A coral-on-a-chip microfluidic platform enabling live-imaging microscopy of reef-building corals

Abstract

Coral reefs, and the unique ecosystems they support, are facing severe threats by human activities and climate change. Our understanding of these threats is hampered by the lack of robust approaches for studying the micro-scale interactions between corals and their environment. Here we present an experimental platform, coral-on-a-chip, combining micropropagation and microfluidics to allow direct microscopic study of live coral polyps. The small and transparent coral micropropagates are ideally suited for live-imaging microscopy, while the microfluidic platform facilitates long-term visualization under controlled environmental conditions. We demonstrate the usefulness of this approach by imaging coral micropropagates at previously unattainable spatio-temporal resolutions, providing new insights into several micro-scale processes including coral calcification, coral–pathogen interaction and the loss of algal symbionts (coral bleaching). Coral-on-a-chip thus provides a powerful method for studying coral physiology in vivo at the micro-scale, opening new vistas in coral biology.

Temperature and Water Quality-Related Patterns in Sediment-Associated Symbiodinium Communities Impact Symbiont Uptake and Fitness of Juveniles in the Genus Acropora

“…The presence of A3, both when dominant or at background levels of abundance, also strongly impacted F v /F m in juveniles and provides corroborative support that numerically rare background symbionts contribute to changes in the photophysiological performance of their hosts (Erwin et al, 2012;Hoadley et al, 2015;Karim et al, 2015;Mortzfeld et al, 2015). Lower F v /F m values in juveniles that acquired symbionts from offshore sediments and spikes in chlorophyll fluorescence may indicate that the symbionts acquired were adapted to higher light environments (due to increased sediment particle size or decreased turbidity) and a stress response (Shapiro et al, 2016), respectively. These results highlight that the establishment of symbiosis is a highly dynamic process governed by a range of interacting factors.…”

Microbial interactions and community assembly at microscales

“…Biologically inspired microfluidic systems, including soil-on-a-chip [35], gut-on-a-chip [36,37], and coral-on-a-chip [38], have been used successfully to study the microscale structure and dynamics of microbial communities. These systems provide precise control of the patch microhabitat (e.g., nutrient concentration, temperature, pH, and fluid flow), thereby producing defined patches for microbes to colonize.…”

Reactive oxygen species (ROS) and dimethylated sulphur compounds in coral explants under acute thermal stress

“…Despite this focus, our understanding of the symbiotic breakdown between the coral host and Symbiodinium cells is hampered by a lack of methods for investigating the symbiotic interaction at the microscale (Shapiro et al, 2016). Previously, small-scale holobiont physiology has been studied using microscopy methods including histology (Downs et al, 2009), electron microscopy (Tchernov et al, 2004) and, more recently, nanoscale secondary ion mass spectrometry .…”

“…Previously, small-scale holobiont physiology has been studied using microscopy methods including histology (Downs et al, 2009), electron microscopy (Tchernov et al, 2004) and, more recently, nanoscale secondary ion mass spectrometry . While these methods provide detailed information about cellular structures and functioning, they are limited in their ability to follow dynamic processes in vivo at relevant time scales, because samples need to be fixed (Shapiro et al, 2016). New approaches allowing study of coral tissues in vivo in real time have recently been developed, including micropropagation of tissue in microfluidic devices (Shapiro et al, 2016) and coral explants (Gardner et al, 2015).…”

“…While these methods provide detailed information about cellular structures and functioning, they are limited in their ability to follow dynamic processes in vivo at relevant time scales, because samples need to be fixed (Shapiro et al, 2016). New approaches allowing study of coral tissues in vivo in real time have recently been developed, including micropropagation of tissue in microfluidic devices (Shapiro et al, 2016) and coral explants (Gardner et al, 2015).…”