Phosphorus limitation of algae living in iron-rich, acidic lakes

Abstract

Very acidic lakes (pH 2.3 to 3.2) have developed in abandoned open cast mines of eastern Germany. Recent research has shown that growth of Chlamydomonas acidophila inhabiting one of these lakes was likely limited by inorganic phosphorus (P). Although most measurements of soluble reactive phosphorus (SRP) concentrations do not identify P as the factor limiting growth (i.e. SRP > 0.1 µmol P l -1 ), the high iron concentrations (up to 10 mmol Fe l -1 ) can decrease the bioavailable P fraction by complexation, or can lower P-uptake rates by adsorption processes. To test for P-limitation, 4 lakes (Lakes 107, 111, 113 and 117) were sampled 5 times in 2006 to measure SRP, particulate phosphate, particulate carbon, dissolved organic carbon, chlorophyll a concentration, algal abundance, maximum P uptake rate, and phosphatase activity; P-enrichment experiments were also conducted. All results suggest that algal growth was P limited, at least during some part of the year, even in the lake with the highest SRP concentration (Lake 107: 1 µmol P l -1). In P-enrichment experiments, C. acidophila always became the dominant species, suggesting that of all species present, this was the most P-limited. In contrast to expectations, the extent of algal P-limitation in these very acidic lakes could not be explained by SRP and iron concentrations.KEY WORDS: Acid mine drainage · Algal community · Chlamydomonas · Metal-rich lakes · P-availability Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 53: [201][202][203][204][205][206][207][208][209][210] 2008 in the German mining lakes it is the main photoautotrophic phytoplankter (Kamjunke et al. 2004). Although species diversity in the acidic lakes is low, taxa from a number of algal classes are present, including several diatom species, chrysophytes, euglenophytes and chlorophytes (Lessmann et al. 2000).The concentration of iron present in the acidic lakes is high and consists mainly of ferric iron, with up to only 10% being reduced ferrous iron (Friese et al. 2002). The high iron concentrations strongly buffer the lake water between a pH of 2 and 4. The ferric iron phosphate complex is more insoluble than ferrous phosphate (Stumm & Morgan 1970), and consequently part of the soluble reactive phosphorus (SRP) might consist of ferric phosphate complexes not available for algal growth. Therefore, high SRP concentrations might not translate to high concentrations of P for algal growth. Furthermore, ferric iron concentrations of 5 mmol l -1 are considered toxic for algal assemblages in a very acidic river in Spain (Rowe et al. 2007). Consequently, the defense mechanisms of algae that overcome toxic iron conditions might consume ATP, resulting in increased metabolic costs (Messerli et al. 2005) and a consequent decrease in population fitness. In addition, P-capturing processes may be inhibited by high iron concentrations that cause Fe to adsorb to the cell surface. As a first study on the possible toxicity of iron under very acidic cond...

The expression of a carbon concentrating mechanism in Chlamydomonas acidophila under variable phosphorus, iron, and CO2 concentrations

“…Recent experiments suggest that high iron concentrations decrease the bio-availability of inorganic phosphorus as Fe-P complexation decreased P incorporation in C. acidophila and resulted in P-limited growth (unpublished results). In addition, phosphorus is often a growth-limiting factor for the phytoplankton in acidic lakes (Spijkerman 2008a), especially for C. acidophila.…”

High Photosynthetic Rates Under a Colimitation for Inorganic Phosphorus and Carbon Dioxide1

“…P i is often a growth‐limiting factor for the phytoplankton in freshwater lakes (Schindler 1977). Also in very acidic mining lakes, phytoplankton growth is P i limited during most of the summer stratification period (Spijkerman 2008a). P i limitation lowers maximum photosynthetic rates ( P max ) and maximum quantum yield (Φ II ) as shown from laboratory experiments (Harris and Piccinin 1983, Wykoff et al.…”

“…2; P p , particulate phosphorus concentration; PVDF, polyvinylidine difluoride; Q 0 , minimum cellular P quota; Q p , cellular P quota; R d , dark respiration; a, initial slope of P-I curve; b, photoinhibition term of P-I curve; l, growth rate; F II , maximum quantum yield P i is often a growth-limiting factor for the phytoplankton in freshwater lakes (Schindler 1977). Also in very acidic mining lakes, phytoplankton growth is P i limited during most of the summer stratification period (Spijkerman 2008a). P i limitation lowers maximum photosynthetic rates (P max ) and maximum quantum yield (F II ) as shown from laboratory experiments (Harris and Piccinin 1983, Wykoff et al 1998.…”

Multiannual variations in phytoplankton populations: what distinguished the blooms of Aphanizomenon ovalisporum in Lake Kinneret in 2010 from 2009?

“…Phosphate availability is considered a major limiting factor to phytoplankton growth in Lake Kinneret (Berman, 1988; Markel et al ., 1994; Eckert et al ., 1997) and many other lakes around the world (a few recent publications from diverse environmental conditions include Ogawa, 1988; Rengefors et al ., 2003; Mhamdi et al ., 2007; Fadiran et al ., 2008; Spijkerman, 2008; Aubriot et al ., 2011; Burford and Davis, 2011; Young et al ., 2011). Measurements of the various forms of phosphate are therefore routinely performed as part of monitoring of Lake Kinneret waters.…”