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531.
Marie-Claude?ArchambaultEmail author V.?Monica?Bricelj Jon?Grant Donald?M.?Anderson 《Marine Biology》2004,144(3):553-565
Increased interest in using ecologically inert clays to flocculate, sediment, and thus mitigate harmful algal blooms at nearshore mariculture sites has prompted studies on the effectiveness of this method on prolific blooms, such as those caused by the neurotoxic dinoflagellate Karenia brevis in the Gulf of Mexico. Potential repercussions of this control strategy revolve around the increased flux of suspended particles to the benthos. Juvenile suspension-feeding bivalves are potentially vulnerable as they could suffer burial, a decrease in clearance rates, and/or an increase in pseudofeces production in response to suspended clay, leading to reduced growth and delay in attaining size refuge from predators. Here we assess lethal and sublethal effects on juvenile hard clams, Mercenaria mercenaria, in a 2-week flume application of phosphatic clay to simulated blooms of the nontoxic dinoflagellates Heterocapsa triquetra and Prorocentrum micans. Flow regimes simulated two contrasting, worst-case field conditions where (1) low flow allowed complete sedimentation and formation of a benthic sediment layer, and (2) high flow allowed complete particle suspension. No clam mortalities occurred in either treatment. The sedimentation treatment showed variable growth inhibition in shell and/or tissue, but effects were not apparent compared to controls (no sediment layer), and clams rapidly resumed siphon contact with the overlying water column. In contrast, a strong growth effect (~90% reduction in shell and tissue growth) occurred in particle-suspension trials compared to no-clay controls. These results suggest that repeated clay applications in the field are likely more detrimental to clams in a high-energy environment leading to prolonged in situ resuspension of clay than in an environment favoring sedimentation.Communicated by R.J. Thompson, St. Johns 相似文献
532.
Three hundred and thirty-nine cases of multiple gestation underwent prenatal diagnosis by amniocentesis. The spontaneous abortion rate (to 28 weeks) in this group was 3.57 per cent compared with our singleton abortion rate of 0.60 per cent. The perinatal mortality rate (PMR) and prematurity rate were not different from the singletons, and compared favourably with the PMR reported in the literature for multiple gestations which did not undergo any intervention during pregnancy. This increased abortion rate following amniocentesis may only represent the increased natural loss rate in multiple gestations, and not indicate any increased risk added by the procedure. 相似文献
533.
Dr. R. L. Anderson M. S. Golbus C. J. R. Curry P. W. Callen W. H. Hastrup 《黑龙江环境通报》1990,10(8):513-518
Four cases of multiple gestation with second trimester death of one fetus and subsequent damage to a survivor are reported. Monochorionic placentation was documented in three of the cases. Central nervous system lesions occurred in all cases, and bowel injury was noted in two of the damaged fetuses. Although rare maternal clotting problems have been reported in similar situations, none was noted in any of these four cases. Prior reports have indicated that losses in the first half of gestation were of no consequence to the surviving fetuses. These four cases contradict this suggestion, and indicate that close sonographic observation of the survivors is important in any multiple gestation where one fetus has died. 相似文献
534.
Identification of sex pheromone components of the pea midge, Contarinia pisi (Diptera: Cecidomyiidae) 总被引:1,自引:0,他引:1
Ylva Hillbur Peter Anderson Heinrich Arn Marie Bengtsson Jan Löfqvist Anthony J. Biddle Olof Smitt Hans-Erik Högberg Ernst Plass Stephan Franke Wittko Francke 《Die Naturwissenschaften》1999,86(6):292-294
Three components in extract of pheromone glands of female pea midges, Contarinia pisi, were found to be active on male pea midge antennae by coupled gas chromatographic-electroantennographic detection. The EAD
active components were identified as 2-acetoxytridecane, (2S,11S)-diacetoxytridecane, and (2S,12S)-diacetoxytridecane. A blend of these compounds proved to be highly attractive to males in windtunnel experiments.
Received: 12 November 1998 / Accepted in revised form: 26 january 1999 相似文献
535.
