton distribution in the joint monitoring program.
Two sodium vanadium phosphates, synthetic analogues of the minerals kosnarite, Na3V2(PO4)3, and yurmarinite, Na7V4(PO4)6, were obtained by hydrothermal synthesis simulating a natural hydrothermal solution. While the Na3V2(PO4)3 phase belongs to the NASICON family and is well-known for its high-ionic conductivity, the new Na7V4(PO4)6 compound is a rare case of V2+-containing oxosalts, which are hard to prepare due to their instability in air. Here we report the crystal structure of heterovalent vanadium phosphate studied by single crystal X-ray diffraction, XANES spectroscopy, and topological ion migration modelling. A discussion of divalent vanadium compounds of both natural and synthetic origin is also given, with a review of the methods for their synthesis and a comparative analysis of V–O bond lengths.
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