In 2010, researchers at the University of South Carolina found that the ranges of blue mussels had shifted 350 kilometers north as summer ocean temperatures rose.
Along the southern portion of its range, intertidal populations of M. edulis have experienced catastrophic mortality directly associated with summer high temperatures. Over the past 50 years, a geographic contraction of the southern, equatorward range edge of M. edulis has occurred, shifting the range edge approximately 350 km north of the previous limit at Cape Hatteras, NC.
So if warming ocean temperatures are causing mussels to shift 350 km northward, no big deal, right? They can just adapt and ship themselves north.
Not if warming temperatures are not the only thing threatening sea life.
A study released this week in Nature showed another way climate change threatens mussels: proteinaceous byssal threads. Essentially, they’re the things that mussels use to anchor themselves to rocks. Byssal threads are non-calcified structures, yet the researchers found that as carbon dioxide levels increased, the byssal threads snapped more easily. It’s a hard life for a mussel when it can’t attach itself to the ocean floor.
The mussels will have a tough time adapting their byssal threads and shells if ocean acidification levels are increasing faster than they did over the last 300 million years. Stronger storms hitting the coastline will only make things harder for mussels.
Does it matter to us? According to researchers at the University of Washington, mussels play a crucial part of the aquatic ecosystem, filtering up to a liter of water per hour:
Mussels play a surprisingly large role in marine ecosystems. They provide habitats for smaller organisms and species, as well as shelter and protection from harmful factors such as heat, desiccation, and predators. Stabilizing soft sediment of the ocean floor by attaching to roots, transferring energy by converting algae into tissue, and filtering water are other valuable mussel occupations, in addition to their status as a decent entree for fish, crabs, birds, and people.
“They are often referred to as a foundation species,” said Emily Carrington, UW professor of biology. “They provide several ecosystem services; mussels filter water very effectively, a liter of water per hour.”
Menus will be affected as well. European researchers released a report card last year saying that if ocean temperatures rise by 1 degree Celsius, mussel harvests could fall by half in the Mediterranean.