Understanding how a crab’s complex life cycle will respond to climate change

Research with implications for species under stress from a warming planet

A Dungeness crab scuttling across a boardwalk. The life cycle of the Dungeness crab offers lessons on potential effects of climate change for other species.
The life cycle of the Dungeness crab offers lessons on potential effects of climate change for other species (Adobe Stock).

For many marine animals, like the Dungeness crab, seasonality and timing are components of complex life cycles, where disruptions can have serious implications for the population. Understanding how climate change will impact each life stage is no small undertaking when considering all variables and moving parts in a changing environment. Despite these challenges, this information is vital for sustainable fishery management and to inform new conservation strategies.

A team of researchers from the University of Washington, the National Oceanic and Atmospheric Administration (NOAA), Simon Fraser University, and the University of Connecticut Department of Marine Science including Ph.D. student Halle Berger, Assistant Professor Catherine Matassa, and Assistant Professor Samantha Siedlecki, looked at the Pacific Northwest portion of the Dungeness crab fishery, which spans from Alaska down to Southern California. In a paper published this week in AGU Advances, they determined which life stages are most vulnerable, and to which stressors.

This research is part of a regional vulnerability assessment and collaboration funded by the NOAA Ocean Acidification Program. It also investigates environmental justice issues, says Siedlecki,

“Tribal communities in the Pacific Northwest identify Dungeness as both culturally and economically important species for their way of life. Species are moving but of course tribal communities don’t have the option of moving their land in response. The tribal communities are very interested and motivated to think about ways they can sustain the fishery.”

This assessment looked at three stressors all resulting from future carbon emissions: ocean acidification (OA), low oxygen levels (hypoxia), and warming temperatures. Berger explains that they integrated several layers of information to create a realistic model to study the consequences of stressors at different times throughout the life stages, from eggs, to larvae, to juveniles, to adults.

When modelling for future conditions, the Intergovernmental Panel on Climate Change (IPCC) has representative carbon pathways (RCP) that are emission scenarios considering differing degrees of carbon emissions mitigation.

“It turned out that the adult life stage is the most critical in driving the overall population vulnerability,” Berger says. “We found that for all three stressors there will be increased population level vulnerability in the future, and the most severe is to hypoxia. Low oxygen events are confined to the upwelling season, in spring and summer which impacts the adults, whereas ocean acidification manifests more year-round in the future, impacting all life stages.”

The researchers say these data could be easily incorporated into decision making processes to protect the vital life stages in particularly stressful conditions to help maintain sustainable fisheries.

University of Connecticut (UCONN), 8 October 2021. Press release.

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