Flight speeds of two seabirds: a test of Norberg's hypothesis

Norberg suggested that birds should increase their flight speed when rearing chicks in order to maximize chick energy intake by reducing commuting time. We measured the incubation and chick-rearing flight speeds of a medium-range (Brünnich's Guillemot Uria lomvia ) and long-range (Northern Fulmar Fulmarus glacialis ) forager near the Prince Leopold Island colony, Nunavut, Canada. The mean flight speed for the long-range forager was significantly higher during chick-rearing than during incubation. The medium-range forager showed no difference in mean flight speed during the two periods. We suggest that because petrels fly close to their minimum power velocity and have a low wing-loading, whereas alcids fly close to their maximum range velocity and have a high wing-loading, petrels have a greater ability than alcids to alter their flight speed according to changes in the demands of different breeding stages. Consequently, whereas Northern Fulmars adapt to the additional cost of chick-rearing partially by altering flight speed, Brünnich's Guillemots can only do so by reducing mass.     

A simple method for studying whole sections of rice grain

We developed a new and simple method to collect sections of a whole brown rice kernel for investigation of histological properties. A single kernel of rice was dehydrated through a graded ethanol series, transferred to xylene, and embedded in paraffin. During sectioning of the blocks using a rotary microtome, we used a special adhesive tape to collect and place the sections on slides so they remained flat. The use of the adhesive tape technique combined with autofluorescence characteristics allowed us to visualize cell walls throughout an entire longitudinal or transverse section of a whole rice kernel. We obtained scanning electron microscopy images of the sections to determine section quality.     

Thermal adaptation of Arctic charr: experimental studies of growth in eleven charr populations from Sweden, Norway and Britain

1. Experimental growth data for Arctic charr (Salvelinus alpinus L.), all fed on excess rations, from 11 European watercourses between 54 and 70°N were analysed and fitted to a new general growth model for fish. The model was validated by comparing its predictions with the growth rate of charr in the wild. 2. Growth performance varied among populations, mainly because of variation in the maximum growth potential, whereas the thermal response curves were similar. The estimated lower and upper temperatures for growth varied between ?1.7 to 5.3 and 20.8–23.2 °C, respectively, while maximum growth occurred between 14.4 and 17.2 °C. 3. There was no geographical or climatic trend in growth performance among populations and therefore no indication of thermal adaptation. The growth potential of charr from different populations correlated positively with fish body length at maturity and maximum weight in the wild. Charr from populations including large piscivorous fish had higher growth rates under standardised conditions than those from populations feeding on zoobenthos or zooplankton. Therefore, the adaptive variation in growth potential was related to life‐history characteristics and diet, rather than to thermal conditions.     

Life cycle assessment of native plants and marginal lands for bioenergy agriculture in Kentucky as a model for south-eastern USA

The Brookings Institute analysis rate both Lexington and Louisville, Kentucky (USA) as two of the nation's largest carbon emitters. This high carbon footprint is largely due to the fact that 95% of electricity is produced from coal. Kentucky has limited options for electric power production from low carbon sources such as solar, wind, geothermal, and hydroelectric. Other states (TN, IN, OH, WV, and IL) in this region are similarly limited in renewable energy capacity. Bioenergy agriculture could account for a proportion of renewable energy needs, but to what extent is unclear. Herein, we found that abandoned agricultural land, not including land that is in fallow or crop rotation, aquatic ecosystems, nor plant-life that had passed through secondary ecological succession totaled 1.9 Mha and abandoned mine-land totaled 0.3 Mha, which combined accounted for 21% of Kentucky's land mass. A life cycle assessment was performed based on local yield and agronomic data for native grass bioenergy agriculture. These data showed that utilizing Kentucky's marginal land to grow native C ₄ grasses for cellulosic ethanol and bioelectricity may account for up to 13.3% and 17.2% of the states 2 trillion MJ energy consumption and reduce green house gas emissions by 68% relative to gasoline.     

Initial verification of the resistance management strategy for Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) in Australia

Shortly after the initial detection of western flower thrips (WFT), Frankiniella occidentalis (Pergande), in Australia during 1993 a resistance management strategy based on the alternation of chemical groups was implemented. This study aimed to verify this strategy by field testing α-cypermethrin against WFT with and without chemical alternation. Up to 114 times α-cypermethrin resistance (at LC50) was detected and resistance increased with and without chemical alternation; however, chemical alternation did significantly reduce numbers of thrips compared with a nonalternation strategy. Resistance has the potential to undermine the sustainable use of those chemicals to which there is no current detectable resistance. Consequently, chemicals with a high frequency and level of resistance against WFT need to be identified through monitoring and quickly eliminated from WFT chemical control recommendations.     

