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61.
DAVID M. CHECKLEY JR MARISA N.C. LITZ RICHARD D. BRODEUR WILLIAM T. PETERSON 《Fisheries Oceanography》2012,21(6):393-404
We examined variability in growth rate during the larval stage of northern anchovy (Engraulis mordax) in response to physical and biological environmental factors in 2005 and 2006. The onset of spring upwelling was anomalously delayed by 2–3 months until mid‐July in 2005; in contrast, spring upwelling in 2006 began as a normal year in the northern California Current. Larval and early juvenile E. mordax were collected in August, September, and October off the coast of Oregon and Washington. Hatch dates ranged from May to September, with peaks in June and August in 2005 and a peak in July in 2006, based on the number of otolith daily increments. Back‐calculated body length‐at‐age in the June 2005 hatch cohort was significantly smaller than in the August 2005 cohort, which had comparable growth to the July 2006 cohort. Standardized otolith daily increment widths as a proxy for seasonal variability in somatic growth rates in 2005 were negative until late July and then changed to positive with intensification of upwelling. The standardized increment width was a positive function of biomass of chlorophyll a concentration, and neritic cold‐water and oceanic subarctic copepod species sampled biweekly off Newport, Oregon. Our results suggest that delayed upwelling in 2005 resulted in low food availability and, consequently, reduced E. mordax larval growth rate in early summer, but once upwelling began in July, high food availability enhanced larval growth rate to that typical of a normal upwelling year (e.g., 2006) in the northern California Current. 相似文献
62.
JR Delaney DS Kelley MD Lilley DA Butterfield JA Baross WSD Wilcock RW Embley M Summit 《Science (New York, N.Y.)》1998,281(5374):222-230
Seafloor diking-eruptive events represent the irreducible, quantum events of upper oceanic crustal accretion. They record events by which a large portion of the oceanic crust has formed through geological history. Since 1993, the U.S. Navy's real-time Sound Surveillance System has allowed location of ongoing acoustic signatures of dike emplacement and basalt eruptions at ridge crests in the northeast Pacific. These diking-eruptive events trigger a sequence of related, rapidly evolving physical, chemical, and biological processes. Magmatic volatiles released during these events may provide nutrients for communities of subseafloor microorganisms, some of which thrive in high-temperature anaerobic environments. Many of the organisms identified from these systems are Archaea. If microorganisms can thrive in the water-saturated pores and cracks within deep, volcanically active portions of our planet, other hydrothermally active planets may harbor similar life forms. 相似文献
63.
64.
NATHALIE B. REYNS DAVID B. EGGLESTON RICHARD A. LUETTICH JR 《Fisheries Oceanography》2007,16(3):257-272
We examined how post‐larval blue crab (Callinectes sapidus) dispersal occurs within Pamlico Sound, NC, USA, a predominantly wind‐driven system. We sampled during multiple 24‐h periods over 2 years (2000–01) to relate the spatial distribution of post‐larvae in the water column with circulation patterns. A hydrodynamic model of the region was used to recreate dispersal trajectories and to assess potential transport mechanisms and pathways that link near‐inlet and across‐Sound nursery habitats. Most post‐larval blue crabs were collected in surface waters at night, and were consistently distributed within the north‐western region of Pamlico Sound. Particle‐tracking simulations suggested that dispersal from the inlets to across‐Sound nursery habitats only resulted from the combination of tidal and wind‐driven currents. Our simulation results further indicated that the northernmost inlet (Oregon Inlet) was the primary supplier of post‐larval blue crabs throughout the northern basin of Pamlico Sound, as crabs ingressing through Hatteras Inlet to the south were not retained within our study area. A dispersal pathway connecting Oregon Inlet and across‐Sound settlement habitats was evident from field observations. Collectively, our results indicate how multiple forcing agents, coupled with post‐larval vertical positioning within the water column, drive estuarine dispersal and connect spatially separated nursery habitats. 相似文献
65.
CL SCHWARTZKOFF JR EGERTON† DJ STEWART‡ PR LEHRBACH§ TC ELLEMAN¶ PA HOYNE¶ 《Australian veterinary journal》1993,70(4):123-126
SUMMARY A multivalent footrot vaccine has been developed, containing pilus antigens produced in recombinant Pseudomonas aeruginosa and representing all nine serogroups of Dichelobacter (Bacteroides) nodosus commonly recognised in the field. The responses of sheep to the multivalent vaccine have been compared with those to monovalent vaccines representing only a single serogroup. Antigenie competition between serogroups occurred in sheep immunised with the multivalent formulation, but high levels of protection were still achieved. The study showed that in multivalent footrot vaccines, antigenic competition is predominantly due to the presence of a family of immunologically-related pilus antigens rather than to interference by extraneous proteins. 相似文献
66.
