COVID‐19 and protected areas: Impacts, conflicts, and possible management solutions

Abstract: During the first wave of the COVID‐19 pandemic, management authorities of numerous Protected Areas (PAs) had to discourage visitors from accessing them in order to reduce the virus transmission rate and protect local communities. This resulted in social–ecological impacts and added another layer of complexity to managing PAs. This paper presents the results of a survey in Snowdonia National Park capturing the views of over 700 local residents on the impacts of COVID‐19 restrictions and possible scenarios and tools for managing tourist numbers. Lower visitor numbers were seen in a broadly positive way by a significant number of respondents while benefit sharing issues from tourism also emerged. Most preferred options to manage overcrowding were restricting access to certain paths, the development of mobile applications to alert people to overcrowding and reporting irresponsible behavior. Our findings are useful for PA managers and local communities currently developing post‐COVID‐19 recovery strategies

Deep drilling reveals massive shifts in evolutionary dynamics after formation of ancient ecosystem

The scarcity of high-resolution empirical data directly tracking diversity over time limits our understanding of speciation and extinction dynamics and the drivers of rate changes. Here, we analyze a continuous species-level fossil record of endemic diatoms from ancient Lake Ohrid, along with environmental and climate indicator time series since lake formation 1.36 million years (Ma) ago. We show that speciation and extinction rates nearly simultaneously decreased in the environmentally dynamic phase after ecosystem formation and stabilized after deep-water conditions established in Lake Ohrid. As the lake deepens, we also see a switch in the macroevolutionary trade-off, resulting in a transition from a volatile assemblage of short-lived endemic species to a stable community of long-lived species. Our results emphasize the importance of the interplay between environmental/climate change, ecosystem stability, and environmental limits to diversity for diversification processes. The study also provides a new understanding of evolutionary dynamics in long-lived ecosystems

Scientific drilling projects in ancient lakes: integrating geological and biological histories

Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information, e.g., through molecular dating of molecular phylogenies. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets for creating an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep drilling projects

Mediterranean winter rainfall in phase with African monsoons during the past 1.36 million years

Mediterranean climates are characterized by strong seasonal contrasts between dry summers and wet winters. Changes in winter rainfall are critical for regional socioeconomic development, but are difficult to simulate accurately1 and reconstruct on Quaternary timescales. This is partly because regional hydroclimate records that cover multiple glacial–interglacial cycles2,3 with different orbital geometries, global ice volume and atmospheric greenhouse gas concentrations are scarce. Moreover, the underlying mechanisms of change and their persistence remain unexplored. Here we show that, over the past 1.36 million years, wet winters in the northcentral Mediterranean tend to occur with high contrasts in local, seasonal insolation and a vigorous African summer monsoon. Our proxy time series from Lake Ohrid on the Balkan Peninsula, together with a 784,000-year transient climate model hindcast, suggest that increased sea surface temperatures amplify local cyclone development and refuel North Atlantic low-pressure systems that enter the Mediterranean during phases of low continental ice volume and high concentrations of atmospheric greenhouse gases. A comparison with modern reanalysis data shows that current drivers of the amount of rainfall in the Mediterranean share some similarities to those that drive the reconstructed increases in precipitation. Our data cover multiple insolation maxima and are therefore an important benchmark for testing climate model performance

Terrigenous organic matter in sediments of the eastern equatorial Atlantic - distribution, reactivity, and relation to Late Quaternary climate

