Benthic diatoms and foraminifera as indicators of coastal wetland habitats: application to palaeoenvironmental reconstruction in a Mediterranean Delta

Amb cinc capítols, la tesi doctoral combina l’estudi dels hàbitats presents, passats i futurs del Delta de l’Ebre, un dels ecosistemes d’aiguamolls més gran del Mediterrani occidental. S’han aplicat diferents aproximacions per cadascuna de les tres escales temporals: i) en el present, la utilitat de diatomees i foraminífers bentònics com a indicadors ecològics dels hàbitats del Delta de l’Ebre, ii) en el passat, l’ús de les comunitats de foraminífers preservades en el sediment per reconstruir els canvis associats a factors naturals i humans, i iii) en el futur, la distribució potencial dels hàbitats assumint un escenari de nul•la intervenció humana. Els resultats posen en evidència la capacitat de cadascun dels dos grups d’indicadors per caracteritzar de forma diferent tot el rang d’hàbitats deltaics, indicant que aquest coneixement pot ser útil en el context de futurs impactes del canvi climàtic (és a dir increment del nivell del mar i retrocés de la costa), ja que els models de distribució dels hàbitats són sensibles a variables eco-geogràfiques com l’elevació i distància a la costa. Per cadascun dels hàbitats identificats, s’han determinat diferents espècies indicadores de diatomees i foraminífers. Algunes d’aquestes espècies podrien detectar canvis primerencs en les comunitats degut a que els hàbitats estan afectats per múltiples factors d’estrès natural i antropogènic. Els resultats també mostren que quan es combinen les comunitats de foraminífers bentònics que habiten en la plana deltaica i els hàbitats marins adjacents, s’obté una nova eina per la reconstrucció paleoambiental en deltes. En el cas del Delta de l’Ebre, el registre de foraminífers de testimonis profunds datats amb carboni-14 va permetre rebutjar la hipòtesi que el Delta era un estuari abans de l’època dels Romans (fa uns 2000 anys). A una escala temporal inferior (10-100 anys), les comunitats de foraminífers indiquen canvis significatius en el tipus d’hàbitat com a resultat de l’introducció del cultiu intensiu de l’arròs. Aquests resultats aporten informació valuosa sobre les condicions de referència dels hàbitats del Delta de l’Ebre per tal d’informar futurs plans de restauració i monitoreig ambiental.En cinco capítulos, la tesis doctoral combina el estudio de los hábitats presentes, pasados y futuros del Delta del Ebro, uno de los humedales costeros más grandes del Mediterráneo occidental. Para cada una de las tres ventanas temporales se han aplicado distintas aproximaciones: i) en el presente, la utilidad de diatomeas y foraminíferos bentónicos como indicadores ecológicos de los hábitats del Delta, ii) en el pasado, el uso de las asociaciones de foraminíferos preservadas en el sedimento para reconstruir los cambios ligados a factores naturales y humanos, y iii) en el futuro, la distribución potencial de los hábitats asumiendo un escenario de nula intervención humana. Los resultados evidencian que cada uno de los dos grupos de indicadores bentónicos es capaz de caracterizar de forma distinta todo el rango de hábitats deltaicos, y señalan que este conocimiento puede ser aprovechable en el contexto de futuros impactos del cambio climático (incremento del nivel del mar y retroceso de la línea costera), debido a que los modelos de distribución de los hábitats son sensibles a variables eco-geográficas como por ejemplo la elevación y distancia al mar. Para cada uno de los hábitats identificados, se han determinado distintas especies indicadoras de diatomeas y foraminíferos. Algunas de estas especies podrían detectar cambios tempranos en las comunidades, debido a que los hábitats están sometidos a múltiples factores de estrés natural y antropogénico. Los resultados también evidencian que cuando se combinan las asociaciones de foraminíferos bentónicos que viven en la llanura deltaica y en los hábitats marinos adyacentes, se obtiene una nueva herramienta para la reconstrucción paleoambiental en deltas. Para el caso del Delta del Ebro, el registro de foraminíferos preservado en sondeos profundos y datados con carbono-14 permitieron rechazar la hipótesis que el Delta era un estuario antes de la época romana (hace 2000 años). A menores escalas de tiempo (10-100 años), las asociaciones de foraminíferos indican cambios significativos de hábitat como resultado de la introducción del cultivo intensivo del arroz. Estos resultados proporcionan información valiosa para determinar las condiciones de referencia en el Delta del Ebro y aportar información a futuros planes de restauración y monitoreo ambiental.In five chapters, this thesis combines the study of present, past and future habitats of the Ebro Delta, one of the largest coastal wetlands in the northwest Mediterranean. Different approaches are applied in each of the three temporal scales: i) in the present, the utility of benthic diatoms and foraminifera as ecological indicators of the Ebro Delta habitats, ii) in the past, the use of buried, well-preserved benthic foraminiferal assemblages to reconstruct natural and human-driven changes, and iii) in the future, the potential habitat distribution across the Delta plain assuming a scenario of no human disturbance. The results show the capacity of each group of indicators to distinctively characterise the whole range of deltaic habitats, and indicate that this knowledge may prove useful in the context of future climate change impacts (i.e. sea-level rise and coastal retreat), since habitat distribution models are sensitive to eco-geographic features such as elevation and distance to the coast. For each habitat type identified, diatom and foraminiferal indicator species are recognized. Some of these species have also a value for detecting early community changes, because habitats are affected by multiple natural and anthropogenic stressors. This thesis also shows that benthic foraminifera, when combines the assemblages inhabiting both the deltaic plain and the adjacent marine area, provide a new tool in palaeoenvironmental reconstruction of deltas. For the Ebro Delta case, the foraminiferal record of radiocarbon-dated boreholes rejected the hypothesis that the central delta plain was an estuary prior to the Roman period (i.e. 2000 years ago). At scales of 10s and 100s of years, down-core foraminiferal assemblages revealed habitat shifts, together with a significant correlation with organic matter increases as a result of human-mediated drainage inputs coming from rice paddies. This knowledge provides valuable information on background conditions for the Delta habitats to inform environmental restoration and monitoring schemes

