®
I
n October 2024, yet another non-native invasive
species was discovered in California waters. Golden
mussel (Limnoperna fortunei), an invasive, non- native freshwater/brackish bivalve, was collected and
positively identified at a water quality station at Rough
and Ready Island near Stockton in San Joaquin County,
California.
As of this writing (January 2025), according to the California Department of Fish and Wildlife web page, golden mussel has been detected at 34 locations throughout the California Delta and in the California aqueduct at San Luis Reservoir.
While introductions and speed of non-native aquatic species in the California Delta is nothing new, the establishment of golden mussel may pose a significant immediate threat to the natural ecosystems, water conveyance systems, infrastructure and water quality in California and across the U.S, according to state authorities. Golden mussels are similar in appearance, biology, and impacts to quagga and zebra mussels, but can establish in waters with considerably lower calcium levels than required by quagga and zebra mussels.
GOLDEN MUSSEL BIOLOGY
Golden mussels are similar in shape and size to quagga and zebra mussels. They are small (typically under 1.5 inches in length), light golden to darker yellowish to brown color and live in fresh and brackish water. Shortly after fertilization, the larvae become mobile; capable of coordinated-swimming and they disperse in the water column.
Once a suitable substrate is found, the mussels attach themselves to the substrate. Maturity is reached when the mussel attains a length of approximately 5.5 mm (almost ¼-inch) which occurs within the first year of its lifespan. Golden mussels live about three years. Golden mussels can grow in dense clumps or colonies containing as many as 80,000 - 200,000 organisms per square meter.
Golden mussels are native to China, Thailand, Korea, Laos, Cambodia, Vietnam and Indonesia.
They inhabit rivers, streams, lakes, and estuaries. They are generally tolerant of a wide range of water quality conditions, and it is tolerant to polluted and contaminated water with low calcium and pH levels. In temperate populations they can survive and proliferate at temperatures between 11 and 28ºC, with confirmed occurrences up to 35ºC. Literature notes the pH tolerance range of 5.8-9.3.
Golden mussel is a freshwater species that can inhabit brackish waters and maintain substantial populations in estuarine habitats. Golden mussel can survive (90%) up to a salinity shock of 2 ppt for periods of at least 10 days and had 41 percent survival in 800mOsm (seawater ~1000mOsm) water.
HOW ARE GOLDEN MUSSELS DIFFERENT THAN QUAGGA AND ZEBRA MUSSELS?
Karatayev et al. (2015), best summarizes the differences between our existing invasive mussels and the golden mussel.
“All three species share several biological traits, such as their sessile mode of life attached to hard substrata by a byssus (although quagga mussels can also dwell on muddy bottoms), similar sizes, similar longevity, and similar time to sexual maturity. Ecologically, they share similarities (e.g., suspension feeding mode), but the dreissenids (zebra and quagga) thrive and reproduce in colder waters and are significantly less tolerant to low pH and calcium concentrations, hypoxic conditions, and pollution. Geographic spread of quagga mussels has been much slower than that of zebra mussels, but once the former colonize waterbodies already populated by zebra mussels, they usually become dominant, both spatially and numerically.
Should the three species overlap, it seems likely that golden mussel will outcompete the dreissenids in warmer, more polluted, less oxygenated, and more acidic waters as well as in waters with lower calcium concentrations. However, the outcome of their competitive interactions when conditions are suitable for all three species is unclear. L. fortunei and both species of Dreissena are functionally similar, and therefore, many of their impacts on the systems they invade are also similar, yet the magnitude of these effects, and in some cases even their sign, can differ widely depending on the invasive species and environmental constraints.”
WHY GOLDEN MUSSEL IS A CONCERN
According to the literature, golden mussel is an ecosystem engineer that significantly alters invaded habitats by altering habitat complexity, sedimentation, and accelerating eutrophication.
In large densities it is possible to shift productivity in the nutrient cycle from the pelagic zone to the benthic zone. This species filters water quickly, clarifying water causing a reduction in primary production occurring within the water
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