Intellectual Merit

The productivity of marine ecosystems depends upon a complex food web of tiny planktonic organisms that provide energy to higher trophic levels, including fish, birds, and marine mammals. Human activities, environmental variability, and decadal-scale change intersect to have diverse effects on plankton, including determining how food web composition and structure change through space and time and how those changes impact ecosystem productivity. To respond appropriately to long-term trends, it is crucial to understand the structure of planktonic food webs, how they function, and how they respond to environmental change. This understanding is facilitated by systematic and detailed measurements over a sufficient length of time so that scientists can observe the responses of these webs to environmental perturbations and uncover the underlying causes and implications; such measurements are most efficiently made by automated instrumentation, the object of this research.

Microscopic phytoplankton cells that capture energy from sunlight comprise the base of the marine food web, and our understanding of the factors that regulate plankton species composition has already been aided by instruments that monitor individual organisms in the ocean. The research team previously developed an instrument to measure and enumerate very small phytoplankton cells (including picoplankton such as Synechococcus, ~1 micrometer diameter), in which optical properties of individual cells are recorded as they pass through a focused laser beam: the submersible flow cytometer FlowCytobot (FCB). FCBs have now been deployed for over 20 years at the Martha’s Vineyard Coastal Observatory (MVCO), providing unprecedented insights regarding this component of the phytoplankton. However, FCB cannot efficiently sample or identify the larger cells such as diatoms or dinoflagellates (10 to >100 micrometers) that often dominate the plankton in coastal waters. Because the larger cells often have recognizable morphologies, the team developed a second submersible flow cytometer to characterize these cells, with imaging capability: Imaging FlowCytobot (IFCB). IFCB is commercially available through partner, McLane Research Laboratories (>100 instruments in use worldwide) but FCB has only been in use at the MVCO.

During this project, the research team developed a prototype hybrid instrument that combines the capabilities of FCB and IFCB: IFCB-eXtended Range (IFCB-XR) captures images of the larger cells and is also sensitive enough to measure fluorescence and light scattering data of picoplankton. These combined approaches allow continuous long-term observations of plankton community structure over a wider range of cell sizes and types, which is important for climate change research, fisheries and aquaculture management, and satellite product validation. The prototype with its new improved features (laser, optics, detectors, data acquisition) has been tested in the laboratory and after final software implementation and field tests could be moved towards commercialization.

Broader Impacts

Automated microscopic imaging (and IFCB technology in particular) is in increasing demand for marine and freshwater resource management needs such as mitigating negative impacts of harmful algal blooms on human and ecosystem health. The technological developments in this project are poised to contribute improved outcomes and reduced risk of negative impacts from such economically and societally relevant events. Successful incorporation of acoustic focusing to extend IFCB dynamic range has set the stage for the commercial manufacturer of IFCB (McLane Research Laboratories) to consider its incorporation into their product line. This project provided research and training experiences for numerous undergraduate, graduate, and postdoctoral scientists interested in the interface of technology development and applications in marine ecology and resource management.

Last Modified: 12/13/2024
Modified by: Heidi M Sosik