A key role of aluminium in phosphorus availability, food web structure, and plankton dynamics in strongly acidified lakes

Abstract

Abstract:We studied extracellular acid phosphatase activity (AcPA) of planktonic microorganisms, aluminium (Al) speciation, and phosphorus (P) cycling in three atmospherically acidified (pH of 4.5-5.1) mountain forest lakes: Čertovo jezero (CT), Prášilské jezero (PR), and Plešné jezero (PL) in the Bohemian Forest (Šumava, Böhmerwald). Microorganisms dominated pelagic food webs of the lakes and crustacean zooplankton were important only in PR, with the lowest Al concentrations (193 µg L −1 ) due to 3-4 times lower terrestrial input. The lakes differed substantially in Al speciation, i.e., in the proportion of ionic and particulate forms, with the highest proportion of ionic Al in the most acid CT (pH = 4.5). The P concentration in the inlet of PL (mean: 22.9 µg L −1 ) was about five times higher than in CT and PR (3.9 and 5.1 µg L −1 , respectively). Average total biomass of planktonic microorganisms in PL (593 µg C L −1 ) was, however, only ∼2-times higher than in CT and PR (235 and 272 µg C L −1 , respectively). Enormous AcPA (means: 2.17-6.82 µmol L −1 h −1 ) and high planktonic C : P ratios suggested severe P limitation of the plankton in all lakes. Comparing 1998 and 2003 seasons, we observed changes in water composition (pH and Al speciation) leading to a significant increase in phytoplankton biomass in the lakes. The increase in the seston C : P ratio during the same time, however, indicates a progressive P deficiency of the lakes. The terrestrial Al inputs, together with in-1ake processes controlling the formation of particulate Al, reduced P availability for planktonic microorganisms and were responsible for the differences in AcPA. At pH < 5, moreover, ionic Al forms caused inhibition of extracellular phosphatases. We postulate that both particulate and ionic Al forms affect P availability (i.e., inhibition of extracellular phosphatases and inactivation of P), specifically shape the plankton composition in the lakes and affect plankton recovery from the acid stress.

Bioaccumulation of aluminium and iron in the food chain of Lake Loskop, South Africa

“…The strong correlation between increasing Al concentrations and the reduction of TP at sampling sites 3 and 4 has also been observed in artificial algal growth media tested by Gensemer (1989). This phenomenon in part is due to the ability of Al to strongly bind phosphorus, thereby reducing the availability of this nutrient to algae (Vrba et al, 2006) Douterelo et al (2004 observed in their study that species in the epilithic cyanobacterial order Oscillatoriales were always associated with highly eutrophic water as observed in our study, while Fernandez-Pinas et al (1991) Oscillatoria, metals and sulfides were removed from the water column over a very short period of time. From the observations in our study, it was evident that the bioaccumulation of Al and Fe in the mixture of different species of algae occurring at different sampling sites may have played a major role in the bioaccumulation of these metals in food chain of resident biota at these sites.…”

Forest Die-Back Modified Plankton Recovery from Acidic Stress

“…Vrba et al 2003bVrba et al , 2006; Ceriodaphnia quadrangula was first recorded in Rachelsee as late as 2009 and has never been abundant). Therefore, it was probably associated with changes in lake water chemistry and/or with the hundredfold increase in rotifer abundance since 2006 ( Fig.…”

“…The possible effect of the rotifer M. clavus upon bacteria and small algae is not known, but its abundant population (grazing on small bacteria) could have caused more intense phosphorus regeneration in the epilimnion and, consequently, its better availability for phytoplankton (cf. Vrba et al 2006) since 2006. An additional supply of phosphorus might have come from higher terrestrial export as recent volume-weighted mean concentrations of P t in the inlet water increased by some 50 % compared to the period 1999-2005.…”

“…2, 3). As bacteria are considered to be superior competitors to phytoplankton for phosphorus (Currie and Kalff 1984), the shift from the dominance of heterotrophic to autotrophic organisms indicates that the plankton has been substantially released from severe phosphorus stress due to reduced aluminumphosphorus interaction (Kopáček et al 2004;Vrba et al 2006). To our knowledge, such a rapid change in plankton structure in a lake recovering from acidity has not been previously documented.…”

Biological recovery of the Bohemian Forest lakes from acidification

“…The levels of total plankton biomass reflect the actual nutrient status of the lakes, which is the result of a complex interplay between pH and phosphorus and aluminium concentrations in tributaries and lake water (for details, see Vrba et al, 2006). Natural P immobilisation by Al part has been recently recognised as a common and important mechanism in any water body with elevated Al input and a pH gradient between its inlet and outlet .…”