Biology subjects

Schoepf, V.

Publications and source records attributed to Schoepf, V..

6 recordsLinked to original sources

bioRxiv2026

Ocean acidification alters hypoxia sensitivity and oxyregulation in reef-building corals

Coastal marine ecosystems are increasingly threatened by multiple stressors such as ocean acidification and deoxygenation, but how these co-occurring stressors interact is often poorly understood. This is especially true for tropical coral reefs where deoxygenation is an emerging yet understudied threat. Using hypoxia response curves combined with rigorous pH control, we show that acidification alters hypoxia sensitivity and oxyregulation of reef-building corals in a species-specific manner: three species exhibited increased sensitivity to various degrees, while the fourth showed enhanced tolerance. Consequently, acidification pushes critical hypoxia thresholds into oxygen regimes already prevalent on reefs today, potentially driving shifts in community composition and accelerating risks to reef resilience as these stressors intensify in the future. Our findings challenge assumptions of uniform coral vulnerability under multi-faceted climate change, emphasizing the need for trait-based approaches and to account for stressor interactions in predictive models to better anticipate coral reef futures under rapid climate change.

ecology↗

bioRxiv2025

Compound hypoxia with heat or acidification stress induces synergistic and additive effects on coral physiology

As climate change accelerates, coastal marine ecosystems are increasingly exposed to co-occurring stressors whose combined effects are nonlinear and difficult to predict. Deoxygenation is a rapidly intensifying yet underrecognized threat to coral reefs that interacts with heat and acidification to alter coral physiology and stress resilience. However, the effects of hypoxia-related compound events on corals are largely unknown, underscoring the need for multi-stressor studies. Here, we conducted two extended-exposure experiments (12-17 days) across the coral species Porites furcata, Porites astreoides and Siderastrea siderea, to disentangle the individual and combined effects of low dissolved oxygen (hypoxia) with either heat or acidification. We measured eight phenotypic traits related to growth, metabolism, and symbiosis health to test whether hypoxia imposes energetic constraints or other physiological stress that amplify the effects of heat or acidification. Standardized effect size analysis across 24 stressor-trait combinations revealed 13 additive, 10 synergistic, and only one antagonistic response. Hypoxia consistently suppressed dark respiration by 37-49% across species and altered photophysiology in the two Porites species, whereas acidification alone had minimal effects, particularly in S. siderea. Heat stress caused the most pronounced declines across nearly all traits, and when combined with hypoxia, it produced the highest number of synergistic interactions. In contrast, the combination of hypoxia and acidification largely resulted in additive responses, suggesting that independent physiological mechanisms underlie these effects. All corals showed strong metabolic depression under hypoxia which is likely beneficial as a short-term adaptive response but may impose energetic constraints in the long-term. These findings highlight deoxygenation as critical yet often overlooked drivers of coral reef vulnerability. More multi-stressor experiments across a range of species are urgently needed to improve predictions of reef resilience under future ocean conditions, where compound stress events are expected to become more frequent and severe.

ecology↗

bioRxiv2025

Physiological mechanisms underlying coral acclimatization capacity to novel, multi-stressor conditions

Reef-building corals are under pressure to acclimatize and/or adapt to multiple co-occurring stressors, including climate change and declines in water quality. However, their capacity to do so is largely unknown. Yet, some corals naturally persist in habitats with multi-stressor conditions which can provide crucial insight into coral adaptive capacity under future ocean conditions. To assess the role of phenotypic plasticity and local adaptation in coral acclimatory responses to novel conditions, we reciprocally transplanted two coral species (Siderastrea siderea, branching Porites) between a multi-stressor, highly variable inland bay and a more stable fringing reef, and measured key phenotypic traits after 0, 4, and 12 months. Reef-origin corals demonstrated high plasticity when transplanted to the bay, as both species maintained high survival and calcification, and matched bay natives phenotypic traits. Yet, both species had reduced photosynthesis-to-respiration ratios, highlighting the risk of metabolic tradeoffs unless compensated for through increased heterotrophy. Conversely, bay-origin corals had enhanced photosynthetic performance but lower calcification on the reef. Reaction norms provided stronger evidence for environmental specialization in bay-origin than reef-origin corals, which could limit their use as stress-tolerant source corals for reef restoration. Overall, our findings suggest multi-stressor variability may promote specialized genotypes, rather than increased phenotypic plasticity.

ecology↗

bioRxiv2023

Sentinels for future coral reef conditions: assessment of environmental variability and water quality in semi-enclosed inland bays in the southern Caribbean

