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Winter Flounder Pseudopleuronectes Americanus (winter + flounder_pseudopleuronectes_americanu)
Selected AbstractsA physiological interpretation of pattern changes in a flatfishJOURNAL OF FISH BIOLOGY, Issue 3 2008D. Burton The pattern-related capacity for the dispersion of previously aggregated melanosomes in low concentrations (3 × 10,6 to 10,8 M) of noradrenaline in vitro was observed in melanophores from winter flounder Pseudopleuronectes americanus. With 10,8 M noradrenaline, dispersion was completed more rapidly than in controls using the incubation vehicle alone. Melanophores from white-spot, dark-band and general background components of the integumentary pattern displayed different ,transition ranges' between melanosome aggregation and dispersion in higher and lower concentrations of noradrenaline. Within each ,transition range' individual noradrenaline concentration decrements could result in highly variable degrees of melanosome dispersion. The relative breadth of the noradrenaline ,transition range' concentrations could be represented as dark bands > general background > white spots. The threshold noradrenaline concentration for dispersion was highest for the dark bands. It is concluded that these differences represent variations in the transition from melanophore ,-adrenoceptor-mediated pigment aggregation to ,-adrenoceptor-mediated dispersion between localized areas of the skin. Such variations in ,transition range' will have an important role in the expression of flatfish patterns and in their changes in colour and texture. [source] Effects of the toxic dinoflagellate, Alexandrium fundyense on three species of larval fish: a food-chain approachJOURNAL OF FISH BIOLOGY, Issue 1 2008J. C. Samson Sublethal behavioural effects of exposure to paralytic shellfish toxins (PST; saxitoxin and its derivatives) from the toxic dinoflagellate Alexandrium fundyense were investigated in newly settled winter flounder Pseudopleuronectes americanus, larval sheepshead minnow Cyprinodon variegatus and larval mummichog Fundulus heteroclitus through an A. fundyense,copepod,fish food chain. Consumption of as few as six to 12 toxin-containing copepods was lethal to the fishes. After consuming fewer toxin-containing copepods, all three fish species exhibited sublethal effects from vector-mediated exposure. Prey-capture ability of mummichogs was reduced in larvae that had consumed toxic copepods, Coullana canadensis. After consuming toxic C. canadensis or mixed copepods, mummichog larvae had reduced swimming performance. Swimming activity was also significantly reduced in winter flounder after consuming toxic copepods, including time spent in motion and distance travelled. Prey capture and predator avoidance were reduced in first-feeding sheepshead minnow larvae that had consumed toxic dinoflagellate cells. Adverse effects on prey capture or predator avoidance may reduce larval survival and facilitate the transmission of PST through the food web. This study provides baseline information on sublethal effects of PST exposure on fishes using a novel food-chain approach with zooplankton as vectors. [source] Development of feeding structures in larval fish with different life histories: winter flounder and Atlantic codJOURNAL OF FISH BIOLOGY, Issue 4 2001I. Hunt von Herbing The size at which feeding structures developed and shifts in head proportions occurred, differed between Atlantic cod Gadus morhua and winter flounder Pseudopleuronectes americanus. The sequence and timing of the development of feeding structures may not be dependent on size, but may occur because they are necessary to meet specific requirements offish larvae feeding in the plankton. In early larval stages development of feeding structures was similar in number and type and was necessary for first-feeding in both species. In later stages, significant differences between species occurred in the timing of the development of feeding structures. In cod differentiation of new structures and changes in head proportions occurred at about two-thirds of the way through larval life, which coincided with an increase in growth. In flounder changes in feeding morphology did not occur during the symmetrical larval stage, but occurred only after metamorphosis to the asymmetrical demersal juvenile stage. Differences between cod and flounder in the size at which feeding structures develop may reflect life history adaptations expressed in the duration of the pelagic larval stage, as well as differences in juvenile habitat and feeding ecology. [source] Early weaning of winter flounder (Pseudopleuronectes americanus Walbaum) larvae on a commercial microencapsulated dietAQUACULTURE RESEARCH, Issue 6 2003I Ben Khemis Abstract Like most small marine fish larvae, the stomachs of winter flounder Pseudopleuronectes americanus are undeveloped at first feeding and have relatively reduced digestive capacity. This work was undertaken to test whether larvae at the onset of stomach differentiation (larval size about 5.5 mm) could be early weaned onto a commercial microencapsulated diet. We assessed the effect of early weaning by first comparing growth performance (standard length, total protein content and age at metamorphosis) of larvae fed enriched live prey from first feeding to a size of 5.5 mm and then reared on three different feeding regimes until metamorphosis: (1) live prey (LP) as a control group; (2) mixed feeding of live prey and microencapsulated diet (LP-ME); (3) exclusively microencapsulated diet (ME) after fast weaning over 4 days (to a larval size of 6.2 mm). No differences were observed between larval development in the two first groups, which began metamorphosis at 40 days old. The larvae of the third group showed significantly slower growth that resulted in a delay of 4 days in the onset of metamorphosis. Differences in live prey availability between the treatments and the short transition period to allow the larvae to adapt to the new diet were identified as possible contributing factors to the slower growth and to the delay in metamorphosis of early weaned larvae. In a second experiment, the transitional weaning period was increased until the larvae were 6.6 mm in length. Weaning at that size resulted in no slowing of growth or delay in metamorphosis, suggesting that the feeding schedule was adequate. [source] | ||||||||||