Alfred Wegener Institute for Polar and Marine Research
Electronic Publication Information CenterNot a member yet
52828 research outputs found
Sort by
Metagenome-assembled-genomes recovered from the Arctic drift expedition MOSAiC
Get PDFAbstract
The Multidisciplinary Observatory for Study of the Arctic Climate (MOSAiC) expedition consisted of a year-long drifting survey of the Central Arctic Ocean. The ecosystems component of MOSAiC included the sampling of molecular data, with metagenomes collected from a diverse range of environments. The generation of metagenome-assembled-genomes (MAGs) from metagenomes are a starting point for genome-resolved analyses. This dataset presents a catalogue of MAGs recovered from a set of 73 samples from MOSAiC, including 2407 prokaryotic and 56 eukaryotic MAGs, as well as annotations of a near complete eukaryotic MAG using the Joint Genome Institute (JGI) annotation pipeline. The metagenomic samples are from the surface ocean, chlorophyll maximum, mesopelagic and bathypelagic, within leads and under-ice ocean, as well as melt ponds, ice ridges, and first- and second-year sea ice. This set of MAGs can be used to benchmark microbial biodiversity in the Central Arctic Ocean, compare individual strains across space and time, and to study changes in Arctic microbial communities from the winter to summer, at a genomic level.</jats:p
Safeguarding Florida's Coral Reefs: The Urgency of Assisted Gene Flow for Elkhorn Coral Conservation
Get PDFThe devastating 2023 heatwave is the latest in a series of disasters that has decimated the Florida population of elkhorn coral (Acropora palmata) to a critically low level, pushing this species to a precarious tipping point. Precautionary management currently forbids outplanting of corals from outside Florida. This precaution is intended to prevent the introduction of novel genes that could cause outbreeding depression and to preserve local adaptive variation in the Florida population. However, the multi-decadal decline of Florida’s elkhorn corals indicates a lack of adaptation to the shifting environmental conditions on
Florida reefs. The potential risks of outbreeding depression associated with introducing new genetic variants from outside sources pale in comparison to the continuous demographic decline through successive heat waves, and the threat of inbreeding depression. Operational risks of Assisted Gene Flow (AGF) can be managed by introducing non-Florida alleles via outplanting of the existing lab-based juveniles rather than adults sourced from the wild. Further, the extent to which new genetic material is introduced should be proportional to Florida’s founder population. NOAA’s Florida Genetic Management Plan (F3P) can guide the introduction of non-Florida alleles versus the introduction of sexually produced offspring from the limited floridian parental stock. We conclude that assisted gene flow via lab-based crossing of Florida’s elkhorn with elkhorn from elsewhere in the
Caribbean is a strategy with manageable risks and mission-critical benefits. AGF should be implemented urgently to introduce new genetic variants, thereby increasing the elkhorn coral’s genetic diversity, and enhancing the resilience of these populations to future stress. Without such intervention, coupled with the high probability of additional 2023-scale heatwaves, the grim prospect of completely losing all elkhorn corals from Florida’s reefs within this decade becomes increasingly probable
A coupled multiscale description of seasonal Physical–BioGeoChemical dynamics in Southern Ocean Marginal Ice Zone
Get PDFSea ice in the polar oceans plays a significant role in regulating global climate and biological ecosystems.
