Significance of food type for growth of ephyrae Aurelia aurita (Scyphozoa)

We studied growth of newly released Aurelia aurita ephyra larvae fed five different food types, including a large-sized copepod, a phytoflagellate, and suspended POM (particulate organic matter) made from bivalve meat. Experiments were run at saturated food concentration in two different temperatures over 10 days. The effect of small differences in temperature was inconsistent and interacted with the effect of food type, which, in turn, was highly significant. A low average growth rate (4-9% day^-1) was shown when feeding on the large-sized copepod Calanus finmarchicus (80 µg AFDW individual^-1), in spite of an extremely high daily ration of up to 1500% of body AFDW. When feeding on the cryptophyte Rhodomonas baltica (ca. 8 µm cell diameter), the ephyrae showed an average growth rate over the 10 day experiment of 7-11%, but with a considerably higher growth rate during the first days. Suspended POM generated an average growth rate of 7-9% day^-1, whereas fresh bivalve meat, manually placed into the stomach of the ephyra, gave an average growth rate of 12-14% day^-1. Artemia nauplii (ca. 3 µg AFDW individual^-1), used as a general reference, resulted in higher growth rates than any of the other food types (17-31% day^-1). We conclude that A. aurita ephyrae can capture and feed on phytoplankton, large copepods, and POM; that phytoplankton might be of nutritive significance early in development; and that the high quantity of large-sized copepods ingested is inefficiently converted to growth during early development. POM is a potential food source because of the ability of the ephyrae to encounter and ingest it, although concentration, size distribution, and nutritional composition of natural POM probably constrain its effect on growth.     

Safety-culture in a Norwegian shipping company

Problem: Although there has been considerable interest in safety culture and safety climate in many industries, little attention has been given to safety culture in one of the world's riskiest industries, shipping. Method: Using both self developed items and items from published research on safety culture, safety climate, and quality and management style, a 40-item safety culture questionnaire was developed. The questionnaire was distributed in a self-administered form to sailors onboard 20 vessels and to officers attending a seminar in Manila. A total of 349 questionnaires were collected (total response rate, 60%). Results, discussion and impact on industry: Principal component analysis (PCA) revealed 11 factors when the Kaiser eigenvalue rule was used and four factors when the scree test criterion was used. The factor structure in the material confirmed structures found in other industries. The relative importance of the factors from the factor analysis on “level of safety” measures was tested by canonical correlation analysis and regression analysis. The results confirmed previous research and showed that the most important factors were influential across industries. To determine weather differences existed between nationalities, occupations, and vessels the factors from the PCA was subjected to Multiple Discriminant Analysis. Significant differences between occupations, nations, and vessels were found on one or more of the factors from the PCA.     

Effect of an uncontrolled fire and the subsequent fire fight on the chemical composition of landfill leachate

Landfill leachates sampled during and after an accidental landfill fire were analysed and the levels of selected metals and chemical compounds compared to those occurring in the leachate under normal conditions. The fire at the landfill site was put out by excavation and cooling by use of water. The investigation during the fire and fire fight revealed a moderate increase in the level of nitrogen and also in pH and conductivity. Heavy metals and COD in the leachate showed considerably increased levels. In general, the determined variables appeared to normalise within one week after the fire was extinguished. It can be concluded that landfill fires extinguished by excavation may lead to elevated leachate levels of especially COD and heavy metals, but that this is only a short-term effect.     

Distribution of lipolytic,proteolytic, and amylolytic marine bacteria between the lipid film and the subsurface water

The biochemical activity of marine bacteria adhering to the lipid film at the airwater interface was compared to that of bacteria inhabiting the subsurface water. The bacteria were isolated from the two levels at 7 stations, all located along Brofjorden on the Swedish West Coast. The isolates were tested for their ability to attack lipids, proteins, and carbohydrates. A higher percentage of active isolates was found in samples from the subsurface water than from the surface film. The accumulation of marine bacteria at the air-water interface is not due to their biochemical activity.     

Quantitative determination of de-conjugated chrysene metabolites in fish bile by HPLC-fluorescence and GC--MS

Two analytical methods have been evaluated for quantitative determination of de-conjugated chrysene metabolites in fish bile. High performance liquid chromatography-fluorescence (HPLC-F) and gas chromatography-mass spectrometry (GC--MS) were compared regarding instrumental and overall limits of detection (LOD) as well as recoveries for the following nine chrysene compounds: 1-, 2,- 3-, 4- and 6-hydroxychrysene (1-, 2-, 3-, 4- and 6-OH-chr), 1,2-dihydroxy-1,2-dihydrochrysene (1,2-DHD-chr), 3,4-dihydroxy-3,4-dihydrochrysene (3,4-DHD-chr), 5,6-dihydroxy-5,6-dihydrochrysene (5,6-DHD-chr) and chrysene. Instrumental LODs were comparable for the two methods whereas the overall LOD was better for HPLC-F. Recoveries varied per chrysene compound for both HPLC-F (62-107%) and GC-MS (48-124%). In vivo formed chrysene metabolites were studied in the bile of Atlantic cod (Gadus morhua) exposed to chrysene (1 mg/kg) via intra-peritoneal (i.p.) and inter-muscular (i.m.) injection. Total amounts of chrysene metabolites were three times higher in i.p. compared to i.m. exposed cod bile, but the relative distribution of determined metabolites was very similar. 1,2-DHD-chr was the most prominent metabolite in de-conjugated bile and constituted more than 88% of the total chrysene metabolites. Additional chrysene metabolites formed were 3,4-DHD-chr and 1-, 2-, 3- and 4-OH-chr. K-region chrysene metabolites (oxidation at carbons 5 and 6) were not detected and seem to be a less favoured biotransformation route. The two methods were applied and evaluated for analysis of chrysene metabolites in two bile reference materials (BCR 720 and 721) and a limited number of field exposed cods.     

