Active role of the mucilage in the toxicity mechanism of the harmful benthic dinoflagellate Ostreopsis cf. ovata.

Ostreopsis cf. ovata is a harmful benthic dinoflagellate, widespread along most of the Mediterranean coasts. It produces a wide range of palytoxin-like compounds and variable amounts of mucus that may totally cover substrates, especially during the stationary phase of blooms. Studies on different aspects of the biology and ecology of Ostreopsis spp. are increasing, yet knowledge on toxicity mechanism is still limited. In particular, the potential active role of the mucilaginous matrix has not yet been shown, although when mass mortalities have occurred, organisms have been reported to be covered by the typical brownish mucilage. In order to better elucidate toxicity dependence on direct/indirect contact, the role of the mucilaginous matrix and the potential differences in toxicity along the growth curve of O. cf. ovata, we carried out a toxic bioassay during exponential, stationary and late stationary phases. Simultaneously, a molecular assay was performed to quantify intact cells or to exclude cells presence. A liquid chromatography – high resolution mass spectrometry (LC-HRMS) analysis was also carried out to evaluate toxin profile and content in the different treatments. Our results report higher mortality of model organism, especially during the late stationary phase, when direct contact between a model organism and intact microalgal cells occurs (LC50-48h <4 cells/ml on Artemia salina). Also growth medium devoid of microalgal cells but containing O. cf. ovata mucilage caused significant toxic effects. This finding is also supported by chemical analysis which shows the highest toxin content in pellet extract (95%) and around 5% of toxins in the growth medium holding mucous, while the treatment devoid of both cells and mucilage did not contain any detectable toxins. Additionally, the connection between mucilaginous matrix and thecal plates, pores and trychocysts was explored by way of atomic force microscopy (AFM) to investigate the cell surface at a sub-nanometer resolution, providing a pioneering description of cellular features

Hydrocarbon Contamination Decreases Mating Success in a Marine Planktonic Copepod

The mating behavior and the mating success of copepods rely on chemoreception to locate and track a sexual partner. However, the potential impact of the water-soluble fraction of hydrocarbons on these aspects of copepod reproduction has never been tested despite the widely acknowledged acute chemosensory abilities of copepods. I examined whether three concentrations of the water-soluble fraction of diesel oil (0.01%, 0.1% and 1%) impacts (i) the swimming behavior of both adult males and females of the widespread calanoid copepod Temora longcornis, and (ii) the ability of males to locate, track and mate with females. The three concentrations of the water-soluble fraction of diesel oil (WSF) significantly and non-significantly affect female and male swimming velocities, respectively. In contrast, both the complexity of male and female swimming paths significantly decreased with increasing WSF concentrations, hence suggesting a sex-specific sensitivity to WSF contaminated seawater. In addition, the three WSF concentrations impacted both T. longicornis mating behavior and mating success. Specifically, the ability of males to detect female pheromone trails, to accurately follow trails and to successfully track a female significantly decreased with increasing WSF concentrations. This led to a significant decrease in contact and capture rates from control to WSF contaminated seawater. These results indicate that hydrocarbon contamination of seawater decreases the ability of male copepods to detect and track a female, hence suggest an overall impact on population fitness and dynamics

The G305 star-forming complex: Embedded Massive Star Formation Discovered by Herschel Hi-GAL

We present a Herschel far-infrared study towards the rich massive star- forming complex G305, utilising PACS 70, 160 {\mu}m and SPIRE 250, 350, and 500 {\mu}m observations from the Hi-GAL survey of the Galactic plane. The focus of this study is to identify the embedded massive star-forming population within G305, by combining far-infrared data with radio continuum, H2O maser, methanol maser, MIPS, and Red MSX Source survey data available from previous studies. By applying a frequentist technique we are able to identify a sample of the most likely associations within our multi-wavelength dataset, that can then be identified from the derived properties obtained from fitted spectral energy distributions (SEDs). By SED modelling using both a simple modified blackbody and fitting to a comprehensive grid of model SEDs, some 16 candidate associations are identified as embedded massive star-forming regions. We derive a two-selection colour criterion from this sample of log(F70/F500)\geq 1 and log(F160/F350)\geq 1.6 to identify an additional 31 embedded massive star candidates with no associated star-formation tracers. Using this result we can build a picture of the present day star-formation of the complex, and by extrapolating an initial mass function, suggest a current population of \approx 2 \times 10^4 young stellar objects (YSOs) present, corresponding to a star formation rate (SFR) of 0.01-0.02 M\odot yr^-1. Comparing this resolved star formation rate, to extragalactic star formation rate tracers (based on the Kennicutt-Schmidt relation), we find the star formation activity is underestimated by a factor of \geq 2 in comparison to the SFR derived from the YSO population.Comment: Accepted by MNRAS, 16 pages, 8 figures, 3 table

Biofouling Processes in Industry - Fouling on artificial substrata

Biofouling on artificial substrata results from several processes, whose rate and extent are influenced by the intertwining of numerous physical, chemical and biological factors in the immediate proximity of the surface. The importance of substratum features in influencing species settlement is considered here. An emphasis is given on how biological systems (micro- and macrofouling) can interplay with the nature of substratum in regulating patterns of biofouling development. The environmental issues related to the deployment of man-made structures in coastal waters are also discussed, and some guidelines on the use of artificial substrata in the management strategies for controlling fouling in industry are provided

Imposex in Pre-pollution times. Is TBT to blame?

3noAn experimental analysis of imposex (a bioindicator of TBT marine pollution) in pre pollution timenonemixedGARAVENTA F; FAIMALI M; A. TERLIZZIGaraventa, F; Faimali, M; Terlizzi, Antoni