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Egg Production (egg + production)
Kinds of Egg Production Terms modified by Egg Production Selected AbstractsEFFECT OF HEN EGG PRODUCTION AND PROTEIN COMPOSITION ON TEXTURAL PROPERTIES OF EGG ALBUMEN GELSJOURNAL OF TEXTURE STUDIES, Issue 2 2001MARIANNE HAMMERSHØJ The effect of hen age, strain and dietary amino acid intake on the egg albumen gel textural properties was studied in two experiments by textural profile analysis (TPA) and uniaxial compression (UC) tests. In experiment 1, eggs from 4 different hen flocks were heat processed industrially. Egg rejection due to poor albumen gelling was correlated to hen age (r = 0.502), albumen dry matter (r =,0.632), gel hardness of 1st compression (r =,0.765), and gel work of 1st compression (r =,0.740) in TPA. In experiment 2 two hen strains, representing two levels of egg production, were fed diets with supplementation of L-lysine, methionine or both amino acids compared to a control diet. The lysine intake ranged from 818,1272 mg/hen/day and methionine intake from 377,575 mg/hen/day among hen groups, but without significant effect on the albumen gel texture parameters. The hen strains differed significantly in egg production (P<0.001), physical (P<0.001), chemical (P<0.05) and gel textural parameters of egg albumen (P<0.01). Hen age was essential, and correlated to the industrial egg rejection (r = 0.729), albumen dry matter (r =,0.902) and gel stress at fracture (r =,0.884). Albumen gels with high fracture stress values were found to contain a modified form of ovofransferrin. [source] Trophic Egg Production in a Subsocial Shield Bug, Parastrachia japonensis Scott (Heteroptera: Parastrachiidae), and its Functional ValueETHOLOGY, Issue 12 2005Mantaro Hironaka Females of the gregarious shield bug, Parastrachia japonensis Scott (Heteroptera: Parastrachiidae) engage in extensive parental care behaviors that include egg and nymph guarding and progressive provisioning of drupes of the solitary host tree, Schoepfia jasminodora (Olacaceae: Rosidae: Santales). We noted that some eggs in every egg mass failed to turn pink and develop eye-spots indicative of developing embryos, suggesting that they are infertile, and therefore non-viable. We also observed newly hatched nymphs probing, and presumably feeding, on the egg mass remains. In the present report, through field observations and experiments involving removal of these non-viable eggs in the laboratory, we demonstrate that their presence is correlated with significant increases in nymphal weight, developmental rate and survival in the absence of other food. Thus, we conclude that an additional manifestation of the parental care behaviors that P. japonensis females use to increase their reproductive success is the production of trophic eggs. Some physical traits of the trophic eggs and their functional role in this system are discussed in the context of our current theoretical understanding of extended parental care. [source] Effects of lipid-lowering pharmaceuticals bezafibrate and clofibric acid on lipid metabolism in fathead minnow (Pimephales promelas),ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009Anna Weston Abstract The lipid-lowering agents bezafibrate and clofibric acid, which occur at concentrations up to 3.1 and 1.6 ,L, respectively, are among the most frequently found human pharmaceuticals in the aquatic environment. In contrast to knowledge about their environmental occurrence, little is known about their effects in the environment. The aim of the present study was to analyze effects of these lipid-lowering agents in fish by focusing on their modes of action, lipid metabolism. Fathead minnows were exposed in aquaria to measured concentrations of 0.1, 1.27, 10.18, 101.56, and 106.7 mg/L bezafibrate and to 1.07, 10.75, and 108.91 mg/L clofibric acid for 14 and 21 d, respectively. After exposure, fish liver was analyzed for expression of peroxisome proliferator-activated receptor , (PPAR,) by quantitative polymerase chain reaction (PCR), and the PPAR-regulated enzyme fatty acyl-coenzyme-A oxidase (FAO) involved in fatty acid oxidation. Bezafibrate had no effect, either on PPAR, expression or on FAO activity, at all concentrations. In contrast, clofibric acid induced FAO activity in male fathead minnows at 108.91 mg/L. No increase in expression of PPAR, messenger ribonucleic acid was observed. Egg production was apparently decreased after 21 d of exposure to 108.91 mg/L clofibric acid. The present study demonstrates that bezafibrate has very little or no effect on PPAR, expression and FAO activity, but clofibric acid affects FAO activity. [source] Evaluation of adult quail and egg production following exposure to perchlorate-treated waterENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2005Angella Gentles Abstract Twenty-three adult female northern bobwhite (Colinus virginianus) quail were exposed to 0, 0.01, 0.1, and 1 mM ammonium perchlorate (AP) in drinking water for 30 d. Eggs laid in all treatment groups, including control, were collected, dated, given an identification number, and weighed. On day 30 of exposure, 10 birds were euthanized by carbon dioxide asphyxiation. Gross toxicological endpoints and thyroid histology were evaluated in 10 birds. Egg production and accumulation of perchlorate in the eggs (n = 10) and liver (n = 5) were determined. Perchlorate did not affect body or organ weights significantly; however, at 1 mM, AP caused alteration of thyroid gland morphology. Perchlorate did not affect egg production, but significant accumulation was observed in the eggs and livers of exposed birds. [source] Spawning of a Captive Population of California Sheephead, Semicossyphus pulcherJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2007Dave Jirsa This study represents the first detailed description of spawning and patterns of egg production in a captive population of California sheephead. In March 2004, females ranged in size from 369 to 430 mm total length (TL) and weighed 0.8,1.5 kg. Males ranged in size from 475 to 510 mm TL and weighed 1.7,2.3 kg. Spawning began in April and continued daily through September and then sporadically through October. Egg production ranged from 1000 to 375,000 eggs/d, with an