First Record of Captive Larval Culture and Metamorphosis of the Pacific Blue Tang,Paracanthurus hepatus          下载免费PDF全文

Matthew A. DiMaggio  Eric J. Cassiano  Kevin P. Barden  Shane W. Ramee  Cortney L. Ohs  Craig A. Watson 《Journal of the World Aquaculture Society》2017,48(3):393-401

The Pacific blue tang, Paracanthurus hepatus, is consistently among the top 20 marine ornamental species imported into the USA, with all specimens presently sourced from wild stocks. Captive culture of this species through metamorphosis has not been previously documented and fundamental information regarding reproduction, larval culture, and production techniques is scarce. This study aimed to elucidate methods that would advance our understanding and success with captive propagation of this species. A total of 50,000 eggs were collected from a single broodstock population and stocked in a 1000‐L tank. Beginning at 3 d posthatch (DPH), larvae were fed three times daily a diet comprised exclusively of copepod nauplii. At 12 DPH, enriched rotifers were first fed followed by powdered feed (20 DPH) and first instar Artemia (21 DPH). Large mortality events were observed at 7 and 20 DPH, corresponding with starvation and flexion, respectively. By 41 DPH, the majority of the remaining larvae began associating with the bottom of the culture tank. On Day 50, the first signs of blue pigmentation marked the beginning of metamorphosis. A total of 27 juvenile blue tangs were cultured during this trial. This effort represents the first successful culture of this species in captivity.  相似文献   

Evaluation of free radical‐generating compounds for toxicity towards the cyanobacterium Planktothrix perornata,which causes musty off‐flavour in pond‐raised channel catfish (Ictalurus punctatus)     

N P Dhammika Nanayakkara  Kevin K Schrader 《Aquaculture Research》2011,42(12):1895-1898

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The rapid rise of streams and rivers in conservation assessment     

Kevin J Collier 《水产资源保护:海洋与淡水生态系统》2011,21(5):397-400

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Influence of oceanographic conditions on abundance and distribution of post‐larval and juvenile carangid fishes in the northern Gulf of Mexico          下载免费PDF全文

John A. Mohan  Tracey T. Sutton  April B. Cook  Kevin M. Boswell  R. J. David Wells 《Fisheries Oceanography》2017,26(5):526-541

Relationships between abundance of post‐larval and juvenile carangid (jacks) fishes and physical oceanographic conditions were examined in the northern Gulf of Mexico (GoM) in 2011 with high freshwater input from the Mississippi River. Generalized additive models (GAMs) were used to explore complex relationships between carangid abundance and physical oceanographic data of sea surface temperature (SST), sea surface height anomaly (SSHA) and salinity. The five most abundant carangid species collected were: Selene setapinnis (34%); Caranx crysos (30%); Caranx hippos (10%); Chloroscombrus chrysurus (9%) and Trachurus lathami (8%). Post‐larval carangids (median standard length [SL] = 10 mm) were less abundant during the spring and early summer, but more abundant during the late summer and fall, suggesting summer to fall spawning for most species. Juvenile carangid (median SL = 23 mm) abundance also increased between the mid‐summer and early fall. Most species showed increased abundance at lower salinities and higher temperatures, suggesting entrainment of post‐larval fishes or feeding aggregations of juveniles at frontal convergence zones between the expansive river plume and dynamic mesoscale eddy water masses. However, responses were species‐ and life‐stage specific, which may indicate fine‐scale habitat partitioning between species. Ordination methods also revealed higher carangid abundances at lower salinities for both post‐larval and juvenile life stages, with species‐ and life‐stage specific responses to SST and SSHA, further suggesting habitat separation between species. Results indicate strong links between physical oceanographic features and carangid distributions in the dynamic northern GoM.  相似文献   

Predicting the spatio‐temporal distributions of pelagic sharks in the western and central North Pacific          下载免费PDF全文

Mikihiko Kai  James T. Thorson  Kevin R. Piner  Mark N. Maunder 《Fisheries Oceanography》2017,26(5):569-582

Spatio‐temporal modeling estimates a species distribution function that represents variation in population density over space and time. Recent studies show that the approach may precisely identify spatial hotspots in species distribution, but have not addressed whether seasonal hotspots are identifiable using commonly available fishery data. In this study, we analyzed the seasonal spatio‐temporal distribution of pelagic sharks in the western and central North Pacific using fishery catch rates and a generalized linear mixed model with spatio‐temporal effects. Different spatial distribution patterns were observed between two shark species. The hotspots of shortfin mako (SFM) appeared in the vicinity of the coastal and offshore waters of Japan and the Kuroshio‐Oyashio transition zone (TZ), whereas the hotspots of blue shark (BSH) were widely distributed in the areas from the TZ to the waters of the Emperor Seamount Chain. Shortfin mako distribution changes seasonally with clear north‐south movement, which follows higher sea surface temperatures (SST). However, preferred spring and summer water temperature was still colder than those in fall and winter, but not as cold as for BSH, which did not show seasonal north‐south movement. BSH exhibits seasonal east‐west movement apparently unrelated to temperature. The spatial fishing effort by season generally follows the seasonal movement of temperature possibly making SFM more vulnerable to the fishery than BSH. These findings could be used to reduce the capture risk of bycatch sharks and to better manage the spatial distribution of fishing for targeted sharks.  相似文献   

Effects of translocation on survival and growth of freshwater mussels within a West Gulf Coastal Plain river system          下载免费PDF全文

Eric T. Tsakiris  Charles R. Randklev  Andrew Blair  Mark Fisher  Kevin W. Conway 《水产资源保护:海洋与淡水生态系统》2017,27(6):1240-1250

