Alfred Wegener Institute for Polar and Marine Research
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Operational perspectives for biodiversity indicators
Get PDFAbstract Smart biodiversity indicators are needed not only for assessing and managing biodiversity (change) but also for informing target setting for environmental policies. This need has created a plethora of indicator frameworks, which are widely debated in terms of their design and usefulness. We propose that these discussions would benefit from more clearly separating different types of indicators and more operationally linking them to management targets and biodiversity goals. Decision makers often consider the multitude of biodiversity indicators as being complicated , whereas scientists emphasize that they barely reflect how complex biodiversity is. It is therefore important to differentiate clearly between indicators for diagnosing (the drivers of) biodiversity change and indicators for steering policies. While the former must be scalable in time and space and reflect the full complexity of biodiversity, the latter need long‐term visions and simplicity. Management targets such as proportions of protected areas or mitigation of biodiversity drivers have the advantage of being operation‐oriented, well quantifiable and immediately responsive to change. Achieving a management target, however, does not necessarily equal achieving a biodiversity goal. Likewise, management indicators that track how well management targets are achieved cannot replace diagnostic or steering indicators. Solution: Biodiversity goals such as ‘bending the curve’ can only be achieved by closely linking diagnosis, steering and management, while accepting that their distinct design principles need to be addressed. Being aware and accepting such tailored types of different indicators and management targets could strongly improve the interplay between science and policy to reverse negative biodiversity trends in the future.
Zusammenfassung Intelligente Biodiversitätsindikatoren werden benötigt, um Zustand und Veränderung der Biodiversität zu bewerten und zu steuern, aber auch als Grundlage für die Zielsetzung in der Umweltpolitik. Dieser Bedarf hat zu einer Vielzahl von Indikatorsystemen geführt, deren Gestaltung und Nützlichkeit kontrovers diskutiert werden. Wir schlagen vor, diese Diskussionen durch eine klarere Trennung der verschiedenen Arten von Indikatoren und eine stärkere operative Verknüpfung mit Managementzielen und Biodiversitätszielen zu bereichern. Entscheidungsträger halten die Vielzahl der Biodiversitätsindikatoren oft für kompliziert, während Wissenschaftler betonen, dass sie kaum die reale Komplexität der Biodiversität widerspiegeln. Daher ist es wichtig, klar zwischen Indikatoren zur Diagnose (der Trends und Treiber) von Biodiversitätsveränderungen und Indikatoren zur Steuerung von Politikmaßnahmen zu unterscheiden. Während erstere zeitlich und räumlich skalierbar sein und die gesamte Komplexität der Biodiversität widerspiegeln müssen, erfordern letztere langfristige Visionen und Einfachheit. Managementziele wie der Anteile geschützter Gebiete oder die Minderung der Einflussfaktoren auf die Biodiversität haben den Vorteil, dass sie handlungsorientiert und gut quantifizierbar sind sowie unmittelbar auf Veränderungen reagieren. Das Erreichen eines Managementziels ist jedoch nicht unbedingt gleichbedeutend mit dem Erreichen eines Biodiversitätsziels. Ebenso können Managementindikatoren, die verfolgen, wie gut Managementziele erreicht werden, Diagnose‐ oder Steuerungsindikatoren nicht ersetzen. Biodiversitätsziele wie ‘bending the curve’ können nur durch eine enge Verknüpfung von Diagnose, Steuerung und Management erreicht werden, wobei ihre unterschiedlichen Gestaltungsprinzipien berücksichtigt werden müssen. Das Bewusstsein für und die Akzeptanz solcher unterschiedlicher Indikatoren und Ziele könnte das Zusammenspiel zwischen Wissenschaft und Politik erheblich verbessern, um negative Biodiversitätstrends in Zukunft umzukehren
Deep-sea corals near cold seeps associate with sulfur-oxidizing chemoautotrophs in the family Ca. Thioglobaceae
Get PDFBackground
Corals are known for their symbiotic relationships, yet there is limited evidence of chemoautotrophic associations. This is despite some corals occurring near cold seeps where chemosymbiotic fauna abound including mussels that host sulfur-oxidizing chemoautotrophs from the SUP05 cluster (family Ca. Thioglobaceae). We investigated whether corals near cold seeps associate with related bacteria and report here that these associations are widespread.