average of 130,000 eggs/d. Egg production peaked in May at 222,000 eggs/d and decreased throughout the remainder of the season. Total annual fecundity from this group was 1,942,000 eggs/kg female body weight. Egg viability ranged from 0 to 80% with an average of 50%. Viability showed a general increase at the beginning of the season and a decrease at the end of the season. Eggs were 0.9,1.0 mm in diameter and hatched in approximately 48 h at 18,19 C. Hatch rates showed a general decline throughout the season. This study shows that California sheephead will spawn readily in captivity providing thousands of viable eggs daily and lays the groundwork for culture of this species. [source] Identification of quantitative trait loci associated with egg quality, egg production, and body weight in an F2 resource population of chickens,ANIMAL GENETICS, Issue 2 2006M. A. Schreiweis Summary Egg production and egg quality are complex sex-limited traits that may benefit from the implementation of marker-assisted selection. The primary objective of the current study was to identify quantitative trait loci (QTL) associated with egg traits, egg production, and body weight in a chicken resource population. Layer (White Leghorn hens) and broiler (Cobb-Cobb roosters) lines were crossed to generate an F2 population of 508 hens over seven hatches. Phenotypes for 29 traits (weekly body weight from hatch to 6 weeks, egg traits including egg, albumen, yolk, and shell weight, shell thickness, shell puncture score, percentage of shell, and egg shell colour at 35 and 55 weeks of age, as well as egg production between 16 and 55 weeks of age) were measured in hens of the resource population. Genotypes of 120 microsatellite markers on 28 autosomal groups were determined, and interval mapping was conducted to identify putative QTL. Eleven QTL tests representing two regions on chromosomes 2 and 4 surpassed the 5% genome-wise significance threshold. These QTL influenced egg colour, egg and albumen weight, percent shell, body weight, and egg production. The chromosome 4 QTL region is consistent with multiple QTL studies that define chromosome 4 as a critical region significantly associated with a variety of traits across multiple resource populations. An additional 64 QTL tests surpassed the 5% chromosome-wise significance threshold. [source] Functional morphology of the postpharyngeal gland of queens and workers of the ant Monomorium pharaonis (L.)ACTA ZOOLOGICA, Issue 2 2006Dieter Eelen Abstract Eelen D., Børgesen L.W. and Billen J. 2006. Functional morphology of the postpharyngeal gland of queens and workers of the ant Monomorium pharaonis (L.). ,Acta Zoologica (Stockholm) 87: 101,111 The postpharyngeal gland (PPG) is unique to ants and is the largest exocrine gland in their head. In queens of the pharaoh's ant, Monomorium pharaonis, the gland contains approximately 15 finger-like epithelial extensions on each side and opens dorsolaterally in the posterior pharynx. In these ants the PPG morphology varies considerably according to age and mating status. The epithelial thickness increases with age and reaches a maximum at 3 weeks in both virgin and mated queens. A considerable expansion of the lumen diameter occurs in both groups between 4 and 7 days. Virgin queens release their secretion into the gland lumen from an age of 7 days, whereas mated queens accumulate large amounts of secretion in their epithelium. The increasing epithelial thickness, together with the increasing lumen diameter, the presence of numerous inclusions in the epithelium and the release of secretion, are indicative for increasing gland activity. The gland ultrastructure indicates involvement in lipid metabolism and de novo synthesis of lipids. The PPG of workers consists of 12 finger-like tubes at each side. There is a significant difference in epithelial thickness between nurses and repletes and between nurses and foragers. We suggest the PPG serves different purposes in pharaoh's ants: it is likely that the PPG of workers and virgin queens is used to feed larvae. In mated queens the gland probably plays a role in providing the queen with nutritious oils for egg production. The PPG may also function in signalling species nestmate and caste identity, as well as in the reproductive capacity of the queens. [source] Nuptial food gifts influence female egg production in the scorpionfly Panorpa cognataECOLOGICAL ENTOMOLOGY, Issue 3 2007LEIF ENGQVIST Abstract 1.,Before copulation, male Panorpa cognata scorpionflies offer females a salivary secretion, which is consumed by the female during copulation. It has previously been demonstrated that this nuptial food gift functions as mating effort by increasing male attractiveness and by increasing ejaculate transfer during copulation. 2.,In this study, the effect of saliva consumption on female reproductive output was investigated, and thus the possibility that nuptial food gifts also serve as paternal investment. The experimental design enabled the effect of nuptial gift consumption to be disentangled from other possible effects of multiple mating or increased copula duration. 3.,The results showed that saliva consumption increases female egg production by on average 8% (4.5 eggs) per consumed salivary mass, whereas mean egg weight was not influenced.4. These results have important implications for the evolution and maintenance of both male nuptial gifts and female polyandry in this and other species. [source] Egg maturation strategy and its associated trade-offs: a synthesis focusing on LepidopteraECOLOGICAL ENTOMOLOGY, Issue 4 2005Mark A. Jervis Abstract., 1.,Insects vary considerably between and within orders, and even within the same genus, in the degree to which the female's lifetime potential egg complement is mature when she emerges as an adult. 2.,The ,ovigeny index' (OI) , the number of eggs females have ready to lay divided by the lifetime potential fecundity , quantifies variation in the degree of early life concentration of egg production, and also variation in initial reproductive effort. 3.,Here, an integrated set of hypotheses is presented, based on a conceptual model of resource allocation and acquisition, concerning trade-offs at the interspecific level between initial investment in egg production (as measured by OI) and other life-history traits in holometabolous insects. 