Vymazal, J., C.B. Craft, and C.J. Richardson. 1994. Periphyton response to nitrogen and phosphorus additions in the Florida Everglades. Algological Studies 73:75-79.

Abstract: The effect of phosphorus and nitrogen on periphyton growth, species composition and biomass nutrient content in three different macrophyte communities of the Florida Everglades was investigated to test for N or P limitation and periphyton response to N and P additions. Nitrogen and phosphorus were applied singly and in combination to 2 x 2 m enclosures at rates of 0.6, 1.2, and 4.8 g P m–2 a–1 and 5.6 and 22.4 g N m–2 a–1. Dried reed stems were placed in the plots in May 1991 and, after 82 days, the periphyton was analysed for species composition, dry mass, and nutrient content of biomass. Single nitrogen additions had no effect on periphyton species composition at the sawgrass and slough sites. Phosphorus additions, however, increased the number of diatom as well as blue-green algae species in these sites. At mixed site (sawgrass – cattail), all fertilizer additions resulted in lower number of species and a disappearance of most filamentous green algae resulting in a decrease of periphyton biomass in fertilizer plots. At the sawgrass site, the high P and the medium and high N + P treatment exhibited a significant increase in periphyton biomass. Nitrogen additions did not result in an increase in n concentrations in periphyton biomass. However, phosphorus additions resulted in higher P concentrations in periphyton biomass. Nitrogen:phosphorus ratios in periphyton biomass ranged between 18:1 and 79:1, indicating P-limitations in our studied areas. Periphyton was highly calcified, up to 26.5% of Ca on a dry mass basis, with less calcification in high phosphorus treatments.

Key words: Algae, calcification, Everglades, periphyton, phosphorus, nitrogen.

1994 E. Schweizerbart’sche Verlagsbuchhandlung. Reproduced by permission.

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