1,721,001 research outputs found
Assessing the spermiotoxicity of butyltin compounds (TBT and DBT) in the sea urchin Paracentrotus lividus Lmk
No full textDespite legislative restrictions about the use of paints containing organotins introduced in
Europe at the end of the ’80, 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
Seasonal changes in physiological responses and evaluation of “well-being†in the Venus clam Chamelea gallina from the Northern Adriatic Sea.
No full textChamelea gallina is an infaunal bivalve, widespread in sandy bottoms along Mediterranean coasts. It is an important economic resource for
fisheries in the Adriatic, although in recent years over-fishing, and other concurrent factors, have dramatically decreased clam harvesting. In this
context, it is of great interest to gain information on seasonal variations in the physiological performance of clams, for an overall evaluation of
their well-being. In this study, laboratory experiments were performed to define allometric relationships and effects of temperature on clearance
and respiration rates of C. gallina. The mean values of b coefficients were calculated and used to correlate physiological measurements to
‘standard’ body mass, when seasonally collected clams were analysed. The highest clearance rate (0.42 L h−1) was measured in clams collected in
July 2000; the highest respiration rate (12.22 μmol O2 h−1) was observed in July 2001, leading to a negative scope for growth (−2.8 J h−1). The
influence of environmental and endogenous factors, mostly reproduction, was discussed. Survival in air and condition indices, showing higher
stress conditions in December 2000 and July 2001, were in good agreement with the other physiological measurements. The physiological
responses examined in this study appear to be suitable for providing detailed indications on the well-being of C. gallina and may be useful for
future studies aimed at eco-sustainable management of the resource
Parametri fisiologici in popolazioni di Tapes philippinarum soggette a diverso impatto di pesca in Laguna di Venezia
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Valutazione degli effetti dello stress da pesca con draga idraulica sulla vongola Chamelea gallina
No full textEvaluation of shell damage to the clam Chamelea gallina captured by hydraulic dredging in the Northern Adriatic Sea
No full textThe 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
Spermotoxicity and embryotoxicity of triphenyltin (TPT) to the sea urchin Paracentrotus lividus Lmk
No full textThe 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 μg TPTA l-1. In proportion to increasing concentrations, the percentage of fertilised eggs decreased, falling to 45% at 10 μg 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 μg l-1. Progressive increases in skeletal anomalies were also detected, highly significant (P <0.001) at 2 μg l-1. Embryonic development was greatly slowed at the highest TPT concentrations: embryos never reached the pluteus stage at 5 μg l-1, and development was blocked at the gastrula stage at 10 μg 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 4-nonylphenol toxicity in the clam Tapes philippinarum
No full textLethal and sublethal effects of 4-nonylphenol (NP) were investigated in the clam Tapes philippinarum from the Lagoon of Venice.
In a 96-h lethality test, bivalves were exposed to the following NP concentrations: 0, 0+acetone, 0.19, 0.38, 0.75, 1.5, and 3.0 mg
NP/L. The 96-h LC50 value was 1.12mg NP/L. No mortality was observed at 0.19 mg NP/L, whereas at 1.5 and 3.0 mg NP/L both
siphons and foot of clams were often cut-off, the animals being unable to withdraw them before shell closure, suggesting the possible
narcotic effect of NP. Lower concentrations (0, 0+acetone, 0.025, 0.05, 0.1, and 0.2 mg NP/L) were then used to evaluate sublethal
NP effects on clearance rate (CR), respiration rate (RR), scope for growth (SFG), and survival in air. Following a 7-day exposure,
decreased RRs were found at all NP concentrations tested. Significant decreases in the CR and SFG were only observed at the two
highest NP concentrations (0.1 and 0.2 mg/L), with SFG reductions reaching 54% and 71%, respectively. Last, the highest
concentrations tested significantly decreased the resistance of clams to exposure to air and enhanced the mortality rate. As the lowest
effective NP concentrations are similar to environmentally realistic levels, a condition of potential risk for the well-being of clam
populations in estuarine areas is highlighted
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