In this study, we explore a new, cost-effective approach to µPIV for resolving detailed flow around free-swimming zooplankton.
Adult copepods used in recordings were collected with a 0.5 m diameter, 150 μm mesh plankton net in surface waters from a pier in Port Aransas, TX (27° 50.3′ N, 97° 03.1′ W).
Several objective lenses were used depending on the size of the animal being recorded.
Plan ×10 and ×40 objective lenses were used with numerical apertures of 0.25 and 0.50, respectively.
Particle image velocimetry (PIV) has become an important and widely used tool in biological research involving fluid motion.The high magnification required to obtain details of most zooplankton locomotory behavior results in a narrow depth of focus, sometimes as little as a few micrometers (Young , 1993). backlit) illumination with sufficiently small seeding particles, this narrow focal depth can be used to provide an “optical slice” of in-focus seeding particles and functionally replace the need for a laser sheet (Bitsch , 2008).However, current applications of brightfield µPIV have also been restricted to narrow channels due to the short focal distance of high-magnification lenses.Bright laser illumination poses a problem as many organisms have bodies that will strongly reflect or refract the light required to illuminate tracer particles.The use of fluorescent seeding particles that emit at a lower wavelength can help to alleviate this problem because reflected light can be effectively filtered while retaining high-contrast particle information (Meinhart ., 1999).