Mass Transfer Performance of a Marine Zooplankton Olfactometer

Abstract

By adopting different methods to the inlet of a zooplankton olfactometer, the current study investigates the effect of the energy of chemical flow on the Gnathiid isopod crustaceans predicted behavior. These are mobile external parasites of fishes that have a significant impact on the health of their hosts. They rely at least in part on olfactory cues to find the host fish. To better understand host-finding dynamics in these parasites, a study was conducted with the simulations as a blueprint for developing a 3-dimensional test apparatus similar to what has been used for studying olfactory orientation in insects. The simulated olfactometer has four legs, each leg forming an inlet where fluids are introduced into the flow domain. There is one outlet at the center of the device. A mixture of water and chemicals is presented by applying a multi-component system. The shear and chemical concentration distribution were conducted to see how fluid physics plays a role in creating a chemical landscape. Computational results show distinct regions separated by high chemical concentration gradients when introducing chemicals from one leg. Changing the fluid inflow from one common inlet to three inlets shows that the chemical distribution exhibits steeper gradients than the typical inlet case, depicting that the gradual chemical concentrations can drive the animal toward the target faster. The best behavior that gives higher chemical gradients is obtained through the study when using three sub-inlets and Schmidt number between 3 and 10.

Assessment of a new olfactometer for study of sensory ecology in small aquatic organisms

“…In a two‐channel choice flume, each source has a consistent concentration of chemical cues throughout, with a “hard divide” between sources. In their natural environments, organisms experience gradients of chemical concentrations that are likely useful in homing in on an attractant or indicating they are getting farther away from a deterrent (Alkhafaji et al 2021). Occasionally, to achieve the desired laminar flow, the water within the flume must flow faster than a test organism can normally swim (Hata et al 2017) and doing so can result in inaccurate results.…”

“…Working with water as a medium rather than air presents some challenges. At similar temperatures, water is 50 times as viscous as air and 830 times as dense (Alkhafaji et al 2021). Alkhafaji et al (2021) used computational fluid dynamics simulations to theorize a potential aquatic olfactometer for use in studying the chemical ecology of small aquatic organisms.…”

“…At similar temperatures, water is 50 times as viscous as air and 830 times as dense (Alkhafaji et al 2021). Alkhafaji et al (2021) used computational fluid dynamics simulations to theorize a potential aquatic olfactometer for use in studying the chemical ecology of small aquatic organisms. More specifically, Alkhafaji et al (2021) predicted the design and conditions under which the aquatic olfactometer would behave similarly to previously used terrestrial olfactometers (Vet et al 1983).…”

“…Alkhafaji et al (2021) used computational fluid dynamics simulations to theorize a potential aquatic olfactometer for use in studying the chemical ecology of small aquatic organisms. More specifically, Alkhafaji et al (2021) predicted the design and conditions under which the aquatic olfactometer would behave similarly to previously used terrestrial olfactometers (Vet et al 1983). As with the terrestrial olfactometer, the aquatic olfactometer would have four distinct “zones,” one coming from each inlet.…”

“…Based on the findings of Alkhafaji et al (2021), a prototype was constructed in the the Strickler lab at the University of Wisconsin‐Milwaukee. Here, we describe its components and basic construction, test its structural integrity and hydrodynamic behavior, and validate its utility for aquatic studies by using Daphnia , a small aquatic organism that has been identified to have chemoreceptor genes (Peñalva‐Arana et al 2009).…”