Study of possibility of reproduction and mass culture of Nereis diversicolor

The present study was firstly conducted to study the rate of sexual maturity in Nereis diversicolor under suitable conditions of temperature and photoperiod. The second objective was to determine the potential of artificial breeding in these worms for mass culture. Nereis diversicolor worms were collected from the Anzali lagoon in 4000 sampling operations during the year’s 2004 to 2006 using Ekman grab with a surface area of 400 cm2. The water salinity, temperature and total organic matter (TOM) of sediments in the sampling region was recorded. The worms were maintained in 0.5 tons (1 x 1 m^2) tanks containing clayey-muddy sediment to a height of 20 cm covered with 10 cm water (5 ‰) until they reached a weight of 200-300 mg. Sexual maturity in this species was attained at 4-6 ºC and spawning occurred at approximately 16 ºC. The first gametes were observed five weeks after the temperature increased from 6 to 16 ºC. Sexual maturity was studied at various salinities (0.5, 5, 12, and 15 ‰). Results indicate that these worms attained earlier sexual maturity at salinity of 15 ‰, compared to other salinities studied. No significant differences (P>0.05) were observed between sexual maturity attained at 12 ‰ and 15 ‰. Stocking density (20, 50, 100, 150 worms) was studied in terms of sex and showed that number of females were higher than males and the ratio was 11:1 (female: male). No significant differences (P>0.05) were observed between the various stocking densities and their replicates. The effect of light and photoperiod in synchronizing reproduction in male and female N. diversicolor was studied. It was evident that reproduction behavior in adult worms increased for a period of one week at the end of each month after they are exposed to a prolonged photoperiod (L:D=16:8) followed by a period of dim light (simulated using 1 W lamps). Feeding trials were carried out with Saccharomyces cerevisiae, formulated fish diets and humus. Results showed that this diet was effective in speeding up sexual maturity in worms and significant effect of treatment was observed (P<0.05) in worms fed a diet of humus alone. Eggs and sperms were fertilized and worms developed from the young monotrochophore with jelly layer to the trochophore larvae

Analytical challenges and the development of biomarkers to measure and to monitor the effects of ocean acidification

Changing ocean-carbonate chemistry caused by oceanic uptake of anthropogenic atmospheric carbon dioxide leads to the formation of carbonic acid, thus lowering the pH of the sea with predictions of a decrease from current levels at 8.15 to 7.82 by the end of the century. The exact measurement of subtle pH changes in seawater over time presents significant analytical challenges, as the equilibrium constants are governed by water temperature and pressure, salinity effects, and the existence of other ionic species in seawater.Here, we review these challenges and how pH also affects dissolved inorganic and organic chemicals that affect biological systems. This includes toxic compounds (xenobiotics) as well as chemicals that are beneficial for marine organisms, such as the chemical signals (i.e. pheromones) that are utilized to coordinate animal behavior. We review how combining analytical, molecular and biochemical tools can lead to the development of biosensors to detect pH effects to enable predictive modeling of the ecological consequences of ocean acidification

Biological responses to contaminants in the Humber Estuary: disentangling complex relationships

Due to the ecological importance of estuaries, it is necessary to understand the biological effects that potentially toxic contaminants induce in bioindicator species. A key aspect is whether effects at lower levels of biological organisation transfer through the system to higher levels. In understanding such processes, characterising multivariate relationships between contaminants, sediment toxicities and detoxification processes are important. Worms (Hediste diversicolor) and sediments were collected along the Humber Estuary, England, and inorganic and organic contaminants were quantified. Sediment toxicities and glutathione-S-transferases (GSTs) activity in the ragworm were analysed. Concentrations of metals were highest near urban and industrial areas, whereas organic contaminants appeared at upstream locations. GST activity correlated with heavy metals. The genotoxicity, oestrogenicity, dioxin and dioxin-like activity were higher at upstream locations. Oestrogenicity correlated with alkylphenols and some organochlorines, whilst genotoxicity correlated with organochlorines and heavy metals. Despite this, higher level biological responses could not be predicted, indicating that homeostasis is operating