4.,The evidence supporting each of these hypotheses is reviewed, and particular attention is paid to the Lepidoptera, as relevant life-history data are rapidly accumulating for this ecologically and economically important group. 5.,There is evidence at the interspecific level supporting: (i) a link between OI and a trade-off between soma and non-soma in Trichoptera and Hymenoptera (the proportionate allocation to soma decreases with increasing OI); (ii) a negative correlation between OI and dependency on external nutrient inputs (via adult feeding) in Hymenoptera and in Lepidoptera; (iii) a negative correlation between OI and the degree of polyandry (and nuptial gift, i.e. spermatophore, use) in Lepidoptera; (iv) negative correlations between OI and resource re-allocation capabilities (egg and thoracic musculature resorption) in Hymenoptera and in Lepidoptera; (v) a negative correlation between lifespan and OI in Trichoptera, Hymenoptera, and Lepidoptera, indicating a cost of reproduction; (vi) a link between winglessness and an OI of one in Lepidoptera; (vii) a negative correlation between OI and the degree of female mobility in winged Lepidoptera; and (viii) a negative correlation between OI and larval diet breadth (as mediated by oviposition strategy) in Lepidoptera. [source] Development, growth, and egg production of Ageneotettix deorum (Orthoptera: Acrididae) in response to spider predation risk and elevated resource qualityECOLOGICAL ENTOMOLOGY, Issue 1 2004Bradford. Abstract., 1.,Predation risk to insects is often size- or stage-selective and usually decreases as prey grow. Any factor, such as food quality, that accelerates developmental and growth rates is likely to reduce the period over which prey are susceptible to size-dependent predation. 2.,Using field experiments, several hypotheses that assess growth, development, and egg production rates of the rangeland grasshopper Ageneotettix deorum (Scudder) were tested in response to combinations of food quality and predation risk from wolf spiders to investigate performance variation manifested through a behaviourally mediated path affecting food ingestion rates. 3.,Grasshoppers with nutritionally superior food completed development , 8,18% faster and grew 15,45% larger in the absence of spiders, in comparison with those subjected to low quality food exposed to spider predators. Growth and development did not differ for grasshoppers feeding on high quality food when predators were present in comparison with lower quality food unimpeded by predators. Responses indicated a compensatory relationship between resource quality and predation risk. 4.,Surviving grasshoppers produced fewer eggs compared with individuals not exposed to spiders. Because no differences were found in daily egg production rate regardless of predation treatment, lower egg production was attributed to delayed age of first reproduction. Results compare favourably with responses observed in natural populations. 5.,Risk of predation from spiders greatly reduced growth, development, and ultimately egg production. Increased food quality counteracts the impact of predation risk on grasshoppers through compensatory responses, suggesting that bottom-up factors mediate effects of spiders. [source] Gamete production and sexual size dimorphism in an insect (Orchesella cincta) with indeterminate growthECOLOGICAL ENTOMOLOGY, Issue 2 2002G. Ernsting Abstract 1. The relationship of growth and body size with reproductive effort in animal species has been studied much less for males than for females. This imbalance applies to Orchesella cincta (L.) (Collembola), an insect with indeterminate growth, in which egg production is related positively to body size and negatively to growth. 2. To allow a comparison of the reproductive effort of male and female O. cincta, development and growth in immature stages of both sexes, and growth and spermatophore production for adult males were studied. 3. Embryonic development time and hatchling size did not differ between prospective males and females, but from hatching on the trajectories diverged, with males growing more slowly and maturing earlier and at a much smaller body size than females. 4. Neither the number of spermatophores deposited in the first adult instar (= inter-moult period) nor the total number of spermatophores deposited during seven instars was related to body size or growth. 5. Differences in growth rate between instars with and without spermatophore deposition indicated that the physiology of spermatophore production inhibits growth, which, however, was compensated for during the next instar. 6. The difference in the relationship of gamete production with body size and growth between males and females explains the divergence of their size at maturity. [source] The relationship between host selection behaviour and offspring fitness in a koinobiont parasitoidECOLOGICAL ENTOMOLOGY, Issue 4 2000Ana Rivero Summary 1. When host quality varies, optimal foraging theory assumes that parasitic wasps select hosts in a manner that increases their individual fitness. In koinobiont parasitoids, where the hosts continue developing for a certain period of time after parasitisation, host selection may not reflect current host quality but may be based on an assessment of future growth rates and resources available for the developing larvae. 2. When presented with hosts of uniform quality, the koinobiont parasitoid Leptomastix dactylopii exhibits a characteristic host-selection behaviour: some hosts are accepted for oviposition on first encounter, while others are rejected several times before an egg is laid in them, a behaviour that is commonly associated with a changing host acceptance threshold during the course of a foraging bout. 3. The fitness of the offspring that emerged from hosts accepted immediately upon encounter was compared with the fitness of offspring emerged from hosts rejected several times before being accepted for oviposition. 4. The pattern of host acceptance and rejection was not related to any of the measured fitness parameters of the offspring emerging from these hosts (development time, size at emergence, sex ratio at emergence, and female offspring egg load). 