Results
We screened corals, water, and sediment for Thioglobaceae using 16S metabarcoding and found ASVs associated with corals at high relative abundance (10 – 91%). These ASVs were specific to coral hosts, absent in water samples, and rare or absent in sediment samples. Using metagenomics and transcriptomics, we assembled the genome of one phylotype associated with Paramuricea sp. B3 (ASV 4) which contained the genetic potential to oxidize sulfur and fix carbon, and confirmed that these pathways were transcriptionally active. Furthermore, its relative abundance was negatively correlated with the stable isotopic composition of its host coral’s tissue suggesting some contribution of chemoautotrophy to the coral holobiont.
Conclusions
We propose that some lineages of Thioglobaceae may facultatively supplement the diet of their host corals through chemoautotrophy at seeps or may provide essential amino acids or vitamins. This is the first documented association between chemoautotrophic symbionts and corals at seeps and suggests that the footprint of chemosynthetic environments is wider than currently understood
Cuerpos-sosteniendo-cuerpos: los temblores de los territorio-cuerpo-tierra de mujeres y las respuestas feministas a los terremotos en la Ciudad de México
Get PDFLos territorios son espacios políticos y vividos, representados colectivamente a través de prácticas cotidianas pasadas y presentes e interacciones entre humanos y no humanos. Los movimientos Indígenas y feministas en Abya Yala (América Latina) llaman al entendimiento plural de los territorios, los cuerpos y la tierra, como inseparables y co-constituidos —territorio-cuerpo-tierra. Basadas en esta relacionalidad analizamos los terremotos del 19 de septiembre de 1985 y de 2017 en México, los cuales transformaron radicalmente la vida de miles de personas, en particular aquéllas con trabajos precarizados. A partir de entrevistas en profundidad realizadas con las activistas participantes en las brigadas de respuesta a desastres, nos centramos en las experiencias de las integrantes de la Brigada Feminista, quienes metafórica y físicamente sostuvieron —y lo siguen haciendo— los cuerpos de mujeres marginalizadas, interrumpiendo la configuración de territorios de violencia para reclamar el acceso a los espacios y a la justicia. Esta brigada se movilizó para proteger los cuerpos de las mujeres no solo de los impactos del terremoto, sino también de la violencia capitalista y patriarcal. Surge aquí, la “sororidad”, como una forma de acto colectivo, una práctica territorial de unirse para resistir las violencias de género y la opresión, y luchar por la supervivencia y expansión de territorios más habitables y seguros para las mujeres. Sostenemos que es necesaria una política relacional del lugar en la academia, que cuestione la separación de los territorios, los cuerpos y los desastres para escuchar, aprender y abrir espacios para las propuestas territoriales contrahegemónicas
Temperature Variability on Coral Reefs Versus Gridded SST – The Long and the Short of It
Get PDFAbstract Coral‐based temperature reconstructions and gridded sea‐surface‐temperature (gSST) data sets both provide valuable insights into tropical climate variability. However, coral records often exhibit greater interannual to decadal variability than is observed in gSST products or Earth System Models (ESMs). This discrepancy is often attributed to large differences in spatial scale: coral records reflect conditions over areas of only a few square centimeters, while gSST and ESM grid cells span 1 to 10,000 km 2 . In situ temperature loggers on coral reefs allow us to isolate the effects of spatial scale from other non‐climatic influences on coral temperature records. Many logger studies focus on hourly to monthly timescales, temperature biases, and whether gSST can capture temperature extremes associated with coral bleaching and mortality; however, paleoclimate reconstructions provide an understanding of variability on longer timescales. Here, we compare the power spectral density and coherence of logger temperature and gSST on daily to decadal timescales using logger data from 42 sites on the Great Barrier Reef. We find that temperature variations recorded by loggers on reefs are well correlated with and have the same amplitude as gSST variations at decadal to annual timescales. Therefore, the excess decadal variability commonly seen in coral‐based temperature reconstructions cannot be attributed to a general effect of spatial scale.
Plain Language Summary Coral‐based temperature records are used to study past ocean temperatures. However, these records sometimes show more year‐to‐year and decade‐to‐decade variation than gridded temperature data sets from satellite‐ and ship‐based measurements. One possible explanation is that corals measure temperature at a very small local scale, while global data sets average conditions over large areas. To test this idea, we analyzed data from temperature loggers placed at 42 sites across the Great Barrier Reef and compared them to gridded sea‐surface temperature (gSST) data sets. We looked at how well the two matched at timescales from days to decades. Our results show that the variability of reef logger temperatures and gSST is very similar at annual to decadal timescales. This means that the extra variability often seen in coral‐based temperature reconstructions is unlikely to be caused by differences in spatial scale alone.
