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My master’s research focused on developing a method that would allow us to gain a more clear understanding of food web dynamics in marine pelagic ecosystems. Specifically, my work has focused on targeting the earliest life stages of copepods, called nauplii. Copepod nauplii are a member of the microzooplankton, which are known to be important grazers in marine ecosystems, however we know little about their role in food webs because of challenges in identification of species and in sampling them quantitatively. Many related species are morphologically very similar, so it can be nearly impossible to tell them apart even with high powered microscopy. Behavioral research has shown that they exhibit species-specific grazing and escape behaviors, suggesting they fill unique niches in the environment, but limitations in identification has left this largely uninvestigated in diverse ecosystems. Sampling has been a problem because they are so small that they are often missed entirely by standard plankton nets.
By combining specific sampling protocols to collect the nauplii, with a molecular method called quantitative PCR (qPCR), I was able to accurately estimate the abundance of a species of nauplii, Parvocalanus crassirostris, from a copepod monoculture, as well as show that the method could be applied in the field. Using DNA as an identifier, qPCR allows both identification and quantification of the abundance of a single copepod species in a mixed plankton sample. Use of qPCR will allow us to estimate species abundances over time, see changes in relative species abundances (which can act as indicators of ecosystem health), or to look at the effects of environmental perturbations like storm events on copepod populations at fine scales. These are potential foci of my future Ph.D. studies.
Advisor: Dr. Petra Lenz