Percorrer por autor "Vivanco-Bercovich, Manuel"
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- Crossing thermal limits: functional collapse of the surfgrass phyllospadix scouleri under simulated extreme marine heatwavePublication . Vivanco-Bercovich, Manuel; Bonet-Melià, Paula; Schubert, Nadine; Marín-Guirao, Lázaro; Muñiz-Salazar, Raquel; Cabello-Pasini, Alejandro; Ferreira-Arrieta, Alejandra; Garcia-Pantoja, Jessica Anayansi; Guzmán-Calderón, José Manuel; Procaccini, Gabriele; Samperio-Ramos, Guillermo; Sandoval-Gil, Jose MiguelMarine heatwaves (MHWs) are intensifying under climate change, yet the physiological limits that constrain seagrass resilience remain poorly defined. We experimentally tested the responses of the surfgrass Phyllospadix scouleri, a foundation species of the Northeast Pacific coast, to simulated MHWs of contrasting intensity. In a 27-day mesocosm experiment, plants were exposed to fluctuating temperatures representing a severe MHW (23.5 ± 1.5 °C) and an extreme MHW (26.5 ± 1.5 °C), while photosynthetic performance, respiration, nitrogen metabolism, oxidative stress, and growth were monitored during and after warming. Phyllospadix scouleri maintained photosynthetic capacity and carbon balance under severe warming but exhibited pronounced physiological disruption at extreme temperatures, including sustained photoinhibition, reduced nitrate assimilation, elevated respiration, and negative daily productivity. These effects persisted after heat stress, leading to reduced growth and indicating incomplete recovery. Multivariate analyses revealed a distinct transition from tolerance to functional breakdown near 26.5 °C, suggesting a physiological tipping point only 5–6 °C above current summer maxima in the area of the studied population. Our findings demonstrate that intensifying MHWs may rapidly erode the thermal safety margin of temperate seagrasses, pushing foundational coastal ecosystems toward metabolic instability and potential regime shifts under continued ocean warming
- Marine heatwaves can limit the role of surfgrasses as biofilters for wastewatersPublication . Bonet-Melià, Paula; Sandoval-Gil, Jose Miguel; Samperio-Ramos, Guillermo; Vivanco-Bercovich, Manuel; Canino-Herrera, Sergio R.; Durazo, Reginaldo; Camacho-Ibar, Víctor F.; Alexandre, AnaMarine heatwaves (MHWs) can have detrimental effects on seagrasses, but knowledge about the impacts on their ecosystem services remains scarce. This work evaluated Phyllospadix scouleri (surgrass) as a biofilter for wastewater discharges, and how warming associated with MHW may affect this ecological function. The nitrogen uptake kinetics and assimilation abilities for ammonium, nitrate, and urea were examined under two different warming scenarios (single and repeated events) simulated in a mesocosm. N-uptake kinetics were related to urban sewage discharges close to surfgrass meadows. Our results revealed that surfgrasses can serve as effective biofilters because of their high nitrogen uptake rates and above-average canopy biomass. Nonetheless, exposure to both experimental warmings resulted in a significant decline in their ability to incorporate and assimilate nitrogen. Consequently, MHWs may reduce the capacity of surfgrasses to function as nitrogen sinks and green filters for sewage waters, jeopardizing their role as Blue Nitrogen systems.
- Marine heatwaves recurrence aggravates thermal stress in the surfgrass Phyllospadix scouleriPublication . Vivanco-Bercovich, Manuel; Sandoval-Gil, Jose Miguel; Bonet-Meliá, Paula; Cabello-Pasini, Alejandro; Muñiz-Salazar, Raquel; Montoya, Leonardo Ruiz; Schubert, Nadine; Marín-Guirao, Lázaro; Procaccini, Gabriele; Ferreira-Arrieta, AlejandraThe surfgrass Phyllospadix scouleri constitutes highly productive meadows along the Pacific coast of North America – a region that has been increasingly affected by severe marine heatwaves (MHWs) in recent years. Our study assessed the effects of consecutive MHWs simulated in mesocosms on critical ecophysiological descriptors of P. scouleri. Generally, our results revealed a progressive deterioration of the plant overall physiological status. Surprisingly, photosynthetic parameters only indicated physiological stress once the first heat exposure ceased (i.e., recovery period). Warming induced elevated oxidative damage and a decline in nitrate uptake rates. By contrast, non-structural carbohydrates and growth rates remained unaffected. Our results highlight the importance of including recovery periods in this sort of experiments, as they reveal delayed stress responses. Further, the accumulative detrimental effects due to the exposure to consecutive intense MHWs indicate that these events can compromise the vitality of surfgrasses and the ecosystem services provided by their meadows.