Growth, Survival, and Feed Conversion Rates of Hatchery-Reared Mutton Snapper Lutjanus analis Cultured in Floating Net Cages     

Daniel D.  Benetti  Jaime A.  Matera  Owen M.  Stevens  Jorge F.  Alarcon  Michael W.  Feeley  Federico J.  Rotman  Yoichi  Minemoto  Gill  Banner-Stevens  Janice  Fanke  Scott  Zimmerman Loyal  Eldridge 《Journal of the World Aquaculture Society》2002,33(3):349-357

Abstract.— The aquaculture performance of mutton snapper Lutjanus analis raised in floating net cages was assessed by measuring their growth, survival, and feed conversion rates during a growout trial conducted in a 3.2‐ha saltwater lake in the Florida Keys, Florida, USA. Approximately 10,500 hatchery‐reared finger‐lings were stocked in two circular, high‐density polyethylene (HDPE) net cages of 7‐m diameter × 7‐m deep (300 m²) and 10‐m diameter × 7‐m deep (600 m³) dimensions. Cages were stocked at 25 fish/m³ (3.2 kg/m³) and 5 fish/m³ (0.72 kg/m³), respectively. Fish grew from a mean of 16.5 g to 302.8 g (25.6 cm TL) in 246 days in the former cage and from a mean of 42.3 g to 245.6 g (23.8 cm TL) in 178 d in the latter cage. Growth rates in weight were best expressed by the following exponential equations: cage 1 (high stocking density): W = 20.716 e^0.0112x (r²= 0.83); cage 2 (low stocking density): W = 38.848 e^0.0118x (r²= 0.81). Length‐weight data indicate that hatcheryraised, cage‐cultured mutton snapper are heavier per unit length than their wild counterparts. There was no significant difference (P < 0.05) between the slopes of the two lines, indicating that fish in the two cages grew at the same rate. The length‐weight relationships for mutton snapper stocked in cages 1 and 2 are expressed, respectively, by the equations W = 0.000009 L ^3.11 (r²= 0.99) and W = 0.000005 L ^3.22 (r²= 0.97). Overall feed conversion rate for both cages combined was 1.4. Approximately 10% of the fish sampled exhibited some degree of deformity, particularly scoliosis. Overall survival rate was 70%. Results suggest that L. analis has potential for aquaculture development in net cage systems.  相似文献   

Responses to supplementation in white fulani cattle under agro-pastoral management in northern nigeria. II. Fodder     

D. A. Campbell  O. A. Ikuegbu  E. Owen  D. A. Little 《Tropical animal health and production》1996,28(3):230-236

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Copper localization in Cannabis sativa L. grown in a copper-rich solution     

Laura Arru  Sara Rognoni  Micaela Baroncini  Piera Medeghini Bonatti  Pierdomenico Perata 《Euphytica》2004,140(1-2):33-38

Summary With the aim to examine its potential as a renewable resource to decontaminate polluted soils, electron microscopy combined with X-ray microanalysis was used to investigate the localization of copper in Cannabis sativa grown in hydroponic copper-rich culture. Cu was found to accumulate preferentially in the upper leaf epidermal cells; it was also detected in spiculae and in abaxial trichomes too. Primary bast fibres seem to be not involved in copper accumulation.  相似文献   

从温室种植者百强榜看美国温室花卉业的过去现在未来     

Sara Tambascio  周艳萍 《中国花卉园艺》2007,(15):47-49

为了庆祝美国温室种植者百强榜的20岁生日,本文回顾了温室行业这20年来走过的岁月,展望了温室行业的未来。  相似文献   

The use of a water budget model and yield maps to characterize water availability in a landscape     

Dennis Timlin  Yakov Pachepsky  Charles Walthall  Sara Loechel 《Soil & Tillage Research》2001,58(3-4):219-231

Crop yield maps may contain substantial corollary information regarding the distribution of yield related soil properties across a landscape. One of these properties is water holding capacity (WHC). Since WHC is an important parameter for crop models and is also critical for crop yield, our objective was to determine if WHC could be estimated by matching simulated yield with yield map data. We collected soil cores for water retention measurements and recorded plant phenological stages from 60 plots on four transects over two growing seasons (1997 and 1998). Soil cores were also sampled on 40 other locations set out on a grid pattern. We utilized a simple water budget model that uses the relative transpiration ratio to calculate relative yield from available water in the soil profile. Rainfall, potential evapotranspiration and soil water holding capacity are input. An optimization program varies the WHC to produce a grain yield similar to the one from the yield map at a particular location. This analysis was carried out over several scales by averaging yields over 55 m×71 m, 27 m×35 m, and 11 m×14 m areas. Yield data from 2 years were used. Yields from the transects in both years were significantly related to measured WHC in the surface 0–10 cm of soil. The calculated stress indices from the water budget model and estimated available WHC calculated for the 1997 data were similar to those calculated for the 1998 data where data were aggregated in 27 by 35 m or larger blocks. The contour map of estimated WHC was similar to the map of measured WHC for some features though there were also some differences. Use of multiple years of yield data are required to give stable results for estimated water holding capacities.. This information could be used in a farm management plan by allowing a producer to classify a field into areas that are buffered against drought and areas more susceptible to drought.  相似文献   

