ABSTRACT1. The last remaining population of Margaritifera margaritifera in the Our River (Luxembourg, Europe) has come close to extinction. It consists predominantly of adult animals and will disappear within a few years without assistance. Juvenile mussels cannot survive in the river bed interstices, which are clogged by fine sediments, and rearing methods are needed to help them through this critical period.2. The objectives of this study were to elucidate the best rearing conditions for juvenile mussels with respect to the food type and density of individuals in order to breed them in the laboratory to a size at which survival in the river is likely.3. Different food mixtures (combinations of algae, detritus and crushed red bloodworms) were fed to juvenile mussels in plastic boxes containing 500 mL of river water during a period of 110 days. To understand fluctuations in the concentrations of nitrate, nitrite and ammonium between water exchanges, these ions were analysed over a period of 8 days.4. The best rearing results were achieved with a combination of detritus and algae. This treatment resulted in a growth rate of 189% (up to 1.13 mm (SD ±0.30) per box) with a survival rate of 80% (101 dead mussels (SD ±163.71) per box). The optimum number of mussels per box was 200. When detritus was added to the boxes, levels of nitrite and ammonium were reduced by more than 50% compared with the initial value within 8 days. Without detritus, ion concentrations increased noticeably (ammonium >50%, nitrite >150%), probably explaining higher mortality rates.5. Juvenile mussels have food reserves for less than 8 days after excystment and need additional food as soon as possible after dropping from the host fish.6. Juvenile mussels showed the most favourable survival rate and growth rate if fed with a mixture of algae and detritus. Detritus functions not only as a food source but also as a biologically active compound which reduces harmful ions such as ammonium and nitrite in the boxes.

This work demonstrates the capabilities of nanoscale secondary-ion mass spectrometry, using the Cameca NanoSIMS50 ion microprobe, to detect and image the copper-ion distribution in microalgal cells exposed to nanomolar and micromolar copper concentrations. In parallel to 63 Cu − secondary-ion maps, images of 12 C −

Freshwater pearl mussel (Margaritifera margaritifera L.) is an endangered species. Rearing in captivity for eventual release is one possible method of increasing the likelihood of persistence in different rivers. As rearing is a time‐consuming procedure, knowledge about conditions that increase survival and growth rates and decrease the period of the parasitic stage would be advantageous. Experiments with two excystment periods (one preterm in January, induced by artificially raising the water temperature, and a natural one in May) were performed, and the growth and survival rates of juvenile mussels were determined. Furthermore, meristic parameters of the host fish (brown trout, Salmo trutta) infested with glochidia in August the year before were investigated before and after both juvenile collection periods. In January the mean intensity was 151.5 glochidia per fish (±260.6) and 80% of host fish were infested. In May, the mean intensity was 142.7 glochidia per fish (±177.0) with 30% of fish infested with glochidia. Although the condition factors of the fish decreased during the experiments to 0.8 ± 0.1 (January) and 0.7 ± 0.2 (May), no apparent influence on the growth or survival rate of the juvenile mussels was obvious. The output of juvenile mussels was higher in the January excystment period (2854 compared with 2310). During both excystment periods, the length of the freshly excysted juveniles increased slightly from the first to the last day of collection. Mussels excysted with a mean length of 0.32–0.33 mm (at the beginning of the excystment period) and 0.38 mm (at the end). Individuals collected after the first few days of the January excystment period were the most suitable for culture. Growth up to a minimum of 1 mm in 110 days and a survival rate of 62–98% were observed. Juvenile survival from the May excystment period was lower (7–38%) presumably owing to poor water quality in the river. Copyright © 2014 John Wiley & Sons, Ltd.

Aims:  NanoSIMS (secondary ion mass spectrometry) is a powerful technique for mapping the elemental composition of a variety of small‐scale samples (e.g. in Material Research, Cosmochemistry and Geology). However, its analytical features are making it also valuable to address biological questions. We demonstrate the ability of the NanoSIMS 50 to map elements at subcellular lateral resolution (approx. 50 nm) within cyanobacteria (Anabaena sp. and Cylindrospermum alatosporum) and its feasibility to investigate the uptake of bromine‐containing substances (NaBr and deltamethrin). Methods and Results:  Elemental maps of O, N, P and S were obtained from semi‐thin sections of different cell types (chemically fixed and resin‐embedded heterocysts, akinetes and vegetative cells). NanoSIMS enabled the detection of various characteristic cell sub‐structures and inclusions. A homogenous bromine distribution was detected following NaBr and deltamethrin exposure, at Br‐concentrations of 0·05, 0·5 (NaBr) and 0·0025 mmol l−1 (deltamethrin). Conclusions:  NanoSIMS allowed study of the mapping of common elements in cyanobacterial cells and the uptake of NaBr and deltamethrin. Significance and Impact of the Study:  These results highlight the potential usefulness of NanoSIMS analysis for tracking elements within cell structures at the nanoscale and the ability to detect marker elements of xenobiotic compounds within exposed organisms.

a Poplar (Populus) species can relatively accumulate high concentrations of heavy metals such as cadmium and zinc in their aboveground tissues. Cd accumulation in poplar is 30 times higher as compared to other woody species. Zn concentrations in leaves ranged from 200 to 1000 mg kg −1 dry weight (DW) and Cd concentrations from 10 to 70 mg kg −1 DW on metal polluted sites. These plants possess effective mechanisms for heavy metal translocation into aerial parts. However cellular localization of zinc and cadmium is still unknown in these species. In order to elucidate the precise localisation of these elements, leaves of poplar (Populus deltoides cv. Lena) was grown on metal polluted soil and analysed by SIMS. Using primary gallium source (FIB) mounted on IMS-6f, it was possible to performed secondary ions positives images with a lateral resolution above to 100 nm. In this study, SIMS analysis has been performed on cross section of leaves. Results were compared with global measurement performed by ICP-AES on reference sample (no contaminated) and poplar exposed to metals. Elemental maps of cadmium and zinc were obtained which revealed the high concentrations of metals in both the mesophyll and in the epidermal cell layer.