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Impact of water level fluctuation in the shaping of zooplankton assemblage in a shallow lake.

Abstract

Shallow lakes are strongly affected by global climate changes reflected in significant parameters of ecosystem deterioration, i.e. biodiversity decrease, and water turbidity. Zooplankton research in Škrčev kut oxbow lake (Krapina River watershed, NW Croatia, Europe) was conducted during the summer of 2012 and 2013 with the aim to determine the effect of inter-annual, short-timescale changes of hydrological regime on environmental conditions, macrophytes, zooplankton and fish assemblage within an oxbow lake in the temperate region. Within one-year period the water level increased by 2 meters. This caused a significant reduction of floating-leaved macrophytes (i.e. Nuphar lutea), while turbidity, ortho-phosphate and chlorophyll a concentrations increased. These altered ecological conditions were reflected in the shift from floating-leaved macrophytes at the lower water level to phytoplankton-dominated lake at the higher water level. Zooplankton underwent significant alteration in assemblage. The results suggest that fish preference suppressed cladocerans and enhanced the rotifer and copepod abundance. Our results indicate that even in a short-timescale zooplankton assemblage mediates in the modification of ecosystem functioning.

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The effect of commercial feed supplemented with selected yeast, probiotics and herbal additives on the growth performance of juvenile dusky kob (Argyrosomus japonicus).

Abstract

The main objective of this investigation was to test the effect of a standard commercial feed (Skretting Active ZA) on the growth performance of juvenile dusky kob (Argyrosomus japonicus), compared to the same feed when supplemented with six commercially available additives over a period of 10 weeks. A common additive in trial treatments contained two yeast strains (84% Candida utilis and 16% Saccharomyces cerevisiae) that were incorporated at 33% of the total feed mass. The yeast combined diet was also tested per se as a base experimental diet (BED). In the remaining five trials the BED was respectively mixed with selected herbal extracts or pharmaceutical probiotics to comparatively measure possible superimposed growth enhancement. Herbal extracts were Aquapro® (herbal powder), Liv-Up® (herbal granule), Liv-Up® (liquid) and UNBP-20® (liquid). The pharmaceutical 2-strain probiotic was Probiflora® (Lactobacillus acidophilus and Bifidobacterium bifidus). Experimental diets closely reflected comparative approximate nutrient values with respect to protein (46-48%), carbohydrate (17-18%), fat (14%) and fibre (11-12%) content. Juvenile dusky kob (n=50 per tank) of about 5.77±1.28 g were experimentally grown for 10 weeks in tanks (465 L) of a suitable recirculating aquaculture system (RAS) (24-25°C) with natural lighting. Supplement added diets induced a substantial average body growth of 43.3 g, except for slower (P<0.05) growth measured for the Live-Up®-liquid additive trial. The SGR was of the same magnitude between the BED and its complex with the mentioned additives. Also, the BED (46.5% protein) mediated a faster SGR (P<0.05) than the control diet without yeast (50% protein). The best FCR (0.95) was achieved with the BED added herbal product UN-BP20®. The dietary inclusion of the inactivated yeast types is recommended for dusky kob commercial diets since it showed enhanced growth performance and possible production viability.

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Immunomodulatory and Growth-Promoting Potential of Lowcost Probiotic Product in Penaeus Monodon Culture System

and some blood. Biotechnology in Animal Husbandry, 25, 5-6, 1079-1085. Jolles, P., Jolles, J. (1984): What’s new in lysozyme research? Always a model system, today as yesterday. Molecular and Cell Biology, 63, 165-189. Lee, Y.K., Nomoto, K., Salminen, S., Gorbach, S.L. (1999): Handbook of Probiotics, John Wiley & Sons, Inc., N.Y. Li, X.Z., Nikaido, H. (2009): Effux-mediated drug resistance in bacteria: an update. Drugs, 69, 1555-1623. Lowry, O.H., Rosebrough, N.J., Farr, A.L., Randal, R.J. (1951

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Distribution and Size of Barnacle Chelonibia patula Fouling Blue Crab Callinectes amnicola in Southeast Nigeria

, Octolasmis mulleri (Coker, 1902), on the blue crab, Callinectes sapidus (Rathbun, 1896). Fieldiana Zoology New Series, 16, 1-10. Jeffries, W. B., Voris, H. K., Poovachiranon, S. (1992): Age of the mangrove crab Scylla serrata at colonization by stalked barnacles of the genus Octolasmis. Biological Bulletin, 182, 188-194. Johansson, J. (2010): An epibiont mediated increase in the susceptibility of Mytilus edulis to predation by Nucella lapillus. Studies by Undergraduate Researchers at Guelph, 4, 1, 65-71. Available at: < https

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Wild-Caught Versus Farmed Fish – Consumer Perception

. (2013a): Structural equation modelling and word association as tools for a better understanding of low fish consumption. Food Research International, 52, 56-63. Mitterer-Daltoé, M. L., Latorres, J. M., Queiroz, M. I., Fiszman, S., Varela, P. (2013b): Reasons underlying low fish consumption where availability is not an issue. A case study in Brazil, One of the World’s largest fish producers. Journal of Sensory Studies, 28, 3, 205-216. Olsen, S. O. (2003): Understanding the relationship between age and seafood consumption: the mediating

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