Award: OCE-1435515

Award Title: Collaborative research: Patterns of diversity in planktonic ciliates: spatio-temporal scales and community assembly in the coastal ocean
Funding Source: NSF Division of Ocean Sciences (NSF OCE)
Program Manager: David L. Garrison

Outcomes Report

This project was focused on measuring the biological diversity of a group of single-celled organisms, the ciliates, that are important in the ocean's plankton food web. Ciliates are one of the principal organisms that eat phytoplankton at the base of the food web and pass the energy from these photosynthetic plankton on to higher organisms, such as zooplankton and fish, that eat them. Because the world ocean is an open system (all oceans are connected to each other and currents circulate plankton everywhere), we do not know if some parts of the ocean have unique species only found there in the same way that terrestrial animals and plants can be restricted in their ranges and habitats, a feature known as endemism. This question is central to understanding overall diversity in the ocean, so we are using the ciliates as an example of how diversity might be controlled in all plankton. In earlier studies, we found that natural ciliate plankton communities are composed of a small number of abundant species and a very large number of rare ones. Because of this, we used two different DNA-based methods to measure the abundance of different species - one rapid method allowed us to process more samples but only gave us the most abundant forms; the other method was more time-consuming but let us observe even the rarest species (1-2 cells in a liter of seawater). We also used RNA-based methods on some samples, which allowed us to estimate the activity level of the ciliates that we were observing by DNA sequencing. Using the rapid technique, we found that the same abundant ciliate species dominated the community in both surface and deep waters on the New England continental shelf all the way out to its edge (about 100 miles). We also found a few common species that could only be found offshore (water deeper than about 200 feet). The rare species, measured with the more time-consuming technique, varied from place to place across the shelf, but we did not see any examples where a very rare species at one place became common someplace else. We also found, surprisingly, that the overall diversity (the total number of species, including rare ones) did not decrease appreciably with depth, a finding that contradicts most earlier microscopic estimations of diversity. As indicated by RNA measurements, ciliates in deeper waters were not less active, although we had thought they might be. As is often the case, sampling the ocean for one thing provides opportunities to sample other things as well. So this project also supported a small study of how satellites could be used to measure the abundance of certain ciliates with unique pigments that occur in enormous blooms that are difficult to predict, and also a study of ciliates that use the photosynthetic apparatus of the phytoplankton they eat to keep it operational inside the ciliate itself. Some of the broader impacts of this project involved hosting a high school student and a teacher in the lab, public outreach during UCONN's "Marine Science Day", judging middle-school and high school projects related to the ocean at the Connecticut Science Fair, and giving guest lectures on several occasions in the Sea Education Association's Bidiversity Program. Last Modified: 11/01/2018 Submitted by: George B Mcmanus

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Principal Investigator: George B. McManus (University of Connecticut)