Key Points Gridded sea‐surface‐temperature (gSST) and in situ loggers record similar temperature variations on decadal to monthly timescales Excess variability in coral‐based temperature reconstructions relative to gSST is not due to differences in spatial scal
Folding due to anisotropy in ice, from drill-core-scale cloudy bands to km-scale internal reflection horizons
Get PDFAbstract. Upright folds in ice sheets are observed on the cm scale in cloudy bands in drill cores and on the km scale in radargrams. We address the question of the folding mechanism for these folds by analysing the power spectra of fold trains to obtain the amplitude as a function of wavelength signal. Classical Biot-type buckle folds due to a rheological contrast between layers develop a characteristic wavelength, visible as a peak in the power spectrum. Power spectra of ice folds, however, follow a power law, with a steady increase in amplitude with wavelength. Such a power spectrum is also observed in a folded, highly anisotropic biotite schist and in a numerical simulation of the deformation of ice Ih with a strong alignment of the basal planes parallel to the shortening direction. This suggests that the folds observed in ice are primarily due to the strong mechanical anisotropy of ice, which tends to have a strong lattice preferred orientation due to ice-sheet flow
Late Holocene Human Impact on Tropical Soil Erosion in the Maritime Continent
Get PDFAbstract Human activities have profoundly modified the fluxes in the global sediment cycle. However, the anthropogenic forcing on soil erosion beyond instrumental records or historical documentation is largely unknown. Here we analyze markers for low‐intensity fires and soil erosion in East Java over the past 5,000 years. We find evidence of a substantial human impact on fire occurrence due to the onset/intensification of swidden cultivation around 3,500 years ago, in the absence of changes in regional hydroclimate or vegetation. Highest soil erosion occurred during the past 500 years, coinciding with a transition toward permanent agriculture. Human‐impacted soil erosion was further amplified by intense monsoonal rainfall and strong rainfall seasonality around 2,000 and 300 years ago. With such rainfall anomalies projected to occur with higher frequency and severity in the tropics under the ongoing greenhouse warming, our results suggest an accelerating erosion rate in the future, posing risks for natural resources.
Plain Language Summary Present‐day human activities, such as agriculture and deforestation, are causing soil erosion and the associated removal of fertile soils. Land use throughout tropical Southeast Asia is especially intense with increased establishment of oil palm plantations. However, the manner and degree to which humans influenced soil erosion in this region in prehistoric times when instrumental records or historical documentations were not available is largely unknown. In an attempt to gain a picture of human land use and its effect on the soils and landscapes of East Java, Indonesia, we analyze chemical fossils preserved in the sediments of the seafloor. We find evidence of an increase in human activities around 3,500 years ago related to early farming practices. This timing corresponds to archeological evidence indicating the arrival of the Austronesian‐speaking people in Java. Human‐impacted soil erosion was further amplified by high summer rainfall and strong rainfall seasonality around 2,000 and 300 years ago. Such rainfall patterns are projected to occur more often and more severely not only in Southeast Asia but also in the global tropics under the ongoing global warming. Our results indicate that under these conditions, greater soil erosion will occur in the tropics in the future. This may pose risks for agriculture and human use of natural resources.
