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Feeding Stage (feeding + stage)
Kinds of Feeding Stage Selected AbstractsEffects of sublethal concentrations of atrazine and nitrate on metamorphosis of the African clawed frogENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2003Karen Brown Sullivan Abstract Tadpoles of the African clawed frog (Xenopus laevis) were exposed to sublethal concentrations of atrazine (0, 40, and 320 ,g/L) and nitrate (0, 37, and 292 mg/L) from feeding stage to metamorphosis. A 3 × 3 factorial design was used to identify both single and interactive effects. At metamorphosis, tadpole weight, snout,vent length (SVL), and hematocrit were determined. Mean mortality was greater in tanks receiving 320 ,g/L atrazine; nitrate had no effect on mortality. Significant differences for all mean traits at metamorphosis occurred among atrazine treatments; higher atrazine exposure increased time to metamorphosis and decreased weight, SVL, and hematocrit. Nitrate treatments were not significantly different. Significant interaction tests between atrazine and nitrate occurred for weight and SVL at metamorphosis; the specific type of interaction varied among treatments. Assuming an additive mixture model, at low atrazine (40 ,g/L), the addition of 37 mg/L nitrate produced SVL values less than expected (a synergistic effect) while the addition of 292 mg/L nitrate yielded SVL values greater than expected (an antagonistic effect). A similar response was noted for tadpoles in the 320-,g/L atrazine treatments. These results indicate that environmentally realistic concentrations of atrazine exert a negative impact on amphibian metamorphosis. Also, this study suggests that mixtures of agricultural chemicals, even if sublethal, may exert negative and not necessarily consistent mixture effects. [source] Food plaquette digestion in the ciliated protozoan Hyalophysa chattoniINVERTEBRATE BIOLOGY, Issue 2 2001Stephen C. Landers Abstract. The digestion of food plaquettes in the ciliated protozoan Hyalophysa chattoni was analyzed by light and electron microscopy. Through the use of nigrosin as a tracer for light microscopy and polystyrene microparticles for electron microscopy, we have demonstrated that food plaquettes transform to late-stage digestive vesicles. Eventually, in the phoront, some of the late-stage vesicles merge to form larger fusion vesicles, which are retained in the peripheral cytoplasm of the ensuing feeding stage. After the feeding stage settles and encysts, these vesicles are either retained by the daughter cells or are left in the divisional cyst as residual bodies. Food plaquettes, digestive vesicles, and fusion vesicles stain positively with neutral red and acridine orange, indicating an acidic pH. These results portray a unique digestive pathway in which stored, undigested material is reorganized into larger fusion vesicles as the cell prepares for additional feeding. [source] Feeding efficiency of planktivorous perch Perca fluviatilis and roach Rutilus rutilus in varying turbidity: an individual-based approachJOURNAL OF FISH BIOLOGY, Issue 7 2010L. Nurminen The feeding rate of perch Perca fluviatilis showed high individual variation at low and moderate turbidities, when one individual had consumed more Daphnia pulex than any other fish, whereas no such variation in feeding efficiency was observed with roach Rutilus rutilus. There was a significant decrease in total consumption of D. pulex by P. fluviatilis with increasing turbidity, but no correlation was observed in the case of R. rutilus. The results suggest that the difference in the ontogeny of P. fluviatilis and R. rutilus may be detectable as behaviour-related species-specific trait differences in the early planktivorous feeding stage of the two common species. [source] Advances in the larval rearing of Siberian sturgeonJOURNAL OF FISH BIOLOGY, Issue 5 2002E. Gisbert Since first large-scale attempts to culture sturgeon from the larval stage were carried out in the former U.S.S.R. at the end of the nineteenth century, rearing technology has advanced considerably during the last 20 years and noticeable improvements in incubation and larval rearing techniques have been implemented in normal hatchery procedures. Siberian sturgeon eggs are incubated in MacDonald jars at 13,14° C to prevent fungal infections. Mass hatching takes place 7 days after fertilization and hatching rate can be predicted as a function of the percentage of eggs fertilized. Survival at the end of the endogenous feeding stage is correlated with hatching rate. Egg size has no direct implications for larval growth and survival of Siberian sturgeon. Experimental studies have demonstrated that behavioural observations are useful criteria to assess the quality of larvae and to synchronize the physiological state of fish with the appropriate rearing procedures. Special attention should be given to the transition to exogenous feeding, where cannibalism, difficulties in adaptation to a new diet, overfeeding and resulting bacterial infections dramatically reduces survival to the fingerling stage. Although a commercial artificial diet specifically formulated for larvae of Siberian sturgeon and other acipenserids is still lacking, commercial non-purified rainbow trout diets and starter marine fish diets are currently used and their results are reasonably acceptable in terms of larval growth and survival. Further research must be focused on the determination of