According to the 2022 Lake Tahoe Clarity report, Lake Tahoe was the clearest it has been since the 1980s in the last half of 2022, with clarity reaching nearly 72 feet using the Secchi disk to measure visibility in the iconic waters.
According to researchers at UC Davis' Tahoe Environmental Research Center, the improved clarity is due in part to a resurgence of the lake's native zooplankton.
Lake Tahoe's Clarity Is The Best It's Been In 40 Years
David Calvert/Getty Images for American Century Investments
They've organized a natural cleanup crew to aid in the restoration of the lake's famously blue waters, as per Phys.org.
Native zooplankton is microscopic creatures.
Because of the growth of its primary predator, the Mysis shrimp, zooplankton populations have declined since the 1960s.
Despite low zooplankton levels, the lake remained clearer in 2021 than it was in 2017, the murkiest year.
At a depth of 61 feet, the clarity in 2021 was the second-worst on record.
Particle levels in the lake also reached an all-time high in 2021, with scientists suspecting that particles from wildfires contributed to the increase in particles and, thus, the low clarity.
Zooplankton are important for lake clarity because they consume the particles that cloud the lake.
In 2022, Lake Tahoe made a comeback, with an average annual clarity of 71.7 feet.
Despite the expected large runoff from this year's record snowpack, researchers anticipate the effect of Daphnia and Bosmina to grow over 2023, and clarity may return to 1970s levels, according to Brant Allen, the research center's boat captain.
According to the report, officials in both California and Nevada want to restore the lake's clarity to its historic level of 97.4 feet.
Mysis shrimp populations are expected to rebound, putting zooplankton at risk, so population control measures may be necessary to preserve the lake's clarity, according to the researchers.
The aquatic food chain relies heavily on the zooplankton community, as per EPA.
These organisms act as a link in the food chain, transferring energy from planktonic algae (primary producers) to larger invertebrate predators and fish that eat them.
Zooplankton is extremely vulnerable to changes in aquatic ecosystems.
Changes in species composition, abundance, and body size distribution can reveal the effects of environmental disturbances.
The types of zooplankton found in the water, as well as the abundance of certain species relative to one another, serve as a measure of a biological condition.
Because they respond quickly to changes in nutrient input to the water body, zooplankton is good indicators of nutrient pollution change over time.
Since their densities and species composition can be sensitive to changes in environmental conditions, zooplankton is frequently included in biomonitoring programs.
Many species of zooplankton, including the spiny water flea (Bythotrephes) and zebra mussel larvae, have been accidentally introduced to Canadian lakes and rivers in recent years.
Some zooplankton species, such as Mysis, have been purposefully introduced into lakes to increase fish production.
Because zooplankton plays such an important role in freshwater food webs, researchers have been collecting and studying them at IISD-ELA for the past 51 years, and their zooplankton collection now exceeds 30,000 samples.
Zooplankton eats algae, and it has been proposed that increasing zooplankton grazing could help control algal blooms.
This is known as "biomanipulation," and it is typically accomplished by reducing predation on zooplankton by planktivorous fish, either by directly removing these fish or by introducing a fish predator such as pike.
