Nutrient limitation in a tropical saline lake: a microcosm experiment

Abstract

There is increasing evidence that nitrogen limitation is of widespread occurrence in tropical lakes. Nonetheless, data on the deep tropical Lake Alchichica (Mexico) show that dissolved inorganic nitrogen (DIN) to soluble reactive phosphorus (SRP) ratio fluctuates widely. To elucidate further the role of nitrogen and phosphorus limitation on the phytoplankton growth in tropical saline lakes, we present the results of a series of nutrient enrichment experiments with natural assemblages of Lake Alchichica phytoplankton conducted monthly for a year. Our assays indicate that phosphorus and nitrogen alternate in limiting Lake Alchichica phytoplankton biomass. Phosphorous limited phytoplankton growth most (41.7%) of the time, followed by nitrogen (33.3% of the time), and both nutrients for the rest of the time (25.0%). This alternation in nitrogen and phosphorus responsible for phytoplankton growth limitation in Lake Alchichica is attributed to the combination of natural conditions (e.g., young volcanic terrain rich in phosphorus) that would favor nitrogen limitation and anthropogenic impacts (e.g., agricultural nitrogen fertilization) which would cause phosphorus limitation.

Relative importance of dust inputs and aquatic biological production as sources of lake sediments in an oligotrophic lake in a semi‐arid area

“…In addition, the overall nutrient concentrations in the mixing layer of Lake Alchichica (<4 mmol l -1 ), as well as the wide (15-35 m) euphotic zone, confirm the oligotrophic status suggested by the chlorophyll a concentration (Oliva et al, 2001;Ramírez-Olvera et al, 2009). Lake Alchichica is close to two dry saline playa lakes that are potential dust sources.…”

Diatom fluxes in a tropical, oligotrophic lake dominated by large-sized phytoplankton

“…Lake Alchichica is warm-monomictic, with mixing taking place from late December/early January to late March/ early April, during the cold-dry season, and remains stratified the rest of the year during the warm-rainy season (Alcocer et al, 2000). Lake Alchichica is oligotrophic (Ramírez-Olvera et al, 2009). In the mixed-layer, dissolved inorganic nitrogen (DIN) concentration ranges from 9.8 to 53.2 lg l -1 , soluble reactive phosphorus (SRP) ranges from 3.1 to 18.6 lg l -1 and chlorophyll a (Chla) concentrations from 0.2 to 2.2 lg l -1 .…”

Limnology in Mexico

“…Bernal-Brooks et al (2002b, 2003 and carried out bioassays to assess the algal growth potential and limiting nutrient in Zirahuén and Pátzcuaro, respectively, and as well as López-López & Dávalos-Lind (1998) found P-limitation in stream waters and NP colimitation in lakes. Ramírez-Olvera et al (2009) and Ramos-Higuera et al (2008) run micro-and mesocosm nutrientenrichment experiments, respectively, in Lake Alchichica. These papers show the relevance of nitrogen as limiting phytoplankton growth and also an alternation between nitrogen and phosphorus, and even colimitation along the year.…”