5. While complex post facto adaptive explanations can be devised to explain the nature of such a time and energy consuming host selection process, it is suggested that physiological constraints on egg production or oviposition may provide an alternative, purely mechanistic, explanation for the results obtained. [source] Lifespan is unrelated to investment in reproduction in populations of mammals and birds in captivityECOLOGY LETTERS, Issue 10 2007Robert E. Ricklefs Abstract We examined the relationship between number of offspring produced to a certain age and subsequent longevity in captive zoo populations of 18 species of mammal and 12 species of bird. The age cut-offs in each analysis were set to include 50%, 75% and 90% of the offspring produced in each of the population samples. Only one of 68 regressions was significant, and its slope was positive. In addition, we examined the relationship between age at first reproduction up to a certain age and longevity after that age, generally 5 years (3,8), among 17 species of mammal and 12 species of bird. Only one of these regressions had a significantly positive slope, indicating that early reproduction rarely reduces lifespan. Overall, we found no evidence that producing offspring in a zoo environment influences the age at death. Thus, although trade-offs might apply in natural populations under resource limitation, neither pregnancy, growth of the foetus and lactation in mammals, nor egg production in birds, reduces lifespan in the absence of such stress. If genetically based or other intrinsic antagonistic pleiotropy underlies the evolution of senescence, it was not evident in our analyses. [source] Total population density during the first year of life as a major determinant of lifetime body-length trajectory in marble troutECOLOGY OF FRESHWATER FISH, Issue 4 2008S. Vincenzi Abstract,,, The conditions experienced early in life can strongly influence life-history trajectories in a variety of animal species. Here, we use data from four isolated populations of the endangered stream-dwelling salmonid marble trout (Salmo marmoratus Cuvier 1817) living in the Soca and Idrijca river basins (Slovenia) to explore the influence of the total density experienced during and after the first year of life by marble trout year-classes on body length of marble trout through the lifetime. Analyses were performed by pooling together the stream-specific datasets to cover a wider range of densities. Mean body length of marble trout year-classes through the lifetime (from age 1+ to 5+) was negatively related to total density of marble trout during the first year of life. The relationship between density during the first growth period and body length through the lifetime was well described by negative power curves. Total population density after the first year of life was not correlated with body length, thus suggesting that body growth trajectories are heavily determined early in life. Given size-dependent sexual maturity and egg production in marble trout, the relationship between density early in life and lifetime individual growth may have strong implications in terms of population dynamics and regulation of population size. [source] Chronic copper toxicity in the estuarine copepod Acartia tonsa at different salinitiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Mariana M. Lauer Abstract Chronic Cu toxicity was evaluated in the euryhaline copepod Acartia tonsa. Male and female copepods were exposed (6 d) separately to different combinations of Cu concentration and water salinity (5, 15, and 30 ppt) using different routes of exposure (waterborne, waterborne plus dietborne, and dietborne). After exposure, groups of one male and three female copepods were allowed to reproduce for 24,h. In control copepods, egg production augmented with increasing water salinity. However, egg hatching rate did not change. Copper exposure reduced egg production and hatching rate in all water salinities tested, but the reproductive response was dependent on the route of Cu exposure. Median effective concentration (EC50) values for egg production after waterborne exposure were 9.9, 36.8, and 48.8,µg/L dissolved Cu at water salinities of 5, 15, and 30 ppt, respectively. For waterborne plus dietborne exposure, they were significantly higher (40.1, 63.7, and 109.9,µg /L, respectively). After dietborne exposure, approximately 40% decrease in egg production was observed, independently of Cu concentration and water salinity tested. At water salinities of 5 and 30 ppt, egg hatching rate reduced after waterborne exposure, together or not with the dietborne exposure. At water salinity of 15 ppt, Cu toxicity was only observed after dietborne exposure. Data indicate that egg production is a more reliable reproductive endpoint to measure chronic Cu toxicity in copepods than egg hatching rate in a wide range of water salinities. They also suggest that both water salinity and route of Cu exposure should be taken into account in the development of a chronic biotic ligand model version for estuarine and marine environments. Environ. Toxicol. Chem. 2010;29:2297,2303. © 2010 SETAC [source] Pulp and paper mill effluents induce distinct gene expression changes linked to androgenic and estrogenic responses in the fathead minnow (Pimephales promelas)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Julieta Werner Abstract Although effluent treatment systems within pulp and paper mills remove many toxicants and improve wastewater quality, there is a need to understand and quantify the effectiveness of the treatment process. At a combined news and kraft pulp and paper mill in northwestern Ontario, Canada, fathead minnow (FHM) reproduction and physiology were examined before, during, and after a short-term (6-d) exposure to 10% (v/v) untreated kraft mill effluent (UTK), 25% (v/v) secondary treated kraft mill effluent (TK), and 100% (v/v) combined mill outfall (CMO). Although UTK exposure significantly decreased egg production, neither TK nor CMO caused any reproductive changes. The expression of six genes responsive to endocrine-disrupting compounds, stress, or metals was then examined in livers of these fish using real-time polymerase chain reaction. In female