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale

Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two–three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.This work was supported by a grant from the U.S. National Science Foundation (#DBI‐1639145) to the National Socio‐Environmental Synthesis Center (Rivershift Project). The work was also financially supported by the Catalan Government through the funding grant ACCIÓ‐Eurecat (Project AquaSCI‐2022)

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale

Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two-three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.info:eu-repo/semantics/publishedVersio

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale

ABSTRACT: Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two-three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides hytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the otherhand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries.This work was supported by a grant from the U.S. National Science Foundation (#DBI-1639145) to the National Socio-Environmental Synthesis Center (Rivershift Project). The work was also financially supported by the Catalan Government through the funding grant ACCIÓ-Eurecat (Project AquaSCI-2022)

Women in limnology: From a historical perspective to a present-day evaluation

Research in limnology is nurtured by the work of many fascinating and passionate women, who have contributed enormously to our understanding of inland waters. Female limnologists have promoted and established the bases of our knowledge about inland waters and fostered the need of protecting the values of those ecosystems. However, on numerous occasions, their contribution to the advancement of limnology has not been duly recognized. Here, we review the presence of women in limnology through the history of the discipline: from the pioneers who contributed to the origins to present day' developments. We aim at visibilizing those scientists and establish them as role models. We also analyze in a simple and illustrative way the current situation of women in limnology, the scientific barriers they must deal with, and their future prospects. Multiple aspects fostering the visibility of a scientist, such as their presence in conferences, awards, or representation in societal or editorial boards show a significant gap, with none of those aspects showing a similar visibility of women and men in limnology. This article raises awareness of the obstacles that women in limnology faced and still face, and encourages to embrace models of leadership, scientific management, and assessment of research performance far from those commonly established.info:eu-repo/semantics/publishedVersio

Left atrial geometry and outcome of atrial fibrillation ablation: results from the multicentre LAGO-AF study

Aims: Left atrial (LA) remodelling is a key determinant of atrial fibrillation (AF) ablation outcome. Optimal methods to assess this process are scarce. LA sphericity is a shape-based parameter shown to be independently associated to procedural success. In a multicentre study, we aimed to test the feasibility of assessing LA sphericity and evaluate its capability to predict procedural outcomes. Methods and results: This study included consecutive patients undergoing first AF ablation during 2013. A 3D model of the LA chamber, excluding pulmonary veins and LA appendage, was used to quantify LA volume (LAV) and LA sphericity (≥82.1% was considered spherical LA). In total, 243 patients were included across 9 centres (71% men, aged 56 ± 10 years, 44% with hypertension and 76% CHA2DS2-VASc ≤ 1). Most patients had paroxysmal AF (66%) and underwent radiofrequency ablation (60%). Mean LA diameter (LAD), LAV, and LA sphericity were 42 ± 6 mm, 100 ± 33 mL, and 82.6 ± 3.5%, respectively. Adjusted Cox models identified paroxysmal AF [hazard ratio (HR 0.54, P = 0.032)] and LA sphericity (HR 1.87, P = 0.035) as independent predictors for AF recurrence. A combined clinical-imaging score [Left Atrial Geometry and Outcome (LAGO)] including five items (AF phenotype, structural heart disease, CHA2DS2-VASc ≤ 1, LAD, and LA sphericity) classified patients at low (≤2 points) and high risk (≥3 points) of procedural failure (35% vs. 82% recurrence at 3-year follow-up, respectively; HR 3.10, P < 0.001). Conclusion: In this multicentre, real-life cohort, LA sphericity and AF phenotype were the strongest predictors of AF ablation outcome after adjustment for covariates. The LAGO score was easy to implement, identified high risk of procedural failure, and could help select optimal candidates. Clinical Trial Registration Information: NCT02373982 (http://clinicaltrials.gov/ct2/show/NCT02373982)

