SCCWRP has constructed a state-of-the-art dynamic exposure laboratory to study how aquatic organisms respond to fluctuations in pH, dissolved oxygen and other environmental parameters in a controlled setting – a type of experimental setup found in only a handful of labs worldwide.
The Dynamic Stressor Exposure Research Facility (DSERF), which was built in June, comes in response to growing awareness among water-quality managers that stressors such as ocean acidification and low dissolved oxygen are negatively impacting aquatic life.
The DSERF lab is designed to help researchers better understand how these multi-stressor biological impacts are playing out in the real world. By automatically adjusting multiple parameters over the course of an experiment, researchers can more accurately mimic fluctuating environmental conditions, including tidal cycles, seasonal changes and other site-specific conditions. DSERF also can be programmed to replicate projected future conditions.
By contrast, a standard laboratory setup would likely replicate only the static, mean state of parameters like pH, dissolved oxygen levels and salinity.
In June, the first experiment to be conducted in the DSERF lab examined whether ocean acidification has the potential to alter the toxicity of sediment contamination. Seawater pH was lowered to reflect intensifying acidification, then a standard sediment toxicity test species was exposed to contaminated sediment. This study, which is now being expanded, is expected to eventually inform whether toxicity tests may need to be recalibrated in response to rising ocean acidity.
In July, SCCWRP and its partners launched a second DSERF study seeking to replicate the role that underwater kelp forests might play in mitigating ocean acidification. This study is a follow-up to field work in Washington’s Puget Sound, where commercially important oysters and mussels were co-cultivated in a kelp forest. Kelp forests draw carbon dioxide out of the water as part of regular photosynthetic processes, which has the potential to offset acidification’s impacts.
Researchers at SCCWRP plan to adjust pH, then examine whether management interventions such as planting kelp forests could provide co-benefits for shellfish cultivation that minimize the negative effects of acidification in coastal habitats.
SCCWRP and its partners also plan to use DSERF to examine the impact of low pH and low dissolved oxygen levels on the commercially important Dungeness crab. A recent study by SCCWRP and its partners found severe physiological impairment in larval crabs attributed to exposure to low pH conditions in the natural environment. Using DSERF, SCCWRP will investigate interactive effects of low pH and low dissolved oxygen levels at the larval stages to better understand if and how these two factors may be combining to exacerbate biological impacts.
The DSERF setup utilizes a modular design offering flexibility to meet a range of experimental needs. The system capacity is about 90 sample containers, spread out over three water baths that can be controlled independently to allow for simultaneous testing at multiple temperatures.
The dynamic control of pH and dissolved oxygen provides up to nine unique treatments. Salinity control allows for experiments to be run from freshwater to seawater conditions, with the ability to vary salinity over time, including conditions that could mimic Southern California brackish estuaries.
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