Periodic Reporting for period 1 - PALAEOCON (Conservation palaeobiology of terrestrial and marine carbon sinks)
Período documentado: 2019-09-01 hasta 2022-08-31
The ecosystems that are able to accumulate and store carbon are of great importance in the context of current and future scenarios of Global Change. Peatlands and seagrass meadows are carbon sink ecosystems. Unfortunately, they are threatened by perturbations originated by both humans and climate, so the environmental and economic consequences of their loss are incalculable. Therefore, the conservation of natural carbon sinks has been proposed as a key objective in order to buffer carbon dioxide emissions, as recognised in the Paris Agreement in 2015. The processes and dynamics of these important ecosystems involve time scales from decades to millennia. However, owing to environmental monitoring covers a few decades at best, millennial-long environmental records capturing long-term dynamics can only be obtained using a palaeoecological approach. The overall aim of PALAEOCON is to use the palaeoecological record to obtain a millennial-long environmental monitoring of terrestrial and marine carbon sinks in order to understand the resilience of peatlands and seagrass meadows. The environmental archives selected are located in Spain, a country that would be severely affected by global change according to IPCC climate scenarios. We propose a multi-proxy approach combining biological and non-biological indicators on peatland cores and Posidonia oceanica mat cores. Using the information stored in these environmental archives we plan the detection of baselines and tipping points that could inform conservation. During the 10 months that the action has lasted, we have obtained several insights.
- Colorimetric and Fourier-transformed infrared spectroscopic analyses of peatland cores allowed us to find that for the peatlands analysed chromo-stratigraphical changes are an indirect proxy for organic matter content, so it can be used as a first approximation when planning further analyses. In addition, the spectroscopic results highlighted the importance of considering the molecular composition of the organic matter together with the elemental composition if information on mineralisation (i.e. carbon dioxide release) of the organic matter wants to be obtained.
- The palynological, charcoal and magnetic susceptibility analyses of P. oceanica mats provided information on human activities in the terrestrial environment that triggered soil erosion and had an impact on the amount of inorganic content entering the coastal area, impacting the organic matter accumulation in the seagrass ecosystem. Finally, the preliminary results of dinoflagellate cyst records from the seagrass cores have supported the study of fossil pigments in order to reconstruct the factors that regulated primary producers’ assemblages in P. oceanica meadows for the last eighteen centuries. Global climate factors explained the detected changes in algal assemblages that could, in turn, impact the seagrass ecosystem functioning.
- Colorimetric and Fourier-transformed infrared spectroscopic analyses of peatland cores allowed us to find that for the peatlands analysed chromo-stratigraphical changes are an indirect proxy for organic matter content, so it can be used as a first approximation when planning further analyses. In addition, the spectroscopic results highlighted the importance of considering the molecular composition of the organic matter together with the elemental composition if information on mineralisation (i.e. carbon dioxide release) of the organic matter wants to be obtained.
- The palynological, charcoal and magnetic susceptibility analyses of P. oceanica mats provided information on human activities in the terrestrial environment that triggered soil erosion and had an impact on the amount of inorganic content entering the coastal area, impacting the organic matter accumulation in the seagrass ecosystem. Finally, the preliminary results of dinoflagellate cyst records from the seagrass cores have supported the study of fossil pigments in order to reconstruct the factors that regulated primary producers’ assemblages in P. oceanica meadows for the last eighteen centuries. Global climate factors explained the detected changes in algal assemblages that could, in turn, impact the seagrass ecosystem functioning.
We worked on samples from several peatlands and several seagrass meadows from Spain. Studying the palaeoecology of peatlands throughout the analysis of peat cores, we aimed to understand the long-term dynamics of terrestrial carbon sinks, while through analysing P. oceanica mat cores from seagrass meadows we wanted to do the same for marine carbon sinks.
In the case of peatlands, we selected two peat cores from north-western Spain covering most of the Holocene for which the host laboratory at the USC already had palynological and geochemical results, as well as chronological frameworks thanks to age-depth models. We complemented the available proxy records with new analyses of non-biological indicators that have been fundamental for the training of the fellow: colorimetry of solids and FTIR-ATR spectroscopy. The two peatlands comprised a bog and a fen, so two different types of peatlands with diverse hydrological dynamics and carbon contents. The results highlight the importance of analysing not only the elemental composition of the peat organic matter, but also its molecular composition. In this way, we can obtain both an overview of the total carbon accumulated and also information on the potential loss of carbon owing to mineralisation (as a function of the proportion of labile components of the organic matter). In addition, analysing the colour of the peat in a quantitative manner allowed us to link colour and organic matter content. This is important as a first, fast and inexpensive screening of large sets of samples in order to plan further analyses.