The mangrove-seagrass-coral reef continuum is of immense ecological and socio-economic importance, supporting biodiversity, carbon storage, coastal protection, fisheries, and tourism. The presence of extreme environmental conditions along this continuum could support adaptive refugia for climate-sensitive taxa such as reef-building corals but physicochemical conditions are rarely assessed at sufficient spatiotemporal resolution. Furthermore, coastal development and low water quality increasingly threaten these interconnected coastal ecosystems. Yet, time-integrated pollution monitoring is absent at most locations. Here, we used a multi-disciplinary approach to assess benthic cover, coral diversity, and >20 abiotic parameters characterizing two mangrove- and seagrass-dominated inland bays and two nearby coral reefs in Curacao (southern Caribbean) during the cool, dry season and warm, wet season. This was combined with time-integrated pollution monitoring using bioindicators to assess nutrients and trace metal pollution (inland bays only), and passive samplers and bioassays to assess organic chemical pollution (all four sites) during the wet season. This approach revealed a previously undocumented extent of strong diel and seasonal environmental variability in the two inland bays, with temperature, pH and dissolved oxygen frequently reaching values predicted under moderate-to-severe future climate scenarios. In addition, the inland bays had greater nutrient concentrations (especially ammonium) and ecotoxicological risks than the nearby reefs during the wet season due to run-off, industrial- and wastewater effluents, ports and boating. Overall, our findings show that Curacaos inland bays have significant potential to serve as natural laboratories to study the effects of future ocean conditions on resident taxa in situ. This however applies within the context of strong diel fluctuations and with the caveat of co-occurring stressors. Our work confirms the important role of mangrove and seagrass habitats as resilience hotspots for climate-sensitive taxa but also highlights the urgent need to improve monitoring, water quality and protection of these valuable habitats along the mangrove-seagrass-coral reef continuum.

ecology↗

bioRxiv2020

Methane emission of humans is explained by dietary habits, host genetics, local formate availability and a uniform archaeome

Archaea are responsible for methane production in the human gastrointestinal tract. Twenty percent of the Western populations exhale substantial amounts of this gas. The underlying principle determining high or low methane emission and its effect on human health was still not sufficiently understood. In this study, we analysed the gastrointestinal microbiome, archaeome, metagenome, metabolome, and eating behaviour of 100 healthy young adults. We correlated high levels of human methane emission (5-75 ppm) with a 1000-fold increase in Methanobrevibacter smithii. This archaeon co-occurred with a bacterial community specialised on dietary fibre degradation, which included members of the Ruminococcaceae and Christensenellaceae. Methane production was negatively affected by high vitamin B12 and fat intake of the subjects, and was positively associated with increased formate concentrations in the gut. Overall, methane emission is explained by dietary habits, host genetics, local metabolite availability and microbiome/archaeome composition, emphasizing the unique biology of high methane-emitters which has potentially positive impact on human health. O_FIG O_LINKSMALLFIG WIDTH=171 HEIGHT=200 SRC="FIGDIR/small/423794v1_ufig1.gif" ALT="Figure 1"> View larger version (79K): org.highwire.dtl.DTLVardef@16eb91org.highwire.dtl.DTLVardef@c3b928org.highwire.dtl.DTLVardef@1b11fa5org.highwire.dtl.DTLVardef@194bed2_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract:C_FLOATNO C_FIG

microbiology↗

bioRxiv2018

Measuring the archaeome: detection and quantification of archaea signatures in the human body

Due to their fundamentally different biology, archaea are consistently overlooked in conventional 16S rRNA gene amplicon surveys. Herein, we evaluate different methodological set-ups to detect and quantify archaea signatures in human samples (nose, oral, appendix, stool, and skin) using amplicon sequencing and quantitative PCR.\n\nWith our optimized protocol, we were able to increase the detection of archaeal RSVs from one (using a so-called \"universal\" approach) to 81 RSVs in a representative sample set. Moreover, we confirmed the presence of about 5% archaeal signatures in the human gut, but found, unexpectedly, an almost 1:1 ratio of archaeal to bacterial 16S rRNA genes in appendix and nose samples. This finding indicates a high prevalence of archaeal signatures in body regions thus far not analyzed for the presence of archaea using appropriate methods.\n\nIn order to assess the archaeome diversity and archaeal abundance, a specific archaea-targeting methodology is required, for which we propose two standard procedures. These methodologies might not only prove useful for analyzing the human archaeome in more detail, but could also be used for other holobionts samples.

microbiology↗