New Study Confirms Warming Ocean's Impact on Ocean Quahog

OCEAN SPRINGS, MS / ACCESSWIRE / April 24, 2024 / A new study examining the fossil record of ocean quahog, one of the longest-lived species in the ocean, further confirms that climate change is impacting the distribution and growth of shellfish across the Atlantic. Building on previous work examining regional ocean quahog populations, the study, funded by the Science Center for Marine Fisheries, expands our understanding on how shellfish species are reacting to warmer waters and changing habitats.

Ocean quahogs are an extremely long-lived species; some of the oldest ocean quahogs living today are over 200 years old, with some of them having lived long enough to pre-date the Industrial Revolution. Like using a tree's rings to learn its life cycle, studying ocean quahog shells can tell us both about the growth and history of an ocean quahog, and about past climate conditions. This study, published in Continental Shelf Research, analyzes the historical growth rate of ocean quahogs off the Delmarva peninsula compared to modern populations, identifies the historical distribution of optimal conditions for ocean quahog growth, and how current warming trends are impacting the species.

Specifically, the study looks at ocean quahog growth rates and compares those rates of growth with known climate conditions, such as historic cold periods like the Little Ice Age and a warmer period known as the Medieval Warm Period. It finds that ocean quahogs once were found well inshore of their present distribution when climates were much colder than today, and that during these times they grew as fast or faster than today, helped by a likely combination of optimal temperatures and abundant food supply.

Ocean quahogs today are also growing at a much slower rate in some regions than similar ocean quahogs in the period from 1740-1940, with the evidence indicating that current temperatures in these areas are above the historical, optimal range that encourages ocean quahog growth.

"This study is further confirmation that ocean temperatures are continuing to move away from the conditions where ocean quahog thrive, which has long-term implications for both the species and the fisheries that depend on them," said Alyssa LeClaire, a Coastal Ecologist at NOAA Fisheries' Beaufort Lab, the lead author of the study. "This is just the beginning of studying the future of climate impacts on this species, and hopefully further research will continue to explore the relationship between ocean quahog and climate."

In a related finding, the study also concluded that, as waters begin to warm, the range of ocean quahogs will begin to slowly retract long before a population is completely gone from an area. Because ocean quahogs are so long-lived, this is a slow process, taking a hundred years or more from the first signs of decrease to be completely gone from an area.

Similar to earlier SCEMFIS-funded studies on ocean quahog, this study relies on an extensive dataset of quahog shells, collected in previous surveys, this time from the Delmarva region of the Atlantic. Previous studies funded by the Center have focused on ocean quahog populations off New Jersey, Long Island and Georges Bank. Together, they draw from one of the largest and most representative sample collections of ocean quahog available, an archive that has potential to aid in future climate research.

"Ocean quahog shells have the potential to be a valuable resource in reconstructing historical climate data," said LeClaire. "Because the species is sensitive to changes in temperature, they can tell us about changes in climate over the decades of a quahog's life cycle, which can help us in modeling future changes."

About SCEMFIS
SCEMFIS utilizes academic and fisheries resources to address urgent scientific problems limiting sustainable fisheries. SCEMFIS develops methods, analytical and survey tools, datasets, and analytical approaches to improve sustainability of fisheries and reduce uncertainty in biomass estimates. SCEMFIS university partners, University of Southern Mississippi (lead institution), and Virginia Institute of Marine Science, College of William and Mary, are the academic sites. Collaborating scientists who provide specific expertise in finfish, shellfish, and marine mammal research, come from a wide range of academic institutions including Old Dominion University, Rutgers University, University of Massachusetts-Dartmouth, University of Maryland, and University of Rhode Island.

The need for the diverse services that SCEMFIS can provide to industry continues to grow, which has prompted a steady increase in the number of fishing industry partners. These services include immediate access to science expertise for stock assessment issues, rapid response to research priorities, and representation on stock assessment working groups. Targeted research leads to improvements in data collection, survey design, analytical tools, assessment models, and other needs to reduce uncertainty in stock status and improve reference point goals.

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SOURCE: Science Center for Marine Fisheries