Do nutrients limit algal periphyton in blackwater coastal plain streams?
Abstract:
We examine the potential for nutrient limitation
of algal periphyton
biomass in blackwater streams draining the Georgia coastal plain.
Previous studies have investigated nutrient limitation of planktonic
algae in large blackwater rivers, but virtually no scientific
information exists regarding how algal periphyton respond to nutrients
under different light conditions in smaller, low- flow streams. We used
a modification of the Matlock periphytometer ( nutrient- diffusing
substrata) to determine if algal growth was nutrient limited and / or
light limited at nine sites spanning a range of human impacts from
relatively undisturbed forested basins to highly disturbed agricultural
sites. We employed four treatments in both shaded and sunny conditions
at each site: (1) control, (2) N (NO3-N), (3) P (PO4-P), and (4) N+P
(NO3-N + PO4-P). Chlorophyll a response was measured on 10 replicate
substrates per treatment, after 15 days of in situ exposure.
Chlorophyll a values did not approach what have been defined as
nuisance levels (i.e., 100-200 mg/m(2)), even in response to nutrient
enrichment in sunny conditions. For Georgia coastal plain streams,
algal periphyton growth appears to be primarily light limited and can
be secondarily nutrient limited (most commonly by P or N + P combined)
in light gaps and / or open areas receiving sunlight.
Carey, R. O.,G. Vellidis, R. Lowrance, and C. M. Pringle. 2007. Do nutrients limit algal periphyton in blackwater coastal plain streams? Journal of the American Water Resources Association. 43(5): 1183-1195.
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