Mussels blow rings: Jet behavior affects local mixing

Abstract

Benthic suspension feeders such as dreissenid mussels (Dreissena polymorpha and D. rostriformis bugensis) are often found in remarkably dense aggregations (i.e. > 105 mussels m− 2), which is surprising, given their high clearance rates and limited mixing within the benthic boundary layer. Results from flow visualization in flow chamber experiments indicate that there is indeed limited mixing around mussel aggregations at low flows and that siphonal jets can increase mixing around and above these aggregations. Using particle image velocimetry (PIV) to further investigate the underlying hydrodynamics of these jets, we characterized differences in velocity and vorticity among four siphonal behaviors (e.g., slow flux, streaming, exhalant jets, and inhalant jets), including both continuous and pulsatile jets, the latter of which generate free vortex rings. Incorporating these hydrodynamic characteristics into a computational fluid dynamic (CFD) model revealed that siphonal jets increased mixing, expressed as vertical diffusivity in the benthic boundary layer. These differences were most pronounced at slow vs. fast cross‐stream velocities, but those differences diminished several body lengths (i.e. 10−1 m to 10−2 m) downstream. The results from PIV measurements and CFD modeling suggest that benthic suspension feeders can influence patterns of local mixing, which would affect mass transport and biogeochemical processes in the near‐bed region. This underscores the need for physical‐biologically linked models to incorporate the behavior of benthic suspension feeding invertebrates.

Adaptive feeding in the American oyster Crassostrea virginica: Complex impacts of pulsatile flow during pseudofecal ejection events

“…The pulsatile flow had strong flow velocities in the middle core zone and the distance of the pulsatile flow can reach several centimeters (Fig. a), which was consistent with the pulsatile jets of siphonal jets of dreissenid mussels (Nishizaki and Ackerman ). Feeding also started from locations with weak pulsatile flow zone (Fig.…”

“…Bivalve feeding consumes energy from cilia movement that transports water, captures particles, and sorts items prior to ingestion (Clemmensen and Jørgensen ; Jorgensen ; Ward ; Riisgård and Larsen ). To improve access to suspended resources that distinctly vary over time and space, some benthic suspension feeders, such as mussels, will invest energy into locally mixing water through their siphonal jet behavior strengthens mass transport (Berg and Newell ; Nishizaki and Ackerman ) and previous observational studies have noted distinct water pumping behaviors that result in specific water transport patterns (Pernet et al ). Although oysters do not have siphon tubes for feeding, they can modify the ambient flow environments through their water pumping behavior, which is also likely to be energetic, costly.…”

The Genome of the Zebra Mussel,Dreissena polymorpha: A Resource for Invasive Species Research

“…Settlement of larvae near adults 71 and gregarious post-settlement behaviors 72 create massive aggregations on lake and river bottom. These behaviors increase settlement success, enable “habitat engineering” in mussel beds 72 , and may enhance feeding and fertilization success 73–75 . Further investigation will be required to determine if the D. polymorpha temptin orthologs serve as aggregation cues or play some other unknown sensory role.…”

Seasonal ecosystem metabolism across shallow benthic habitats measured by aquatic eddy covariance

“…The high annual GPP at the mussel bed, which amounted to almost half of that at the F. vesiculosus site, and was comparable to that measured at the Z. marina canopy, suggests efficient recycling of nutrients and C between heterotrophs and autotrophs in the absence of other substantial sources of regenerated nutrients such as sediment deposits. Filter‐feeding bivalves such as mussels may play a similar important role in nutrient regeneration through active filtration, deposition of feces and pseudo‐feces, and efficient exchange of nutrient‐rich waters near the seabed (Kautsky and Evans ; Nishizaki and Ackerman ). These processes may be important in maintaining high benthic GPP, thereby providing a significant autochthonous organic matter subsidy that was equivalent to ~ 50% of the annual R rate of the mussel reef habitat in our case.…”