Breeding apomictic bahiagrass (Paspalum notatum Flügge) with improved turf traits          下载免费PDF全文

Esteban Rios  Kevin Kenworthy  Ann Blount  Kenneth Quesenberry  Bryan Unruh  John Erickson  Fredy Altpeter  Patricio Munoz 《Plant Breeding》2017,136(2):253-260

The development of a turf‐type bahiagrass could have a remarkable impact on the billion‐dollar turf industry in the south‐eastern United States. The goals of this study were to (i) select bahiagrass genotypes with improved turf attributes and (ii) determine the reproductive mode and seed fertility of selected genotypes. The population included mutants, wild types, hybrids and standard cultivars evaluated at two locations for two years. Morphological variation was observed and clonal repeatability (H²) ranged from 0.27 to 0.90. Flowering was extremely reduced in some mutants, which also exhibited dark green colour, finer texture and reduced canopy height. Cytoembryological observations revealed that diploids reproduced sexually and tetraploids by obligate or facultative apomixis. Genotypes with superior seed fertility were identified, while others were comparable to the standard cultivars. While mutant plants exhibited great morphological variation, the random mutations did not affect their reproductive mode, validating the use of mutagenesis in apomictic species. The high H² indicated that selection for improved turf attributes could be successfully performed with the advantage of clonal seed propagation.  相似文献   

Wildfire and exotic grass invasion alter plant productivity in response to climate variability in the Mojave Desert     

Kevin J. Horn  Samuel B. St. Clair 《Landscape Ecology》2017,32(3):635-646

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Estrogen sex-reversal of Tilapia aurea     

Kevin D. Hopkins  William L. Shelton  Carole R. Engle 《Aquaculture (Amsterdam, Netherlands)》1979,18(3):263-268

Chemical treatments were used to produce sex-reversed female (genetic male) Tilapia aurea, which can be bred to produce monosex offspring. Various combinations of estrogens, two synthetic and one natural, an antiandrogen, and a ‘pituitary blocking agent’ were orally administered to sexually undifferentiated fry. Treatment periods were 4, 5, 6 and 8 weeks. Seven of the 36 treatments produced more than 50% females (α = 0.05). Two treatments were more successful than the others: (1) 17-α-ethynylestradiol (EE) at 100 mg kg^?1 diet in combination with methallibure (ME) at 100 mg kg^?1 for 6 weeks and (2) EE-100 with ME-100 and cyproterone acetate (CA) at 100 mg kg^?1 for 6 weeks. These treatments produced fish that were 90% female. Comparisons of the treatments with and without CA indicated that CA may lessen the hormone effectiveness of the treatments. Diethylstilbestrol was as potent as EE in comparable CA treatments.  相似文献   

Denitrification, N2O and CO2 fluxes in rice-wheat cropping system as affected by crop residues, fertilizer N and legume green manure   总被引：1，自引：0，他引：1  

Milkha S. Aulakh  Tejinder S. Khera  John W. Doran  Kevin F. Bronson 《Biology and Fertility of Soils》2001,34(6):375-389

Use of renewable N and C sources such as green manure (GM) and crop residues in rice-wheat cropping systems of South Asia may lead to higher crop productivity and C sequestration. However, information on measurements of gaseous N losses (N₂O+N₂) via denitrification and environmental problems such as N₂O and CO₂ production in rice-wheat cropping systems is not available. An acetylene inhibition-intact soil core technique was employed for direct measurement of denitrification losses, N₂O and CO₂ production, in an irrigated field planted to rice (Oryza sativa L.) and wheat (Triticum aestivum L.) in an annual rotation. The soil was a coarse-textured Tolewal sandy loam soil (Typic Ustochrept) and the site a semi-arid subtropical Punjab region of India. Wheat residue (WR, C:N=94) was incorporated at 6 t ha^-1 and sesbania (Sesbania aculeata L.) was grown as GM crop for 60 days during the pre-rice fallow period. Fresh biomass of GM (C:N.=18) at 20 or 40 t ha^-1 was incorporated into the soil 2 days before transplanting rice. Results of this study reveal that (1) denitrification is a significant N loss process under wetland rice amounting to 33% of the prescribed dose of 120 kg N ha^-1 applied as fertilizer urea-N (FN); (2) integrated management of 6 t WR ha^-1 and 20 t GM ha^-1 supplying 88 kg N ha^-1 and 32 kg FN ha^-1 significantly reduced cumulative gaseous N losses to 51.6 kg N ha^-1 as compared with 58.2 kg N ha^-1 for 120 kg FN ha^-1 alone; (3) application of excessive N and C through applying 40 t GM ha^-1 (176 kg N ha^-1) resulted in the highest gaseous losses of 70 kg N ha^-1; (4) the gaseous N losses under wheat were 0.6% to 2% of the applied 120 kg FN ha^-1 and were eight- to tenfold lower (5-8 kg N ha^-1) than those preceding rice; (5) an interplay between the availability of NO₃^- and organic C largely controlled denitrification and N₂O flux during summer-grown flooded rice whereas temperature and soil aeration status were the primary regulators of the nitrification-denitrification processes and gaseous N losses during winter-grown upland wheat; (6) the irrigated rice-wheat system is a significant source of N₂O as it emits around 15 kg N₂O-N ha^-1 year^-1; (7) incorporation of WR in rice and rice residue (C:N=63) in wheat increased soil respiration, and increased CO₂ production in WR- and GM-amended soils under anaerobic wetland rice coincided with enhanced rates of denitrification; and (8) with adequate soil moisture, most of the decomposable C fraction of added residues was mineralized within one crop-growing season and application of FN and GM further accelerated this process.  相似文献