The Nitrogen Relationships of Marine Macroalgae

Seasonal nitrogen metabolism in an intertidal population ofGelidium latifolium(Gelidiaceae, Rhodophyta)

“…As shown in Fig 3A, C/N values below 20 roughly correspond to N content values above 2%. Hanisak (1983Hanisak ( , 1987Hanisak ( , 1990 recommended plotting N content in preference to C/N ratios, due to the possibility of changes in carbon metabolism. More recently Duarte (1992) demonstrated an asymptotic relationship between N and C/N in 180 species of aquatic plants when the values are below 4% and above 9, respectively.…”

“…Carbon and nitrogen metabolism are related by a demonstrable inverse relationship between agar synthesis and carbon metabolism on one hand, and protein synthesis and nitrogen metabolism on the other (Hanisak, 1983), that has been shown indirectly for some species of Gelidium in culture (Macler, 1986(Macler, , 1988Fredriksen & Rueness, 1989, Torres et al, 1991. In addition, populations of red algae, including members of the Gelidiales, around the world show a characteristic summer 'bleaching', described as a loss of pigmentation related to environmental conditions (Neish et al, 1977;Santelices, 1988).…”

“…l',Iit~,gen is an essential nutrient for the growth of marine algae: (DeBoer, 1981;Hanisak, 1983). In red algae, research has concentrated on the economically important species of Gracilaria and Chondrus (DeBoer, 1978;Ryther et al, 1978;Rosenberg & Ramus, 1982;Bird et al, 1982;Bird, 1984;Friedlander & Dawes, 1985;Fujita, 1985;Dawes & Koch, 1990;Friedlander et al, 1990;Hanisak, 1990) and tank cultures of Palmaria palmata (Morgan & Simpson, 1981a, b) and Chondrus crispus (Neish et al, 1977).…”

“…To assess the physiological status of seaweeds in relation to nitrogen, several indicators have been used: nitrogen availability in seawater (Rosenberg & Ramus, 1982;Fujita et al, 1989), total thallus nitrogen, usually expressed as the C/N ratio (Hanisak, 1979(Hanisak, , 1983, carbohydrate content with respect to nitrogen content (Rosenberg & Ramus, 1982) or protein content (Bird, 1984). However, the ecological significance of these indicators, especially the C/N ratio (Niell, 1976;Hanisak, 1979;Niell & Mourifio, 1981;Atkinson & Smith, 1984;Duarte, 1992) has received less attention (Greenwell et aI., 1984;Lapointe et aI., 1987;Kopczak et al, 1991; and the emphasis has been put on more physiological approaches, related to cultivation procedures (cf.…”

Nitrate Assimilation: The Role of In Vitro Nitrate Reductase Assay as Nutritional Predictor

“…Macroalgae have either the plasticity or preference to uptake several forms of nitrogen. Hanisak (1983) noted that the uptake rate of ammonium generally exceeds that of nitrate. Chow et al (2001) registered the same trend for Gracilaria chilensis, with total uptake of only ammonium, when present together with nitrate and nitrite.…”