Land use affects coastal stream phytoplankton nutrient and light limitation
Public Deposited- Last Modified
- February 26, 2019
- Creator
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Couper, Lisa
- Affiliation: Institute of Marine Sciences, College of Arts and Sciences
- Abstract
- Human land use alterations in the watersheds of coastal streams flowing into the New River Estuary (NRE) have resulted in changes in nutrient concentrations, irradiance, and light attenuation of receiving systems. Two watersheds draining into the NRE were selected for comparison given their contrasting land use characteristics. Significant differences in NH_4^+, and NO_x^- were found between sites during previous in situ monitoring, and differences in light attenuation and surface irradiance were found during this study. In order to understand the mechanisms influencing native phytoplankton abundance in these coastal streams, nutrient and light addition bioassays were conducted for each site at base and storm flow, and further light level manipulations were conducted using site as an additional factor given the difference in optical water properties. In the nutrient and light bioassays, it was found that N additions stimulated increased phytoplankton abundance; N additions and light have an interactive effect on abundance; and P additions and light additions alone had no effect at either site. In light level manipulation bioassays, the difference in phytoplankton response was much greater between different light treatments for a given site than between the two sites at a given light level. This result implies that canopy has a relatively greater effect than inherent optical water properties in governing light availability as indicated by phytoplankton abundance. Results of light-level manipulation bioassays and P-I curves indicate that phytoplankton have a lower photosynthetic efficiency and maximum rate when disruptions to their light regime occur, and phytoplankton adapted to greater light environments have decreased susceptibility to photoinhibition.
- Date of publication
- spring 2014
- Keyword
- DOI
- Resource type
- Rights statement
- In Copyright
- Note
- Funding: None
- Advisor
- Piehler, Michael
- Degree
- Bachelor of Science
- Honors level
- Highest Honors
- Degree granting institution
- University of North Carolina at Chapel Hill
- Extent
- 8
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