Dissolved organic matter (DOM), one of the largest pools of carbon on Earth, plays a pivotal role in mediating global climate changes. To resolve the ecological drivers of this enormously complex carbon pool in complex natural environments, researchers from the Institute of Marine Science and Technology of Shandong University led a pioneer study that investigated the intrinsic linkages among the complex dissolved organic matter (DOM, Molecular carbon fingerprint), microbial communities (microbial fingerprint), and environmental heterogeneity using sophisticated ecological models. This study, entitled "Disentangling drivers of mudflat intertidal DOM chemo diversity using ecological models", was recently published as a featured article in Nature Communications.

One of the central goals of ecology is to comprehend the composition, diversity, and distribution of biological entities across various temporal and spatial scales, as well as the underlying maintenance mechanisms. Dissolved organic matter (DOM), closely linked with microorganisms, is a pivotal component in the global carbon cycle and serves as a critical nourishment source for heterotrophic microorganisms. This intricate mixture of organic compounds comprises a vast array of molecules and is omnipresent in Earth's biosphere. In the ocean, an immense quantity of DOM molecules contributes to approximately 660 Pg of carbon and encompasses a broad spectrum of organic matter classes, including lipids, proteins, lignin, and polycyclic aromatic hydrocarbons. Recent studies have shown that the chemical diversity and composition of DOM are closely related to molecular properties, hydrological factors, climate change, and microbial dynamics. However, it remains unclear whether the ecological patterns and drivers of DOM chemodiversity are analogous to those of microbial communities. Investigating whether DOM compounds in natural ecosystems adhere to these well-established ecological models can offer not only insights into understanding the complex relationship with microorganisms, but also novel perspectives on the enduring question of whether universal ecological laws govern the diversity and distribution of biological entities, including the non-living DOM pools.

Figure1.Sampling sites and taxonomic composition of dissolved organic matter (DOM) pools, bacterial and fungal communities along the sampled intertidal zones

In this study, multiple cutting-edge technologies are employed, including the fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS)to resolve DOM molecules, amplicon sequencing to resolve microbial profiles, and sophisticated ecological models and statistical methods. The key findings include:

1. DOM follows similar ecological patterns as microbial communities, such as species abundance distribution (SAD), Taylor's Law, Distance-decay relationships (DDR), and latitudinal diversity gradients (LDG).

2. In addition to diversity, the molecular traits of DOM also follow latitudinal patterns, including molecular intensity, transformation level and other characteristics.

3. Negative cohesion, bacterial diversity, and molecular traits are the main drivers of DOM chemo diversity. Comparatively, bacteria are more important than fungi in mediating DOM chemodiversity. Deterministic processes mainly governed the compositional variations of both DOM and microbes in the intertidal zones.

Figure2.Structural equation modeling (SEM) of the effects of both biotic and abiotic factors on DOM chemodiversity

"This study not only deepens our understanding of the driving mechanisms of DOM chemo diversity in intertidal zones," says the team leader Prof. Tu Qichao, "but also reveals universal ecological mechanism entities in the Earth's biosphere, including living microbial communities and non-living DOM molecules, are regulated by unified ecological models." The research is supported and funded by the National Key Research and Development Program "Theories and Applications of Carbon Fingerprint and Carbon Footprint Identification Systemsin Typical Chinese Seas", the National Natural Science Foundation of China, the Taishan Young Scholarship of Shandong Province, and contributes to the Ocean Negative Carbon Emissions (ONCE) program.

Link: https://www.nature.com/articles/s41467-024-50841-9