Biology subjects

Buck-Wiese, H.

Publications and source records attributed to Buck-Wiese, H..

3 recordsLinked to original sources

bioRxiv2026

Macroalgal fucoidan can activate the biological carbon pump

Macroalgae secrete complex carbohydrate polymers, their extracellular matrix, as protection against microbial degradation. By resisting breakdown, these carbohydrates can contribute to marine carbon sequestration, though mechanisms, extent, and timescales remain unknown. Using ship-based sampling and experiments, we found that brown macroalgae release 1.7-4.2% of carbon fixation as fucoidan, equivalent to 0.32-0.88 mg fucoidan per gram of dry seaweed tissue per day. A Bayesian model trained on our empirical data, coupled with Monte Carlo simulations suggests an annual global release of 13-37 megatons fucoidan carbon. Moreover, degradation resistance combined with surface-activity enabled fucoidan to act as glue that cross-linked allochthonous organic carbon including microbes and proteins into marine snow. Notably, substantial fucoidan exudation was universally conserved across all tested species and regions. Thus, any brown macroalgal species can be used e.g. via aquafarming to enhance the formation of marine snow.

ecology↗

bioRxiv2026

Macro evolutionary patterns do not predict micro evolutionary trajectories

As the worlds oceans change in response to climate change, phytoplankton communities will adapt to warmer, more stratified surface waters via plasticity, evolution, and range shifts. Current global ocean models assume that size structured phytoplankton communities have fixed trait relationships, and as a result generally predict that smaller size classes will become more dominant globally. However, this general expectation fails to consider how intra-species trait tradeoffs may operate orthogonally from large-scale inter-species tradeoffs--allowing for alternative evolutionary pathways given the limits and/or possibilities available to ancestral populations. To identify evolutionary pathways phytoplankton populations might take, we develop a novel modeling framework that combines a trait-based phytoplankton quota model with stochastic evolution (ecoTRACE). EcoTRACE explicitly decouples key phytoplankton traits from interspecific allometric relationships, allowing for novel phenotypes to emerge. We validated ecoTRACE against a long-term artificial size selection experiment on Dunaliella tertiolecta. We show that ecoTRACE captures multi-dimensional evolved phenotypes that quota models based on interspecific relationships fail to reproduce. Under fluctuating multi-stressor growth, model populations evolve phenotypic plasticity that deviates from predicted interspecific allometric relationships. EcoTRACE provides a framework for generating hypotheses as to the evolutionary trajectories that phytoplankton will experience in a warmer, more variable ocean.

microbiology↗

bioRxiv2024

Selective preservation of fucose-rich oligosaccharides in the North Atlantic Ocean

The ocean has a substantial capacity to store carbon dioxide fixed via photosynthesis in dissolved organic molecules. An estimated 20% of the 660 Gt dissolved organic carbon in the ocean pool consists of structurally uncharacterized oligosaccharides, which appear to resist microbial degradation (Aluwihare et al., 1997). Current technologies lack the sensitivity and molecular resolution to identify these oligosaccharides. Here, we adapted graphitized carbon chromatography to extract and separate marine oligosaccharides for liquid chromatography high resolution mass spectrometry analysis. Using a newly-developed de novo annotation tool, we found 110 oligosaccharide structures in surface and deep ocean seawater at two distant locations in the North Atlantic Ocean. One group of the detected oligosaccharides was found only in surface seawater and consisted of larger and more abundant molecules detected by our analysis. A second group of smaller, less abundant oligosaccharides was detected in both the surface and deep ocean seawater of both sampled locations. The composition of oligosaccharides differed between the surface and deep ocean, with deep ocean samples relatively enriched in hard-to-metabolize deoxy-sugars, and xylose, amino sugars and uronic acids compared to simple hexoses. Notably the deoxy-sugar fucose constituted 35-40% of the monomers in deep-sea oligosaccharides, twice the percentage in surface ocean oligosaccharides. The ubiquity of deep ocean oligosaccharides indicates that they represent a preserved fraction of the carbohydrate pool. Their enrichment in specific monosaccharides suggests selective preservation of fucose-rich oligosaccharides in the deep ocean.

ecology↗