Motility of sea urchin Paracentrotus lividus spermatozoa in the post‐activation phase

The characterization of sperm motility patterns, particularly post-activation changes, is the first step in setting up species-specific protocols involving gamete management and embryo production, for both aquaculture and laboratory research purposes. This study is aimed at the characterization of the sperm motility pattern of the purple sea urchin Paracentrotus lividus. Semen samples were individually diluted in artificial sea water for sperm motility activation. They were then incubated at 18°C for up to 24 hr. Motility was evaluated on dilution, and 1 hr, 3 hr and 24 hr after activation, by computerized analyser. The semen fertilization capacity was also evaluated. Under our experimental conditions (dilution 1:1,000 in artificial sea water plus 0.05% BSA, 18°C, in the dark), P. lividus semen remained viable for up to 24 hr, as the total motile sperm and the fertilization percentages did not change significantly during the incubation time. In contrast, the mean curvilinear velocity and the subpopulation of rapid sperm (those having a curvilinear velocity > 100 µm/s) slightly but significantly decreased after 3 hr, thereafter remaining unchanged for up to 24 hr after activation. In conclusion, our results show that diluted P. lividus semen can be used for a longer period than that of most fish species, with no need for motility inhibition procedures, supporting its wider use in laboratory research. In addition, the development of artificial fertilization protocols for aquaculture production is simplified by long-lasting sperm motility

Increasing the stocking density in Paracentrotus lividus larviculture: Effects on survival and metamorphosis rates

The development of sustainable methods for sea urchin juvenile production is currently constrained by high mortality rates during larval growth and the high costs of larval rearing systems management. With the aim of developing a method for the production of juveniles of the purple sea urchin Paracentrotus lividus in a medium-scale recirculating system, the present study focused on the effects of high stocking densities on larval growth. Plutei larvae were reared at three different densities (up to 7 ind/ml) in a semi-static culture system. Larval survival and metamorphosis success were evaluated in order to identify the most effective density range. The highest metamorphosis rates (80%-95%) were obtained at 4 and 7 larvae/ml. These results are comparable with (and in some cases higher than) those reported for the same species at much lower larval densities. In conclusion, the rearing conditions tested here show for the first time that a significantly higher (4 ind/ml) stocking density than those of traditional P. lividus rearing methods (based on large volumes and low densities) can be adopted, thus supporting the feasibility of an increase in the final output of competent larvae with no increase in rearing volumes

Development of Biopolymers as Binders for Feed for Farmed Aquatic Organisms

Feed for farmed aquatic organisms should guarantee reasonable degree of stability in aquatic medium, long enough for organisms to consume it. Indeed, there is a general complaint about the loss of nutritional and attractive properties upon exposure of a diet to water. Natural substances able to generate firm pellet feed are therefore highly sought. Such binders should improve the stability of feed, be low cost, and hopefully make and extra source of energy. Biopolymers, have properties that make them suitable for use as aquatic feed binders. Some biopolymers are derived from biomass, biodegradable and renewable. The purpose of this chapter is therefore to review recent reports and progress surrounding the possible employment of sustainable biopolymers as binders for feed for farmed aquatic organisms

Sperm motility and fertilization performance of Nodipecten nodosus (L., 1758) exposed at two different cryoprotectants

Cryopreservation is a valuable tool for aquaculture as it provides continuous seed production, regardless of the spawning season of the brood stock. The selection of a suitable cryoprotectant with low toxicity and high water solubility is important to avoid membrane injuries and intracellular ice crystallization. This study has been aimed at the assessment of the toxic effects of two usually applied cryoprotectants, 1-2 propylene glycol (PG) and methanol (MetOH), on spermatozoa of the of lion-paw scallop Nodipecten nodosus, by evaluating the sperm motility and the development of D larvae after fertilization procedure. Sperm was exposed at room temperature (22°C) for 10, 20 and 30 min to different concentration ranges of two cryoprotectants. Regarding the sperm motility, PG5%, PG7%, MetOH4% and MetOH6% did not show differences compared to control (semen incubated in seawater) (P < 0.05). The development of D larvae was not affected by the exposition to PG5%, MetOH 4% and MetOH 6%. These results indicate the potential use of both cryoprotectants for cryopreservation procedures

Gonad quality of sea urchin Paracentrotus lividus cultured in an offshore pilot‐scale trial on the south‐east Italian coast

