Growth and lipid class composition of the Arctic pelagic amphipod <Emphasis Type=Italic>Themisto libellula</Emphasis>

Carnivorous zooplankton is a key element to the energy transfer through the arctic food web, linking lipid rich herbivores to the top predators. We investigated the growth and lipid dynamic of the Arctic pelagic amphipod Themisto libellula in Kongsfjorden (Svalbard, 79°N) from May to October 2007. Additional samplings were performed in spring and summer 2006 and further north in Rijpfjorden (80°N), in September 2006 and 2007. In Kongsfjorden, the first free-swimming stages (3 mm) appeared early May and reached their adult length (25 mm), in October. During their first year, they grew according to a Von Bertalanffy model and most probably constituted a single cohort. Juveniles had the highest growth rate (0.19 mm day⁻¹) and revealed relatively low total lipid (TL) content (about 2.5% wet weight (WW)) with phospholipids as the major lipid class. Sub-adults showed a distinct decrease of growth rates which coincided with the increase of neutral lipid storage, reflecting a switch in energy allocation, from somatic growth to lipid storage. Indeed wax esters (WE) increased up to 48.5% TL on average in adults in 2006 while triacylglycerols (TAG) remained almost constant below 25.2% TL. The absence of lipid accumulation (in disproportion of the weight) in 2007 could be explained by a higher metabolism of T. libellula or preys of lower quality. In Rijpfjorden, adults in their second year continued accumulating lipid (up to 10% WW) with high and similar proportions of both lipid classes, WE and TAG. We highlighted that T. libellula exhibited a variable lipid metabolism along its life cycle depending on its physiological needs and environmental conditions.     

A challenge to the assumed generalizability of prediction and countermeasure for risky driving: different factors predict different risky driving behaviors

In road safety, it may be debated whether all risky behaviors are sufficiently similar to be explained by similar factors. The often assumed generalizability of the factors that influence risky driving behaviors has been inadequately tested. Study 1 (N=116) examined the role of demographic, personality and attitudinal factors in the prediction of a range of risky driving behaviors, for young drivers. Results illustrated that different driving behaviors were predicted by different factors (e.g., speeding was predicted by authority--rebellion, while drink driving was predicted by sensation seeking and optimism bias). Study 2 (N=127) examined the generalizability of these results to the general driving population. Study 1 results did not generalize. Predictive factors remained behavior-specific, but different predictor-behavior relationships were observed in the community sample. Overall, results suggest that future research and practice should focus on a multi-factor framework for specific risky driving behaviors, rather than assuming generalizability across behaviors and driving populations.     

Use of the digestive gland of the oyster Crassostrea rhizophorae (Guilding, 1828) as a bioindicator of Zn,Cd and Cu contamination in estuarine sediments (south-east Brazil)

This study demonstrates the accumulation of Zn, Cd and Cu in the digestive gland of the oyster Crassostrea rhizophorae in response to the contamination of sediments and discusses the potential use of this specific organ in monitoring metal contamination in tropical areas. Sediment and oyster samples were collected from coastal Rio de Janeiro sites with different levels of human impact: Sepetiba Bay, Guanabara Bay and the Paraty coast. Metal concentrations were measured using inductively coupled plasma optical emission spectrometry (ICP OES). Significant statistical differences (p<0.001; p<0.05) were observed for Zn and Cd concentrations in the digestive gland; the highest Zn concentrations were found at Sepetiba, followed by Guanabara and Paraty. The highest digestive gland Cd concentrations were found at Paraty, followed by Sepetiba and Guanabara. These concentrations were proportional to those found in the sediments. There was no significant difference (p>0.05) in Cu among the sampling sites. The highest digestive-gland Cu concentration was also found at Sepetiba, followed by Guanabara. The biosediment accumulation factor indicated a gradient of sediment contamination for Zn and Cd. The digestive gland of C. rhizophorae can be a potential indicator of trace metal contamination in sediments from tropical estuarine environments.     

