Deep Focus Plankton Imager (DPI-2)
The Deep Focus Plankton Imager (DPI-2; formerly the ISIIS-2) is an underwater imaging system aimed at capturing in situ, real time images of marine zooplankton of relatively low abundance such as fish larvae and fragile gelatinous organisms.
The DPI-2 system utilizes a high-resolution line-scanning camera with a Light Emitting Diode (LED) light source, modified by plano-convex optics, to back-light a parcel of water. The imaged parcel of water passes between the forward portions of two streamlined pods, and thereby remains unaffected by turbulence.
The resulting very high-resolution image is of plankton in their natural position and orientation. When a sufficient volume of water is imaged this way, quantification of density and fine scale distribution is possible. DPI-2 is capable of imaging a maximum of 162 liters of water per second (when flying at 5 knots) with a pixel resolution of 70 µm. DPI-2 is capable of imaging particles from 1 mm to 13 cm in size.
Multiple Open Closing Net Environmental Sensing System (MOCNESS)
The Multiple Open Closing Net Environmental Sensing System (MOCNESS) we use consists of a rectangular frame that carries sensors and controls between 5 to 9 nets. The RV Walton Smith tows the MOCNESS at 5 knots. The cable connecting the MOCNESS to the ship also carries data, allowing scientists to control the instrument’s depth. MOCNESS can sample as deep as 6,000 meters (3.7 miles).
As MOCNESS tows behind a research ship, each net can be opened and shut independently so that it samples plankton in a discrete patch of water. The researcher chooses exactly when by using the environmental sensing system. This is an array of sensors mounted on the instrument frame that relays water conditions up to the ship in real time. Sensors report conductivity (salinity), temperature, depth, and chlorophyll, oxygen and light levels.