Search

Understanding the physiological responses of intertidal seaweeds to environmental factors is fundamental to characterize their local physiological adaptation and success in the face of climate change. We measured the photosynthetic activity and the total phenolic content of the intertidal alga Cystoseira compressa and explored their relationship with latitude or local ambient air and seawater temperatures. Our results show that, when submerged, the photosynthetic activity of C. compressa showed values typical for non-stressed thalli, and the seawater temperatures found across sites explained the variability of these values. We observed a decrease in the photosynthetic activity of C. compressa when exposed to air, compared to a submerged condition. This activity remained stationary up to 28°C and then started to decrease with higher air temperatures. The total phenolic content of C. compressa at the end of low tide changed across the study sites from 0.12 to 0.53 % DW. Phenolic variability was explained by the long-term thermal water conditions experienced by the algae, rather than short-term variations encountered during tidal cycles. Overall, our results suggest a crucial role played by temperature in driving the physiological traits of the intertidal C. compressa.

In this study the effects of an anionic surfactant, sodium dodecyl sulfate (SDS), are assessed on the Mediterranean mussel (. Mytilus galloprovincialis), exposed for 18 days at a concentration ranging from 0.1. mg/l to 1. mg/l. The effects are monitored using biomarkers related to stress response, such as regulatory volume decrease (RVD), and to oxidative stress, such as reactive oxygen species (ROS), endogenous antioxidant systems and Hsp70 levels. The results demonstrate that cells from the digestive gland of M. galloprovincialis, exposed to SDS were not able to perform the RVD owing to osmotic stress. Further, SDS causes oxidative stress in treated organisms, as demonstrated by the increased ROS production, in comparison to the controls (. p