Effects of hydraulic dredging on the physiological responses of the target species <i>Chamelea gallina</i> (Mollusca: Bivalvia): laboratory experiments and field surveys

El efecto del stress mecánico en la chirla Chamelea gallina durante el dragado hidráulico se estimó tanto en el laboratorio como en estudios de campo, midiendo algunos marcadores fisiológicos a nivel de los organismos (tasa de aclarado, tasa de respiración, energía disponible para el crecimiento y supervivencia en pruebas fuera del agua). En el laboratorio se simuló el stress mecánico mediante agitación de las chirlas en un mezclador vortex. En el campo, las chirlas se recolectaron estacionalmente en dos puntos de muestreo a lo largo de la costa del Adriático norte (Lido y Jesolo) y se aplicaron cuatro niveles de stress: el más alto fue el utilizado en la pesca comercial (i.e. alta presión de agua y separación mecánica) y el más bajo fue el muestreo manual por submarinistas. La supervivencia fuera del agua fue el marcador más sensible en la evaluación del stress mecánico en el laboratorio. La tasa de aclarado también decreció significativamente cuando se aplicó agitación. Los resultados de campo indicaron que la alta presión de agua y separación mecanizada afectaron el aclarado, la energía disponible para el crecimiento y la supervivencia fuera del agua, mostrando todos ellos tendencias decrecientes a medida que el stress mecánico incrementaba en los dos puntos de muestreo. Los efectos perjudiciales de la perturbación mecánica pueden ser enfatizados dependiendo de la estación, cuando incrementa el stress endógeno y externo. Se destaca un riesgo potencial para las chirlas pequeñas que son pescadas y posteriormente descartadas

Transcriptome sequencing and microarray development for the Manila clam, Ruditapes philippinarum: genomic tools for environmental monitoring

Abstract Background The Manila clam, Ruditapes philippinarum, is one of the major aquaculture species in the world and a potential sentinel organism for monitoring the status of marine ecosystems. However, genomic resources for R. philippinarum are still extremely limited. Global analysis of gene expression profiles is increasingly used to evaluate the biological effects of various environmental stressors on aquatic animals under either artificial conditions or in the wild. Here, we report on the development of a transcriptomic platform for global gene expression profiling in the Manila clam. Results A normalized cDNA library representing a mixture of adult tissues was sequenced using a ultra high-throughput sequencing technology (Roche 454). A database consisting of 32,606 unique transcripts was constructed, 9,747 (30%) of which could be annotated by similarity. An oligo-DNA microarray platform was designed and applied to profile gene expression of digestive gland and gills. Functional annotation of differentially expressed genes between different tissues was performed by enrichment analysis. Expression of Natural Antisense Transcripts (NAT) analysis was also performed and bi-directional transcription appears a common phenomenon in the R. philippinarum transcriptome. A preliminary study on clam samples collected in a highly polluted area of the Venice Lagoon demonstrated the applicability of genomic tools to environmental monitoring. Conclusions The transcriptomic platform developed for the Manila clam confirmed the high level of reproducibility of current microarray technology. Next-generation sequencing provided a good representation of the clam transcriptome. Despite the known limitations in transcript annotation and sequence coverage for non model species, sufficient information was obtained to identify a large set of genes potentially involved in cellular response to environmental stress.This work was partially supported by a grant from European Union-funded Network of Excellence "Marine Genomics Europe". CS wishes to acknowledge additional funding from the Ministry of Education and Science (Spain) through grant AGL2007-60049. MM had a PhD scholarship from the University of Florence, Italy. RL was recipient of PhD fellowship SFRH/BD/30112/2006, from the Portuguese Science and Technology Foundation (FCT) and LC and RL acknowledge a grant from FCT project ISOPERK (PTDC/CVT/72083/2006).Peer Reviewe

The influence of salinity on the effects of Multi-walled carbon nanotubes on polychaetes

Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multiwalled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.publishe

Assessing the spermiotoxicity of butyltin compounds (TBT and DBT) in the sea urchin Paracentrotus lividus Lmk