Paul E. Bibbins JR. Robert L. Anderson Dr. Jack M. Rary Howard W. Jones JR. 《黑龙江环境通报》1982,2(2):123-125
A 48,XXYY fetus was diagnosed prenatally in a 34-year old female who was seen at 18-5 weeks of pregnancy for genetic counselling and amniocentesis for advanced maternal age. The pregnancy was terminated, and skin and peripheral blood samples were obtained at the time of delivery. These samples also exhibited the 48,XXYY chromosomal complement. 相似文献
536.
The morphometry of the sea urchin Evechinus chloroticus from habitats of contrasting algal abundance but of similar urchin density was examined at two localities in southern New
Zealand during 1993. Populations from habitats of high algal abundance (Dusky Sound) had similar relationships of demipyramid
(jaws) to test diameter, but individuals had significantly smaller jaws relative to their test diameter than those from a
locality where algal abundance was low (Arapawa Island). The body wall mass (in relation to total wet weight) was similar
for populations from both localities but, for Dusky Sound populations, individuals from exposed sites had greater relative
body mass than those from sheltered sites. The ratios of gonad weight:total weight were similar between localities. However,
E. chloroticus from Arapawa Island reached reproductive maturity at a smaller size than those from Dusky Sound. Growth rates of E. chloroticus varied among localities in Dusky Sound. Growth was modelled by the Tanaka function, which allows for rapid early growth until
reproductive maturity is reached and declining growth rates thereafter. The results show that sea urchins respond to low resource
availability by increasing the size of the food-gathering apparatus, maturing at a smaller size, and growing to a smaller
size than individuals from food-rich habitats.
Received: 3 December 1996 / Accepted: 29 January 1997 相似文献
537.
F. A. Green Jr. J. W. Anderson S. R. Petrocelli B. J. Presley R. Sims 《Marine Biology》1976,37(1):75-81
The results of toxicity experiments have shown that a level of 17 ppb ionic mercury is acutely toxic (96-h LC50) to postlarval white shrimp (Penaeus setiferus). In addition, the size of the shrimp, within the range tested (7 to 35 mm) did not significantly alter the toxicity values of mercury to this species. Fifty-seven days pre-exposure to low levels of mercury (0.5 and 1.0 ppb) had no effect on the acute toxicity (96-h LC50) of mercury to the shrimp. The effect of chronic exposure to low levels of mercury on the respiratory rate, growth, and molting rate of postlarval P. setiferus was studied, and the results showed that 60 days exposure to 0.5 and 1.0 ppb mercury did not significantly affect any of these parameters for the postlarvae. 相似文献
538.
539.
William C. Anderson Sukanta Basu Chris W. Letchford 《Environmental Fluid Mechanics》2007,7(3):195-215
Several non-dynamic, scale-invariant, and scale-dependent dynamic subgrid-scale (SGS) models are utilized in large-eddy simulations
of shear-driven neutral atmospheric boundary layer (ABL) flows. The popular Smagorinsky closure and an alternative closure
based on Kolmogorov’s scaling hypothesis are used as SGS base models. Our results show that, in the context of neutral ABL
regime, the dynamic modeling approach is extremely useful, and reproduces several establised results (e.g., the surface layer
similarity theory) with fidelity. The scale-dependence framework, in general, improves the near-surface statistics from the
Smagorinsky model-based simulations. We also note that the local averaging-based dynamic SGS models perform significantly
better than their planar averaging-based counterparts. Lastly, we find more or less consistent superiority of the Smagorinsky-based
SGS models (over the corresponding Kolmogorov’s scaling hypothesis-based SGS models) for predicting the inertial range scaling
of spectra. 相似文献
540.
Summary The linked gas chromatographical/electroan-tennogram (GC/EAG) technique revealed that the parasitic reindeer nose bot fly is able to specifically sense components produced by the interdigital pheromone gland of reindeer. The head-space extraction technique, with Porapak Q as the collecting polymer, was used to trap pheromone gland and urine components used to assess fly responses. One component from reindeer urine also was a potent stimulus for the sensory neurons of the fly. These components can be important chemical signals to the flies for long distance orientation towards host animals. This is the first report on EAG in Oestridae. 相似文献