Biology subjects

Hellige, I.

Publications and source records attributed to Hellige, I..

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↗

bioRxiv2024

Roots of coastal plants stabilize carbon fixed by marine algae

Coastal vegetated ecosystems are key-nature based solutions for climate change mitigation. Mangroves, seagrass meadows and saltmarshes contribute to carbon sequestration not only through their photosynthetic activity but also by anchoring sediments with their extensive root systems. By modulating flow coastal vegetation creates a low energy environment for sediment that includes carbon to accumulate. These roots physically stabilize the sediment, prevent erosion and enhance long-term retention of organic carbon. Hence, we hypothesized marine, algae derived organic matter may especially accumulate in plant vegetated ecosystems. We used algal and plant glycans as carbon sequestration proxy to trace the input and stabilization from source to sink and found those molecules in 93 sediment cores across different coastal vegetated ecosystems from temperate to tropical regions. Specific monoclonal antibodies showed algal-derived fucoidans were present in sediments of coastal vegetated ecosystems. Our findings suggest that the restoration of plant ecosystems that fix carbon dioxide, protect coasts and enhance biodiversity should also be enumerated for the stored carbon from distant donors. Conclusively, carbon sequestration is a synergistic outcome of photosynthetic contributors acting in concert across different ecosystems.

biochemistry↗

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↗