Key Points Elevated fire occurrence and soil erosion around 3,500 years ago was most likely due to early swidden agriculture and Austronesian dispersal The impact of human land use on soil erosion was further amplified by increased rainfall intensity and seasonality The transition from swidden to permanent agriculture likely further accelerated soil erosio
Comparison of ECHAM6-wiso near-surface water vapour isotopic composition with in situ measurements at Neumayer Station III
Get PDFWater isotope records from polar ice cores are crucial proxies for reconstructing past Antarctic climate and temperature changes. For such task, a robust understanding and accurate quantification of the temporal changes between δ18O and temperature is necessary. One option to facilitate this is employing simulations from atmospheric general circulation models that incorporate stable water isotopes. In this context, we assess in this study the results of the isotope-enabled AGCM ECHAM6-wiso model. We analyse results from a high-resolution simulation covering the period 2017–2020, where the atmospheric dynamics is nudged to ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF). Our investigation evaluates the agreement between different observed and simulated key physical and isotope quantities, including temperature, humidity, and the isotopic composition of surface water vapour ( δ18O_v and δD_v ), at Neumayer Station III in East Antarctica. Additionally, our study evaluates the skill of the ECHAM6-wiso model in simulating stable water isotope ratios in snow (δ18O_snow and δD_snow) at Neumayer Station III for the recent past. The ECHAM6-wiso model exhibits skill in replicating the daily, monthly, and seasonal fluctuations of temperature, humidity, surface water vapour δ18O_v and δD_v. However, it demonstrates limitations in accurately simulating d-excess values on the different time scales. While the model does not precisely reproduce the observed surface δ18O-temperature relationship on a daily scale, it closely approximates this relationship on a monthly scale. For snow, the model slightly underestimates the δ18O_snow-temperature relationship when compared to observational data. To test if the ECHAM6-wiso model correctly simulates the water vapour sources and transport pathways to Neumayer Station III, we have performed related back trajectory studies. Based on simulation results of the FLEXPART model, we find that the water vapour back-trajectory results with ECHAM6-wiso are consistent with those based on ERA5 data. This result leads to the conclusion that ECHAM6-wiso is a very useful tool for analysing atmospheric moisture sources and transport pathways to East Antarctica under present climate conditions
Yedoma: Late Pleistocene ice-rich syngenetic permafrost of Beringia
Get PDFYedoma is a permafrost deposit widely distributed across the Arctic and found exclusively within the unglaciated regions in northern Siberia, Alaska, and the Yukon, which are the core regions of Beringia. Yedoma deposits accumulated during the late Pleistocene Stage and are characterized by their predominantly fine-grained texture and association with syngenetic perma-frost formation. The very high ground ice content is most commonly present as pore ice and wedge ice that formed contemporaneously with sediment deposition. In the last decade, research has transitioned from debates about the origin of the Yedoma deposits towards increasing attention on the large carbon and nitrogen pools in Yedoma, their vulnerability to thaw, and increasing mobilization as the climate has warmed across the Arctic. In addition to classical cryolithological and sedimentological research, new methods such as stable isotope paleoclimate reconstruction and ancient sedimentary DNA studies have been more widely applied to better understand the characteristics of Yedoma deposits and helped emphasize their value as archives of Quaternary climate and paleoecological conditions during Ice Age Beringia
Dominant inflation of the Arctic Ocean’s Beaufort Gyre in a warming climate
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The Arctic Ocean’s Beaufort Gyre, the largest Arctic freshwater reservoir, plays a crucial role for climate and marine ecosystems. Understanding how it changes in a warming climate is therefore essential. Here, using high-resolution simulations and Coupled Model Intercomparison Project phase 6 data, we find that the Beaufort Gyre will increasingly accumulate freshwater, elevate sea level, and spin up its circulation as the climate warms. These changes, collectively referred to as inflation, are more pronounced in the Beaufort Gyre region than in other Arctic areas, amplifying the spatial asymmetry of the Arctic Ocean. The inflation is driven by increased surface freshwater fluxes and intensified surface stress from wind strengthening and sea ice decline. Current climate models tend to underestimate this inflation, which could be alleviated by high-resolution ocean models and improved atmospheric circulation simulations. The inflation of the Beaufort Gyre underscores its growing importance in a warming climate.</jats:p
The Contrasting Role of Marine- and Land-terminating Glaciers on Biogeochemical Cycles in Kongsfjorden, Svalbard
Get PDFThis case study of Kongsfjorden, western coastal Svalbard, provides insights on how freshwater runoff from marine- and land-terminating glaciers influences the biogeochemical cycles and distribution patterns of carbon, nutrients, and trace elements in an Arctic fjord system. We collected samples from the water column at stations along the fjord axis and proglacial river catchments, and analyzed concentrations of dissolved trace elements, together with dissolved nutrients, as well as alkalinity and dissolved inorganic carbon. Statistical tools were applied to identify and quantify biogeochemical processes within the fjord that govern the constituent distributions. Our results suggest that the glacier type affects nutrient availability and, therefore, primary production. Glacial discharge from both marine-terminating glaciers and riverine discharge from land-terminating glaciers are important sources of dissolved trace elements (dAl, dMn, dCo, dNi, dCu, and dPb) that are involved in biological and scavenging processes within marine systems. We identified benthic fluxes across the sediment-water interface to supply fjord waters with silicate, dFe, dCu, and dZn. Our data show that intensive carbonate weathering in proglacial catchments supplies fjord waters with additional dissolved carbonates and, therefore, attenuates reduced buffering capacities caused by glacial runoff. Our study provides valuable insight into biogeochemical processes and carbon cycling within a climate-sensitive, high-latitude fjord region, which may help predict Arctic ecosystem changes in the future