美国红鱼试养的初步研究

笔者自行培育的美国红鱼苗体长25～30mm．1996年6月上、中旬到当年12月中旬．其个体的平均重量分别达到了750g和800g，生长速度优于我国其他养殖鱼种。     

茶皂素对几种鱼类和对虾的毒性研究

本研究以茶皂素类作为“清池剂”,试图解决对虾养殖的基础和应用技术问题。试验结果表明:对虾对茶皂素和油茶皂素有较高的耐受力;茶皂素与油茶皂素均具鱼毒活性,油茶皂素则较强。鱼种不同,中毒反应也略有差异;两种茶皂素的鱼毒速度快,在致死浓度时16h内出现中毒死亡,毒性降解也快,浓度为5×10~(-6)时40h后不再引起鱼类中毒。     

人工养虾池生态系统结构特点及其控制对策

为养殖对虾而修筑的大大小小的养虾池都是一相对独立的生态系统。在池内生态条件适于对虾正常要求的情况下，对虾可以在其中生存、生长。如果生态条件逐步恶化，非但影响对虾的正常生活、生长，严重时甚至导致全部对虾死亡。粗放式的养殖，其影响也相对小些，高密度养殖情况下潜在的危险较大，对养殖池的环境状况要特别注意。ｌ人工养虾生态系统的基本特点１·１人工养殖池是一个结构简单的生态系统。在池内除放养的对虾（有时混养贝类等）外自然存在的生物通常是浮游植物和浮游动物，食物链大体上是二个层次（对虾靠投饵喂养例外）。养虾池…     

Anomalous lithospheric structure of Northern Juan de Fuca plate — a consequence of oceanic rift propagation?

Anomalous crustal and upper mantle structure of northern Juan de Fuca plate is revealed from wide-angle seismic and gravity modelling. A 2-D velocity model is produced for refraction line II of the 1980 Vancouver Island Seismic Project (VISP80). The refraction data were recorded on three ocean bottom seismometers (OBSs) deployed at the ends and middle of a 110 km line oriented parallel to the North American continental margin. The velocity model is constructed via ray tracing and conforms to first-arrival amplitude observations and travel time picks of direct, converted and reflected phases. Between sub-sediment depths of 3 to 11 km, depths normally associated with the lower crust and upper oceanic mantle, the final model shows that compressional-wave velocities decrease significantly from southeast to northwest along the profile. At sub-sediment depths of 11 km at the northwestern end of the profile, P-wave velocities are as low as 7.2 km/s. A complementary 2-D gravity model using the geometry of the velocity model and velocity–density relationships characteristic of oceanic crust is produced. The high densities required to match the gravity field indicate the presence of peridotites containing 25–30% serpentine by volume, rather than excess gabbroic crust, within the deep low velocity zone. Anomalous travel time delays and unusual reflection characteristics observed from proximal seismic refraction and reflection experiments suggest a broader zone of partially serpentinized peridotites coincident with the trace of a pseudofault. We propose that partial serpentinization of the upper mantle is a consequence of slow spreading at the tip of a propagating rift.     

Abundance,distribution, and feeding patterns of juvenile coho salmon (Oncorhynchus kisutch) in the Juan de Fuca Eddy

The Juan de Fuca Eddy is a seasonal, counter-clockwise gyre off the mouth of the Strait of Juan de Fuca between Washington, USA and British Columbia, Canada that may provide favorable feeding habitat for juvenile coho salmon (Oncorhynchus kisutch) during their early marine existence. In late September 2002, physical and biological sampling was conducted along two transects of the eddy region. Surface rope trawling was conducted to capture juvenile salmon and other nekton, along with bongo and neuston net tows to examine potential mesozooplanktonic salmon prey. Presence of the Juan de Fuca Eddy was confirmed with vertical water profiles. In addition, nutrient and chlorophyll a concentrations collected from 3-m depth were within the range observed in previous studies within the eddy region. In the mesozooplankton community, euphausiids, chaetognaths, and decapod megalopae were common. In the diet of juvenile coho salmon, euphausiids and decapod megalopae were dominant by percent number, and larval and juvenile fish were dominant by percent weight. Feeding intensity (percent body weight) based on stomach contents was variable, but not significantly different among stations. To compare the Juan de Fuca Eddy region with an upwelling area, we sampled along a transect off La Push (LP), Washington, USA which is south of the eddy. The eddy region was found to be less productive than the LP transect. Nutrients were lower, chlorophyll a concentrations were higher, and zooplankton abundance was generally higher along the LP transect than in the eddy region. In addition, more juvenile coho salmon were captured from the LP transect than the eddy region. Prey items in stomachs of salmon from the LP transect were heterogeneous compared to those from the eddy region. Feeding intensity along the LP transect was slightly lower and more variable than in the eddy region, and differences in feeding intensity among LP stations were significant. In addition, feeding intensities among stations nested within regions were significantly different.     

