Biology subjects

Eich, A.

Publications and source records attributed to Eich, A..

4 recordsLinked to original sources

bioRxiv2026

Delayed bleaching-induced coral mortality limits reef recovery after a marine heatwave

The increased frequency and intensity of coral bleaching events expose reefs to disturbance-recovery cycles that threaten their long-term dynamics. Understanding the impact of thermal stress requires evaluating coral mortality and recovery rates after disturbances. By integrating two long-term monitoring datasets, we examined coral mortality and recovery patterns at 13 sites in Mo'orea, French Polynesia, following the 2019 bleaching event, the most severe heat stress on record for the island. The maximum accumulated heat stress (AHSmax) varied from 5.76 to 6.26 {degrees} C weeks and enabled a direct analysis of heat-stress-related mortality. One year after bleaching, Pocillopora mortality increased with AHSmax, reducing mean coral cover from 35% to 17%. Regardless of AHSmax, Acropora mortality was high at all sites (median: 84%), reducing mean cover from 5% to 1% and indicating greater heat tolerance of Pocillopora than Acropora. Within four years after the bleaching event, no recovery occurred, and coral cover further declined relative to pre-bleaching levels. This decline was stronger for sites exposed to more intense heat stress. The impact of colony size was assessed by tracking 3090 individual Pocillopora colonies over six years and estimating size-dependent mortality and growth with a Bayesian mixed model. Immediately after the bleaching event, large Pocillopora corals exhibited a higher probability of complete and partial mortality than smaller colonies, highlighting size-specific consequences of bleaching. Even three years after the heat stress ended, large Pocillopora corals remained stressed, as evidenced by the continuously high probability of partial mortality. The lack of recovery observed here may be related to increased spatial competition with macroalgae. The disappearance of large fecund colonies and high mortality of coral recruits could have catastrophic consequences for the resilience of Mo'orea's reefs.

ecology↗

bioRxiv2025

Native and regenerated cellulose show similar environmental biodegradation behavior across global terrestrial and aquatic ecosystems

Cellulose is the most abundant natural polymer and serves as the structural scaffolding molecule of plants, and materials from cellulose fibers are considered important to the global shift toward renewable materials. Yet, uncertainty remains about their persistence in natural environments. Here we show that native and regenerated cellulose, ranging from cotton and linen to viscose, modal, and lyocell, despite minor structural differences, are biodegraded at comparable rates, indicating that there is no scientifically justified distinction regarding environmental behavior. We assessed the biodegradation of diverse cellulosic materials, including powders, loose fibers, fabrics, and nonwovens, under technical and natural conditions across soil, home compost, freshwater, and marine coastal and deep-sea environments. Our study combined a total of 152 scenarios with laboratory tests, mesocosm and field experiments, spanning from polar to tropical regions and temperatures from -1.8 {degrees}C in the high Arctic Ocean to 38.4 {degrees}C in a marine beach in the Mediterranean Sea, and between -6.1 to 54.1 {degrees}C in agricultural soil. All neat cellulosic fibers showed inherent biodegradability, with biodegradation half-lives typically ranging from weeks to months. Biodegradation rates were primarily driven by water availability, temperature, and nutrient levels, while the role of oxygen was indifferent. Standardized lab tests aligned well with field observations, confirming their validity for assessing inherent biodegradability with environmental relevance. However, biodegradation of biodegradable polymers in real-world scenarios is influenced by product-level modifications such as dyeing and finishing. By distinguishing the effects of fiber chemistry separately from those of finishing treatments, this study clarifies the role of cellulose in a sustainable materials economy and supports evidence-based regulation of fiber biodegradability claims and product labeling.

microbiology↗

bioRxiv2021

Half-life of biodegradable plastics in the marine environment depends on material, habitat, and climate zone

The performance of the biodegradable plastic materials polyhydroxyalkanoate (PHA), polybutylene sebacate (PBSe) and polybutylene sebacate co-terephthalate (PBSeT), and of polyethylene (LDPE) was assessed under marine environmental conditions in a three-tier approach. Biodegradation lab tests (20 {degrees}C) were complemented by mesocosm tests (20 {degrees}C) with natural sand and seawater and by field tests in the warm-temperate Mediterranean Sea (12 - 30 {degrees}C) and in tropical Southeast Asia (29 {degrees}C) in three typical coastal scenarios. Plastic film samples were exposed in the eulittoral beach, the pelagic open water and the benthic seafloor and their disintegration monitored over time. We used statistical modelling to predict the half-life for each of the materials under the different environmental conditions to render the experimental results numerically comparable across all experimental conditions applied. The biodegradation performance of the materials differed by orders of magnitude depending on climate, habitat and material and revealed the inaccuracy to generically term a material marine biodegradable. The half-life t0.5 of a film of PHA with 85 m thickness ranged from 54 d on the seafloor in SE Asia to 1247 d in mesocosm pelagic tests. t0.5 for PBSe (25 m) ranged from 99 d in benthic SE Asia to 2614 d in mesocosm benthic tests, and for PBSeT t0.5 ranged from 147 d in the mesocosm eulittoral to 797 d in Mediterranean benthic field tests. For LDPE no biodegradation could be observed. These data can now be used to estimate the persistence of plastic objects should they end up in the marine environments considered here and will help to inform the life cycle (impact) assessment of plastics in the open environment.

microbiology↗

bioRxiv2020

Field and mesocosm test methods to assess the performance of biodegradable plastic under marine conditions

The pollution of the natural environment, especially the worlds oceans, with conventional plastic is of major concern. Biodegradable plastics are an emerging market bringing along potential chances and risks. The fate of these materials in the environment and their possible effects on organisms and ecosystems has rarely been studied systematically and is not well understood. For the marine environment, reliable field test methods and standards for assessing and certifying biodegradation to bridge laboratory respirometric data are lacking. In this work we present newly developed field tests to assess the performance of (biodegradable) plastics under natural marine conditions. These methods were successfully applied and validated in three coastal habitats (eulittoral, benthic and pelagic) and two climate zones (Mediterranean Sea and tropical Southeast Asia). Additionally, a stand-alone mesocosm test system which integrated all three habitats in one technical system at 400-L scale independent from running seawater is presented as a methodological bridge. Films of polyhydroxyalkanoate copolymer (PHA) and low density polyethylene (LD-PE) were used to validate the tests. While LD-PE remained intact, PHA disintegrated to a varying degree depending on the habitat and the climate zone. Together with the existing laboratory standard test methods, the field and mesocosm test systems presented in this work provide a 3-tier testing scheme for the reliable assessment of the biodegradation of (biodegradable) plastic in the marine environment. This toolset of tests can be adapted to other aquatic ecosystems.

ecology↗