Review and assessment of models for predicting the migration of radionuclides from catchments

The present paper summarises the results of the review and assessment of models developed for predicting the migration of radionuclides from catchments to water bodies. The models were classified and evaluated according to their main methodological approaches. A retrospective analysis of the principles underpinning the model development in relation to experimental finding and results was carried out. It was demonstrated that most of the various conceptual approaches of different modellers can be integrated in a general, harmonised perspective supported by a variety of experimental evidences. Shortcomings and advantages of the models were discussed.     

Combustion of gasolines in premixed laminar flames European certified and California phase 2 reformulated gasoline

Two gasoline qualities, European unleaded certified gasoline (EUCG) and California phase 2 reformulated gasoline (P2 RFG), were analysed. EUCG contained about twice the amount of alkyl benzenes compared to P2 RFG and a large amount of cyclohexane. As a balance, P2 RFG contained higher amounts of isooctane and MTBE. The gasolines were burned in a premixed laminar flame burner at 1 atm and at about stoichiometric fuel/air ratio. The species profiles were measured using on-line GC/MS. About 40 compounds were be detected in the gasoline flames. The EUCG resulted in formation of more reactive and toxic compounds. The combustion profiles of the fuel components showed a similar slope, which suggests that the fuel components burn quite independently of each other. Ethene and propene were the dominating species produced from the two gasolines. Commonly, substantial amounts of higher alkenes were found. Combustion of P2 RFG produced higher amounts of isobutene, propene, propyne, propadiene and methanol compared to combustion of EUCG. The high amount of isobutene is reasonably a result of high concentration of isooctane and MTBE in the fuel. The high amount of methanol formed is probably due to the MTBE present in the gasoline. EUCG produced significantly higher amounts of 1,3-butadiene, which quite likely is formed from the cyclohexane in the fuel. The benzene profiles from both gasolines shows an almost constant level up to 800 microm from the burner surface; this is probably due to formation of benzene from alkyl benzenes.     

Consumers affect prey biomass and diversity through resource partitioning

Consumer presence and nutrient availability can have contrasting and interactive effects on plant diversity. In a factorial experiment, we manipulated two levels of nutrient supply and the presence of two moderately specialized grazers in different combinations (no grazers, two species in monoculture, and both in combination). We tested how nutrients and grazers regulated the biomass of marine coastal epiphytes and the diversity of algal assemblages, based on the prediction that the effect of consumers on prey diversity depends on productivity and consumer specialization. Nutrient enrichment increased the epiphytic load, while monocultures of single grazer species partly prevented epiphyte growth. However, only the presence of two species with complementary feeding preferences effectively prevented epiphyte overgrowth. The epiphytes comprised micro- and macroalgal species, and the diversity of these algal assemblages differed, depending on grazer identity. For the microalgae, diversity was reduced by nutrient addition when grazer control was inefficient, but not when specialist microalgal grazers were present. Macroalgal diversity was reduced in ambient water with specialist macroalgal grazers compared to the treatment with inefficient ones. These results indicate that grazer composition and productivity are crucial in determining whether consumer pressure will have a positive or negative effect on algal diversity.     

A comparison of taxon co-occurrence patterns for macro- and microorganisms

We examine co-occurrence patterns of microorganisms to evaluate community assembly "rules". We use methods previously applied to macroorganisms, both to evaluate their applicability to microorganisms and to allow comparison of co-occurrence patterns observed in microorganisms to those found in macroorganisms. We use a null model analysis of 124 incidence matrices from microbial communities, including bacteria, archaea, fungi, and algae, and we compare these results to previously published findings from a meta-analysis of almost 100 macroorganism data sets. We show that assemblages of microorganisms demonstrate nonrandom patterns of co-occurrence that are broadly similar to those found in assemblages of macroorganisms. These results suggest that some taxon co-occurrence patterns may be general characteristics of communities of organisms from all domains of life. We also find that co-occurrence in microbial communities does not vary among taxonomic groups or habitat types. However, we find that the degree of co-occurrence does vary among studies that use different methods to survey microbial communities. Finally, we discuss the potential effects of the undersampling of microbial communities on our results, as well as processes that may contribute to nonrandom patterns of co-occurrence in both macrobial and microbial communities such as competition, habitat filtering, historical effects, and neutral processes.     

Pre-dispersal seed predation: the role of fruit abortion and selective oviposition

Oviposition sites of phytophagous insects should correlate with plant traits that maximize survival of the progeny. Plants, on the other hand, should benefit from traits and developmental patterns that complicate oviposition decisions. In the antagonistic interaction between plant and pre-dispersal seed predator the time lag between egg laying and seed development may allow for abortion of fruits in plants, potentially reducing fitness loss through predation. We studied the perennial herb Lathvrus vernus and the beetle pre-dispersal seed predator Bruchus atomarius in Sweden to determine the fitness consequences of nonrandom fruit abortion in the plant and oviposition patterns of the beetle. The beetle had a sophisticated ability to locate fruits with high probability of retention, partly by fruit position and phenology but also by some additional unidentified cue. Mortality of eggs was density dependent, but still the egg-laying pattern was clumped. We found no defensive strategy in the plant; instead the predictable fruit abortion pattern was associated with decreased plant fitness. We discuss how interactions may pose simultaneous selection pressures on plant and insect traits and how life history traits and other selective forces may shape the adaptive outcome of the interaction in plant and insect, respectively.