Browsing by Author "Gurgel, Carlos F. D."
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- Global impacts of projected climate changes on the extent and aboveground biomass of mangrove forestsPublication . Gouvêa, Lidiane; A, Serrão; Cavanaugh, Kyle; Gurgel, Carlos F. D.; Horta, Paulo A.; Assis, JorgeAim: Over the past 50 years, anthropogenic activities have led to the disappearance of approximately one-third of the world's mangrove forests and their associated ecosystem services. The synergetic combined effect of projected climate change is likely to further impact mangroves in the years to come, whether by range expansions associated with warming at higher latitudes or large-scale diebacks linked to severe droughts. We provide an estimate of future changes in the extent and aboveground biomass (AGB) of mangrove forests at global scales by considering contrasting Representative Concentration Pathway scenarios (decade 2090-2100 under RCP 2.6 in line with the Paris Agreement expectations, and RCP 8.5 of higher emissions). Location: Global. Methods: Boosted regression trees fitted occurrence and AGB of mangroves against high-resolution biologically meaningful data on air temperature, precipitation, wave energy, slope and distance to river Deltas. Results: On the global scale, models produced for present-day conditions retrieved high accuracy scores and estimated a total area of 12,780,356 ha and overall biomass of 2.29 Pg, in line with previous estimates. Model projections showed poleward shifts along temperate regions, which translated into comparable gains in total area, regardless of the RCP scenario (area change RCP 2.6: 17.29%; RCP 8.5: 15.77%). However, biomass changes were dependent on the emission scenario considered, remaining stable or even increasing under RCP 2.6, or undergoing severe losses across tropical regions under RCP 8.5 (overall biomass change RCP 2.6: 12.97%; RCP 8.5: -11.51%). Such losses were particularly aggravated in countries located in the Tropical Atlantic and Eastern Pacific, and the Western and Eastern Indo-Pacific regions (regions with losses above similar to 20% in overall biomass). Conclusions: Our global estimates highlight the potential effect of future climate changes on mangrove forests and how broad compliance with the Paris Agreement may counteract severe trajectories of loss. The projections made, also provided at the country level, serve as new baselines to evaluate changes in mangrove carbon sequestration and ecosystem services, strongly supporting policy-making and management directives, as well as to guide restoration actions considering potential future changes in niche availability.
- Golden carbon of Sargassum forests revealed as an opportunity for climate change mitigationPublication . Gouvêa, Lidiane P.; Assis, Jorge; Gurgel, Carlos F. D.; A, Serrão; Silveira, Thiago C.L.; Santos, Rui; Duarte, Carlos M.; Peres, Leticia M. C.; Carvalho, Vanessa F.; Batista, Manuela; Bastos, Eduardo; Sissini, Marina N.; Horta, Paulo A.Marine climate change mitigation initiatives have recently attracted a great deal of interest in the role of natural carbon sinks, particularly on coastal systems. Brown seaweeds of the genus Sargassum are the largest canopyforming algae in tropical and subtropical environments, with a wide global distribution on rocky reefs and as floating stands. Because these algae present high amounts of biomass, we suggest their contribution is relevant for global carbon stocks and consequently for mitigating climate change as CO2 remover. We modelled global distributions and quantified carbon stocks as above-ground biomass (AGB) with machine learning algorithms and climate data. Sargassum AGB totaled 13.1 Pg C at the global scale, which is a significant amount of carbon, comparable to other key marine ecosystems, such as mangrove forests, salt marshes and seagrass meadows. However, specific techniques related to bloom production and management, or the utilization of biomass for biomaterials, should be fostered.
- Phenotypic plasticity in sargassum forests may not counteract projected biomass losses along a broad latitudinal gradientPublication . Gouvêa, Lidiane; Horta, Paulo A.; Fragkopoulou, Eliza; Gurgel, Carlos F. D.; Peres, Leticia M. C.; Bastos, Eduardo; Ramlov, Fernanda; Burle, Giulia; Koerich, Gabrielle; Martins, Cintia D. L.; Serrao, Ester; Assis, JorgePhenotypic plasticity and local adaptation can adjust individual responses to environmental changes across species' ranges. Studies addressing the implications of such traits have been underrepresented in the marine environment. Sargassum cymosum represents an ideal model to test phenotypic plasticity, as populations along the southwestern Atlantic Ocean display a sharp decrease in abundance toward distributional range limits. We (1) characterized the macroecological environment of S. cymosum across a latitudinal gradient, (2) evaluated potential differences in ecophysiological adjustments (biomass, photosynthetic pigments, phenolic compounds, total soluble sugars and proteins, and carbon-nitrogen-CN-content), and (3) tested for differences in thermal tolerance based on time series analyses produced from the present to contrasting representative concentration pathways scenarios (RCP) of future climate changes. Our results showed distinct macroecological environments, corresponding to tropical and warm temperate conditions, driving biomass and ecophysiological adjustments of S. cymosum. Populations from the two environments displayed contrasting thermal tolerances, with tropical individuals better coping with thermal stress when compared to more temperate ones (lethal temperatures of 33 degrees C vs. 30 degrees C); yet both populations lose biomass in response to increasing thermal stress while increasing secondary metabolites (for example, carotenoids and phenolic compounds) and decrease chlorophyll's content, Fv/Fm, total soluble sugars concentration and CN ratio, owing to oxidative stress. Despite evidence for phenotypic plasticity, significant future losses might occur in both tropical and warm temperate populations, particularly under the no mitigation RCP scenario, also known as the business as usual (that is, 8.5). In this context, broad compliance with the Paris Agreement might counteract projected impacts of climate change, safeguarding Sargassum forests in the years to come.