In the case of the seagrass meadows, we selected five P. oceanica mat cores form two bays at Cabrera Island (Balearic Islands) covering the last two millennia, in collaboration with the partner organisation CEAB-CSIC. We have performed magnetic susceptibility, charcoal and palynological analyses on the seagrass mat samples. Magnetic susceptibility analyses were performed in the five cores, showing a synchronous trend of increasing values during the last centuries. Palynological and charcoal analyses are still in progress, and preliminary data suggest that charcoal records show the same trend than magnetic susceptibility and that terrestrial pollen records agree with larger human impact on the terrestrial landscape during the last centuries. Finally, we have obtained, for the first time in seagrass cores, dinoflagellate cysts (dinocysts) records. Our preliminary dinocysts results allowed supporting a study of fossil pigments on the same cores published in collaboration with the CEAB-CSIC. In this study we demonstrated that fossil pigments can be used to reconstruct algal communities in seagrass meadows and how these communities were affected by local and global environmental factors.
Several activities have been done to disseminate and communicate parts of the action to academic and non-academic beneficiaries. First, a journal paper has been published so far while further manuscripts will be sent to journals in the future once the proxy analyses are completed and the numerical analyses performed. Second, the fellow was invited as speaker in a conference organised at the USC for master students in which she presented the importance of palynological analyses. Third, the fellow was invited in a workshop for the general public as an expert in the study of botanical remains from archives. Finally, during the duration of the project, the fellow engaged in activities such as teaching undergraduate and master students, supervising dissertations, and grant writing; valuable resources towards a fruitful career as independent researcher.
In the case of peatlands, we selected two peat cores from north-western Spain covering most of the Holocene for which the host laboratory at the USC already had palynological and geochemical results, as well as chronological frameworks thanks to age-depth models. We complemented the available proxy records with new analyses of non-biological indicators that have been fundamental for the training of the fellow: colorimetry of solids and FTIR-ATR spectroscopy. The two peatlands comprised a bog and a fen, so two different types of peatlands with diverse hydrological dynamics and carbon contents. The results highlight the importance of analysing not only the elemental composition of the peat organic matter, but also its molecular composition. In this way, we can obtain both an overview of the total carbon accumulated and also information on the potential loss of carbon owing to mineralisation (as a function of the proportion of labile components of the organic matter). In addition, analysing the colour of the peat in a quantitative manner allowed us to link colour and organic matter content. This is important as a first, fast and inexpensive screening of large sets of samples in order to plan further analyses.
In the case of the seagrass meadows, we selected five P. oceanica mat cores form two bays at Cabrera Island (Balearic Islands) covering the last two millennia, in collaboration with the partner organisation CEAB-CSIC. We have performed magnetic susceptibility, charcoal and palynological analyses on the seagrass mat samples. Magnetic susceptibility analyses were performed in the five cores, showing a synchronous trend of increasing values during the last centuries. Palynological and charcoal analyses are still in progress, and preliminary data suggest that charcoal records show the same trend than magnetic susceptibility and that terrestrial pollen records agree with larger human impact on the terrestrial landscape during the last centuries. Finally, we have obtained, for the first time in seagrass cores, dinoflagellate cysts (dinocysts) records. Our preliminary dinocysts results allowed supporting a study of fossil pigments on the same cores published in collaboration with the CEAB-CSIC. In this study we demonstrated that fossil pigments can be used to reconstruct algal communities in seagrass meadows and how these communities were affected by local and global environmental factors.
Several activities have been done to disseminate and communicate parts of the action to academic and non-academic beneficiaries. First, a journal paper has been published so far while further manuscripts will be sent to journals in the future once the proxy analyses are completed and the numerical analyses performed. Second, the fellow was invited as speaker in a conference organised at the USC for master students in which she presented the importance of palynological analyses. Third, the fellow was invited in a workshop for the general public as an expert in the study of botanical remains from archives. Finally, during the duration of the project, the fellow engaged in activities such as teaching undergraduate and master students, supervising dissertations, and grant writing; valuable resources towards a fruitful career as independent researcher.
This project has delivered long-term ecological case studies on paradigmatic terrestrial and coastal marine carbon sinks. The palaeoecological outcomes will allow the unravelling of trends and changes in the ability to store carbon at decadal to millennial scales, as well as the human and climate drivers of those changes. This is the starting point for the conservation of the ecosystem services that carbon sinks provide. Therefore, our results are not only providing insights on the ecological functioning of peatland and seagrass meadows ecosystems, but will also have the potential to inform conservation thanks to the detection of i) baselines that will help to select background conditions for restoration, and ii) tipping points that will aid in understanding the perturbations that change the resilience and vulnerability of the carbon sink systems.