A comparative study of three air-lift samplers used for sampling benthic macro-invertebrates in rivers

SUMMARY. From 16 air-lift samplers described in the literature, three were selected for operation from a small boat: Mackey, Pearson et al. and Verollet & Tachet samplers. Random samples (number of sampling units n= 10) were taken in a large tank with a known number of dried peas, representing invertebrates, amongst stones of uniform size. Separate experiments were performed with three sizes of stones (modal sizes 2–4, 16–20 and 32–36 mm). Stratified-random samples (usually n= 10) were taken in rivers at lour sites with modal particle sizes of < 0.1 2–4. 32–128 and 64–128 mm. The samplers were compared with a Ponar grab in the tank experiments and the field, and with a Naturalist's dredge in the field. Rates of pumping at different air-flows were established for each sampler. Water-How increased with increasing air-How and increasing submergence of the riser-pipe. The Mackey sampler achieved the highest water-flow and lifted more substratum and larger stones (64–128 mm) than the other samplers. The Verollet & Tachet sampler had the lowest pumping rate and failed to lift stones > 8 mm long, whilst the Pearson et al. sampler, with an intermediate performance, lifted mud and stones < 32 mm long. In the tank experiments, the area from which the Mackey and Pearson et al. samplers collected peas varied with air-flow, operating time and type of substratum. The Maekey sampler over-sampled and the Pearson et al. sampler usually under-sampled their respective sampling areas, except the latter sampler at high air-flows gave approximately quantitative results comparable to those of the Ponar grab for peas on the surface of stones 16–20 mm. No sampler collected much at a depth of 3 cm on larger stones (32–36 mm), and the Verollet & Tachet sampler failed completely on all substrata. In field trials, the Mackey and Pearson et al. samplers provided good qualitative samples except on large stones (32–128mm). The Verollet & Tachet sampler lifted little material. The relative abundance of taxa often differed between samplers. Estimates of the number of invertebrates per m² differed widely between samplers except for the Pearson et al. and Ponar grab which gave similar quantitative results at three sites. Values were very low for the Verollet & Tachet sampler and Naturalist's dredge and always very high for the Mackey sampler which often grossly over-sampled its sampling area. Therefore, these three samplers cannot be considered as quantitative. The relationship between the variances and the means of samples of peas in the tank and most invertebrates in the field followed a power law with values of the exponent b in the range 1.13–2.51. The present study completes the evaluation of 14 samplers used to sample benthic macro-invertebrates in deep rivers, and the more important conclusions from the comparative studies of seven grabs, four dredges and three air-lift samplers are summarized in a table.     

Predicting the spatial dominance of phytoplankton in a light limited and incompletely mixed eutrophic water column using the PROTECH model

1. A phytoplankton community model [Phytoplankton RespOnses To Environmental CHange (PROTECH)] was used to examine the effect of a wide range of varied light intensities and mixed depths upon simulated phytoplankton populations. Two different column lengths of the simulated water body were examined (the upper 5 m and the whole 14.5 m water column) for each scenario.
2. The hypotheses tested were that: (i) under low light intensity and/or deep mixing the simulated community will be dominated by a phytoplankter with a low critical light intensity; (ii) at high light intensity and shallow mixing the simulated community will be dominated by small, fast-growing phytoplankters; (iii) under all conditions, except deep mixing, the largest proportion of phytoplankton biomass will be found near the surface.
3. It was found under most conditions that, although there was a bloom in the upper column (dominated by algae such as Chlorella , Ceratium or Rhodomonas ), the largest phytoplankton biomass in the water column was located 9 m below the surface and consisted of solely Asterionella . This bloom was missed by the 5-m samples. Thus, using the whole column sample lengths, hypothesis (i) was not rejected but hypotheses (ii) and (iii) were refuted.
4. The inclusion of specific movement characteristics of phytoplankton in the model allowed the possibility of the dominance of multiple spaces within the water column and should be included in any model-based investigation of this topic. Further, the results from the model suggest that a reduced depth of mixing creates greater environmental heterogeneity, allowing more species to persist.     

Interstitial Protozoa and Algae of Louisiana Salt Marshes

SYNOPSIS. The majority of Louisiana salt marshes consists of stagnant pools among a vegetation of Spartina spp. and Distichlis spicata. The sediments constitute a "sulphide biome,'with Eh values reaching to –350 mV. The 200 interstitial ciliate species had definite stratification. Generally, algivores and omnivores occurred in the upper, and bactivores in the lower layers of the sediments. Compaction of particles prevented the flexible and large ciliates from inhabiting the lower layers, while Eh below –200 mV limited the distribution of some species but favored certain bactivores. The pH/Eh range and the abundance of nutrients in the sulfide biome provide habitable conditions for all the major groups of microflora. These, in turn, support nutritionally diverse predatory ciliate populations.     

Rates of gastric evacuation in brown trout, Salmo trutta L.

Brown trout of similar length and weight were fed a standard meal which contained a known number of food organisms of the same size-group and taxon (seven taxa were used). The weight of digestible organic matter in a trout stomach decreased exponentially with time. i.e. at a constant relative rate. At a particular water temperature, the food organisms were either evacuated from the stomach at similar rates (Group 1: Gammarus pulex, Baetis rhodani, Chironomidae, Oligochaetes) or at progressively slower rates (Group 2: Protonemura meyeri, Hydropsyche spp., Tenebrio molitor). Rates of gastric evacuation were not significantly different for food organisms of different size groups of the same taxon, or for different sized meals, or for different sizes of trout (range 20–30 cm), or for mixed and multiple meals (three meals over 16 h). Times are given for the gastric evacuation of 50%, 75%, 90% and 99% of the digestible organic matter in a meal. Starvation periods of 1, 2, 3,4 and 5 days prior to feeding did not affect evacuation rates. The rates were slightly, but not significantly, slower for starvation periods of 6 and 7 days, and were often significantly slower for starvation periods of 10, 15 and 20 days. Evacuation rates increased exponentially with increasing water temperature. It was possible to estimate both the rate and time for the gastric evacuation of different meals at water temperatures between 3–8°C and 19·1°C.