The nutrient stoichiometry of benthic microalgal growth: Redfield proportions are optimal

Abstract

Abstract-Cellular nutrient ratios are often applied as indicators of nutrient limitation in phytoplankton studies, especially the so-called Redfield ratio. For periphyton, similar data are scarce. We investigated the changes in cellular C : N : P stoichiometry of benthic microalgae in response to different levels and types of nutrient limitation and a variety of abiotic conditions in laboratory experiments with natural inocula. C : N ratios increased with decreasing growth rate, irrespective of the limiting nutrient. At the highest growth rates, the C : N ratio ranged uniformly around 7.5. N : P ratios Ͻ13 indicated N limitation, while N : P ratios Ͼ 22 indicated P limitation. Under P limitation, the C : P ratios increased at low growth rate and varied around 130 at highest growth rates. For a medium with balanced supply of N and P, an optimal stoichiometric ratio of C : N : P ϭ 119 : 17 : 1 could be deduced for benthic microalgae, which is slightly higher than the Redfield ratio (106 : 16 : 1) considered typical for optimally growing phytoplankton. The optimal ratio was stable against changes in abiotic conditions. In conclusion, cellular nutrient ratios are proposed as an indicator for nutrient status in periphyton.

Mapping the distribution, biomass and tissue nutrient levels of a marine benthic cyanobacteria bloom (Lyngbya majuscula)

“…8b) in the current study are similar to ratios (46-51) reported from Deception Bay in 2005 but are higher than the ratio (14) reported for Deception Bay in 1999-2000 (Watkinson et al 2005) and the Eastern Banks (16.4-22.4) (Ahern et al 2007). The N : P ratios reported in the present study, particularly during the incipient, rapid growth and plateau phases (47-72), were substantially higher than the various optimum N : P ranges published in the literature, including optimum ratios for unicellular phytoplankton (16) (Redfield et al 1963), freshwater periphyton (18) (Hecky et al 1993), medium ratio (30) for benthic plants (Atkinson and Smith 1983) and the optimum range (13-22) for benthic microalgae (Hillebrand and Sommer 1999). The higher N : P ratios recorded in the present study are not unusual for nitrogen-fixing species, which have often been documented as having higher N : P stoichiometry than non-diazotrophic species (Table 4).…”

“…8a). These ratios were at the higher end of the optimum range (5-10) for marine microalgae (Hillebrand and Sommer 1999) and much higher than the Redfield stoichiometry (6.6) for unicellular phytoplankton (Redfield et al 1963), or for the optimum ratio (8.8) for freshwater periphyton (Kahlert 1998). The higher C : N ratios of L. majuscula recorded in the current study are consistent with data from previous studies in Deception Bay: 9.8-10.4 in 2005 and 12.8 in 1999-2000 (Watkinson et al 2005) and in eastern Moreton Bay (8.8-9.4; Ahern et al 2007).…”

“…Although very limited data are available on the stoichiometry or range of elemental ratios for L. majuscula and other benthic marine nitrogen-fixing cyanobacteria, comparison to critical values developed for phytoplankton (Redfield et al 1963;Hecky et al 1993), freshwater periphyton (Kahlert 1998) and marine microalgae (Hillebrand and Sommer 1999) can provide some insight into the physiology and nutritional status of L. majuscula. The C : N ratio of L. majuscula in the current study was relatively consistent (9.8-10.5; 9.4-10 adjusted for carbonate) and had very low standard errors during the incipient, rapid growth and plateau phases of the bloom (Fig.…”

Efeito de diferentes níveis de enriquecimento por fósforo sobre a estrutura da comunidade perifítica em represa oligotrófica tropical (São Paulo, Brasil)

“…O conteúdo de nitrogênio e fósforo e a razão N:P da massa perifítica têm sido usados com sucesso para indicação do potencial de limitação nutricional do perifíton (Biggs 1995, Borchardt 1996, Hillebrand & Sommer 1999. Trabalhos mais abrangentes, em escala espacial, utilizaram a o estado nutricional do perifíton para comparar o potencial de limitação algal entre ecossistemas, a exemplo de Maberly et al (2002) e Francouer et al (1999, os quais compararam 30 lagos e 12 rios de regiões temperadas, respectivamente.…”

Characterization of cyanophyte biomass in a Bureau of Reclamation reservoir

“…This difference could be related to the large concentration of protein in AFA or to an optimal growth rate of AFA. Benthic algae (including cyanophytes) have been reported to produce C:N ratios that decreased with increasing growth rate (Hillebrand and Sommer, 1999).…”