FHMs, none of the three effluents induced significant expression changes in any genes investigated. By contrast, in males there were significant increases in the mRNA levels of androgen receptor, estrogen receptor (ER) ,, and cytochrome P4501A (CYP1A) upon UTK and TK exposure but no changes in ER, or vitellogenin (VTG) gene expression, whereas CMO exposure significantly increased the mRNA levels of ER,, VTG, and CYP1A. Together, these results suggest that kraft effluent before and after biological treatment contained compounds able to induce androgenic effects in FHMs, and that combination of kraft and newsmill effluents eliminated the androgenic compounds while inducing distinct and significant patterns of gene expression changes that were likely due to estrogenic compounds produced by the newsmill. Environ. Toxicol. Chem. 2010;29:430,439. © 2009 SETAC [source] Effects of dietary esfenvalerate exposures on three aquatic insect species representing different functional feeding groupsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2008Katherine R. Palmquist Abstract Given the chemical properties of synthetic pyrethroids, it is probable that compounds, including esfenvalerate, that enter surface waters may become incorporated into aquatic insect food sources. We examined the effect of dietary esfenvalerate uptake in aquatic insects representing different functional feeding groups. We used three field-collected aquatic insect species: A grazing scraper, Cinygmula reticulata McDunnough (Ephemeroptera: Heptageniidae); an omnivorous filter feeder, Brachycentrus americanus Banks (Trichoptera: Brachycentridae); and a predator, Hesperoperla pacifica Banks (Plecoptera: Perlidae). Laboratory-cultured algae were preexposed for 24 h to esfenvalerate concentrations of 0, 0.025, 0.05, and 0.1 ,g/L and provided to two C. reticulata age classes (small and final-instar nymphs). Reduction in small nymph growth was observed following three weeks of feeding on algae exposed to 0.05 and 0.1 ,g/L of esfenvalerate, and the highest dietary exposure reduced egg production in final-instar nymphs. The diet for B. americanus and H. pacifica consisted of dead third-instar Chironomus tentans larvae preexposed for 24 h to esfenvalerate concentrations ranging between 0.1 and 1.0 ,g/L. Consumption of larvae exposed to 0.5 to 1.0 ,g/L of esfenvalerate caused case abandonment and mortality in B. americanus caddisfly larvae. Although H. pacifica nymphs readily consumed esfenvalerate-exposed larvae, no adverse effects were observed during the present study. Furthermore, no evidence of esfenvalerate-induced feeding deterrence was found in any of the species tested, suggesting that aquatic insects may not be able to distinguish between pyrethroid-contaminated and uncontaminated food sources. These findings indicate that feeding deterrence is not a factor in regulating aquatic insect dietary exposures to synthetic pyrethroids. [source] Altered reproduction in fish exposed to pulp and paper mill effluents: Roles of individual compounds and mill operating conditionsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2008L. Mark Hewitt Abstract For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size, decreased circulating and gonadal production of reproductive steroids, altered expression of secondary sex characteristics, and decreased egg production. Several studies also have shown that effluent constituents are capable of accumulating in fish and binding to sex steroid receptors/binding proteins. Studies aimed at isolating biologically active substances within the pulping and papermaking process have provided clues about their source, and work has progressed in identifying opportunities for in-mill treatment technologies. Following comparisons of manufacturing processes and fish responses before and after process changes, it can be concluded that effluent from all types of mill processes are capable of affecting fish reproduction and that any improvements could not be attributed to a specific process modification (because mills normally performed multiple modifications simultaneously). Improved reproductive performance in fish generally was associated with reduced use of molecular chlorine, improved condensate handling, and liquor spill control. Effluent biotreatment has been effective in reducing some effects, but biotreated effluents also have shown no difference or an exacerbation of effects. The role of biotreatment in relation to effects on fish reproduction remains unclear and needs to be resolved. [source] Effects of the estrogen agonist 17,-estradiol and antagonist tamoxifen in a partial life-cycle assay with zebrafish (Danio rerio)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007Leo T. M. van der Ven Abstract A partial life-cycle assay (PLC) with zebrafish (Danio rerio) was conducted to identify endocrine-disrupting effects of 17,-estradiol (E2) and tamoxifen (TMX) as reference for estrogen agonist and antagonist activity. Adult zebrafish were exposed for 21 d and offspring for another 42 d, allowing differentiation of gonads in control animals. The assessed end points included reproductive variables (egg production, fertilization, and hatching), gonad differentiation of juveniles, histopathology, and vitellogenin (VTG) expression. With E2, the most sensitive end points were feminization of offspring (at 0.1 nM) and increased VTG production in males (at 0.32 nM). At 1 nM, decreased F1 survival, increased F1 body length and weight, VTG-related edema and kidney lesions, and inhibited spermatogenesis were observed. Oocyte atresia occurred at even higher concentrations. Exposure to TMX resulted in specific effects at an intermediate test concentration (87 nM), including oocyte atresia with granulosa cell transformation and disturbed spermatogenesis (asynchrony within cysts). In F1, decreased hatching, survival, and body weight and length as well as decreased feminization were observed. Decreased vitellogenesis and egg production in females and clustering of Leydig cells in males occurred at higher concentrations. Toxicological profiles of estrogen agonists and antagonists are complex and specific; a valid and refined characterization of endocrine activity of field samples therefore can be obtained only by