Implications of landscape configuration on understory forage productivity: a remote sensing assessment of native forests openings

Agroforestry Systems - Sound management of native forests used for cattle grazing requires understanding the dynamics of forage productivity in the openings. Despite their importance, forage...     

The hydraulically integrated serial turbidostat algal reactor (HISTAR) for microalgal production

A hydraulically integrated serial turbidostat algal reactor (HISTAR) for the mass production of microalgae was designed, constructed and preliminarily evaluated. The 9266-l experimental system consists of two enclosed turbidostats hydraulically linked to a series of six open continuous-flow, stirred-tank reactors (CFSTRs). The system was monitored and controlled using GENESIS process control software. A production study was preformed using Isochrysis sp. (C-iso) to assess system stability and production potential under commercial-like conditions. The study was performed at the following target system parameters: system dilution rate of 0.49 per day, pH 7.6, NITROGEN=10 mg l⁻¹, PHOSPHORUS=2 mg l⁻¹, and artificial illumination (photosynthetic photon flux density) from 1000 W metal halide LAMPS=800 μmol s⁻¹ m⁻². At steady state conditions, daily harvested algal paste was 1454 g (wet), mean areal system PRODUCTIVITY=47.8±3.04 g m⁻² per day (17.1±1.09 g C m⁻² per day) and mean CFSTR6 DENSITY=105.5±6.71 mg l⁻¹.     

Bench-Scale Evaluation of a Micro-Computer Automated Algal Turbidostat

A bench-scale, micro-computer automated algal turbidostat was constructed and its production and culture maintenance capabilities were evaluated. The computer program "Supervisor," written in Turbo Pascal, consisted of a series of functions and procedures integrated through a core program consisting of a: 1) stack; 2) bubble sort routine; and 3) supervisor procedure. The program controlled the daily routine procedures including harvesting, feeding, monitoring and a semimonthly disinfection process. Data received from the monitoring devices were used by the computer for decision making processes concerning changes in operation. In addition to reducing labor, continuous computer monitoring insured more reliable system operation.
The system operated successfully for five months, reliably producing Chlorella minutissima . For each harvesting event, the percent volume removed from each chamber depended on the solar cell reading recorded immediately before the harvest cycle began. Significant correlations between millivolts and algal biomass concentrations allowed the use of solar cells as a reliable and inexpensive method of culture density management. Kinetic studies using Chlorella minutissima resulted in a maximum biomass concentration of approximately 190 g/m³ and an average specific growth rate of 0.66/d. Experimental data combined with a first order computer analysis projected a daily harvest of 82 g/m³/d (dry weight) based on a 38% turnover rate, the average observed harvest rate for the three chambers.     

奶牛产酸乳诊治

由于营养供给不合理,导致的泌乳奶牛发生瘤胃酸中毒,而出现产酸乳现象。本研究通过营养调整,结合药物治疗法,有效地防止了奶牛产酸乳的现象。     

Nuclear acidic protein changes during differentiation in Physarum polycephalum

A class of acidic nuclear phosphoproteins has been isolated throughout the mitotic cycle and at two points during differentiation in the slime mold Physarum polycephalum. The electrophoretic profiles of these proteins are reproducible and unchanging throughout the mitotic cycle, but reproducible changes occur during differentiation. The proteins are rapidly synthesized after mitosis, and their molecular weights range from 34,000 to 88,000. The proteins rapidly incorporate [(32)P]orthophosphate, and the content of alkali-labile phosphate increases 20 percent during the period after DNA synthesis. The proteins comprise 6.5 percent by dry weight of nuclear material while the DNA comprises about 5.5 percent. These acidic nuclear proteins may have a role in control of gene activity.     

Local and landscape effects of agricultural intensification on Carabid community structure and weed seed predation in a perennial cropping system

Context

The effects of agricultural intensification on service-providing communities remain poorly studied in perennial cropping systems. However, such systems differ greatly from annual cropping systems in terms of spatio-temporal dynamics and levels of disturbance. Identifying how land use changes at different scales affect communities and ecosystem services in those habitats is of major importance.

Objectives

Our objectives were to examine the effects of local and landscape agricultural intensification on ground beetle community structure and weed seed predation services.

Methods

We examined the effects of local vegetation management and landscape context on ground beetle community structure and weed seed predation in 20 vineyards of southwestern France in 2013 and 2014. Vineyards were selected along a landscape complexity gradient and experienced different management of local vegetation.

