Climatic, physical, and biogeochemical changes drive rapid oxygen loss and recovery in a marine ecosystem

Abstract

Dissolved oxygen (DO) concentrations shape the biogeochemistry and ecological structure of aquatic ecosystems; as a result, understanding how and why DO varies in space and time is of fundamental importance. Using high-resolution, in situ DO time-series collected over the course of a year in a novel marine ecosystem (Jellyfish Lake, Palau), we show that DO declined throughout the marine lake and subsequently recovered in the upper water column. These shifts were accompanied by variations in water temperature and were correlated to changes in wind, precipitation, and especially sea surface height that occurred during the 2015–2016 El Niño-Southern Oscillation event. Multiple approaches used to calculate rates of community respiration, net community production, and gross primary production from DO changes showed that DO consumption and production did not accelerate nor collapse; instead, their variance increased during lake deoxygenation and recovery, and then stabilized. Spatial and temporal variations in rates were significantly related to climatic variability and changes in DO, and causality testing indicated that these relationships were both correlative and causative. Our data indicate that climatic, physical, and biogeochemical properties and processes collectively regulated DO, producing linked feedbacks that drove DO decline and recovery.

Substantial microbial community shifts in response to an exceptional harmful algal bloom in coastal Southern California

“…Many ecological studies have found that increased variance in ecological function (here, AOU) indicates a critical transition and overall regime shift (Carpenter and Brock, 2006;Scheffer et al, 2009;Scheffer et al, 2012;Wang et al, 2012). Though this concept has not been widely applied to natural microbial systems due to a lack of high frequency data that can capture variance on microbial timescales, one study using high frequency data from a marine lake saw ecosystem metabolism flicker as the epilimnion changed depth and a new normal was established (Wilson et al, 2019). If such a situation applies to our system, the L. polyedra bloom and the 'bloom' and 'post-bloom' subnetworks can be thought of as regime shifts on timescales relevant to microorganisms.…”

Applications of biogeochemical models in different marine environments: a review

“…In coastal areas, such as coastal Antarctica, diverse sources, including glacial melt and diagenesis, are considered to understand the origins of iron (Gerringa et al, 2012;Sherrell et al, 2018;Dinniman et al, 2020). Dissolved oxygen is another crucial state variable in ocean biogeochemical models, impacting the ecological and biogeochemical structure of marine ecosystems (Wilson et al, 2019). Oxygen depletion and hypoxia can occur due to factors like nutrient loading and insufficient oxygen replenishment.…”