Androgenic and antiandrogenic activities in water and sediment samples from the river Lambro, Italy, detected by yeast androgen screen and chemical analyses

The river Lambro is the most polluted tributary of the river Po in North Italy and was chosen as a representative water course discharging industrialized areas. Water and sediment samples of the river Lambro were investigated regarding the presence of endocrine disrupting compounds. A combined procedure was used consisting of solid-phase extraction and HPLC based fractionation of samples, of screening for (anti)androgenic activity using the yeast androgen screen (YAS) and of chemical analysis using HPLC-MS/MS and GC-MS. Androgenic and antiandrogenic activities were found in specific fractions of the water and sediment while the total extracts showed antiandrogenic activity only. The chemical analysis of the fractions and total extracts with antiandrogenic activities revealed the presence of compounds with suspected antiandrogenic potency such as bisphenol A, iprodione, nonylphenol, p,p'-DDE and tert-octylphenol but other unknown compounds contributed mainly to the observed antiandrogenic activities. The antiandrogenic load of the river Lambro ranged between 1.34 and 17.1 microM flutamide-equivalents and may pose a risk to aquatic environments. Future screenings for EDC in the environment that have the potential to interfere with reproduction of aquatic organisms should be extended to different modes of actions including (anti)androgenic ones.     

Life cycle of the rhizostome jellyfish <Emphasis Type="Italic">Rhizostoma octopus</Emphasis> (L.) (Scyphozoa,Rhizostomeae), with studies on cnidocysts and statoliths

Stages in the life cycle of the rhizostome jellyfish Rhizostoma octopus (L.) were reared in the laboratory from planula to young medusa and are described here. Fertilization of eggs was external, and planulae, 110–150 μm in length, appeared after 2 days. These settled and developed into the scyphistoma stage. Scyphistomae reached a maximum size of 2.3 mm, bore up to 24 tentacles, and had a large manubrium. Polyps reproduced asexually mainly by podocysts. Strobilation was induced by temperature change. Each strobila released up to five ephyrae that measured 2.7–5.8 mm in diameter at liberation. During transformation from newly released ephyra to young medusa, velar lappets appeared and increased in number, the manubrium developed eight branched oral arms with epaulettes, and a marginal gastric network arose. Only one cnidocyst type, the “a”-atrichous haploneme, was present in the planula. In addition to these haplonemes, heterotrichous microbasic euryteles were observed in polyps, ephyrae, and medusae. Statoliths, located in the rhopalia, had a characteristic compact shape. These sensory structures increased in number and size with the growth of ephyrae and medusae.     

Thermoluminescence as a tool for monitoring ozone-stressed plants

The effect of ozone (6 h, various concentrations from 0 to 350 ppb) on barley (Hordeum vulgare L., cv. Bomi) and tomato (Lycopersicon esculentum L., cv. Yellow Cherry) leaves was investigated in parallel by thermoluminescence (TL) and fluorescence (FL) methods. Several significant changes were found in TL glow curves measured after excitation by one single turnover flash at +2 degree C in the temperature range from 2 to 170 degree C immediately after ozone exposure. Contrary to TL, ozone induced only negligible changes in FL parameters F0, FM and Fv/FM. Measurements done 24 h after ozone exposure showed partial recovery of ozone-induced changes. The extent of recovery was not the same in different parts of TL curves. Fluorescence parameters were not significantly changed. The results demonstrate that TL parameters are more sensitive to ozone than conventially used FL parameters F0, FM and Fv/FM. Moreover, TL measurements seem to give information not only about the PSII electron transport, but also about the extent of oxidative damage and membrane lipid peroxidation. It is concluded, that TL can be a highly informative tool for monitoring the impact of ozone on plants.     

New evidence for habitat-specific selection in Wadden Sea Zostera marina populations revealed by genome scanning using SNP and microsatellite markers

Eelgrass Zostera marina is an ecosystem-engineering species of outstanding importance for coastal soft sediment habitats that lives in widely diverging habitats. Our first goal was to detect divergent selection and habitat adaptation at the molecular genetic level; hence, we compared three pairs of permanently submerged versus intertidal populations using genome scans, a genetic marker-based approach. Three different statistical approaches for outlier identification revealed divergent selection at 6 loci among 46 markers (6 SNPs, 29 EST microsatellites and 11 anonymous microsatellites). These outlier loci were repeatedly detected in parallel habitat comparisons, suggesting the influence of habitat-specific selection. A second goal was to test the consistency of the general genome scan approach by doubling the number of gene-linked microsatellites and adding single nucleotide polymorphism (SNP) loci, a novel marker type for seagrasses, compared to a previous study. Reassuringly, results with respect to selection were consistent among most marker loci. Functionally interesting marker loci were linked to genes involved in osmoregulation and water balance, suggesting different osmotic stress, and reproductive processes (seed maturation), pointing to different life history strategies. The identified outlier loci are valuable candidates for further investigation into the genetic basis of natural selection.     

The trophic link between squid and the emperor penguin <Emphasis Type="Italic">Aptenodytes forsteri</Emphasis> at Pointe Géologie,Antarctica

Cephalopod beaks retrieved from stomachs of dead emperor penguin chicks at Pointe Géologie, Terre Adélie, provide information on taxonomic and size composition of the penguin’s squid diet, on the trophic range of the squid species preyed upon and on the fractional trophic impact of the penguin on the whole food web. Emperor penguins prey upon four squid species (Psychroteuthis glacialis, Kondakovia longimana, Gonatus antarcticus, Alluroteuthis antarcticus) and do not take squid larger than 480 mm mantle length. Larger squid live either below the penguin’s diving range or are beyond its handling capacity. Nitrogen stable isotope ratios indicate that squids cover a range of about two trophic levels (2.5–8‰ δ¹⁵N). The impact of the emperor penguin, however, concentrates on the upper part of this range, about 68% of its squid prey being >6‰ δ¹⁵N. The principal components of the emperor’s diet, fish, krill and squid, differ distinctly in average trophic level. Consequently the trophic position of the emperor penguin changes accordingly with diet composition and may differ by almost one trophic level between different emperor penguin colonies.     

