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Departamento de Botánica y Fisiología Vegetal, Universidad de Malaga

Summary: trophic levels: a measure of functional diversity stable isotope tools: bulk vs. compound-specific analyses the basis: differential isotopic fractionation trophic indicators: trophic position, baselines, and much more application examples progress: multitrophic models, fingerprinting Invited lecture. Online live Session 2 MCIN/AEI/10.13039/501100011033

INDITUN

The endemic species Pinna nobilis is the most endangered Mediterranean bivalve, facing nearly extinction all over the Mediterranean Sea, hosting its last reservoirs in highly impacted coastal lagoons. Thus, knowledge about the populations' conservation status in these ecosystems is essential. In 2019, the Mar Menor lagoon’s population was considered as a highly vulnerable population (Nebot-Colomer et al., 2021) due to several ecological disasters. The present study represents a continuation of the previous work, which aims to evaluate the resilience of the population, by assessing its reproductive success and maintenance of the population. To do so, between 2019 to 2022, we installed between 23-45 larvae collectors, monitored 13 permanent individual’s plots, and conducted visual searches and censuses. Overall, densities remained stable over years, although the number of individuals alive monitored in permanent plots decrease each year. Moreover, none of the methodologies carried out detected the incorporation of recruits in the population. Our results pointed out to opposite signs of recovery of the species, increasing its vulnerability to future disturbances. Therefore, urgent management and conservation actions focused on restoring the ecosystem and protecting P. nobilis individuals are needed to avoid this population extinction.

Recent changes in oceanic plankton are being reported at unprecedented rates. Most changes are related to environmental factors and many were identified as driven by climate, either through natural cycles or by anthropogenic effects. However, the separation of both effects is difficult because of the small size of most observational series. Moreover, some changes are related to trends and cycles while others were perceived as system shifts, often synchronized over large spatial scales. Here, studies on observational series of plankton, with the focus in the N Atlantic, are reviewed. Two main quasi-synchronic shifts in species assemblages were identified: one in late 1980’s and a most recent one in the first decade of the new millennium. While the origin and extent of most shifts vary locally, their synchronization seems to confirm the lagged response of plankton to changes in warming and in large-scale climatic factors. Changes in species abundance patterns are generally related to the strength of currents, but also to non-linear effects of warming, the latter particularly affecting species in regions near the limits of their thermal niche. Indeed, most of the changes are attributed to trade-offs between different biological strategies. Taken together, the reviewed case studies indicate a lagged biological response to variations in the local environment driven by large-scale climate forcing. The challenges for the interpretation of future changes include the consideration of local changes in a wider regional context, variations in species life-traits and possible top-down effects of plankton predators PID2020-115620RB-100 funded by MCIN/AEI/10.13039/501100011033 Invited lecture