Florida manatees, Trichechus manatus latirostris, respond to approaching vessels     

Stephanie M Nowacek  Randall S Wells  Edward C.G Owen  Richard O Flamm 《Biological conservation》2004,119(4):517-523

Florida manatees inhabit shallow coastal and estuarine waters of the southeast US, a range that brings them into frequent contact with vessels. More than 30% of documented annual mortalities are attributed to vessel collisions, and most living animals bear the scars of multiple, non-lethal encounters. To document the behavior of manatees in the presence of vessels, we recorded their movements with an overhead video system. We scored six aspects of behavior during 170 vessel approaches, and compared their behavior with 187 control segments when no boats were present. Manatees in shallow waters and at the edge of the channel responded to approaches by orienting towards the nearest deep water, a boat channel, and increasing their swimming speed. Close boat approaches and shallow water depths exacerbated these responses. Our results indicate that manatees detect and respond to approaching vessels with an apparent flight response, a response which includes movement towards deeper water. If given sufficient time, i.e., approached or passed slowly, the manatees may then be able to reach deeper water and safe depths.  相似文献   

Long-term trends in stream chemistry and biology in North-East Scotland: Evidence for recovery     

C. Soulsby  D. Turnbull  S. J. Langan  R. Owen  D. Hirst 《Water, air, and soil pollution》1995,85(2):689-694

Since 1983 stream chemistry and macroinvertebrate ecology were monitored in ten streams draining the eastern Cairngorms. All streams have exhibited a decline in sulphate concentrations in response to reduced acid deposition; in the more acidic systems this has been reflected by a parallel increase in acid neutralizing capacity (ANC). In some streams this coincides with an increase in the abundance of acid-sensitive mayflies which may provide evidence for biological recovery. In the most chronically acidified systems no increased abundance has been observed despite significant increases in ANC. This suggests that further reductions in deposition and sufficient time for a reversal of soil acidification is required before any biotic recovery occurs.  相似文献   

Perceived risk, displacement and refuging in brown bears: positive impacts of ecotourism?     

Owen T. Nevin  Barrie K. Gilbert 《Biological conservation》2005,121(4):611-622

Ecotourism is a rapidly growing industry with unknown impacts on viewed wildlife that may require novel management action. We examined the impact of viewing activities on the behaviour of brown bears (Ursus arctos) in coastal British Columbia.Domination of the best feeding sites and human avoidance by large male bears has consistently been reported. We, however, saw displacement in time rather than space - during the viewing day large males were less active than at other times, while females with cubs tended to be more active.In each year, females with cubs spent similarly high proportions of their time fishing when people were present. In years with large male activity, less time was spent fishing when people were absent. When freed from the potential threat of large male bears, females with cubs showed no measurable impact of controlled human activity.Human presence at a feeding site impacts the behaviour of brown bears, but not as expected. Temporal avoidance of human activity by large males was observed; indications that they departed upon satiation, before the arrival of morning tours, however, suggests that there was little energetic impact. By displacing large males, viewing activities created a temporal refuge, enhancing feeding opportunities for subordinate age/sex classes. With the strong positive relationships between mean female mass and litter size, this may in turn increase population productivity.  相似文献   

Interaction of contaminated sediment from a salt marsh with estuarine water: evaluation by leaching and ecotoxicity assays and salts from leachate evaporation     

Sara Peres  M. Clara F. Magalhães  Maria Manuela Abreu  Sara Leitão  Ana Santos  Maria José Cerejeira 《Journal of Soils and Sediments》2016,16(5):1612-1624

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Sex and population differences in the incidence of a plasma cholinesterase variant   总被引：2，自引：0，他引：2  

A H Lubin  P J Garry  G M Owen 《Science (New York, N.Y.)》1971,173(992):161-164

Accumulating knowledge of polymorphic enzyme systems poses intriguing possibilities of anthropologic genetics. Development of an automated procedure for determination of heterozygosity or homozygosity of the atypical plasma cholinesterase allele (E(1)(a)) permitted screening of 2317 individuals during a national Preschool Nutrition Survey and several smaller population studies. Frequencies of the allele (E(1)(a)) closely parallel those previously reported. Caucasians manifested a heterozygote male preponderance of 1.85: 1.  相似文献