Lorena Cristina Cojoc1, Sonia de Caralt1, Cristina Galobart2, Jorge Santamaria2, Cèlia Sitjà2, Fabio Rindi3, Silvia Bianchelli3,4, Roberto Danovaro3, Simonetta Fraschetti5,4, Erika Fabbrizzi5, Marco Munari6, Jana Verdura7, Luisa Mangialajo7, Sotiris Orfanidis8, Emma Cebrian2
1University of Girona (UdG), Spain - 2Centre for Advanced Studies (CEAB-CSIC), Spain - 3 Polytechnic University of Marche (UNIVPM), Italy - 4National Biodiversity Future Center (NBFC), Italy - 5University of Naples Federico II (UNINA), Italy - 6University of Padova (UNIPD), Italy - 7Côte d’Azur University (UCA), France - 8Hellenic Agricultural Organization-Dimitra, Greece
Understanding the mechanisms driving the vulnerability and recovery of macroalgal forests following environmental disturbances is essential to predict their resilience in a changing climate. Canopy macroalgal species are increasingly threatened by rising sea temperatures, yet their ability to withstand and recover from heat stress are still poorly understood. Many studies propose that intraspecific variability in thermal tolerance across regions can be related to their native thermal range. Also, connectivity between populations and their conservation status may play a crucial role in enhancing resilience and resistance to extreme temperature conditions. This study experimentally evaluates the role of native thermal regime on the resistance and resilience to Marine Heat Waves (MHW) of canopy forming macroalgal habitats using the endemic Mediterranean Gongolaria barbata as a case study.
Six populations of G. barbata, from diverse Mediterranean thermal regimes and conservation levels were studied. Cold range populations included Ancona, Chioggia, and Lerins Islands, while warm range populations were from Thessaloniki, Menorca Miami and Menorca Teulera. The populations from Menorca are considered isolated, with Teulera being the result of a restoration action. In a mesocosm experiment, the individuals underwent temperature treatments of 24°C, 27°C, and 31°C for two months, followed by a recovery period at 13ºC for five months. To evaluate physiological performance, biomass variation and surface area were measured. The results showed that the populations from warmer regions exhibited greater thermotolerance, sustaining more biomass when exposed to higher temperatures. On the contrary, populations in colder areas suffered significant biomass declines, with losses exceeding 50% at 31 °C. For recovery capacity, populations from colder yet connected and well-preserved areas performed better, suggesting that resilience is not solely linked to thermotolerance. The recovery phase revealed that resistance and resilience are regulated by distinct mechanisms, where genetic variances might play a crucial role in shaping the species’ recovery potential.
Biography
Lorena Cristina Cojoc is an environmental scientist and PhD candidate investigating the resilience and recovery of Mediterranean macroalgal forests under environmental stress. Her research focuses on how key stressors—such as temperature, pollutants, and herbivory—affect the functioning and recovery capacity of canopy-forming species like Cystoseira.