Research

At any given time we are conducting a variety of research projects that are focused on specific aspects of protistan ecology. Linked below are short descriptions of some of our ongoing programs. Some of these projects are predominantly descriptive or observational, while others are much more experimental in nature. All of our ongoing studies employ an array of tools, techniques and instruments adapted from a variety of related disciplines including light and electron microscopy, flow cytometry and other imaging technologies.

In addition to microscopical analyses which help resolve morphological characters for identifying protistan species, genetic (DNA sequencing and probing, DNA fragment analysis) and immunologic (antibody tagging) methods are now commonly employed in our lab. These tools aid in ecological investigations of protistan biodiversity of various environments, and in the determination of the presence and abundance of species of special interest. Genetic approaches rely on exploiting unique base sequences of deoxyribonucleic acid (DNA) that can be used as ‘signatures’ of protistan species in natural water samples, while immunologic approaches involve the production and application of antibodies that react specifically with ‘target’ species of interest. These approaches have been adapted largely from biomedical research where technological advances have revolutionized the identification of pathogenic microorganisms. These applications aid the accuracy and precision with which we can study the diversity, distribution, behavior and physiology of marine protists. For simplified description of how these methods are applied go here.

Many basic questions of protistan physiology and ecology can be addressed using species that can be cultured in the laboratory. As more species are brought into culture and examined, more information is acquired that helps determine the limits of protistan physiology, and can be used to help interpret the role of protists in natural ecosystems. Basic questions of biology still remain unanswered for many species of protists.

Additionally, experimental studies using natural protistan assemblages can reveal information that studies on individual species in culture cannot. Manipulation experiments (e.g. addition of nutrients, removal of predators), can often provide insights into the complex trophic interactions among protists and other micro- and macroorganisms, and the factors controlling the abundances and activities of protistan species.

Examples of the types of questions addressed by this research include:

• What are the rates of growth of microalgae in nature?
• How are particular species of algae able to form massive blooms in nature?
• What do heterotrophic protists eat (i.e. what are their trophic roles)?
• How fast do these species consume prey, and how fast do they grow?
• How do environmental conditions affect these rates (e.g. light, nutrients, prey, consumers)?
• How do protists affect energy production, utilization and elemental cycling?

Despite many decades of study, the breath of protistan diversity in natural ecosystems is still rather poorly known, as is the extent to which many of these species are distributed on our planet. One major reason for this situation is that, owing to the huge range of sizes and morphologies of protists, it is very difficult to identify all of the protists in a single sample.

Another issue with which we are grappling is that new approaches for examining protistan biodiversity (specifically, DNA sequencing) have revealed many sequences that are not from species that have been previously described and cultured. These ‘unknown, uncultured phylotypes’ represent species, genera and higher-level taxa of protists that have not yet been described based on morphological criteria, and for which we have no knowledge of their ecology.

Examples of the types of questions addressed by this research include:

• What is the true species diversity of natural assemblages of protists?
• How does this diversity, or changes in this diversity, affect the processes conducted by protists (e.g. production and utilization of plant material, energy flow in aquatic food webs, nutrient cycling)?
• How well does the diversity of protists in culture collections describe protistan diversity in nature?