Evaluating seasonal dynamics of bacterial communities in marine fish aquaculture: a preliminary study before applying phage therapy

The increasing problem of antibiotic resistance in common pathogenic bacteria and the concern about the spreading of antibiotics in the environment bring the need to find new methods to control fish pathogens. Phage therapy represents a potential alternative to antibiotics, but its use in aquaculture requires a detailed understanding of bacterial communities, namely of fish pathogenic bacteria. Therefore, in this study the seasonal dynamics of the overall bacterial communities, microbiological water quality and disease-causing bacteria were followed in a marine aquaculture system of Ria de Aveiro (Portugal). Analysis of the bacterial diversity of the water samples by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments indicates that the bacterial community structure varied seasonally, showing a higher complexity during the warm season. The diversity of the main fish pathogenic bacteria, assessed by DGGE targeting the Vibrio genus, showed lower seasonal variation, with new dominating populations appearing mainly in the spring. Bacterial indicators, faecal coliforms and enterococci, enumerated by the filter-membrane method, also varied seasonally. The fluorescent in situ hybridization (FISH) results showed that the specific groups of bacteria varied during the study period and that the non-indigenous Enterobactereaceae family was the most abundant group followed by Vibrio and Aeromonas. The seasonal variation detected in terms of density and structure of total and pathogenic bacterial communities demonstrates the need for a careful monitoring of water through the year in order to select the suitable phages to inactivate fish pathogenic bacteria. The spring season seems to be the critical time period when phage therapy should be applied.     

Bioassays for the evaluation of reclaimed opencast coal mining areas

Environmental Science and Pollution Research - This study aimed to use bioassays (single and multispecies) with organisms from different trophic levels to assess soil quality in reclaimed coal...     

Correlating pH and Swelling Degree Parameters to Understand the Sorption and Desorption Process of Diquat Herbicide from Nanocomposites Based on Polysaccharide and Clinoptilolite

Journal of Polymers and the Environment - Zeolite-based nanocomposites have become an efficient option for application in herbicide removal and controlled release systems. Our group previously...     

Biochemical methane potential of food and garden waste co-digestion with variation in solid content and inoculum:substrate ratio

Journal of Material Cycles and Waste Management - The objective of this study is to evaluate the influence of the addition of garden waste (GW) on the performance of food waste (FW) anaerobic...     

Settled,symbiotic, then sexually mature: adaptive developmental anatomy in the deep-sea,chemosymbiotic mussel Idas modiolaeformis

The Bathymodiolinae are pervasive in reducing environments in the deep sea, yet data on post-larval and juvenile development and on the process of symbiont acquisition remain elusive. To understand how these opportunistic metazoans survive in ephemeral reducing habitats, individuals of the small bathymodiolin, Idas modiolaeformis, were examined histologically to trace their reproductive development, and with fluorescence and transmission electron microscopy to identify patterns of infection by their environmentally acquired bacterial symbionts. A size series of these mussels was retrieved from larval colonisation devices containing vegetative substrates, deployed for 51 weeks (November 2006–2007) in the central ‘Pockmarks’ region (site 2A) of the Nile deep-sea fan in the eastern Mediterranean (NDSF), a zone where methane seepage can occur (N 32° 31.97, E 30° 21.18, 1,693 m deep). Developmental patterns of germ cell migration, size at first maturity, and symbiont acquisition and localisation are presented for the post-larva to adult transition. The smallest mature adult was a male with shell length (SL) 2.35 mm. All larger individuals in the series were male (maximum SL 6.54 mm). Based on the absence of bacterial signals, plantigrades were asymbiotic, indicating strict heterotrophy in larvae and early post-larvae. During the early stages of dissoconch deposition, extracellular symbiont infection was non-specific. This was followed by increasing specificity on non-ciliated gill epithelia in adults. These observations on early development in I. modiolaeformis represent evolutionary adaptations to their ephemeral, reducing habitats.