Paleolimnological responses of Ecuadorian páramo lakes to local and regional stressors over the last two millennia

Increasing surface air temperatures and human influences (e.g., agriculture, livestock grazing, tourism) are altering lacustrine ecosystems in the South American Andean páramo, and these influences are evident in changes in the diatom-species composition in sediment cores from the region that span the last ~ 150 years. Existing studies are limited by their short temporal scales and limited spatial extent. We analyzed two sediment cores spanning the last two millennia from the northern (Laguna Piñan) and southern (Laguna Fondococha) Andean páramo of Ecuador to provide a longer-term perspective on lake dynamics. Both lakes show shifts in the dominant diatoms through time. Fondococha diatoms shifted in dominance between two Aulacoseira species and in the planktic to benthic ratio, and these shifts are interpreted as evidence of changing lake level. The inferred shifts are corroborated by changes in sediment geochemistry. Piñan shows a directional shift in the diatom assemblage over the period of the record, from benthic diatoms tolerant of high dissolved organic carbon (DOC), low pH, and low nutrients, to an assemblage characteristic of lower DOC, higher pH, nutrients and lake levels. Shifts in Piñan’s diatoms are correlated with tephra layers in the sediment, suggesting that local volcanic deposition may have been responsible for altering the catchment and lake geochemistry. This is supported by relatively high δ13C values in organic matter associated with tephra layers, which become more negative up-section. Our study suggests that remote lakes in spatially heterogenous montane regions act as sentinels of different facets of environmental change and provide insights into Andean ecosystem responses to environmental perturbations.info:eu-repo/semantics/acceptedVersio

Diatom and waterbodies database of tropical South America

This database consists of two different datasets: diatom presence/absence data and associated environmental variables of the waterbodies of the individual regions of stud

Ecosystem-level effects of re-oligotrophication and N:P imbalances in rivers and estuaries on a global scale

Altres ajuts: by the Catalan Government through the funding grant ACCIÓ-Eurecat (Project AquaSCI-2022).Trends and ecological consequences of phosphorus (P) decline and increasing nitrogen (N) to phosphorus (N:P) ratios in rivers and estuaries are reviewed and discussed. Results suggest that re-oligotrophication is a dominant trend in rivers and estuaries of high-income countries in the last two-three decades, while in low-income countries widespread eutrophication occurs. The decline in P is well documented in hundreds of rivers of United States and the European Union, but the biotic response of rivers and estuaries besides phytoplankton decline such as trends in phytoplankton composition, changes in primary production, ecosystem shifts, cascading effects, changes in ecosystem metabolism, etc., have not been sufficiently monitored and investigated, neither the effects of N:P imbalance. N:P imbalance has significant ecological effects that need to be further investigated. There is a growing number of cases in which phytoplankton biomass have been shown to decrease due to re-oligotrophication, but the potential regime shift from phytoplankton to macrophyte dominance described in shallow lakes has been documented only in a few rivers and estuaries yet. The main reasons why regime shifts are rarely described in rivers and estuaries are, from one hand the scarcity of data on macrophyte cover trends, and from the other hand physical factors such as peak flows or high turbidity that could prevent a general spread of submerged macrophytes as observed in shallow lakes. Moreover, re-oligotrophication effects on rivers may be different compared to lakes (e.g., lower dominance of macrophytes) or estuaries (e.g., limitation of primary production by N instead of P) or may be dependent on river/estuary type. We conclude that river and estuary re-oligotrophication effects are complex, diverse and still little known, and in some cases are equivalent to those described in shallow lakes, but the regime shift is more likely to occur in mid to high-order rivers and shallow estuaries

My Teaching Is Not Gender Biased, Is It?

Gender bias and underrepresentation in society are likewise pervasive in Science, Technology, Engineering, and Math fields and are difficult to balance out. In Aquatic Sciences, large efforts have been made to increase awareness on Diversity, Equity, Inclusion, and Justice and yet, gender- and diversity-gaps remain. Reducing these gaps requires work in different dimensions: individual, community, education, and society. As scientists, we can act at all those levels in various ways and one effective approach is through education. When teaching and supervising students we can be role models, actively, consciously, and explicitly including diverse and historically underrepresented scientists in our teaching material or creating an inclusive class environment. But, where to start?CML participation at the conference was funded by the German Research Foundation (DFG, FlowReSet project ME 5498/2-1) and the work has been developed within the funding framework of NutFlows (ME 5498/3-1). AP was supported by the Beatriu de Pinós postdoctoral program under the Ministry of Research and Universities of the Government of Catalonia (Grant Reference No. 2020 BP-00237). PR-L and AF were supported by MCIN/AEI through the Juan de la Cierva - Incorporación program (IJC2019-041601-I and IJC2019-039181-I).Peer reviewe