Results

The activity-density of ground beetles decreased with increasing landscape complexity while species richness and evenness remained unchanged. Phytophagous and macropterous species dominated ground beetle communities. Seed predation was positively related to the activity-density of one species, Harpalus dimidiatus, and was not affected by local management or landscape context. We found that within-year temporal diversity in ground beetle assemblages increased with landscape complexity.

Conclusions

Our study shows that increasing the proportion of semi-natural habitats in vineyard landscapes enhances the temporal diversity of ground beetles. However, we also found that measures targeting specific species delivering biological control services are a reasonable strategy if we are to maximize natural pest control services such as weed seed regulation to support crop production and reduce agrochemical use.

     

Kemp's Ridley Sea Turtle Waste Characterization Study: Precursor to a Recirculating Holding System Design

The decreasing population of the endangered Kemp's ridley sea turtle ( Lepidochelys kempi ) has necessitated research into more cost effective captive nurseries. Captive nurseries are an attempt to increase the survival of the Kemp's ridley past the first year of life. Presently, Kemp's ridleys are reared in captivity at the Headstart rearing facility in Galveston, Texas. This facility consists of a labor intensive, flow-through system. Alternatively, recirculating systems permit development of inshore facilities with decreased labor and operating costs. This paper presents baseline excretion data necessary for designing filtration units required for water quality maintenance in recirculating holding systems. The total ammonia nitrogen excretion rate based on a 24 hour isolation period (fed) was fairly constant at 0.19 mg N/g-turtle-day, while the BOD₅ loading rate was highly variable, averaging nearly 0.50 mg O₂/g-turt1e-day. In addition, comparisons of filtered versus nonfiltered samples suggest that a suspended solids removal mechanism prior to the filtration unit would dramatically decrease BOD₅ and, thus, improve filter efficiency and increase its capacity.     

Performance of a commercial recirculating alligator production system employing a paddle-washed floating bead filter

A 2.83 m³ prototype paddle-washed bead filter for combined solids capture and biological filtration was successfully operated in a commercial recirculating alligator (Alligator mississippiensis) facility. The bead filter was originally designed and operated as a downflow filter but due to operational and water quality problems, it was reconfigured to operate in an upflow mode. Water quality conditions and filter performance improved dramatically, with the upflow bead filter capable of handling the equivalent loading of 10.3 kg m⁻³ beads per day of 40% protein feed, despite oxygen limitations and hydraulic problems associated with the retrofitted alligator system.     

Nutritional Properties of the Marine Rotifer Brachionus plicatilis Fed the Freshwater Microalgae Selenastrum capricornutum

This study examined the effects of storage time on the fatty acid composition of freshwater Selenastrum capricornutum algal paste under 4 C refrigeration, the fatty acid composition of rotifers fed the fresh and stored algal paste, and the toxicological properties of the algal paste. Microalgae were produced in a hydraulically integrated serial turbidostat algal reactor (HIS-TAR), harvested as a paste, refrigerated and analyzed every 2 wk. Fresh Selenastrum capricornutum paste had almost three times greater concentration of unsaturated fatty acids than saturated fatty acids. Over 50% of the unsaturated fatty acids were made up of n-3 and n-6 fatty acids. Total unsaturated, n-3 group and n-6 group fatty acids decreased ( P 0.05) during storage, including the nutritionally important fatty acids (C20:4n6, C20:5n3, C22: 6n3). Rotifers fed 2– and 4-wk-old algal paste had a significantly lower ( P 0.05) total unsaturated fatty acid percentage and significantly greater ( P 0.05) total saturated fatty acids than those fed fresh algae. There were no significant changes in the n-6 group fatty acid level in the 4-wk-old paste feeding study or for the n-3 or n-6 groups in the 2-wk-old paste feeding study as compared to fresh algae. The levels of the three nutritionally important fatty acids (C20:4n6, C20:5n3, C22:6n3) did not differ between rotifers fed fresh and stored algae. Stored algae did not present toxicity to rotifers and Daphnia at the normal feeding concentration. These results indicated that the use of refrigerated freshwater algal paste for production of rotifers results in live feed with adequate nutritional properties for marine larviculture. This could eliminate the costs associated with production of marine algae, which could be replaced with freshwater algae, and may provide an alternative to cryopreservation.