In the Elbe estuary, a sharp decline in phytoplankton concentration is observed as the river reaches the deep shipping channels of the Port of Hamburg. This collapse significantly impacts the estuarine food web and carbon cycle, shifting the ecosystem from autotrophic to heterotrophic. Previous studies hypothesized that this decline is primarily due to zooplankton grazing. We propose an alternative hypothesis focused on the ro...

Understanding the effect of hydrodynamics on aggregate size and structure is key to predicting mass transport in the aquatic environment. Aggregation theory of particles is well established but our knowledge of deformation processes, biological bonding forces, and their effects on fragmentation of aquatic aggregates is still limited. To better comprehend fragmentation processes and adhesion forces we implemented breakup experi...

Microbes (bacteria, phytoplankton) in the ocean are responsible for the copious production of exopolymeric substances (EPS) that include transparent exopolymeric particles. These materials act as a matrix to form marine snow. After the Deepwater Horizon oil spill, marine oil snow (MOS) formed in massive quantities and influenced the fate and transport of oil in the ocean. The processes and pathways of MOS formation require fur...

Fishes are the dominant vertebrates in the ocean, yet we know little of their contribution to carbon export flux at regional to global scales. We synthesize the existing information on fish‐based carbon flux in coastal and pelagic waters, identify gaps and challenges in measuring this flux and approaches to address them, and recommend research priorities. Based on our synthesis of passive (fecal pellet sinking) and active (mig...

Organic matter (OM) plays a major role in both terrestrial and oceanic biogeochemical cycles. The amount of carbon stored in these systems is far greater than that of carbon dioxide (CO 2 ) in the atmosphere, and annual fluxes of CO 2 from these pools to the atmosphere exceed those from fossil fuel combustion. Understanding the processes that determine the fate of detrital material is important for predicting the effects that...

Diel vertical migration (DVM) has been hypothesized to actively transport organic material out of the euphotic layer, thus forming a novel part of the “biological pump.” However, quantifying DVM is made difficult by observational limitations. Conventionally, the difference between night and day biomass from net trawls in the surface has been assumed to be a consequence of species that have migrated up from their deep daytime d...