I study zooplankton, specifically the single-celled protozoans that are responsible for most of the consumption in planktonic food webs. These organisms, which are comprised principally of a variety of flagellates and ciliates, can grow rapidly and have high metabolic rates in general. They form important links in the food web between microbial producers and multicellular organisms such as copepods and fish.

My current research projects focus on two questions related to marine protozoa: (1) What is the role of ciliates in controlling the growth of phytoplankton populations; and how do these grazers respond to species of phytoplankton that contain toxins or other compounds that serve as feeding deterrents? This project involves both laboratory cultivation of ciliates isolated from the sea and shipboard studies with natural populations. (2) How much intra- and interspecific genetic diversity is there among the ciliates? This project requires sampling and cultivation of ciliates, and aims to study diversity on scales ranging from weekly changes at a single location to global biogeography. In collaboration with colleagues at Smith College in Massachusetts molecular tools are used to create species and community ?fingerprints? of ciliates. We can then make comparisons with other species and communities in different parts of the world. For the future, I plan to use other molecular methods to study growth rates and other metabolic processes in marine protozoa.

McLeroy-Etheridge, S.L. and G.B. McManus. 1999. Food type and concentration affect chlorophyll and carotenoid destruction during copepod feeding. Limnol. Oceanogr. 44:2005-2011.

McManus, G. B. and C. A. Foster. 1998. Seasonal and fine-scale spatial variations in egg production and triacylglycerol content of the copepod Acartia tonsa in a river-dominated estuary and its coastal plume. J. Plankton Res. 20:767-785.

McManus, G.B. 1995. Phytoplankton abundance and pigment changes during simulated in situ dilution experiments in estuarine waters: possible artifacts caused by algal light adaptation. J. Plankton Res. 17: 1705-1716.

McManus, G.B. and R. Dawson. 1994. Phytoplankton pigments in the deep chlorophyll maximum of the Caribbean Sea and the western tropical Atlantic Ocean. Mar. Ecol. Prog. Ser. 113: 199-206.

McManus, G.B. 1993. Growth rates of natural populations of heterotrophic nanoplankton. In: P.F. Kemp, B.F. Sherr, E.B. Sherr and J.J. Cole (eds.), Current Methods in Aquatic Microbial Ecology. Lewis Publishers. pps. 557-562.

McManus, G.B. and M.C. Ederington-Cantrell. 1992. Phytoplankton pigments and growth rates, and microzooplankton grazing in a large temperate estuary. Mar. Ecol. Prog. Ser. 87: 77-85.

McManus, G.B. 1991. Flow analysis of a planktonic microbial food web model. Mar. Microb. Food Webs 5: 145-160.

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