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Simple Summary: Determining the age of cephalopods is essential for understanding their life history, which is in turn crucial for assessment and management. The short lifespan with a single reproductive event, high natural mortality rates, and rapid growth in these species make the application of traditional age-based models impractical. Most hard structures of cephalopods, such as mandible (beaks) and statoliths, can store ontogenetic events through the formation of periodic marks or growth increments. Statoliths are paired calcareous structures located in two anterior chambers of the head. In this work, for the first time in the Mediterranean, we successfully performed age estimation in wild cuttlefish Sepia officinalis using beaks and statoliths. Based on daily increments that were previously validated in statoliths, the beaks were cross-verified. As the beak presented more advantages in age studies than statoliths, due to the relative simplicity of its processing method, it was eventually proposed as a suitable hard structure to study the age of S. officinalis. Establishing the age of cephalopods is crucial for understanding their life history, which can then be used for assessment and management. This is particularly true for the common cuttlefish Sepia officinalis (Linnaeus, 1758), one of the most important resources for coastal fisheries. For this reason, an age analysis of S. officinalis was performed for the first time in the Mediterranean, using beaks and statoliths from 158 wild specimens (55–222 mm mantle length; 23–1382 g total weight) at different maturity stages (immature to mature). Growth increments were counted in the lateral wall of the upper beaks and the lateral dome of statoliths. In both cases, a good relationship was found between the counts and the sizes of the animals. The low values of coefficients of variation between the readings obtained for beaks (3.96 ± 1.87%) and statoliths (4.00 ± 1.89%) showed a high level of precision and accuracy in the readings. However, the analysis was simpler for beaks, which were all successfully analyzed, while it was more complex for statoliths, with 69% being lost due to rejection or overgrinding. Based on daily increments previously validated in statoliths, the beaks were cross-verified by comparing their counts with those from statoliths extracted from the same 83 specimens, obtaining a statistically significant relationship between the two counts, confirmed by the ANOVA test. Absolute growth rates that were assessed using both beaks and statoliths indicated that the two sexes had a higher growth rate at 122 and 182 days, which subsequently declined in older specimens. Due to the relative simplicity of its processing method, the beak was finally proposed as a suitable hard structure to study the age of S. officinalis. We also confirmed the good readability of increments in the lateral wall of the beak, which could be considered a valid alternative to the rostrum surface. [ABSTRACT FROM AUTHOR]

The aim of this study was to provide new insights into the stability in water of the prepared feeds for echinoculture. The stability tests of four prepared feeds were carried out in laboratory in two different trials corresponding to different temperature levels (24°C and 19°C) and four different times of immersion (up to 72 h). Temperature and duration of immersion significantly affected the stability of feeds. Feed 1 was the most stable whereas Feed 3 was the least stable feed, as it started to dissolve in a few hours. Feed 2 and Feed 4 remained stable at 19°C all along the trial, whereas at 24°C remained intact for only 30 h. To optimize the echinoculture practice at temperature >19°C, we recommend a feeding regime at least 3 times a week, whereas at lower temperature we suggest an intermittent feeding regime. [ABSTRACT FROM AUTHOR]

Mussels close their shell as a protective strategy and the quantification of this behavioral marker may represent an alarm signal when they are exposed to environmental stressors. In the present study, we investigated the ability of the Mediterranean mussel Mytilus galloprovincialis to recover and then the resilience or inertia of valve activity after a pulsing exposition to diverse levels of salinity (5, 10, 20, and 35 PSU as reference value). The trial simulated an event of drastic and sudden reduction of seawater salinity thus mimicking an event of flash flood from intense rain. Valve gaping and movements were measured in continuous cycle for 10 days using a customized magneto‐electric device which uses Hall sensors. Results showed that under normal conditions of salinity (35 PSU), the general pattern of valve movements was a continuously open state with sporadic spikes indicating a closing motion. At salinity of 5, PSU mussels reacted by closing their valves, leading to a 77% mortality on the 4th day. At salinity of 10, PSU animals were observed with closed valves for the entire duration of the exposure and no mortality occurred, they showed a significant reduction in the valve activity once the reference value of salinity was re‐established. In contrast, salinity of 20 PSU did not trigger a significant behavioral response. Interestingly, there no define rhythms of valve movements were recorded during salinity challenges. [ABSTRACT FROM AUTHOR]

Establishing the age of cephalopods is crucial for understanding their life history, which can then be used for assessment and management. This is particularly true for the common cuttlefish Sepia officinalis (Linnaeus, 1758), one of the most important resources for coastal fisheries. For this reason, an age analysis of S. officinalis was performed for the first time in the Mediterranean, using beaks and statoliths from 158 wild specimens (55-222 mm mantle length; 23-1382 g total weight) at different maturity stages (immature to mature). Growth increments were counted in the lateral wall of the upper beaks and the lateral dome of statoliths. In both cases, a good relationship was found between the counts and the sizes of the animals. The low values of coefficients of variation between the readings obtained for beaks (3.96 ± 1.87%) and statoliths (4.00 ± 1.89%) showed a high level of precision and accuracy in the readings. However, the analysis was simpler for beaks, which were all successfully analyzed, while it was more complex for statoliths, with 69% being lost due to rejection or overgrinding. Based on daily increments previously validated in statoliths, the beaks were cross-verified by comparing their counts with those from statoliths extracted from the same 83 specimens, obtaining a statistically significant relationship between the two counts, confirmed by the ANOVA test. Absolute growth rates that were assessed using both beaks and statoliths indicated that the two sexes had a higher growth rate at 122 and 182 days, which subsequently declined in older specimens. Due to the relative simplicity of its processing method, the beak was finally proposed as a suitable hard structure to study the age of S. officinalis . We also confirmed the good readability of increments in the lateral wall of the beak, which could be considered a valid alternative to the rostrum surface.