This study focuses on factors controlling temporal variations in quantity and quality of terrigenous organic matter (terrigenous OM) export from tropical Africa to the continental margin by two major rivers, the Congo and the Niger. High-resolution multi-proxy investigations were performed on late Quaternary sections of ODP Site 1075 (Congo deep-sea fan, 1200 - 9 ka) and core GeoB 4901 (Niger deep-sea fan, 245 - 0 ka) to characterize the bulk sedimentary OM and to reappraise the role of terrigenous OM. At both river fans, supply of terrigenous OM is closely connected to the dynamics of the African hydrological cycle (humidity/aridity, chemical weathering intensity, fluvial run-off, vegetation) that is primarily determined by cyclic fluctuations of insolation. Significant differences in OM quality and the dynamics of OM sedimentation and preservation however distinguish the two river systems. It is a fundamental result of this study that soil organic matter (SOM) is a major bulk OM component in the Congo and Niger deep-sea fan sediments. Different types of SOM (stable/reactive, nitrogen-rich/-poor, 12C-depleted/-enriched) exported during arid and humid climate stages determine the geochemical characteristics of the deep-sea fan sediments, especially C/N ratios and bulk d13Corg signatures. Due to low C/N ratios that may even reach values of marine OM and due to depletion of 12C, both resulting from intense humification processes, SOM may lead to massive underestimation of terrigenous OM proportions in marine sediments. Additionally, the supply of heavy terrigenous OM originating from C4 plants significantly shifts bulk d13Corg signatures towards marine values especially at the Niger fan where C4 grasses are an important element of the vegetation cover throughout the late Quaternary. The contribution of SOM and C4 plant remains thus rules out the conventional application of two end-member models for C/N and bulk d13Corg to assess marine and terrigenous OM amounts

Terrigenes organisches Material in Sedimenten des östlichen äquatorialen Atlantiks - Verbreitung, Reaktivität und Beziehung zum spätquartären Klima

This study focuses on factors controlling temporal variations in quantity and quality of terrigenous organic matter (terrigenous OM) export from tropical Africa to the continental margin by two major rivers, the Congo and the Niger. High-resolution multi-proxy investigations were performed on late Quaternary sections of ODP Site 1075 (Congo deep-sea fan, 1200 - 9 ka) and core GeoB 4901 (Niger deep-sea fan, 245 - 0 ka) to characterize the bulk sedimentary OM and to reappraise the role of terrigenous OM. At both river fans, supply of terrigenous OM is closely connected to the dynamics of the African hydrological cycle (humidity/aridity, chemical weathering intensity, fluvial run-off, vegetation) that is primarily determined by cyclic fluctuations of insolation. Significant differences in OM quality and the dynamics of OM sedimentation and preservation however distinguish the two river systems. It is a fundamental result of this study that soil organic matter (SOM) is a major bulk OM component in the Congo and Niger deep-sea fan sediments. Different types of SOM (stable/reactive, nitrogen-rich/-poor, 12C-depleted/-enriched) exported during arid and humid climate stages determine the geochemical characteristics of the deep-sea fan sediments, especially C/N ratios and bulk d13Corg signatures. Due to low C/N ratios that may even reach values of marine OM and due to depletion of 12C, both resulting from intense humification processes, SOM may lead to massive underestimation of terrigenous OM proportions in marine sediments. Additionally, the supply of "heavy" terrigenous OM originating from C4 plants significantly shifts bulk d13Corg signatures towards "marine" values especially at the Niger fan where C4 grasses are an important element of the vegetation cover throughout the late Quaternary. The contribution of SOM and C4 plant remains thus rules out the conventional application of two end-member models for C/N and bulk d13Corg to assess marine and terrigenous OM amounts

Organic matter in river-influenced continental margin sediments:The land-ocean and climate linkage at the Late Quaternary Congo fan (ODP Site 1075)

Author Posting. © American Geophysical Union 2003. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 4 (2003): 1109, doi:10.1029/2003GC000590.Late Quaternary sections (1.2 Ma) of ODP-Site 1075 from the Congo deep-sea fan are investigated to reconstruct variations of terrigenous organic matter supply to the eastern equatorial Atlantic. To characterize the organic matter (OM) with regard to marine and terrigenous amounts we used elemental analysis (C, N, S), stable carbon isotopes (bulk δ13Corg), Rock-Eval pyrolysis, and terrigenous biomarkers (lignin phenols from CuO oxidation). The records of total organic carbon (TOC) contents, Corg/Ntot ratios, bulk OM degradation rates (Corg/Corg*), and the ratios of hydrocarbons (HC) from low-mature versus HC from high-mature OM (lm/hm) reveal pronounced cyclic changes in OM abundance, preservation, and reactivity that are closely related to the precessional controlled record of insolation, and thus, to variations in upwelling intensity and fluvial run-off. Primary productivity off the Congo is stimulated by both, enhanced nutrient supply in response to trade-induced upwelling during arid African climates (insolation minima) and fluvial nutrient delivery during humid stages (following insolation maxima), especially due to the contribution of dissolved silica that is taken up preferably by diatoms. However, results stemming from a multiparameter approach reveal that the fluvial supply of degraded OM and black carbon (BC) associated with fine-grained sediments from soil erosion is a decisive factor for the preservation of marine OM and, in addition, significantly influences the geochemical signature of bulk and terrigenous OM. Riverine and eolian supply of C4 plant matter, as well as enhanced concentrations of BC, during arid and arid-to-humid transitional climate stages, may lead to a severe underestimation of terrigenous organic carbon, if its amount is calculated from bulk isotopic ratios using binary end-member models. During the humid stages, it is the massive supply of 13C-enriched soil OM with low Corg/Ntot ratios that may suggest a mainly marine composition of bulk OM. In fact, terrigenous OM governs bulk OM geochemical signatures in the sediments of the Congo deep-sea fan, a result that is contradictory to earlier studies, especially to the conventional interpretation of the bulk δ13Corg signal.This research was funded by the Deutsche Forschungsgemeinschaft, grant Wa 1036/5, and kindly supported by the Max-Planck Society