During the winter months, seawater freezes to form porous ice, which also serves as a habitat for sea ice
algae to survive in harsh winter conditions. However, accurate description of mechanisms and interactions
associated with formation of ice, and its interaction with photosynthesis and carbon assimilation have not
been well understood. This paper presents a modeling framework to describe coupled small scale Physical (P)
and BioGeoChemical (BGC) processes associated with sea ice. Critical processes associated with photosynthesis along with growth and loss of algal carbon are considered. Appropriate parametrization for environmental factors such as temperature, light, salinity, and nutrients are employed to model the photosynthetic rate. Summer and winter environmental conditions are presented and discussed in detail. Finally, monthly data is taken from literature to simulate a typical year in the Southern Ocean
Temperature effects on the impact of two invasive parasitic copepods on the survival, growth, condition, and reproduction of native mussels
Get PDFAbstract
An increase in temperature due to climate change may affect the geographic ranges of invasive parasites and alter their impact on native hosts. Our goal was to determine if the effects of infection by two species of invasive endoparasitic copepods on native blue mussel hosts (Mytilus edulis) change with increasing temperatures. We investigated this with a laboratory experiment using temperatures that represent annual mean and mean summer water temperatures of past observations and future predictions for the study area, the European Wadden Sea (10–26 °C). Over a period of 8–20 weeks, infection with Mytilicola intestinalis lowered mussel condition and infection with Mytilicola orientalis decreased mussel shell growth. High temperatures decreased mussel growth and condition in general, but only at low temperatures (10–14 °C) the parasite-induced loss of condition was evident compared to uninfected mussels. Mussel mortality and reproductive activity were not affected by parasite infection, although both were impacted by temperature: the highest temperature (26 °C) increased mussel mortality, and gamete ripening only occurred at lower temperatures (10–18 °C). Taken together, these results suggest that both infection and high temperatures have independent negative effects. However, an increase in temperature does not worsen the effect of infection on individual mussel hosts, and neither does infection decrease host tolerance for long-term exposure to high temperatures. These findings add to our understanding of the interplay between increasing temperature and the interaction between invasive parasites and native hosts, and help predicting host and parasite dynamics in systems affected by species invasions and climate change.</jats:p
Pathways for converting zooplankton traits to ecological insights are paved with findable, accessible, interoperable, and reusable (FAIR) data practices
Get PDFThe use of trait-based approaches and trait data in zooplankton ecology is rapidly growing to better understand and predict the patterns of zooplankton distributions and their role in aquatic ecosystems and biogeochemical cycles. Although the number of zooplankton trait-based studies and available trait datasets is increasing, several challenges remain for the findability, accessibility, interoperability, and reusability (FAIR) in trait-based approaches that, if unaddressed, may stifle progress in this research area. Here, we review recent applications of trait-based approaches in zooplankton research and summarize the currently available trait data resources. To realize the potential of trait-based approaches to resolve ecological roles of zooplankton, datasets and approaches must adhere to FAIR principles. We provide recommendations and pathways forward to ensure FAIRness while highlighting the importance of collaborative efforts. These practical and easily implementable strategies will enhance the FAIRness of trait data, ultimately advancing zooplankton ecological research and connecting these findings to aquatic ecosystem functioning
Physiological responses of Arctic and Baltic Sea populations of toxigenic Alexandrium ostenfeldii (Dinophyceae) to different climate change stressors
Get PDFThe harmful algal bloom species Alexandrium ostenfeldii has a worldwide distribution from polar to tropical habitats and from oceanic to brackish waters. Among other species of the genus Alexandrium, it is one of the causative organisms of paralytic shellfish toxins, but additionally, A. ostenfeldii has also been shown to produce another class of toxins, cyclic imines. The wide distribution of A. ostenfeldii suggests population-specific adaptations to a multitude of environmental parameters and therefore, variable responses to global change drivers, such as warming and shifts in sea surface salinity. In this study we quantified growth and toxin cell quota of two strains of A. ostenfeldii isolated from the arctic Kongsfjord and two strains from the northern European Baltic Sea at various temperature conditions, to assess the impact of global warming on locally adapted populations. Overall, growth of the arctic strains was detected at temperatures between 7.5 and 20 °C, with a maximum growth rate at 15 °C for both strains. The two strains from the Baltic Sea revealed intraspecific differences concerning their thermal tolerance. One strain showed no growth at 25 °C, while the other still had a positive growth rate at 27 °C. Furthermore, three of the strains were exposed to salinities between 10 and 40, revealing a tolerance to a broad range of salinities. Neither temperature nor salinity affected the qualitative toxin composition of any strain, but we detected novel cyclic imines in three of the four tested strains. Furthermore, different temperatures and salinities led to dynamic shifts in total toxin cell quota. Additionally, we detected novel spirolides in both arctic strains of A. ostenfeldii. These findings suggest that arctic A. ostenfeldii might significantly benefit from global warming, while populations from the Baltic Sea may not, and that the Baltic Sea might become unfavourable for western Baltic A. ostenfeldii due to climate change driven decreasing salinity in this area
Synthesis of Population Trends Reveals Seascape‐Wide Reorganisation of Biodiversity From Microalgae to Birds