DJ Hutchinson EM Jones JM Pay JR Clarke MT Lohr JO Hampton 《Australian veterinary journal》2023,101(8):313-319
There is a growing recognition of the harmful effects of lead exposure on avian and mammalian scavengers. This can lead to both lethal and non-lethal effects which may negatively impact wildlife populations. Our objective was to assess medium-term lead exposure in wild Tasmanian devils (Sarcophilus harrisii). Frozen liver samples (n = 41), opportunistically collected in 2017–2022, were analysed using inductively coupled plasma mass spectrometry (ICP-MS) to determine liver lead concentrations. These results were then used to calculate the proportion of animals with elevated lead levels (>5 mg/kg dry weight) and examine the role of explanatory variables that may have influenced the results. The majority of samples analysed were from the south-east corner of Tasmania, within 50 km of Hobart. No Tasmanian devil samples were found to have elevated lead levels. The median liver lead concentration was 0.17 mg/kg (range 0.05–1.32 mg/kg). Female devils were found to have significantly higher liver lead concentrations than males (P = 0.013), which was likely related to lactation, but other variables (age, location, body mass) were not significant. These results suggest that wild Tasmanian devil populations currently show minimal medium-term evidence of exposure to lead pollution, although samples were concentrated in peri-urban areas. The results provide a baseline level which can be used to assess the impact of any future changes in lead use in Tasmania. Furthermore, these data can be used as a comparison for lead exposure studies in other mammalian scavengers, including other carnivorous marsupial species. 相似文献
67.
Sudden blindness associated with protothecosis in a dog 总被引:1,自引:0,他引:1
68.
Abstract. Characteristics of 18 strains of Yersinia ruckeri the causative agent of enteric redmouth disease, from a variety of hosts and a wide geographic range were compared. Except for variations in colonial morphology and in citrate, sorbitol, and trehalose reactions, the strains were morphologically and biochemically homogeneous. Sixteen strains reacted with antiserum against the first serotype reported, and one strain reacted with antiserum against a more recently reported serotype. One strain represented a third serotype. Evidence presented indicated that extension of the geographic range may not be entirely a result of the transport of carrier fish. 相似文献
69.
Francisco A Macías Francisco JR Mejías Jos MG Molinillo 《Pest management science》2019,75(9):2413-2436
Allelopathy is the biological phenomenon of chemical interactions between living organisms in the ecosystem, and must be taken into account in addressing pest and weed problems in future sustainable agriculture. Allelopathy is a multidisciplinary science, but in some cases, aspects of its chemistry are overlooked, despite the need for a deep knowledge of the chemical structural characteristics of allelochemicals to facilitate the design of new herbicides. This review is focused on the most important advances in allelopathy, paying particular attention to the design and development of phenolic compounds, terpenoids and alkaloids as herbicides. The isolation of allelochemicals is mainly addressed, but other aspects such as the analysis and activities of derivatives or analogs are also covered. Furthermore, the use of allelopathy in the fight against parasitic plants is included. The past 12 years have been a prolific period for publications on allelopathy. This critical review discusses future research areas in this field and the state of the art is analyzed from the chemist's perspective. © 2019 Society of Chemical Industry 相似文献
70.
In a cross-over study, six Greyhounds were dosed by mouth with ampicillin and amoxycillin at 20 mg/kg, using three different feeding regimens (no food, canned food prior to dosing, and dry food ad lib ) with each drug. Antibiotic levels in plasma were determined by microbiological assay at intervals after dosing.
Plasma ampicillin concentrations tended to be lower in fed than in starved Greyhounds, but amoxycillin levels were relatively unaffected by feeding. In starved Greyhounds, ampicillin gave higher early levels than amoxycillin. 相似文献
Plasma ampicillin concentrations tended to be lower in fed than in starved Greyhounds, but amoxycillin levels were relatively unaffected by feeding. In starved Greyhounds, ampicillin gave higher early levels than amoxycillin. 相似文献