Ecology and genetics of Mytilus galloprovincialis: A threat to bivalve aquaculture in southern Brazil

Abstract

The commercial mussel Mytilus galloprovincialis is invasive in the Southern Hemisphere having a large impact on rocky shore communities. It recently appeared in the state of Santa Catarina (SC) which is the most important shellfish aquacultural region in Brazil. Whether this introduction was intentional or accidental is unclear. We used single nucleotide polymorphisms (SNPs) to study population genetics of four introduced populations within at most 70 km from one another in SC; strong similarity among these populations suggests a single introduction event. The Mediterranean Sea is the most probable origin. We monitored recruitment of the invasive Mytilus in the site most affected by the invasion and compare it with Perna perna, the local commercial species. Results reveal that both species have similar seasonal recruitment trends along the year, which makes it impossible to control the invasive species by recruitment management. We recommended the suppression of Perna perna production in the most affected site for at least one year, beginning prior to the reproductive season, followed by cleaning all mussel fouling on submerged and floating structures. This study provides baseline data of an invasive process at its beginning and adds ecological and genetic information for one of the 100 most invasive species worldwide. This information, and continued study will help us understand the evolutionary process of invasion, and the rate of and degree to which M. galloprovincialis adapts to a new, warm environment in the southern hemisphere.