Get PDFMany monitoring programs aim to understand regional biodiversity patterns in relation to global and regional conservation targets, using either community-wide biodiversity metrics to describe the community status or trends of pre-selected “key” species as biodiversity change indicators. However, the former often lacks information on which species are changing, and the latter is heavily skewed towards specific taxa, potentially overlooking changes in other, functionally important taxa. We gathered an extensive set of monitoring data with over 3000 population trends (ranging from 5 to 91 years in duration) for a wide range of taxa across the Wadden Sea. We combined a systematic and quantitative categorization of population trends (weighted vote count) with a meta-analysis on different taxonomic levels. This allowed the first cross-taxa synopsis of species declines and increases and determined their directionalities throughout time. Our meta-analysis showed an overall decrease in population size for fish, zooplankton, and plant species, while birds showed an overall increase. However, these increases mask recent negative trends within specific bird groups since the late 1990s. In contrast, fish populations exhibited declines over the entire monitoring period. Species with declining populations (losers) were phylogenetically related, whereas species with increasing populations (winners) represented various organismal groups. Directionality and onsets of change in population trends were temporally synchronized throughout several groups, such as bivalves, fish, and birds, and may provide warning signals for future local extinctions in these taxa. Our analysis moves beyond typical indicator species by including the entire species inventory of the system. Basal trophic levels of aquatic ecosystems, such as zooplankton and phytoplankton, are often missing from policy assessments but are among the most important organism groups for ecosystem functioning. Here, we show that without additional monitoring effort, a systematic analysis of population trends adds to our understanding of trophic and compositional restructuring of ecosystems
Cross-feeding Creates Tipping Points in Microbiome Diversity
Get PDFA key unresolved question in microbial ecology is how the extraordinary diversity of microbiomes emerges from the interactions among their many functionally distinct populations. This process is driven in part by the cross-feeding networks that help to structure these systems, in which consumers use resources to fuel their metabolism, creating by-products which can be used by others in the community. Understanding the effects of cross-feeding presents a major challenge, as it creates complex interdependencies between populations which can be hard to untangle. We address this problem using the tools of network science to develop a structural microbial community model. Using methods from percolation theory, we identify feasible community states for cross-feeding network structures in which the needs of consumers are met by metabolite production across the community. We identify tipping points at which small changes in structure can cause the catastrophic collapse of cross-feeding networks and abrupt declines in microbial community diversity. Our results are an example of a well-defined tipping point in a complex ecological system and provide insight into the fundamental processes shaping microbiomes and their robustness. We further demonstrate this by considering how network attacks affect community diversity and apply our results to show how the apparent difficulty in culturing the microbial diversity emerges as an inherent property of their cross-feeding networks
A Leverage Points Framework To Manage Changes in River Health
No full textRiver health worldwide has deteriorated throughout the past century due to human activity, jeopardising biodiversity, ecosystem services, and human health. Restoration efforts to curve this decline range from localised in-channel modifications to river basin-scale stakeholder engagement aimed to facilitate adaptive management. To address this challenge, it is necessary to view rivers as social-ecological systems which include a set of feedbacks between human systems and river ecosystems. It is then possible to use a ‘systems thinking’ approach to identify key leverage points to enable widespread improvements to river health. Donella Meadows' leverage points framework categorises interventions based on their potential in achieving transformative change and the feasibility of being able to take action. By applying this framework, we provide insight into how transformative change can be leveraged to support river restoration, with a focus on catchment-scale dynamics, specifically in the UK. Our analysis reveals a misalignment between active (i.e., in-situ restoration) and passive (i.e., governance and societal support) restoration due to governance, social design, and the underlying societal values. We propose two scenarios to leverage greater restoration efforts: (i) top-down governance changes to emphasise the societal value of natural ecosystems, and (ii) bottom-up initiatives to alter societal values around restoration and influence governance. The latter, by proximising the benefits of reinstating natural processes. However, the clash of simultaneously operating restoration and conservation paradigms was shown to hinder progress, highlighting the need for empirical research to further understand active and passive restoration dynamics. It is essential that these interactions are explored further to leverage effective restoration strategies to improve river health
Seasonal dynamics of greenhouse gases in a large river
Get PDFRivers represent a significant source of greenhouse gases (GHGs), with the three main gases emitted being carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). To comprehend the spatio-temporal variability of these gases, it is essential to consider the regulating factors that influence their concentration. In larger rivers GHG concentrations are mostly regulated by in-river processes. Thus, the concentration of all these GHGs is supposed to be governed by the trophic state and the activity of phytoplankton.
We performed a monthly monitoring for the three GHGs at the river Elbe (Germany) over 5 years (2020-2024); together with chlorophyll concentrations and other basic water chemical variables.
CO2 concentrations showed a clear seasonal pattern with minimum values in summer, mainly driven by light availability and chlorophyll concentration (photosynthesis). CH4 concentrations showed an opposite seasonal dynamic with maximum values in summer, as indicated by its dependence on temperature and particulate organic carbon (POC). N2O concentrations were mostly near saturation and mainly determined by temperature dependent solubility. The total GHG-potential of the three gases in terms of CO2 equivalents was dominated by CO2 and its seasonal cycle. We successfully used this comprehensive dataset to develop data-driven models based on machine-learning methods, reaching coefficients of determination greater than 0.75. Looking ahead to subsequent research these models enable predictions of GHG concentrations and emissions under potential future climate scenarios