Screening volatile organic compounds (VOCs) emissions from five marine phytoplankton species by head space gas chromatography/mass spectrometry (HS-GC/MS)

Five marine cosmopolitan phytoplankton species namely; Calcidiscus leptoporus, Emiliania huxleyi, Phaeodactylum tricornutum, Chaetoceros neogracilis and Dunaliella tertiolecta were screened for emissions of selected VOCs using head space gas chromatography/mass spectrometry (HS-GC/MS) in single ion mode. The VOCs investigated included isoprene and various halogenated compounds. Among the different algae groups, the two diatoms Ch. neogracilis and P. tricornutum were the strongest emitters of methyl bromide (CH3Br), and Ch. neogracilis was the strongest emitter of isoprene. Furthermore, we present evidence that several chlorinated organic compounds, normally considered as anthropogenic, can be produced from marine phytoplankton (namely chloroform, dichloromethane, trichloroethylene, tetrachloroethylene, chlorobenzene and dichlorobenzene).     

Mangrove recruitment after forest disturbance is facilitated by herbaceous species in the Caribbean.

Plant communities along tropical coastlines are often affected by natural and human disturbances, but little is known about factors influencing recovery. We focused on mangrove forests, which are among the most threatened ecosystems globally, to examine how facilitation by herbaceous vegetation might improve forest restoration after disturbance. We specifically investigated whether recovery of mangrove forests in harsh environments is accelerated by nurse plants and whether the beneficial effects are species-specific. Quantification of standardized effects allowed comparisons across performance parameters and over time for: (1) net effect of each herbaceous species on mangrove survival and growth, (2) effects of pre- and post-establishment factors associated with each herbaceous species, and (3) need for artificial planting to enhance growth or survival of mangrove seedlings. Mangrove recruitment in a clear-cut forest in Belize was accelerated by the presence of Sesuvium portulacastrum (succulent forb) and Distichlis spicata (grass), two coastal species common throughout the Caribbean region. The net effect of herbaceous vegetation was positive, but the magnitude of effects on mangrove survival and growth differed by species. Because of differences in their vegetative structure and other features, species effects on mangroves also varied by mechanism: (1) trapping of dispersing propagules (both species), (2) structural support of the seedling (Distichlis), and/or (3) promotion of survival (Sesuviumn) or growth (Distichlis) through amelioration of soil conditions (temperature, aeration). Artificial planting had a stronger positive effect on mangrove survival than did edaphic conditions, but planting enhanced mangrove growth more in Sesuvium than in Distichlis patches. Our study indicates that beneficial species might be selected based on features that provide multiple positive effects and that species comparisons may be improved using standardized effects. Our findings are not only relevant to the coastal environments found in the Caribbean region, but our assessment methods may be useful for developing site-specific information to restore disturbed mangrove forests worldwide, especially given the large pool of mangrove associates (>45 genera) available for screening.     

Environmental signals: synthetic humic substances act as xeno-estrogen and affect the thyroid system of Xenopus laevis

According to outdated paradigms humic substances (HS) are considered to be refractory or inert that do not directly interact with aquatic organisms. However, they are taken up and induce biotransformation activities and may act as hormone-like substances. In the present study, we tested whether HS can interfere with endocrine regulation in the amphibian Xenopus laevis. In order to exclude contamination with phyto-hormones, which may occur in environmental isolates, the artificial HS1500 was applied. The in vivo results showed that HS1500 causes significant estrogenic effects on X. laevis during its larval development and results of semi-quantitative RT-PCR revealed a marked increase of the estrogenic biomarker estrogen receptor mRNA (ER-mRNA). Furthermore, preliminary RT-PCR results showed that the thyroid-stimulating hormone (TSHbeta-mRNA) is enhanced after exposure to HS1500, indicating a weak adverse effect on T3/T4 availability. Hence, HS may have estrogenic and anti-thyroidal effects on aquatic animals, and therefore may influence the structure of aquatic communities and they may be considered environmental signaling chemicals.     

Life cycle of the jellyfish <Emphasis Type="Italic">Rhizostoma pulmo</Emphasis> (Scyphozoa: Rhizostomeae) and its distribution,seasonality and inter-annual variability along the Catalan coast and the Mar Menor (Spain,NW Mediterranean)

Rhizostoma pulmo is one of the most abundant scyphomedusae along the Mediterranean coasts. To understand changes in the population densities of the medusa stage and its relationship with the benthic stage, we describe all developmental stages from the life cycle of R. pulmo, from the scyphistoma stage to young medusae reared in the laboratory. Mature scyphistomae showed a mean total body length of 1.7 mm and the average tentacle number was 16. Asexual reproduction occurred by lateral budding, podocyst and pedalocyst production. Each strobila released up to 8 ephyrae that had a mean total body diameter of 3.5 mm. Moreover, we also present data on the temporal and spatial distribution of the species in the Catalan Sea and the coastal lagoon on Mar Menor (NW Mediterranean) during the years 2007–2009. In the Catalan Sea, the presence of adult R. pulmo was recorded as extended along the whole coast, but most of the observation was concentrated in the central area; the highest abundances were recorded during the months of July and August. The highest number of observations was detected in 2008 in coincidence with the inter-annual variation observed in the Mar Menor lagoon.