Welcome to The Hill’s Sustainability newsletter, I’m Sharon Udasin — every week we follow the latest moves in the growing battle over sustainability in the U.S. and around the world.

Pacific oyster density has grown up to 32-fold in Southern California waters in the past decade, due to climate-induced surges in summer seawater temperatures, a new study has found.  

That increase is raising concerns about how such warming is accelerating the establishment and dominance of non-indigenous species, according to the study, published on Wednesday in PLoS ONE.  

The good and the bad: The Pacific oyster, which originates in Japan, is also known as the Miyagi oyster or Magallana gigas, per the National Oceanic and Atmsopheric Administration. 

• These animals, which grow up to 10 inches in size, are filter feeders and can clean up to 50 gallons of water every day as they eat.
• In 2019, the U.S. produced 42.3 million pounds of Pacific and Eastern oysters collectively, valued at $221 million.
• While such oysters improve water quality and have a negligible ecological footprint, there is some concern that they could outcompete native oysters.  

An unanticipated ‘feral escape’: The global expansion of the Pacific oyster “may have been facilitated by climate change,” according to the study authors.  

• The species was at first “introduced as an idea aquaculture fishery” animal in more temperate waters, under the assumption that it would not undergo a “feral escape” in colder conditions.
• Yet “warming seawater during summer has facilitated” their reproduction.  

Oyster outcomes in balmier bays: To evaluate the oyster’s growth and impacts in Southern California, the researchers surveyed conditions at eight sites in Newport Bay and San Diego Bay from 2010 to 2020.  

• They found that population densities increased by between 2.2 and 32.8 times at seven of those locations.
• The growth coincided with surges of 2 to 4 degrees Celsius (3.6 to 7.2 degrees Fahrenheit) in median monthly seawater temperature during summer months.   

The point of no return: While the authors acknowledged that the precise effects of this non-indigenous species on Southern California estuaries remains unknown, they cited “significant impacts elsewhere” on native oyster species as cause for concern.  

As such, they recommended that resource managers factor these findings into their future decision-making.  

“Abundance is among the most significant factors determining the impact of an invader and once a threshold is crossed, the whole structure of a community can be irreparably altered,” they added.