Response to Comment on "Dilution limits dissolved organic carbon utilization in the deep ocean"

A significant gap exists in understanding how dissolved organic carbon (DOC) is processed in the deep ocean. Prior research has shown that DOC is a major component of the global carbon cycle, but its fate remains unclear. Some studies suggest that DOC is rapidly consumed by microbes, while others argue for long-term preservation. The concept of lability has been central to these discussions, with assumptions that labile DOC is quickly utilized. However, this assumption may not capture the full complexity of DOC dynamics. Recent work has proposed a new definition of recalcitrant DOC, which challenges traditional interpretations. This shift in perspective has led to renewed debate about the mechanisms governing DOC utilization. The dilution hypothesis has emerged as a potential explanation for observed patterns. Yet, the connection between lability and utilization remains a point of contention.

This study aims to address a recent critique of the dilution hypothesis regarding dissolved organic carbon (DOC) utilization in the deep ocean. The critique is based on the assumption that lability equates to rapid and complete utilization. The authors seek to clarify how this misconception affects interpretations of DOC dynamics. They focus on experimental data that contradicts the critique's assumptions. The study's goal is to demonstrate that the dilution hypothesis remains the most accurate explanation for observed patterns. By re-examining the redefined concept of recalcitrant DOC, the authors aim to reinforce their original findings. They also seek to highlight the limitations of equating lability with complete utilization. This work contributes to ongoing discussions about the mechanisms of DOC processing in marine environments.

The authors employed a combination of experimental data and theoretical analysis to address the critique of the dilution hypothesis. They first reviewed the assumptions underlying the critique, focusing on the relationship between lability and utilization. Next, they compared the critique's claims with their original experimental findings. This comparison revealed inconsistencies in the critique's interpretation of lability. The authors then examined the redefined concept of recalcitrant DOC proposed by Jiao et al. They evaluated how this redefinition affects the interpretation of DOC utilization patterns. Using this framework, they demonstrated that the dilution hypothesis better explains the observed data. The study also considered alternative explanations for DOC dynamics. Finally, the authors emphasized the importance of distinguishing between lability and complete utilization in future research.

The authors found that the critique of the dilution hypothesis relies on a flawed assumption equating lability with rapid and complete utilization. Their experimental data do not support this interpretation. Instead, the dilution hypothesis best explains the observed patterns of DOC utilization. The redefined concept of recalcitrant DOC proposed by Jiao et al. does not invalidate the dilution hypothesis. The authors showed that the critique's assumptions are inconsistent with their findings. They demonstrated that lability does not necessarily imply complete utilization. The dilution hypothesis remains the most accurate explanation for the observed data. These results reinforce the importance of distinguishing between lability and utilization in future studies.

The authors conclude that the dilution hypothesis remains the best explanation for the observed patterns of dissolved organic carbon (DOC) utilization in the deep ocean. They emphasize that the critique of their findings is based on a misconception about lability and utilization. The redefined concept of recalcitrant DOC does not contradict their original conclusions. Their experimental data support the dilution hypothesis over alternative explanations. The authors caution against equating lability with complete utilization in future research. They argue that this distinction is critical for understanding DOC dynamics. Their findings suggest that dilution plays a central role in limiting DOC utilization. These conclusions align with their original study and reinforce the need for further investigation into DOC processing mechanisms.