The effects of temperature,body size and growth rate on energy losses due to metabolism in early life stages of haddock (<Emphasis Type="Italic">Melanogrammus aeglefinus</Emphasis>)

Rates of routine respiration (R _R, μl O₂ fish⁻¹ h⁻¹) and total ammonia nitrogen excretion (E _R, μg NH₄–N + NH₃–N fish⁻¹ h⁻¹) were measured on larval and juvenile haddock (Melanogrammus aeglefinus) to ascertain how energy losses due to metabolism were influenced by temperature (T), dry body mass (M _D, mg) and specific growth rate (SGR, % per day). R _R and E _R increased with M _D according to y = a  · M _D ^b with b-values of 0.96, 0.98, 1.14, and 0.89, 0.78, 0.74, respectively, at 10, 7, and 4°C, respectively. Multiple regressions explained 98% of the variability in the combined effects of M _D and T on R _R and E _R in larval haddock: R _R = 0.97 · M _D ^0.98  · e^0.092 · T ; E _R = 0.06 · M _D ^0.79  · e^0.092 · T . In young juvenile (24–30 mm standard length) haddock, R _R tended to decline (P = 0.06) and E _R significantly declined (P = 0.02) with increasing SGR. O:N ratios significantly increased with increasing SGR suggesting that N was spared in relatively fast-growing individuals. Our results for young larval and juvenile haddock suggest: (1) nearly isometric scaling of R _R with increasing body size, (2) allometric scaling of E _R with increasing body size, (3) Q ₁₀ values of 2.5 for both R _R and E _R, (4) metabolic differences in substrate utilization between relatively fast- and slow-growing individuals, and (5) that rates of routine energy loss and growth were not positively related. The measurements in this study will provide robust parameter estimates for individual-based models that are currently being utilized to investigate how variability in climatic forcing influences the vital rates of early life stages of haddock. Our results also stress that inter-individual differences in rates of energy loss should not be overlooked as a factor influencing growth variability among individuals.     

A comparison of predicted and measured levels of runoff-related pesticide concentrations in small lowland streams on a landscape level

Short-term pollution events via runoff are typical of streams in agricultural areas. Existing runoff models that simulate pesticide loss from agricultural fields require extensive input of information. There is thus a need for a simple model that can predict runoff-related pesticide concentrations in many streams on a landscape level when only limited data are available. To validate such a model, the runoff-related pesticide load of 18 small lowland streams was predicted with an extended version of the model "simplified formula for indirect loadings caused by runoff" (available from the Organisation for Economic Cooperation and Development, OECD). The authors suggest that the model presented here is suitable for use in routine exposure assessment of pesticides on a landscape level, as all input data (soil, slope, precipitation, pesticide application) are readily available from public authorities or could be generated by simple regional flood hydrograph curves. The predicted concentrations were compared with measured concentrations obtained by runoff-triggered sampling. Fungicides, insecticides and herbicides were detected in 17 streams, with max. concentrations measuring up to 29.7 microg/l for the fungicide azoxystrobin and 0.3 microg/l for the insecticide parathion-ethyl. Herbicides were detected in 16 streams, with max. concentrations between 13.7 and 1.2 microg/l. The linear regression between the predicted and measured concentrations (log-values) shows significant correlations for the following pesticides: azoxystrobin: r2=0.43; p=0.03; epoxiconazole: r2=0.71; por=0.5 microg/l).     

