About This Project

All organisms shed DNA into the environment (eDNA). Research suggests that detecting aquatic invasive species (AIS) early can be better done with eDNA methods than through conventional means [1]. I am testing different ways of eDNA sampling to identify which is most effective for detecting existing invasive mollusks in Lake Tahoe. This approach could then be used by managers to detect new mollusk invaders, including the golden mussel, which is rapidly spreading throughout California [4].

Ask the Scientists

What is the context of this research?

AIS can cause significant damage to an ecosystem. Invaders can eat native species or outcompete them, altering entire food webs. Invasive freshwater mollusks such as zebra, quagga, and golden mussels are very efficient filter feeders [1], competing with fishes and other native invertebrates for plankton food. In addition, these mussels cause significant damage to human infrastructure – they latch onto hard surfaces such as marina infrastructure, the insides of water pipes, and boat hulls. Control of these mussels can be extremely expensive, with ~$51 billion spent on invasive zebra and quagga mussel management in North America and Europe between 1980 and 2020 [2]. Although Lake Tahoe has only two invasive mollusk species currently (Corbicula fluminea and Potamopyrgus antipodarum), the high number of visitors from throughout the nation (including areas infested with zebra, quagga, and golden mussels) and warming water temperatures increase the risk of invasion [3].

What is the significance of this project?

The spread and proliferation of invasive species is considered one of the greatest threats to biodiversity globally [1]. With average temperatures increasing faster in montane regions compared to adjacent lower elevation regions [2,3], unique high-elevation aquatic communities like the one present in Lake Tahoe are more susceptible than ever to invasive species establishment.

Compared to a delayed management response, early preventative measures to reduce the establishment and spread of AIS can save trillions of dollars in a few decades [4] . Our project will develop the best methods for detecting mollusks in Lake Tahoe from their eDNA so that if/when new invasive mollusks are introduced, regular monitoring will detect them before they spread and establish.

What are the goals of the project?

The goal of this project is to compare our ability to detect Corbicula and Potamopyrgus, the invasive mollusks already prevalent in Lake Tahoe, as well as other invasive species, by comparing detections from different sampling locations, times, and mediums. I will determine 1) what lake region is best to sample (nearshore, away from shore in the water column, or away from shore near the bottom of the lake), 2) when it is best to sample (when the lake is stratified or mixing), and 3) whether water or sediment is the best sample type to detect eDNA. To answer these questions, I have collected 336 water samples from different lake regions in mixed and stratified seasons as well as 42 littoral sediment samples. At this stage in my project, I am looking for funds specifically to detect invasive mollusk eDNA. When the eDNA is sequenced, I’ll use computational methods to detect sequences specific to invasive mollusks and see which of these sampling parameters are best for detection.