Many marine invertebrates, including Dungeness crab, have pelagic life stages that take them on an oceanic journey before they settle into life on the seafloor. Often, these early larval stages look, behave, and experience life quite differently from the adult forms we are familiar with. The timing of arrival and spatial distribution of young crabs are key to replenishing populations each year, and the number of new recruits has been shown to predict the abundance of adult Dungeness crabs years later. This project tracks dispersal patterns using light traps. Many marine invertebrate larvae, including crabs, are attracted to light. Light traps take advantage of this behaviour and allow us to trap and track Dungeness megalopae, the last larval crab stage before they stop swimming and start crawling.
Relying on a network of communities and partners, we have established a series of light traps throughout the Salish Sea. This project complements an existing project led by the Pacific Northwest Crab Research Group in the southernmost portion of the Salish Sea where a collection of partners from tribal, state, and federal governments, as well as NGOs and academia, have deployed their own network of light traps. Click here to read more about our community partners.
In addition to monitoring larval invertebrates, we are investigating the annual development of benthic invertebrates in subtidal habitats. We use Autonomous Reef Monitoring Systems (ARMS), which are essentially mini condominiums (actually, stacks of PVC plates) that act as habitat for marine invertebrates. These structures are secured to the ocean floor in locations all around the world, from the shallows to depths of 300 metres, as part of the Global ARMS Program. Because ARMS are all made the same, we can compare marine communities across places and over time. ARMS can also tell us how different conditions such as pollution or protection affect ocean health, essentially acting as "biological weather stations." By pairing ARMS with our light trap stations, we can build a more detailed picture of the regional patterns of invertebrate biodiversity and change throughout the Salish Sea.
We are using genetic analysis to complement both the light trap and ARMS components of the project and to further illuminate marine invertebrate communities and patterns. Genetic analysis will be used in a variety of ways:
Barcoding individual species to contribute to the "barcode of life" database - a library of known DNA sequences which can be used to identify a species from small fragments of DNA in seawater - called environmental DNA or eDNA.
Metabarcoding ‘bulk’ material sampled from the ARMS units will provide us with thousands of snippets of DNA which, using the BOLD database, we can use to identify who settled on the ARMS units.
Metabarcoding water samples (eDNA) to paint a picture of what species are in the water around our stations. Check out Hakai's Integrated Coastal Observatory to learn more **will need to link this https://ico.hakai.org/