Meeting Abstract

P1-89    Stirring It Up: Comparison of Biogenic Currents in Two Mussel Species French, LC*; Litle, J; Reidenbach, MA; Carrington, E; William & Mary; University of Washington; University of Virginia; University of Washington lrcfrench1@gmail.com

Foundation species in the benthos which form dense aggregations can facilitate other species by mitigating harsh flow conditions. However, low flow and high metabolic activity in aggregates can cause steep concentration gradients in interstices. Some aggregating organisms may counter these gradients by generating currents themselves, thereby increasing mixing and preventing unfavorable chemical and physical conditions in the interstices. Mussels are sessile aggregating suspension feeders which draw large amounts of water into their mantle cavity and jet water out after filtration. In doing so, the mussels may flush their aggregates of nutrient- and oxygen-deprived water and induce biomixing in the benthic boundary layer. However, the fluid flow generated by this filtering behavior remains largely unquantified. We used Particle Image Velocimetry (PIV) to quantify the biogenic flows created by two species (M. trossulus and M. californianus) with differing habitats, morphology, and life history strategies. We found the water velocities entering and exiting the incurrent and excurrent pseudosiphons, respectively, did not differ between species, but the excurrent jet flow was roughly 5 times faster than the incurrent flow for both species, primarily due to varying pseudosiphon diameters. Species differed in the location where water was drawn in along the shell, with M. trossulus drawing in water from two distinct locations rather than the one central location of M. californianus. Differences between angles at which water was jetted from the excurrent pseudosiphon were also found, with M. californianus jetting water more vertically relative to the long axis of their shell. Our findings support the hypothesis that mussels induce biomixing in the benthos, and show that closely related species exhibit distinct characteristics in their generation of biogenic flows.