egg quality indicators in order to provide the producer with the tools to estimate the viability and performance of theprogeny. [source] Relating the ontogeny of functional morphology and prey selection with larval mortality in Amphiprion frenatusJOURNAL OF MORPHOLOGY, Issue 6 2010Justin Anto Abstract Survival during the pelagic larval phase of marine fish is highly variable and is subject to numerous factors. A sharp decline in the number of surviving larvae usually occurs during the transition from endogenous to exogenous feeding known as the first feeding stage in fish larvae. The present study was designed to evaluate the link between functional morphology and prey selection in an attempt to understand how the relationship influences mortality of a marine fish larva, Amphiprion frenatus, through ontogeny. Larvae were reared from hatch to 14 days post hatch (DPH) with one of four diets [rotifers and newly hatched Artemia sp. nauplii (RA); rotifers and wild plankton (RP); rotifers, wild plankton, and newly hatched Artemia nauplii (RPA); wild plankton and newly hatched Artemia nauplii (PA)]. Survival did not differ among diets. Larvae from all diets experienced mass mortality from 1 to 5 DPH followed by decreased mortality from 6 to 14 DPH; individuals fed RA were the exception, exhibiting continuous mortality from 6 to 14 DPH. Larvae consumed progressively larger prey with growth and age, likely due to age related increase in gape. During the mass mortality event, larvae selected small prey items and exhibited few ossified elements. Cessation of mass mortality coincided with consumption of large prey and ossification of key elements of the feeding apparatus. Mass mortality did not appear to be solely influenced by inability to establish first feeding. We hypothesize the interaction of reduced feeding capacities (i.e., complexity of the feeding apparatus) and larval physiology such as digestion or absorption efficiency contributed to the mortality event during the first feeding period. J. Morphol., 2010. © 2010 Wiley-Liss, Inc. [source] The Effects of Temperature and Salinity on Early Life Stages of Black Sea Bass Centropristis striataJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2004David L. Berlinsky Along the Atlantic coast black sea bass occur from the Gulf of Maine to Florida and support important commercial and recreational fisheries. Interest in commercial production of black sea bass has increased in recent years due to high demand and limited seasonable availability. Efforts towards large-scale production have been hampered by a high incidence of early larval mortality. Two of the most important environmental variables affecting hatchery production of marine finfish larvae are temperature and salinity. In the wild, larval black sea bass are found in waters with temperatures of 12,24 C and salinity levels of 30,35 ppt. Studies were conducted to define the temperature and salinity ranges that support growth and development of black sea bass during early life stages. Three developmental phases were investigated: 1) fertilization to hatch: 2) hatch through yolk sac absorption: and 3) during the initial exogenous feeding stage (5,14 days post hatch: DPH). Fertilized eggs were obtained by manual spawning of fish following administration of LHRHa. Fertilized eggs were transferred to 300-mL glass Petri dishes or 500-mL beakers to assess the effects of salinity and temperature through hatch and yolk sac absorption, respectively. To determine environmental effects on growth and survival during initial exogenous feeding 400 actively feeding larvae were cultured in green water and fed enriched rotifers for a 9-d period. For investigation of the effect of salinity, sea water (35 ppt) was diluted gradually to 15, 20, 25, and 30 ppt and maintained at 21 C. For examination of the effect of temperature, seawater was adjusted from 21 C to 12, 15, 21, 27, or 30 C at a rate of 3 C/h. No eggs hatched at 12 C or when salinity was maintained at 0 or 5 ppt. Hatching was uniformly high (, 85%) at temperatures between 15 and 27 C and at salinities , 15 ppt. Survival through yolk sac absorption was greatest at temperatures between 18 and 27 C and at salinities , 20 ppt. Survival through first feeding stage was highest at temperatures , 18 C and 30 ppt salinity. Larval growth through first feeding was not significantly affected by salinity level but did increase with rearing temperature. The results indicate that survival and development of black sea bass during early life stages are most favorable at temperatures >18 C with salinity levels approaching full strength seawater. [source] Effects of turbidity on feeding of the young-of-the-year pikeperch (Sander lucioperca) in fishpondsAQUACULTURE RESEARCH, Issue 2 2010Priit Zingel Abstract The effect of water turbidity on the prey selection and consumption of the young-of-the-year (YOY) pikeperch in the planktivorous feeding stage was studied. Attention was paid particularly to the question of how the food selectivity depends on the size of YOY pikeperch and how the turbidity affects feeding in different size classes. Studies were carried out in ponds of two fish farms in Estonia over 4 years. Small cladocerans were the most preferred prey in the smallest pikeperch size class. In larger size classes, the most selected prey were the large cladocerans. Water turbidity affected the prey selection of the planktivorous pikeperch significantly. In more turbid