Title:	Associate Professor of Aquatic Ecology
	Phone:	814-865-9219
	Email:	hjc11@psu.edu
	Address:	The Pennsylvania State University School of Forest Resources 434 Forest Resources Building University Park, PA 16802

Education:

B.A. State University of New York at Binghamton (1983)
M.S. Bowling Green State University (1985)
Ph.D. The University of Michigan (1990)

Academic Interests:

Aquatic ecosystems ecology, Limnology, Food web dynamics and nutrient cycling, Ecology and taxonomy of microbes (bacteria, algae, protozoa), Biostatistics

Courses Taught:

Ecosystem Management (ERM 413w), Pollution in Aquatic Systems (ERM 432)

Professional Affiliations :

Association of International Biologists (member since 1996)
International Association for Great Lakes Research (member since 1985) Society of International Limnology (member since 1998)
The American Society of Limnology and Oceanography (member since 1985)
The Phycological Society of America (member since 1990)

Professional Service :

American Society of Limnology & Oceanography (Organizer, 2001 meeting) Environmental Protection Agency (Short-course instructor)
Hudson River Foundation Grants Program (Reviewer)
National Sea Grant College Program (Reviewer Ohio, Michigan)
National Science Foundation (Panel member, DEB, DUE, BioResearch)
United States Department of Agriculture (Reviewer Ecosystem Sci Program)

Cultural Eutrophication: Linking Ecosystem Productivity to Land-use The cultural eutrophication of aquatic ecosystems is a problem of epidemic proportion throughout the world, such that changes in watershed-scale land use can have measurable impacts on the productivity and trophic function of aquatic systems. Regression analysis revealed that the in-lake phosphorus content of a chain of lakes that serves as a major source of water to south Florida was predicted to increase with agriculture and urban utility land coverage in the region. Such models may be helpful in identifying consequences associated with swift development in the region and its implications such changes may have on restoration efforts in the Everglades.

Global Climate Change: Effects of UV-Radiation in High Elevation Lakes
Long-term studies are instrumental in evaluating the effects changing climatic conditions have on food web dynamics and productivity. A collaboration with scientists at University of California-Davis and Utah State University indicates that ultraviolet radiation (UV) penetration in Castle Lake (California) and other high elevation systems (e.g., Crater Lake and Lake Tahoe) is great due to high incident UV radiation and low concentrations of dissolved organic carbon in the water. While UV depresses algal growth in the lake, the addition of limiting nutrients can override the UV effect. Therefore, due to its sensitivity to both nutrients and UV, Castle Lake may serve as an important, early-warning system to subtle changes in the gas balance of the atmosphere.

Exotic Species Introductions: Altering Patterns of Primary Production
The recent invasion of the exotic zebra (Dreissena polymorpha) and quagga (Dreissena bugensis) mussels appears to have augmented desirable changes in Lake Erie's water quality, in addition to decreases in nutrient loads through on-going international nutrient abatement programs. Studies were carried out to assess how the current zebra mussel infestation might affect the oxygen balance in Eastern Lake Erie. Increased light penetration in the basin appears to coincide with the occurrence of a deep phytoplankton assemblage in the metalimnion and a benthic algal assemblage. Nonetheless, dissolved oxygen depletion rates in the basin remain unchanged since the 1970's, suggesting that these changes are resilient to reductions that have occurred in phytoplankton biomass and phosphorus loading in Lake Erie over the same time-period.

The Role of Microbes in Food Web: A Changing Ecological Paradigm?
The recent development of technology suggests that microbes (bacteria, small algae, and protozoa) may play a more important role in terrestrial and aquatic food webs then once thought. To evaluate their role in aquatic food webs, 70 lakes with contrasting nutrient income and food web structure were sampled throughout the United States. Results indicate that small plankton were a dominant feature of all food webs. Given their ubiquitous occurrence and high metabolic rates, small plankton may buffer ecosystems from change by maintaining the structural integrity and biogeochemical function of aquatic food webs.

Carrick, R. Barbiero, and M.L. Tuchman. 2001. Variation in Lake Michigan plankton: Temporal, spatial, and historical trends. J. Great Lakes Res. 27: 467-485.

Higley B., H.J. Carrick, M. Brett, C. Luecke, and C.R. Goldman. 2000. Effects of ultraviolet radiation and nutrients on periphyton growth in Castle Lake, California. Internat. Review Hydrobiol. 86: 145-161.

Carrick, H.J., and C.L. Schelske. 1997. Have we underestimated the importance of small phytoplankton in productive waters? Limnol. Oceanogr. 42: 1613-1621.

Carrick, H.J., and G.L. Fahnenstiel. 1995. Common planktonic protozoa in the upper Great Lakes: An illustrated guide. Pine Press, Ann Arbor, MI. 68 p.

Carrick, H.J., D. Worth, and M.L. Marshall. 1994. The influence of water circulation on chlorophyll-turbidity relationships in Lake Okeechobee as determined by remote-sensing. J. Plankton Res. 16: 1117-1135.

Carrick, H.J., F.J. Aldridge, and C.L. Schelske. 1993 . Wind influences phytoplankton biomass and composition in a shallow, productive lake. Limnol. Oceanogr. 38: 1179-1192.

Carrick, H.J., G.L. Fahnenstiel, E.F. Stoermer, and R.G. Wetzel. 1991. The importance of zooplankton-protozoan trophic couplings in Lake Michigan. Limnol. Oceanogr. 36: 1335-1345.

Fahnenstiel, G.L., and H.J. Carrick. 1988. Primary production in Lakes Huron and Michigan: In vitro and in situ comparisons. J. Plankton Res. 10: 1273?1283.