Compound-specific isotopic analysis of fatty acids in three soil profiles to estimate organic matter turnover in agricultural soils.

9 páginas.- Presentación nº 18526 en EGU General Assembly 2020, Online, 4–8 May 2020Soil lipids encompass substances of mainly plant or microbial origin that are insoluble in water and soluble in organic solvents such as ether, hexane, benzene, chloroform or dichloromethane. This soil organic fraction is of great interest because it encompasses biomarkers associated to soil microbial communities, i.e. Gram positive/negative bacteria, mycorrhizae, actinomycetes, etc. and because of its transitory nature that provides insights into soil organic matter (SOM) dynamics and soil carbon turnover. Compound-specific isotope analysis (CSIA) have been used in biomarker studies to investigate the assimilation of carbon from external inputs into SOM. This study determined the distribution and d13C composition of fatty acids as dominant part of the soil lipid fraction to assess turnover times in agricultural practice. Soil samples were taken from three depth intervals (0-5, 5-20, 20-40 cm) from a Mediterranean agricultural soil at ¿La Hampa¿ experimental station used for a crop rotation experiment with wheat (C3 plant) and maize (C4 plant). Using the C4 biosynthetic pathway, maize discriminates less strongly against 13C, i.e. d13C values of fatty acids originating from maize are less negative than those of fatty acids from wheat. Soil lipids were extracted using a DCM:MeOH (3:1) solvent mixture. Fatty acids were transmethylated with MeOH:acetyl chloride (30:1) to form fatty acid methyl esters (FAMEs) while the hydroxy groups of hydroxy acids, alcohols, sterols and other compounds were silylated using BSTFA prior to analysis by gas-chromatography combustion chamber isotope ratio mass spectrometry (GC-C-IRMS) for carbon isotope ratios. Compounds were identified through their mass spectra by gas-chromatography mass spectrometry (GC-MS) and quantified by gas chromatography with flame ionization detection (GC-FID). Only two maize harvests after wheat cultivation, a significant 13C enrichment of up to 2 ¿ was found in the saturated C20, C22 and C23 FAMEs and the mono-unsaturated C22 FAME and of up to 5 ¿ in the leaf wax-derived C29 and C31 n-alkanes relative to the control treatments without maize input. No significant differences, however, were found for alcohols and hydroxy acids. These differences may respond to the high specificity of the long-chain n-alkanes from plant origin, whereas the other compounds FAMEs, and mainly alcohols and hydroxyl acids are less specific plant markers and may have a diverse origin. No significant differences in the isotopic composition were observed at different depths within treatments apart from a slight d13C enrichment of 1.5 ¿ in the upper soil layer (0-5 cm) in the maize plots relative to the deeper layers. It is worth noticing that SOM content remained very low (< 1.3%) over the entire duration of the experiment, with no significant differences despite the high amount of C4 biomass presumably added to the soil during the two growth periods. Together with the d13C enrichment observed in the maize plots, this points to high mineralization rates in these soils and implies both a rapid turnover of plant debris into the SOM.Ministerio de Ciencia Innovación y Universidades (MICIU) for INTERCARBON project (CGL2016-78937-R). L. San Emeterio also thanks MICIU for funding FPI research grants (BES-2017-07968). Mrs Desiré Monis is acknowledged for technical assistance