using a varied set of end points, including histology, as applied in the presented PLC. Evaluation of only a single end point can easily produce under- or overestimation of the actual hazard. [source] Neuropharmaceuticals in the environment: Mianserin-induced neuroendocrine disruption in zebrafish (Danio rerio) using cDNA microarraysENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2006Karlijn van der Ven Abstract Because of their environmental occurrence and high biological activity, human pharmaceuticals have received increasing attention from environmental and health agencies. A major bottleneck in their risk assessment is the lack of relevant and specific effect data. We developed an approach using gene expression analysis in quantifying adverse effects of neuroendocrine pharmaceuticals in the environment. We studied effects of mianserin on zebrafish (Danio rerio) gene expression using a brain-specific, custom microarray, with real-time polymerase chain reaction as confirmation. After exposure (0, 25, and 250 ,g/L) for 2, 4, and 14 d, RNA was extracted from brain tissue and used for microarray hybridization. In parallel, we investigated the impact of exposure on egg production, fertilization, and hatching. After 2 d of exposure, microarray analysis showed a clear effect of mianserin on important neuroendocrine-related genes (e.g., aromatase and estrogen receptor), indicating that antidepressants can modulate neuroendocrine processes. This initial neuroendocrine effect was followed by a "late gene expression effect" on neuronal plasticity, supporting the current concept regarding the mode of action for antidepressants in mammals. Clear adverse effects on egg viability were seen after 14 d of exposure at the highest concentration tested. Based on the specific molecular impact and the effects on reproduction, we conclude that further investigation of the adverse effects on the brain-liver-gonad axis is needed for a correct ecological risk assessment of antidepressants. [source] Use of paired fathead minnow (Pimephales promelas) reproductive test.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2006Part 1: Assessing biological effects of final bleached kraft pulp mill effluent using a mobile bioassay trailer system Abstract Reproductive effects have been recorded in wild fish in waters receiving pulp mill effluent (PME) since the mid to late 1980s. Laboratory assays with fathead minnow (FHM; Pimephales promelas) have been developed to better understand fish responses to PME. However, observations from laboratory studies have been variable, making it difficult to establish cause/effect relationships. A lack of environmental relevance in these laboratory studies may have contributed to the variability observed. The objectives of the present study were, first, to determine the effects of bleached kraft PME (BKME) on FHM under environmentally realistic conditions (i.e., ambient water and effluent quality) and, second, to determine the suitability of pair-breeding FHM to better link BKME-induced changes in indicators at the biochemical, individual, and population levels. A mobile bioassay trailer was situated on-site at a bleached kraft mill for 60 d, allowing supply of both ambient water (Lake Superior, Canada) and final BKME. The reproductive output of FHM was initially assessed for 21 d to obtain baseline data pre-exposure. At the end of the pre-exposure period, selected breeding pairs were exposed to final BKME (100% v/v and 1% v/v) for 21 d. Results demonstrated a stimulatory response pattern at 1% BKME (e.g., increased egg production) compared to control. In the 100% treatment, spawning events were reduced and fewer eggs were produced during the first two weeks of exposure. Exposure to 100% (v/v) BKME also resulted in ovipositor development in males and development of male secondary sex characteristics in females. Obtaining pre-exposure data and use of pair-breeding FHM in this assay gave a sensitive indication of effluent effects and allowed accurate comparisons of endpoints to be made. [source] Use of paired fathead minnow (Pimephales promelas) reproductive test.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2006Part 2: Source identification of biological effects at a bleached kraft pulp mill Abstract Reproductive effects of pulp mill effluents on fish continue to be reported in Canadian waters. Spawning delays, reduced gonad size, and altered levels of sex steroid hormones have been found in both sexes of various fish species exposed to effluents. We initiated a project to identify the source/cause of such effects. In part 1 of this two-part series, we exposed mature adult fathead minnow (FHM; Pimephales promelas) for 21 d to final treated effluent (1% and 100% v/v) from a bleached kraft pulp mill in Terrace Bay (ON, Canada). Results suggested pulp mill effluent from this mill affected reproductive indicators in FHM and effects were dependent on effluent concentration, duration of exposure, and method of data analysis. The main objective of this paper was to use the FHM assay to identify waste stream sources within the mill that affect reproductive indicators. Various process streams were selected, characterized with respect to effluent chemistry and acute toxicity, and a subset was tested on-site with the 21-d FHM bioassay. Results showed that both the combined mill effluent (before secondary treatment) and the combined alkaline stream (CALK) caused both decreased spawning events (,55% for both streams) and decreased egg production (28 and 74%, respectively), and the CALK stream resulted in significant male ovipositor development. By comparing response patterns we were able to identify the CALK stream as a source of compounds at this mill affecting reproductive indicators in FHM and highlight this stream for further toxicity identification evaluation. [source] Evaluation of adult quail and egg production following exposure to perchlorate-treated waterENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2005Angella Gentles Abstract Twenty-three adult female northern bobwhite (Colinus virginianus) quail were exposed to 0, 0.01, 0.1, and 1 mM ammonium perchlorate (AP) in drinking water for 30 d. Eggs laid in all treatment groups, including control, were collected, dated, given