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Paracentrotus lividus roe enhancement by a short-time rearing in offshore cages using two agar-based experimental feed

In this study, we tested the effect of two agar-based biocomposites (differing for the fish meal source), on the Paracentrotus lividus gonad cycle progression and biochemical composition, in an offshore pilot scale trial. The purpose of this study was to identify a feeding regime for P. lividus that would allow adequate gonadal growth without accelerating the gamete maturation, in order to extend the market period. The purpose was pursued through the use of agar as a binding agent in the manufacturing of biocomposites to be used as feed for P. lividus and the realization of special offshore cages. The gonad index, histology, biochemical composition of fatty acids (FA) and free amino acids (FAA) and volatile molecule fingerprint were evaluated. Both the gonad index and the histological analysis showed a slower gametogenesis progression in the gonads of caged sea urchins with respect to the field collected ones, consistent with our previous results obtained testing a similar feed composition in a recirculating system. The amount and the relative proportions of FA and FAA in the gonads of wild and cultured gonads were similar, while the analysis of the volatile substances of the gonads of the sea urchin conducted using the electronic nose, shows that they vary as a result of the different feeding treatments. These results show that P. lividus sea urchins can be housed, under this feeding regime during the recovery phase of the gonads, without acceleration of the maturation of the gametes and thus in conditions to allow the extension of the market period. Moreover, the here tested agar-based biocomposites make it possible to reduce the management costs of the rearing system as they need to be replaced only once a week, and its environmental impact as they guarantee a limited nutrient dispersion in the water

Abra segmentum (Mollusca: Pelecypoda) of the Lesina Lagoon (Southern Adriatic coast, Italy): Observations on variations in the population in relation to the main environmental parameters

1 - The aim of this work was to evaluate the effects of the main chemical and physical environmental parameters on the dynamics of the population of A. segmentum living in the Lesina Lagoon, as a part of a wider study aimed at characterizing all the phases of the species' reproduction cycle in relation to the specific environmental conditions of the Lagoon. 2 - Sediment samples were collected at monthly intervals by using an Ekman scoop from May 2003 to May 2005; at each sampling site temperature, salinity and pH were recorded by multiparametric probe; in the laboratory the A. segmentum specimens were sorted by a 1 mm mesh sieve and the shell length was measured. 3 - During the two years of samplings, density levels tended to increase, a trend that was inversely correlated with the recorded decrease in salinity (Pearson's r=-0.66). 4 - Differences in the size class patterns were also found: in the 2003-04 samplings, the &#8805; 13mm individuals represented the 20%÷50% of the total population, while juveniles disappeared on July 2003 and clearly reappeared only on February 2004. In 2004-05 samplings, juveniles were always recovered, while the oldest specimens, although increased in number, were never higher than 10% of the total population. 5 - The decreasing trend of salinity is supposed to be most important factor involved in the observed increase in population density, and in the consequent differences in the size class patterns

Computerized sperm motility analysis in toxicity bioassays: A new approach to pore water quality assessment

The aim of this study was to test the sensitivity of computerized sperm motility analysis in the sea urchin Paracentrotus lividus as the endpoint in toxicity bioassays. The tested matrices were pore water samples collected in an agriculture-impacted Mediterranean lagoon, Lake Varano (Italy). Two standardized bioassays were also conducted as controls, the P. lividus spermiotoxicity test and the Vibrio fischeri (Microtoxs) test. VCL (curvilinear velocity), VSL (straight line velocity), VAP (average path velocity), and the percentage of rapid spermatozoa recorded by the Sperm Class Analyzers system showed high sensitivity and discrimination ability, to a degree comparable with the larval development endpoint of the spermiotoxicity test. The test evaluated in this study requires small volumes of matrices, involves minimal sample manipulation, and can easily be extended to many other bioindicator species. It may therefore be considered a promising ‘‘quick response tool’’ following hazardous events that may adversely affect an aquatic ecosystem

I popolamenti zoobentonici litorali dei fondi mobili di un sito ad elevato impatto antropico: il golfo di Manfredonia, Italia.

This study was conducted on the benthic macrofauna of the Manfredonia Gulf (Adriatic sea). This site is dominated by bivalves (35%), whose dominant species was Lucunella divaricata (43%) and Corbula gibba (28%), considered as indicators of environmental instability. The most abundant species was the Ophiuroidea Amphiphopolis squamata (29.2%). Homogeneity of spatial distribution was assessed by cluster analysis