Experimental tests of the information-center hypothesis with black vultures (Coragypsatratus) and turkey vultures (Cathartesaura)

In field tests of the information-center hypothesis (ICH) in south Texas with black vultures (Coragyps atratus) and turkey vultures (Cathartes aura), large carcasses were provided and kept under continuous observation. The use vultures made of these bait sites and their patterns of arrival were recorded to evaluate predictions derived from the ICH. Turkey vultures discovered most bait sites (30 of 31) first, but frequently were displaced from the food by later-arriving black vultures. This competitive exclusion by black vultures limited subsequent feeding opportunities for turkey vultures sufficiently that few (27%) returned on subsequent days to bait sites they had previously visited. I found no evidence that those turkey vultures that did return to bait sites acted as leaders for groups of naive birds and led them to bait sites – knowledgeable and naive turkey vultures did not arrive at bait sites together, and groups arriving at bait sites were not larger on subsequent days than on the first days carcasses were available. In contrast, a significantly larger percentage (47%) of knowledgeable black vultures returned to bait sites they had visited on previous days, and the first groups of black vultures arriving at bait sites on subsequent days were significantly larger than the equivalent groups on first days. Nine flocks of black vultures that arrived on subsequent days at bait sites before sunrise (which suggests the birds had commuted directly from a roost) contained knowledgeable birds, and two of these flocks contained both knowledgeable and naive individuals. Overall, 10 of 54 naive tagged black vultures (18.5%) arrived at bait sites under circumstances that suggested they had followed conspecifics to the food from a roost. However, most black vultures apparently found carcasses through independent search or by using local enhancement. Therefore, I conclude that while following from roosts to food sites is a strategy used by black vultures, at this study site it is one they use relatively infrequently. Received: 20 February 1997 / Accepted after revision: 28 June 1997     

Giardia and Cryptosporidium in pristine protected catchments in central eastern Australia

We report the first confirmed records of the pathogenic protozoa Giardia lamblia and Cryptosporidium parvum from small remote streams in pristine protected areas in Australia, beyond the reach of urban or agricultural contamination.     

A short-cut method for assessing absorbents for post-combustion carbon dioxide capture

A short-cut method for the estimation of the minimum regeneration energy and optimum solvent flow rate in post-combustion carbon dioxide capture by absorption is presented. It is developed for comparing solvents of which only little thermo-physical data is known. The closed absorber–desorber cycle is described by an equilibrium stage model (modified Kremser equation with discretized equilibrium curves). The method can be implemented in any mathematical toolbox or as stand-alone solution. The only required input is the solubility data at absorber and desorber conditions, the heat of absorption and heat capacities. The caloric data may be estimated. The method was applied to monoethanolamine (MEA) and two solvents from the EU-project CASTOR. Comparisons with experimental results from pilot-plant studies with MEA show that the method, despite its simplicity, gives reasonable results. The method should also be useful in other applications where absorbents, of which only little data is available, need to be screened.     

Nativ-basierte Grundöle für die Produktion von Kühlschmierstoffen

Aims and Scope

Compared to mineral oil products, cooling lubricants based on fatty acid esters have technological advantages. Moreover, they are more environmentally compatible and make a contribution to a sustainable economy. Nevertheless, they are rarely applied in practice, because of their comparably high price, that is based on raw-material and synthesis costs. Alternatives concerning raw-materials and synthesis pathways are considered and properties of resulting ester products are compared.

Methods

The investigations aimed at three fatty acid-2-ethyl-hexylesters that were synthesized in an enzymatic-catalytic routine based on peanut oil, suet, and waste edible fat and at esters that were conventionally produced from animal and plant fats and 2-ethyl-1-hexanol. Physical properties, fatty acid patterns, contents of free fatty acids, as well as oxidative and hydrolytic stabilities were determined. Thermolysis experiments were performed.

Results

The physical properties of the seven esters, density, viscosity, pourpoint, and flash point, were comparable and gave reason for the assumption, that the products could be used as basis oils in lubricant formulations. Hydrolysis stabilities of the esters were high and thermal stress did not point at high potential of hazardous compounds formation. Especially the enzymatic-catalytically produced esters showed deficits concerning oxidation stabilities and free fatty acid contents.

Outlook

For practice it will be necessary to define minimum qualities for raw-materials and resulting ester oils to be used as lubricant basis oils. Moreover, processes have to be developed, that yield high quality ester products from waste edible and animal fats without loosing the advantage of low-cost raw-materials by high production and refinement costs. Surely, one contribution is the further development of the energy-saving enzymtic alcoholysis for ester production.