Spatial Distribution and Burrowing Behavior of the Invasive Mussel Arcuatula Senhousia in a Southern California Estuary

The Asian mussel, Arcuatula senhousia, has successfully invaded estuarine habitats globally, including those in southern California, USA. Historically, A. senhousia was found more abundantly in finer grained sediment than in coarser grained sediment. We hypothesize that because of this pattern, A. senhousia will be able to completely cover themselves more (and produce more byssal threads?) in finer grained sediment and will show less success in coarser sediment. Historical field data from various locations within Mission Bay, San Diego, California were used to observe habitat preferences in relation to sediment grain size from (year) to 2019. A lab study was conducted to observe the percent mussels buried themselves and byssal thread production in various sediment composition treatments. A. senhousia were found in finer grained sediments in field studies. In lab studies, they were completely burrowed and produced more byssal threads in finer grain sediment treatments. The behavior exhibited may be because sediment pore space is smaller in finer grained sediment, making it easier to dig deeper as there is less water and more sediment present. The production of byssal mats should be further investigated to find any physiological factors that may cause this discrepancy. This study was important to further evaluate how anthropogenic sediment such as dredging could alter community composition and ecology in habitats.