Despite legislative restrictions about the use of paints containing organotins introduced in Europe at the end of the \u201980, contamination levels in marine coastal environment are still relevant and represent a cause of concern for aquatic life. In the present study, the spermiotoxic effects of tributyltin (TBT) and dibutyltin (DBT) were assessed in the sea urchin Paracentrotus lividus. A series of preliminary experiments were performed in order to determine the appropriate sperm:egg ratio for this species which allows to enhance the sensitivity of the test. As indicated by various standard protocols for other species, we chose the lowest sperm:egg ratio (1250:1) giving a fertilisation success of approximately 90%. For each compound, six replicated experiments were carried out at concentrations ranging from 0.01 to 10 lg/l for TBT, and from 0.5 to 20 lg/l for DBT. A significant reduction of fertilisation was observed from 0.1 lg TBT/l (p<0.05); with respect to controls, the fertilised eggs were 48% at 1 lg TBT/l and 0.75% at 10 lg TBT/l. As for DBT, the lowest concentration tested (0.5 lg DBT/l) caused a slight but significant reduction in the percentage of fertilised eggs (p < 0.05) that fell to 86% at 1 lg DBT/l and to 7% at the highest concentration tested (20 lg DBT/l). Spermiotoxic effects were demonstrated at environmentally realistic levels for both compounds, the higher toxicity of TBT being confirmed. Nevertheless, with reference to our previous studies, TBT and DBT exhibited higher embryotoxic than spermiotoxic effects

Spermiotoxicity and embryotoxicity of triphenyltin (TPT) to the sea urchin Paracentrotus lividus Lmk

The most important sources of pollution by triphenyltin (TPT) in marine coastal ecosystems are its employment as a fungicide in agriculture and, in association with tributyltin, as a biocide in anti-fouling paints. In this study, spermiotoxicity and embryotoxicity (from post-fertilisation to pluteus stage) experiments were carried out to better clarify the ecotoxicological effects of TPT during the development of the sea urchin Paracentrotus lividus. Sperm exposed to triphenyltin acetate (TPTA) for 60 minutes showed a significantly reduced capability to fertilise eggs even at the lowest concentration of 0.1 \ub5g TPTA l-1. In proportion to increasing concentrations, the percentage of fertilised eggs decreased, falling to 45% at 10 \ub5g TPTA l-1, the maximum tested concentration. In embryotoxicity experiments at 48 h post-fertilisation, the length of the pluteus somatic rods was significantly reduced (P<0.001) from 1.5 \ub5g l-1. Progressive increases in skeletal anomalies were also detected, highly significant (P <0.001) at 2 \ub5g l-1. Embryonic development was greatly slowed at the highest TPT concentrations: embryos never reached the pluteus stage at 5 \ub5g l-1, and development was blocked at the gastrula stage at 10 \ub5g l-1. As observed in previous experiments using butyltin compounds, embryotoxic effects on both skeletal deposition and blocked development are presumed to be due to interference of TPT with intracellular calcium homeostasis. Sea urchin gametes are more sensitive to TPT than embryos, this condition emphasising the environmental risk due to TPT contamination

Evaluation of shell damage to the clam Chamelea gallina captured by hydraulic dredging in the Northern Adriatic Sea

The impact of experimental hydraulic dredging was assessed on Chamelea gallina populations in two sites along the north-western Adriatic coast (Lido and Jesolo) by detecting and quantifying shell damage caused by fishing operations on both captured and discarded clams. Various levels of stress were applied, the highest being that used by commercial fishing vessels, which employ high water pressure and mechanised sorting and the lowest manual sampling of clams by scuba divers. Water pressure and sorting significantly increased shell damage, the highest levels always being observed in commercially dredged clams. At Lido, damage was mostly due to the action of the mechanised sorter; at Jesolo, the effect of high water pressure was more clearcut. Moreover, clams collected at Jesolo had both higher mean damage level and higher numbers of damaged individuals compared to the Lido samples. These differences seem to be mostly related to differing bottom features in the two sites. A positive relationship was observed between damage level and clam size: small-sized samples (length <17 mm) were less damaged than medium-sized ones (25mm < length <17 mm) and commercial size clams (<25 mm) showed the highest damage level. The severe and harmful physical impact of hydraulic dredging was apparent in captured and then discarded animals, a small fraction of which appears able to recover, as shown by the presence of clams with repaired shells

An ecotoxicological approach for the Boka Kotorska Bay (south-eastern Adriatic Sea): First evaluation of lysosomal responses and metallothionein induction in mussels

Mytilus galloprovincialis was used as a biomonitoring organism in Boka Kotorska Bay, a coastal transitional ecosystem in south-western Montenegro. Native mussels were collected in June 2008 at four sites thought to be differently impacted. Biological effects were investigated analysing both generic and specific biomarkers at cellular level (metallothionein content, lysosomal membrane stability, lipofuscin and neutral lipid accumulation, lysosomal structural changes). Trace element levels in mussels were quite low, only Cu and Zn exhibiting slight increases in the two sampling sites of Tivat Bay, the first one in front of a small working dockyard and the other in the water area of a former Naval dockyard. Mussels collected from these sites exhibited the highest values in neutral lipid and lysosomal volume density and the lowest neutral red retention times. Metallothionein content was always low, reflecting the minor body burden of the trace elements and suggesting a non-relevant environmental induction