Life at Planktonic Scales:
By Tom Hata     Awards: Myers

Breaking waves along rocky shores are responsible for transporting marine organisms to new habitats in some cases and dislodging organisms from their homes in other cases.  This fact may be immediately obvious when observing a set of waves repeatedly washing over a mussel bed attached to a rock, but it is also important to consider what is happening at much smaller size scales.  For the mussel bed to even exist, their larvae, which are smaller than the size of the period at the end of this sentence, had to adhere to the rock in the face of hydrodynamic forces imparted on them by local water flow.

Techniques have been developed to measure water velocities at the size scale of centimeters along the physically extreme conditions of rocky, wave-swept shores, but until now, there has been no way to measure flow at the sub-millimeter scale—a size range relevant to numerous microscopic organisms as well as the larval and spore stages of many macroscopic organisms.  To this end, I have designed a triangular pressure block able to measure flows in the field just 250 microns (the thickness of two sheets of paper) above the substrate.  By measuring the ratios of pressures among the ports, I am able to calculate the magnitude and direction of water motion at an extremely fine temporal resolution (1000 Hz).  By investigating the flow regimes across sites of differing topography along the shore, we may be able to more accurately predict who can settle where in the rocky intertidal zone, and how long they can survive.