environments, the larger zooplankters were more positively selected than the smaller ones. Turbidity decreased both total zooplankton consumption and Fulton's condition factor of fish only in the largest size class of pikeperch. The effect of turbidity on foraging and growth, and thus on the size of juvenile pikeperch of a particular year class is substantial under conditions where juveniles cannot shift from planktivory to piscivory. [source] The effect of maternal size on larval characteristics of Persian sturgeon Acipenser persicusAQUACULTURE RESEARCH, Issue 9 2009Rajab Mohammad Nazari Abstract The objective of this work was to study the relationship between female size (weight) and variables of egg and larval stage of Persian sturgeon Acipenser persicus. In this study, 19 female breeders were captured in Caspian Sea and fertilized by routine methods. Positive significant correlations (P<0.05) were established between female weight and ovulated eggs per female, time of second mitosis division and volume of yolk-sac at hatching. There was not significant correlation (r=0.33, P=0.161) between female weight and egg diameter. Female weight was not affected weight of larvae at hatching time (r=0.37, P=0.119), as well as larval length (r=,0.14, P=0.558) and larval weight at the end of the experiment (48 hours after first feeding) (r=0.16, P=0.491). Mortality rate during yolk-sac absorption was higher with increased female weight but their correlation was not significant (r=0.40, P=0.076). During the first feeding stage, mortality rate was 13.39% and there was no significant correlation between mortality rate in this period and female weight (r=,0.12, P=0.613). Conclusively, as a result female size influenced fecundity, time of second mitosis division and yolk-sac volume at hatching time without affecting mortality rate during yolk-sac absorption and first feeding stage in Persian sturgeon. Thus, smaller female broods do not cause more mortality than larger ones in larval production and they can be used in reproduction procedure. [source] The expression patterns of a eukaryotic initiation factor 3 subunit H in the silk glands in Bombyx moriARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2010Jia-Lin Wang Abstract Eukaryotic initiation factor 3 subunit H has been characterized in many organisms, and it has been found to play many roles including help regulate translation initiation. In this work, we studied the tissue distribution and expression profiles of Bombyx mori (B. mori) eIF3 subunit H (BmeIF3h). BmeIF3h was prominently expressed in silk glands, with anterior silk glands (ASGs), middle silk glands (MSGs), and posterior silk glands (PSGs) all expressing BmeIF3h. The expression levels of BmeIF3h in MSGs and PSGs were higher than that in ASGs during 0 d and 2 d of the 5th instar larvae. The expression levels of BmeIF3h in MSGs and PSGs were up-regulated once the silk glands began to synthesize silk protein during the feeding stage of the 4th instar larvae. Immunohistochemistry showed that BmeIF3h was distributed in the cytoplasm of MSGs cells and in both the nucleus and the cytoplasm of PSGs cells. These data suggest that BmeIF3h had different action behaviors in the MSGs and PSGs related to the production of the silk glue proteins and silk fibre proteins, respectively. © 2010 Wiley Periodicals, Inc. [source] Impact of avian and arthropod predation on lepidopteran caterpillar densities and plant productivity in an ephemeral agroecosystemECOLOGICAL ENTOMOLOGY, Issue 5 2003Cerruti R. R. Hooks Abstract., 1.,Most studies evaluating the combined impact of spiders and other predators on herbivore densities in agroecosystems have focused primarily on their trophic connections with invertebrate predators (e.g. carabids, chrysopids); however linkages among spiders and vertebrate predators may also help structure the population dynamics of insect herbivores. A field experiment was conducted to examine the impact of avian and spider predation on lepidopteran caterpillar densities and plant productivity within a Brassica agroecosystem. 2.,Arthropod abundance, leaf-chewing damage, and final plant productivity associated with broccoli, Brassica oleracea L. (var. italica), were recorded for four treatments: (1) bird present but spiders removed; (2) both birds and spiders present; (3) birds excluded, spiders present; and (4) birds and spiders both excluded. 3.,Densities of Artogeia rapae L. (Lepidoptera: Pieridae) and Trichoplusia ni Hübner (Lepidoptera: Noctuidae) large caterpillars and post feeding stages were reduced significantly by bird predation. The abundance of large caterpillars was also reduced on spider-inhabited plants during early plant growth; however the assemblage of birds and spiders did not suppress caterpillar densities more significantly than either predator alone. 4.,Plants protected by birds, spiders, and birds plus spiders sustained less folivory attributable to leaf chewing caterpillars than check plants. Plant productivity was also greater for predator-protected plants than check plants. 