From Nano-Gels to Marine Snow: A Synthesis of Gel Formation Processes and Modeling Efforts Involved with Particle Flux in the Ocean

Abstract

Marine gels (nano-, micro-, macro-) and marine snow play important roles in regulating global and basin-scale ocean biogeochemical cycling. Exopolymeric substances (EPS) including transparent exopolymer particles (TEP) that form from nano-gel precursors are abundant materials in the ocean, accounting for an estimated 700 Gt of carbon in seawater. This supports local microbial communities that play a critical role in the cycling of carbon and other macro- and micro-elements in the ocean. Recent studies have furthered our understanding of the formation and properties of these materials, but the relationship between the microbial polymers released into the ocean and marine snow remains unclear. Recent studies suggest developing a (relatively) simple model that is tractable and related to the available data will enable us to step forward into new research by following marine snow formation under different conditions. In this review, we synthesize the chemical and physical processes. We emphasize where these connections may lead to a predictive, mechanistic understanding of the role of gels in marine snow formation and the biogeochemical functioning of the ocean.

Impact of Microbial Uptake on the Nutrient Plume around Marine Organic Particles: High-Resolution Numerical Analysis

“…The morphology and composition of marine aggregates strongly affect their sinking behavior [ 89 , 96 ], and underpin the significant scatter of data observed in Figure 8 . Marine aggregates consist of exopolymer substances (EPS), microorganisms, mineral particles and detritus [ 4 , 5 , 6 , 7 , 8 ]. The EPS matrix, inclusive of transparent exopolymer particles (TEP), acts as a glue and provides cohesion and structural stability to the aggregate.…”

“…This interesting trend is partly attributed to the interstitial water, which is physico-chemically absorbed by the EPS matrix during aggregate formation. Marine gels, the precursors of aggregates [ 5 ], usually form in low salinity waters of the epipelagic layer or freshwater rivers, hence binding interstitial water of low excess density. Thereafter, as the aggregates sink through denser seawater, they slow down and increase their residence time or even get trapped in strong pycnoclines [ 83 , 100 , 101 ].…”

“…The oceanic carbon cycle is modulated by the interactions between marine microbes and particulate organic matter (POM) via a multistep process known as the biological carbon pump [ 1 , 2 , 3 ]. In the euphotic zone, phytoplankton converts atmospheric CO 2 to organic polymers that coagulate and form composite hydrogel particles called marine snow [ 4 , 5 , 6 ]. The polymeric matrix of marine snow hosts diverse microbial populations, embeds mineral particles, and concentrates metabolites, lysate and essential inorganic nutrients (N, P, Fe, Si) [ 6 , 7 , 8 ].…”

Editorial on Special Issue “Marine Gels”

“…The deep, dark ocean stores most of the organic stock present in seawater; it presents some of the most intriguing questions in marine science, and has a special place in this set of reports. Finally, closing this set of news from the frontier is the recent and significant discovery that marine gels can be exported to the atmosphere, likely playing a significant role in cloud formation and climate change [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ].…”

Diversidade e distribuição de procariotos na zona mesopelágica da Bacia de Santos - Brasil

“…Esses agregados macroscópicos tendem a afundar, processo conhecido como neve marinha. A neve marinha funciona como um transporte passivo de matéria orgânica e nutrientes para áreas mais profundas do oceano, e é a principal fonte de substrato que sustenta as teias alimentares dos heterotróficos nas regiões mais profundas (QUIGG et al, 2021).…”