EXPLORING PORPHYRA SPECIES FOR USE AS NITROGEN SCRUBBERS IN INTEGRATED AQUACULTURE

Abstract

Carmona, R.1, Kraemer G. P.2, Zertuche, J. A.3, Chanes, L.4, Chopin, T.5, Neefus C.4,6 & Yarish, C.1 1Dept. of Ecol. and Evol. Biol., University of Connecticut, One University Place, Stamford, CT 06901, USA; 2Department of Environmental Sciences, State University of New York, Purchase, NY 10577 USA; 3IIO, Universidad Autonoma de Baja California. Ensenada,B.C., Mexico; 4DGETI‐CBTis41, Mexico; 5CCSA, Dept. of Biol., University of New Brunswick, Saint John, N.B., E2L 4L5, Canada; 6Department of Plant Biology, University of New Hampshire, Durham, NH 03824, USAFinfish mariculture along the Northeast US coast continues to develop into a strong industry. At a regional level, mariculture can be a significant contributor to nutrient loading in coastal waters. Since macroalgae are able to concentrate nutrients and grow at high rates, they can be an useful tool for alleviating this problem. In addition, seaweed mariculture is by itself a multi‐billion dollar industry, with the red alga Porphyra (nori) valued at over $US 1.8 billion. Local species and strains of Porphyra from the Northeast U.S.A. are being studied to determine their capacity as nutrient scrubbers under different nutrient and temperature conditions. P. purpurea was grown under two N sources (NO3‐ vs. NH4+). The fastest growth (up to 13% d‐1) and greatest N content (ca. 7% DW) were measured in plants grown at 300 µM NH4+. Short‐term NH4+ uptake by P. purpurea (strains from Maine and Long Island Sound) and by P. amplissima was not saturated at 150 µM, the highest concentration tested. The P. purpurea isolate from Maine took up NH4+ faster than did the Long Island Sound isolate. NH4+ uptake by P. amplissima was faster than uptake by either P. purpurea strain. The high growth rates obtained and the ability for N uptake and tissue accumulation make these species suitable for using as a biological nutrient removal system.