5.,Although spiders and parasitoids were responsible for some of the mortality inflicted upon lepidopteran caterpillars, it was concluded that in this study system, birds are the most important natural enemies of folivores. [source] Influence of prey species on immature survival, development, predation and reproduction of Coccinella transversalis Fabricius (Col., Coccinellidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2004Omkar Abstract: Six aphid species, viz. Aphis craccivora, Aphis gossypii, Aphis nerii, Myzus persicae, Lipaphis erysimi and Uroleucon compositae were provided as prey to the feeding stages of Coccinella transversalis (Fabricius). All of them were found to be essential prey, however the relative prey suitability varied. All the predatory stages of C. transversalis consumed and preferred A. gossypii, the most and A. nerii, the least. Significant effect of prey quality was observed on pre-imaginal developmental periods, wet weights and adult longevity. The complete development was shortest on A. gossypii (13.01 ± 0.18 days) and longest on A. nerii (20.51 ± 0.25 days). The total prey consumption by larva, adult male and female in their lifetime was maximum (665.30 ± 5.75, 4831.10 ± 123.54 and 5412.30 ± 94.51, respectively) on A. gossypii and minimum (434.80 ± 4.03, 802.80 ± 34.37 and 905.20 ± 52.48, respectively) on A. nerii. Immature survival, growth index and adult emergence of C. transversalis was maximum (68.33, 7.82 and 88.21%, respectively) when larval instars consumed A. gossypii and minimum (37.75, 2.18 and 60.69%, respectively) after feeding on A. nerii. Female reproduction was also prey quality dependent showing maximum reproductive performance in terms of fecundity and percentage viability, with a highest reproductive period and lowest non-reproductive period on A. gossypii, followed by A. craccivora, L. erysimi, M. persicae, U. compositae and A. nerii. Regression analysis revealed a positive correlation between: (1) daily prey consumption and relative growth rate, (2) adult weight and developmental rate, (3) weights of adult male and female, and (4) female longevity and fecundity. [source] Effects of Light Intensity and Salinity on Growth, Survival, and Whole-Body Osmolality of Larval Southern Flounder Paralichthys lethostigmaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2003James P. Henne The southern flounder Paralichthys lethosligma is a high-valued flatfish found in estuarine and shelf waters of the south Atlantic and Gulf coasts of the United States. Wide temperature and salinity tolerances exhibited by juveniles and adults make it a versatile new candidate for commercial culture, and studies are underway in the southeastern U.S. to develop hatchery methods for this species. The objectives of this study were to establish illumination and salinity conditions that optimize growth and survival of larval southern flounder reared through the yolk-sac and first feeding stages to 15-d post-hatching (15 dph). Early embryos were stocked into black 15-L tanks under light intensities of 5, 50, 100, and 1,000 Ix and at salinities of 24 and 34 ppt in a 4 ± 2 factorial design. Significant (P 0.05) effects of both light intensity and salinity on growth and survival were obtained, with no interaction between these effects. On 11 dph and 15 dph, growth was generally maximized at the intermediate light intensities (50 and 100 Ix) and minimized at the extremes (5 and 1,000 Ix). By 15 dph, growth was higher at 34 ppt than at 24 ppt. Survival to 15 dph showed trends similar to those of growth. Survival was higher at 100 Ix (avg. = 46%, range = 41,54%) than at 5 Ix (avg. = 11%, range = 6,17%) and higher at 34 ppt (avg. = 43%, range = 3145%) than at 24 ppt (avg. = 17%, range = 8,38%). Whole-body osmolality (mOsmol/kg) was significantly lower in larvae reared at 24 ppt (avg. = 304, range = 285,325) through 11 dph than in larvae reared at 34 ppt (avg. = 343, range = 296,405). Larvae reared under the extreme light intensity treatments (5 and 1,000 Ix) at 34 ppt appeared to exhibit osmoregulatory stress, particularly on 11 dph, when a marked increase in whole-body osmolality was observed. The mid-intensity treatments (50 and 100 Ix) at 34 ppt optimized growth and survival of larval southern flounder in this study; and elicited the most stable osmotic response. These conditions appear to be consistent with those that southern flounder larvae encounter in nature during this early developmental period. [source] Microarray analysis of gene expression changes in feeding female and male lone star ticks, Amblyomma americanum (L)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2009Majd N. Aljamali Abstract A collection of EST clones from female tick Amblyomma americanum salivary glands was hybridized to RNA from different feeding stages of female tick salivary glands and from unfed or feeding adult male ticks. In the female ticks, the expression patterns changed dramatically upon starting feeding, then changed again towards the end of feeding. On beginning feeding, genes possibly involved in survival on the host increased in expression as did many housekeeping genes. As feeding progressed, some of the survival genes were downregulated, while others were upregulated. When the tick went into the rapid feeding phase, many of the survival genes were downregulated, while a number of transport-associated genes and genes possibly involved in organ degeneration increased. In the males, the presence of females during feeding made a small difference, but feeding made a larger difference. Males showed clear differences from females in expression, as well. Protein synthesis genes were expressed more in all male groups than in the partially fed females, while the putative secreted genes involved in avoiding host defenses were expressed less. © 2009 Wiley Periodicals, Inc. [source] | |||||||||||||