an identification number, and weighed. On day 30 of exposure, 10 birds were euthanized by carbon dioxide asphyxiation. Gross toxicological endpoints and thyroid histology were evaluated in 10 birds. Egg production and accumulation of perchlorate in the eggs (n = 10) and liver (n = 5) were determined. Perchlorate did not affect body or organ weights significantly; however, at 1 mM, AP caused alteration of thyroid gland morphology. Perchlorate did not affect egg production, but significant accumulation was observed in the eggs and livers of exposed birds. [source] Impact of perfluorooctanoic acid on fathead minnow (Pimephales promelas) fatty acyl-coa oxidase activity, circulating steroids, and reproduction in outdoor microcosmsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2004Ken D. Oakes Abstract This study investigates reproductive impairment and biochemical changes in fathead minnow (Pimephales promelas) exposed for 39 d to varying concentrations of perfluorooctanoic acid (PFOA) under microcosm conditions. While the concentrations tested in this study were much higher than those normally found in the environment, no mortality was associated with PFOA exposure. Only modest changes were observed in condition factor and in relative liver and gonad size. Significant declines in circulating plasma steroids were observed, but these were accompanied by only limited increases in time to first oviposition and decreases in overall egg production. Peroxisome proliferation, as quantified by fatty acyl-CoA oxidase (FAO) activity, was elevated with low PFOA concentrations but attenuated with exposure to higher PFOA doses. Little evidence was seen of differential induction of peroxisome-associated enzyme activity with sex. Oxidative stress, as quantified by the 2-thiobarbituric acid reactive substances (TBARS) assay, was only modestly influenced by PFOA exposure and is not a significant consequence of FAO activity in fathead minnow. Perfluorooctanoic acid appears to be relatively nontoxic at environmentally relevant concentrations but may impact biochemical and reproductive endpoints under conditions associated with environmental spills. [source] Fishery-induced demographic changes in the timing of spawning: consequences for reproductive success,FISH AND FISHERIES, Issue 3 2009Peter J. Wright Abstract Demography can have a significant effect on reproductive timing and the magnitude of such an effect can be comparable to environmentally induced variability. This effect arises because the individuals of many fish species spawn progressively earlier within a season and may produce more egg batches over a longer period as they get older, thus extending their lifetime spawning duration. Inter-annual variation in spawning time is a critical factor in reproductive success because it affects the early environmental conditions experienced by progeny and the period they have to complete phases of development. By reducing the average lifetime spawning duration within a fish stock, fishing pressure could be increasing the variability in reproductive success and reducing long-term stock reproductive potential. Empirical estimates of selection on birth date, from experiments and using otolith microstructure, demonstrate that there is considerable variation in selection on birth date both within a spawning season and between years. The few multi-year studies that have linked egg production with the survival of progeny to the juvenile stage further highlight the uncertainty that adults face in timing their spawning to optimize offspring survival. The production of many small batches of eggs over a long period of time within a season and over a lifetime is therefore likely to decrease variance and increase mean progeny survival. Quantifying this effect of demography on variability in survival requires a focus on lifetime reproductive success rather than year specific relationships between recruitment and stock reproductive potential. Modelling approaches are suggested that can better quantify the likely impact of changing spawning times on year-class strength and lifetime reproductive potential. The evidence presented strengthens the need to avoid fishing severely age truncated fish stocks. [source] Testing hypotheses about fecundity, body size and maternal condition in fishesFISH AND FISHERIES, Issue 2 2004Marten A. Koops Abstract Recent research suggests that maternal condition positively influences the number of eggs spawned in fishes. These studies commonly choose a priori to use body length rather than weight as an explanatory variable of offspring production, even though weight is usually the better predictor of fecundity. We are concerned that consistent exclusion of body weight as a predictor of egg production inflates the variance in fecundity attributable to maternal condition. By analysing data on three populations of Atlantic cod (Gadus morhua, Gadidae) and 10 populations of brook trout (Salvelinus fontinalis, Salmonidae), we illustrate the need for a statistically defensible method of model selection to distinguish the effects of maternal condition on egg production from the effects of body size alone. Forward stepwise regression and null model analyses reveal how length-based regressions can significantly over-estimate correlations between condition and fecundity, leading us to conclude that the effect of condition on egg productivity may not be as ubiquitous or as biologically important as previously thought. Our work underscores the need for greater statistical clarity in analyses of the effects of maternal condition on reproductive productivity in fishes. [source] Importance of the Straits of Florida spawning ground to Atlantic sailfish (Istiophorus platypterus) and blue marlin (Makaira nigricans)FISHERIES OCEANOGRAPHY, Issue 6 2009DAVID E. RICHARDSON Abstract Much of the uncertainty in managing highly migratory pelagic species results from the scarcity of fisheries-independent data relevant to determining long-term trends in abundance, migratory movements, and the relative importance of different spawning grounds. To address these issues, we used an ichthyoplankton-based method to quantify the overall level of spawning of sailfish (Istiophorus platypterus) and blue marlin (Makaira