Project: A framework to characterize inhalant siphon flows of aquatic benthos

Description from NSF award abstract:
Inhalant siphon flows produced by benthic invertebrates such as clams and tunicates through suspension feeding and respiration can directly affect a wide range of physical and chemical processes in benthic marine ecosystems. These flows are energetically costly and influence the feeding and reproductive biology of the individual. Moreover, an understanding of siphon flows at multiple scales can be widely used not only to address questions of flow fields for other aquatic organisms and exchange processes, but that understanding has direct impacts on a variety of engineering problems such as sewer designs. Despite the importance of these flow fields in biology, relatively little research has been conducted on this topic, specifically on inhalant (vs. exhalant) flows. For this study, the PIs have modeled the flow outside the siphon entrance of several important benthic marine animals and have found radically different results from those commonly assumed.  Given these findings, the PIs propose to test the results of their numerical simulation on inanimate physical models, and then verify their accuracy using live organisms.

The proposed numerical modeling will examine and predict effects of several parameters including inhalant siphon wall thickness, siphon height, disturbances caused by exhalant flows, and sensitivity to ambient flows. Predictions will be initially tested by using inanimate analog models. To provide a broad ecological framework, the PIs will then focus on five model suspension feeders, each of which has been extensively studied, and include a species of benthic shrimp, a tunicate, a soft shelled clam, the parchment worm, and a tube-dwelling amphipod. This suite of species will provide a broad description of intake flows as the combination of feeding systems spans nearly the full range of Reynolds numbers observed in animals that produce siphon flows. The results of this study will improve current understanding the effects of organismal intake flows on near-bed processes such as vertical fluxes of organic and inorganic nutrients, an important aspect of benthic ecology. Direct deliverables will include verified quantitative models of inhalant flows of marine benthos, connecting form and function and detailing fluid mechanical costs of operation.