An integrated approach to assess the ecological and chemical status of lakes with HOD/AHOD: a case study of two lakes

The thermal strati?cation of the lakes impedes the transfer of atmospheric oxygen into the lower layers of the lake. In lakes which are af fected by diverse anthropogenic in?uences, the increasing organic matter amounts lead to a sharp decrease in hypolimnetic oxygen amounts, aided by thermal strati?cation,and anaerobic conditions arise. The determination of hypolimnetic oxygen demand(HOD) and areal hypolimnetic oxygen demand(AHOD) and their monitoring represent an integrated approach to investigate the oxygenation of lakes, the nutrient conditions, and the physicochemical dynamics. In this study, two lakes dif fering by size and af fected by dif ferent anthropogenic sources, are investigated in this respect. At?rst, bathymetric studies were conducted to determine the depth, surface area, and volume relationships.Then, based on monitoring studies conducted in 2013 and 2014, the thermal strati?cation dynamics and layer properties were established using the relative thermal resistance to mixing(RTRM) index based on temperature and density pro?les. Following this, the oxygen depletion rates were determined by oxygen and temperature pro?ling in the hypolimnion. For the years of 2013 and 2014, the AHOD values for the Borabey Pond which is far from anthropogenic in?uences, were found to be 0.848 and 0.569 g O 2/(m·d), respectively.The AHOD values for the Porsuk Reservoir which was overburdened for years by industrial and domestic pollution were found to be 4.263 and 5.099 g O 2/(m·d), larger than its counterpart by almost sevenfold. The HOD and AHOD monitoring can be considered to a valuable tool for assessing the ecological and chemical status of lakes within Annex 5 of the Water Framework Directive and as an integrated approach to assess and monitor the status of lakes.     

鱼塭产斑节对虾(Penaeus monodon)催熟繁殖技术研究

以综合催熟措施和移植精荚手术相结合的技术方法,解决了鱼塭产斑节对虾催熟效应期长,产卵率低,易蜕壳失去精荚等难题。使用 ２７８ 尾雌虾,催熟率达９０％ 以上,在４０ ｄ 内共产卵６０８ 尾次,卵量１８ ５３０ 万粒,孵出无节幼体１１ ９９８ 万尾,平均孵化率 ６４．７％ ,平均每尾雌虾孵出无节幼体 ４３．１ 万尾,育成商品虾苗 １ ０２８．５ 万尾,育苗平均成活率 １３．６％ ,试养成活率５７．１％     

An integrated data-directed numerical method for estimating the undiscovered mineral endowment in a region

An integrated data-directed numerical method has been developed to estimate the undiscovered mineral endowment within a given area. The method has been used to estimate the undiscovered uranium endowment in the San Juan Basin, New Mexico, U.S.A. The favorability of uranium concentration was evaluated in each of 2,068 cells defined within the Basin. Favorability was based on the correlated similarity of the geologic characteristics of each cell to the geologic characteristics of five area-related deposit models. Estimates of the undiscovered endowment for each cell were categorized according to deposit type, depth, and cutoff grade. The method can be applied to any mineral or energy commodity provided that the data collected reflect discovered endowment.     

Comparative analysis of cladoceran microfossils in the Don and Scarborough Formations,Toronto, Canada

Pleistocene deposits at Toronto, consisting of Don Formation (considered to be of Sangamonian interglacial age) and Scarborough Formation (interpreted to be Early Wisconsinan, >50 000 years B.P.) were examined at three sites: Don Valley Brickyard, Leaside, and at the south end of Brimley Road at the foot of the Scarborough Bluffs. Comparison of the cladoceran microfossil assemblages described from these sites has enabled reconstruction of the lacustrine environment of the region.Cladoceran microfossil evidence from each site confirmed the disparity in community composition and structure, and in environmental conditions that existed during deposition of the Don and Scarborough Formations. Cladocera community composition averaged 40–45% remains of littoral species in the warmer Don interval at all three sites. The Scarborough Formation contained a more homogeneous cladoceran assemblage, with higher community similarity across sites than observed in the Don Formation. However, there was greater variation in the littoral: planktonic ratio among sites, ranging from >0.90 at Leaside to <0.10 at Brimley Road.Stratigraphically constrained cluster analysis of cladoceran microfossil assemblages clearly separated the communities in the Don Formation from those in the Scarborough Formation at each site. During the interglacial, the Don Brickyard site appears to have been a shallow, protected embayment on the lake shore, whereas the other sites are more distinctly lacustrine. The Scarborough assemblage at each site is representative of deeper, oligotrophic, subarctic lakes.     

Application of Generalized Likelihood Uncertainty Estimation (GLUE) at different temporal scales to reduce the uncertainty level in modelled river flows

ABSTRACT

In this study, the distributed catchment-scale model, DiCaSM, was applied on five catchments across the UK. Given its importance, river flow was selected to study the uncertainty in streamflow prediction using the Generalized Likelihood Uncertainty Estimation (GLUE) methodology at different timescales (daily, monthly, seasonal and annual). The uncertainty analysis showed that the observed river flows were within the predicted bounds/envelope of 5% and 95% percentiles. These predicted river flow bounds contained most of the observed river flows, as expressed by the high containment ratio, CR. In addition to CR, other uncertainty indices – bandwidth B, relative bandwidth RB, degrees of asymmetry S and T, deviation amplitude D, relative deviation amplitude RD and the R factor – also indicated that the predicted river flows have acceptable uncertainty levels. The results show lower uncertainty in predicted river flows when increasing the timescale from daily to monthly to seasonal, with the lowest uncertainty associated with annual flows.