The Invasive Mussel Project (IMP) Peter Wimberger and Lyle Rudensey

Genetics and Exotic Mussels Marine Invasive Species Blue Mussels and the Species Problem Blue Mussels on the West Coast and Puget Sound Genetic Monitoring of the Mediterranean Blue Mussel

European Green Crab Asian Copepod Spartina or Cordgrass Manila Clams Ciona – a tunicate

Where do they come from? Shipping – ballast waterAquaculture

Why are they a problem? Take over space/ outcompete natives Introduce Disease Economic Impacts ($100 billion/year!) Impact Endangered and Threatened Species Predators Hybridize with native species

SPECIES CONCEPTS Biological Species Concept Reproductive Isolation is key, but what about hybrids? Morphological Species Concept Species differ consistently in form Concept that is most used In practice – Species are: a) groups of individuals or populations that are reproductively isolated from each other or b) groups that for the most part retain their genetic identity over most of their range.

A little mussel history Lamy – 1936 Described group of species including Mytilus edulis, M. galloprovincialis and M. trossulus (our native species) Soot Ryen – 1955 Lumped all species together as subspecies and races of M.edulis Numerous workers – early 1990s Resurrect earlier 3 species as result of genetic work

Mytilus edulis – north Atlantic (both coasts) Mytilus galloprovincialis – Mediterranean and Atlantic to England Mytilus trossulus – “Our” native – Pacific coast and NW Atlantic All species can hybridize

Mediterranean blue mussels introduced to Pacific coast early 20 th century through ballast water. Now used extensively in aquaculture (meatier, grows quickly, disease resistant) Taken over southern Californian coastline, established in SF Bay, increasingly common in Washington and BC More Mussel History

Blue Mussels are Sibling Species - very tough to tell apart trossulusgalloshybrids

Genetics can do the trick! PCR – Polymerase Chain Reaction Way of making LOTS of specific piece of DNA Revolutionized molecular biology– Nobel Prize ‘92

How does PCR work?

PCR Genetic Markers Now, a number of genes w/ unique alleles in the three species Byssal Thread Protein variants M. edulis 180 bp M. trossulus 168 bp M. galloprov.126 bp

PCR Gel Mt Hybrid Mg 168 bp 128 bp

We know little about spread of gallo mussels in Puget Sound/WA First documented 1979 Small surveys documented presence of gallos and hybrids in Puget Sound and Strait of Juan de Fuca in past 10 years Culture of gallos spreading including to SJI We have found hybrids throughout Puget Sound

Aquaculture will increase

Potential ecological impact - unknown In southern California, gallo now only mussel in intertidal In South Africa, gallo mussels have taken over parts of intertidal and altered community structure Here - ? Behooves us to know where it is and determine potential ecological effects

First question: where are gallos? LocationTrossulusGalloHybrids Totten Inlet Tacoma36019 South Sound 4111 PS Totals

Second question: Can we find morphological characters to distinguish the two species and hybrids? Length Width And Height (not pictured)

Take-home messages Genetics provides a reliable way of distinguishing mussel species and hybrids Shape isn’t a reliable indicator of species identity Even though you can’t tell a book by its cover, size does matter – mussels over 65 mm are probably gallos or hybrids.

IMP participants (IMPS) can monitor and measure mussels near their schools and contribute to a growing database.