nigricans) in the Straits of Florida (SF). We estimated that during the 2 years (2003,2004) of the study, 4.60 × 1011 sailfish eggs and 4.49 × 1011 blue marlin eggs were produced on an annual basis in this region. These egg production values, when combined with estimates of annual fecundity for each species and the most recent stock assessment estimate of total biomass, indicate that about 2.1% of Western Atlantic sailfish spawning and 1.6% of Atlantic-wide blue marlin spawning occurs in the SF. Additionally, pop-up satellite tags deployed on sailfish at the start of the spawning season revealed their short residency times in the SF, suggesting that a large (,13%) transient portion of the sailfish population is responsible for the SF egg production. Overall, this study provides a critically needed fisheries-independent method of quantifying spatial and temporal trends in the abundance of highly migratory species. The application of this methodology in the SF indicated that above-average levels of sailfish and blue marlin spawning occur in this area and, possibly more importantly, that the SF is a migratory bottleneck for these species. [source] Spawning habitat and daily egg production of sardine (Sardina pilchardus) in the eastern MediterraneanFISHERIES OCEANOGRAPHY, Issue 4 2006S. SOMARAKIS Abstract Spawning habitats of two eastern Mediterranean sardine, Sardina pilchardus (Walbaum, 1792), stocks (coastal waters of central Aegean and Ionian Seas) are characterized from daily egg production method (DEPM) surveys conducted during the peak of the spawning period. The latter occurs earlier in the Aegean Sea (December) than in the less-productive Ionian Sea (February). Single-parameter quotient analysis showed that the preferred bottom depth for spawning was 40,90 m in both areas but sardine selected sites of increased zooplankton in the Aegean Sea during December and increased fluorescence in the Ionian Sea during February. Estimates of daily egg production (P) and spawning stock biomass (B) were about four times lower for the Ionian Sea (P = 7.81 eggs m,2, B = 3652 tonnes) than the Aegean Sea (P = 27.52 eggs m,2, B = 16 174 tonnes). We suggest that zooplankton biomass might not be sufficient to support sardine reproduction in the highly oligotrophic Ionian Sea where the very small sardine stock may rely on the late-winter phytoplankton bloom. Actively selecting sites with increased zooplankton or phytoplankton and feeding plasticity (the well-known switching from selective particle feeding to non-selective filter feeding in sardines) are interpreted as adaptations to grow and reproduce optimally at varying prey conditions. Despite differences in temperature and productivity regimes, reproductive performance of sardine in the Ionian Sea was very similar to that in the Aegean Sea during the peak of the spawning period. In comparing adult parameters from DEPM applications to Sardina and Sardinops stocks around the world, a highly significant linear relation emerged between mean batch fecundity (F) and mean weight of mature female (W, g) (F = 0.364W, r2 = 0.98). The latter implies that, during the peak of the spawning period, mean relative batch fecundity (eggs g,1) of sardine is fairly constant in contrasting ecosystems around the world. [source] The influence of life history dynamics and environment on the determination of year class strength in North Sea herring (Clupea harengus L.)FISHERIES OCEANOGRAPHY, Issue 4 2005R. D. M. NASH Abstract The inter-annual variability in year class strength (1976,2000) of North Sea herring (Clupea harengus) was investigated using Paulik diagrams based on survey data and Virtual Population Analysis. The herring life cycle was split into five stages: spawning stock biomass (SSB), egg production, larvae, fish with 0 winter rings on the otolith (0-wr), 1-wr and 2-wr. Surveys were used as indices and Paulik analysis revealed relationships between stages. In 80% of the years, year class strength reflected SSB. Poorer than expected year classes were determined during the larva to 0-wr phase, whilst stronger than expected year classes were apparently determined during the 0-wr to 1-wr stage. There was no clear relationship between survival of young stages of herring and the abundance of Calanus finmarchicus but the year class strength of 0-wr and 1-wr had a negative relationship to bottom water temperature. Lower sea water temperatures in the North Sea are associated with higher Calanus abundance. The analysis shows that the strength of aberrant year classes of North Sea herring is determined between the pelagic larval and the juvenile stages. [source] Patterns in the spawning of cod (Gadus morhua L.), sole (Solea solea L.) and plaice (Pleuronectes platessa L.) in the Irish Sea as determined by generalized additive modellingFISHERIES OCEANOGRAPHY, Issue 1 2000Eleven ichthyoplankton cruises were undertaken covering most of the Irish Sea during the period February to June, 1995. To identify spawning localities and investigate temporal trends in egg production, the data on stage 1 A egg distributions of cod (Gadus morhua), plaice (Pleuronectes platessa) and sole (Solea solea) have been modelled using generalized additive models (GAMs). A two-stage approach was adopted where presence/absence was firstly modelled as a binary process and a GAM surface subsequently fitted to egg production (conditional on presence). We demonstrate that this approach can be used to model egg production both in space and in time. The spawning sites for cod, plaice and sole in the Irish Sea were defined in terms of the probability of egg occurrence. For cod, we demonstrate that by integrating under predicted egg production surfaces, a cumulative production curve can be generated and used to define percentiles of production and thus delimit the extent of the spawning season. However, for plaice and sole, the surveys did not fully cover the spawning season and the limitations that this imposes on GAM modelling of these data are discussed. Comparison of the spawning sites in 1995 with historical data suggests that the locations of cod, plaice and sole egg production in the Irish Sea have probably remained relatively constant over the last 30 years. [source] | |||||||||||||||||||||||||||||||