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  1. Abstract

    In shallow coastal systems, sediments are exposed to dramatic and complex variability in environmental conditions that influences sediment processes on short timescales. Sediment oxygen demand (SOD), or consumption of oxygen by sediment‐dwelling organisms and chemical reactions within sediments, is one such process and an important metric of aquatic ecosystem functioning and health. The most common instruments used to measure SOD in situ are batch‐style benthic chambers, which generally require long measurement periods to resolve fluxes and thus do not capture the high temporal variability in SOD that can be driven by dynamic coastal processes. These techniques also preclude linking changes in SOD through time to specific features of the sediment, for example, shifts in sediment faunal activities which can vary on short time scales and can also be affected by ambient oxygen concentrations. Here we present an in situ semi‐flow through instrument to repeatedly measure SOD in discrete areas of sediment. The system isolates patches of sediment in replicate benthic chambers, and measures and records oxygen decrease for a short time before refreshing the overlying water in the chamber with water from the external environment. This results in a sawtooth pattern in which each tooth is an incubation, providing an automated method to produce direct measurements of in situ SOD that can be directly linked to an area of sediment and related to rapid shifts in environmental conditions.

     
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  2. Animals with long, skinny bodies are often called “worms,” but there are many kinds of worms—even in the ocean. Annelids (segmented worms) include garden earthworms, but their ocean relatives come in many colors, shapes, and sizes. Some are so small that they live between grains of sand, while others can be longer than a human and eat fish! Marine worms are essential to the ocean food web, as both predators and prey. They help create homes for plants and animals by burrowing and building tubes in ocean sediments. Scientists are still discovering new worm species, and there are still many mysteries about how worms eat, why they live in the places they do, and what roles they play in ocean ecosystems. Worms are a fascinating and important part of ocean communities. 
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  3. The Association for the Sciences of Limnology and Oceanography (ASLO) sponsors Eco-DAS, which is now in its 30th year. The program aims to unite aquatic scientists, develop diverse collaborations, and provide professional development training opportunities with guests from federal agencies, nonprofits, academia, tribal groups, and other workplaces (a previous iteration is summarized in Ghosh et al. 2022). Eco-DAS XV was one of the largest and most nationally diverse cohorts, including 37 early career aquatic scientists, 15 of whom were originally from 9 different countries outside the United States (Fig. 2). As the first cohort to meet in-person since the COVID-19 pandemic, Eco-DAS participants convened from 5 to 11 March 2023 to expand professional networks, create shared projects, and discuss areas of priority for the aquatic sciences. During the weeklong meeting, participants developed 46 proposal ideas, 16 of which will be further developed into projects and peer-reviewed manuscripts. 
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    Free, publicly-accessible full text available July 3, 2024
  4. Changes in dissolved oxygen concentration can cause dramatic shifts in chemical, biological, and ecological processes in aquatic systems. In shallow coastal areas, this can happen on short timescales, with oxygen increasing during the day due to photosynthesis and declining at night due to respiration. We present a system controlled by an Arduino microprocessor that leverages the oxygen-consuming capacity of sediments to manipulate dissolved oxygen in an aquarium tank to planned concentrations. With minor adjustments to the Arduino code, the system can produce a variety of dissolved oxygen patterns, including a diel cycle. Designed to be user-friendly and scalable if needed, the system uses easily acquired, low-cost electronic and aquarium components. Its simplicity and accessibility permit deeper exploration of the effects of dissolved oxygen variability in aquatic systems, and the use of Arduino code and basic electronics makes it a potential tool for teaching experimental design and instrument fabrication. 
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