OAKLAND, Calif. – A viewer-captured image reveals a leopard shark swimming in Lake Merritt on Monday evening.
While this is an unusual sight, leopard sharks and other marine creatures occasionally travel from the San Francisco Bay to the lake.
In the past, local citizen scientists have reported sightings of bat rays, sea lions, and river otters in Lake Merritt, as reported by Oaklandside.
Members of the Lake Merritt Rowing Club have also observed sea lions and bioluminescence in the lake over time.
Lake Merritt is a natural, brackish body of water that was formed around 10,000 years ago, at the tail end of the Ice Age.
During the previous summer, the lake witnessed a surge in bat ray numbers and an algal bloom, which many experts believe contributed to a significant spike in fish mortality.
“This was deemed to be an outbreak of an organism known as Heterosigma akashiwo, often referred to as a harmful red tide of algae,” stated Jon Rosenfield from San Francisco Baykeeper.
The algal bloom from the previous year may have been triggered by an overload of nutrients, such as nitrogen and phosphorus, in the bay. These nutrients are likely to have originated from around 40 wastewater treatment plants that release treated water into the bay.
This year, there have been reports of an increase in the death toll of leopard sharks and bat rays in Berkeley’s Aquatic Park, according to Berkeleyside.