Effects of Nutrient Limitations and Watershed Inputs on Community Respiration in a Deep, Tropical Lake: Comparison of Pelagic and Littoral Habitats (original) (raw)
Limnology and Oceanography, 1984
Five types of physiological assay were applied to samples from three sites in Lake Titicaca, Peru-Bolivia (16"s) to assess the magnitude and seasonality of N or P limitation of algal growth. Phosphorus appeared to be in abundant supply relative to growth requirements throughout 1982. Alkaline phosphatase levels were low (~3 nmol substrate converted.cc.g-'Chl aeliter-l), 3zP0.,3turnover times were always long (> lo3 min in the main body of the lake), and little or no phosphorus was accumulated by the seston during short term enrichments. Ammonium enhancement assays suggested a persistent cellular shortage of nitrogen throughout all seasons in the plankton of a large shallow bay, and in the main basin when the water was stratified. High ammonium uptake capacities, as measured with the NH,+ analogue [L4C]methylammonium, and selective accumulation of nitrogen from N plus P enrichments provided supportive evidence of cellular N deficiency. Winter mixing brought large quantities of NO,-and SRP into the surface euphotic zone of the main basin, and throughout this period neither N nor P appeared to be limiting. Polymixis in the shallow bay resulted in large variations in nitrogen supply and deficiency, and these effects were modulated in part by changes in depth of the euphotic zone. Nitrogen was always in low abundance relative to phosphorus in Lake Titicaca, but the extent of nutrient control on algal growth varied considerably with site and time of year.
OPINION Endless summer: internal loading processes dominate nutrient cycling in tropical lakes
Freshwater Biology, 1990
1. Fossi! diatom assemblages deposited in more than a dozen African lakes roughly y5(X) years BP were dominated by a single planktonic species, Stephanodiscus astraea (Ehrenb.) Grun. (although realistically this is likely to be a species complex). These diatoms flourished when lake-levels were maximal. Data are included from many of the large African lakes, and others extending from Lake Abh6, Ethiopia, to Lake Cheshi. Zambia.
Nutrient dynamics and phytoplankton resource limitation in a deep tropical mountain lake
Inland Waters, 2015
Managing lake eutrophication requires a clear understanding of resource limitation of primary productivity, yet historically research on this subject has focused on temperate lakes. In 2010, we quantified several metrics of resource limitation in Lake Atitlán, Guatemala, Central America's deepest tropical mountain lake that has recently experienced extensive phytoplankton blooms. In contrast to many temperate lakes, Lake Atitlán did not show a relationship between total phosphorus (TP) and chlorophyll a (Chl-a) concentrations. Average molar ratios of total nitrogen (TN) to TP decreased from 16.4 to 4.5 between stratified and mixing conditions. During our monitoring period, Tropical Storm Agatha landed on Guatemala, washing in sediment from the watershed, and concentrations of P temporarily increased in the lake by >60%. Initial experimental bioassays indicated phytoplankton growth was colimited by N and P prior to the storm, whereas post-storm assays suggested limitation by P and trace elements. Compared to previous years, Limnoraphis robusta, an N-fixing cyanobacterium, increased in abundance earlier in the year; however, there was no bloom event during our sampling period. Experimental studies indicated that nitrogenase activity was limited by P and iron availability while light was secondarily limiting of overall phytoplankton growth. This study illustrates the potential for baseline nutrient and phytoplankton growth dynamics to substantially differ for tropical lake systems from conventionally studied temperate lakes and the potential for "pulse" events (e.g., tropical storms) to alter those dynamics.
Hydrobiologia
The determination of the metabolic activity of organisms at various trophic levels is crucial for the proper assessment of the energy flow through the ecosystem, which is the basic process determining ecosystem functioning. We estimated the respiration rate in nine shallow, eutrophic lakes (macrophytedominated and phytoplankton-dominated) from northeastern Poland. Respiratory carbon loss (RCL) through bottom microbial communities, macrophytes, plankton and macrozoobenthos was estimated by measuring the Electron Transport System activity. The shares of the particular ecosystem components in respiration processes differed among the lake types and seasons. The bottom microbial communities contributed most to the RCL (from 50% in the macrophyte-dominated lakes to 90% in the shallower phytoplankton-dominated lakes) except in macrophytes-dominated lakes in summer, where the macrophyte contribution prevailed (80%). The contribution of plankton was considerable only in the deeper phytoplankton-dominated lakes (20%). Macrozoobenthos was important (20%) only in the macrophytedominated lakes in spring and autumn. The RCL through bottom microbial communities was substantially higher in the shallow lakes (especially phytoplankton-dominated) than in deep, stratified eutrophic lakes. Shallow eutrophic lakes can be highly productive due to intensive organic matter mineralization at the bottom and rapid flow and cycling of carbon and nutrients resulting from their polymictic character.
1979
The seasonal cycles of respiration of net zooplankton and microplankton were determined for euphotic zones of Lake Washington and Findlcy Lake. In Lake Washington net zooplankton respiration rates estimated from ETS activity ranged from 22.4 to 1,194 mg 0 * rnd2. d-l with the maximum occurring during the spring bloom. Net zooplankton respiration rates in Findlcy Lake ranged from 27 mg 0. mm2 * d-l under ice cover to a maximum of 205 mg 0 * rnp2 * d-l, which occurred well after the bloom. Respiration rates estimated from ETS activity agreed well with those estimated from zooplankton species abundance. Zooplankton community respiration never exceeded 60% of primary production in Lake Washington; however, in Findlcy Lake zooplankton community respiration rates exceeded primary production during the latter part of the ice-free growing season. Phosphorus regeneration rates calculated from zooplankton respiration appeared sufficient to supply most of the phytoplankton phosphorus reqtlirement during summer stratification in Lake Washington.
Nutrient limitation in a tropical saline lake: a microcosm experiment
Hydrobiologia, 2009
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.
Canadian Journal of Fisheries and Aquatic Sciences, 2000
We assessed planktonic respiration in whole-lake manipulations of nutrient loading and food web structure in three manipulated and one unmanipulated lake over 7 years. The manipulations created strong contrasts in zooplankton body size across a series of nutrient loads. Large-bodied zooplankton were suppressed by planktivorous fish in one lake, while in the other two manipulated lakes, large-bodied zooplankton dominated community biomass. Nutrients were added as inorganic N and P. Nutrient loads ranged from background to conditions resembling eutrophic lakes. Planktonic respiration was measured weekly in each lake by dark bottle oxygen consumption. Respiration was low when lakes were not fertilized (average 8.5 mmol O 2 ·L -1 ·day -1 ) and was correlated with differences in dissolved organic carbon among the lakes. Respiration increased with nutrient addition to a mean range of 12-25 mmol O 2 ·L -1 ·day -1 ; however, respiration differed among lakes at the same nutrient loading. Further, respiration was independent of dissolved organic carbon in the fertilized lakes. Differences in the intensity of zooplankton grazing as determined by food web structure strongly regulated primary and bacterial production across the range of nutrient loads. Consequently, respiration was positively related to primary production, phytoplankton biomass, and bacterial production and inversely related to the average size of crustacean zooplankton.
Limnology and Oceanography, 1979
The seasonal cycles of respiration of net zooplankton and microplankton were determined for euphotic zones of Lake Washington and Findlcy Lake. In Lake Washington net zooplankton respiration rates estimated from ETS activity ranged from 22.4 to 1,194 mg 0 * rnd2. d-l with the maximum occurring during the spring bloom. Net zooplankton respiration rates in Findlcy Lake ranged from 27 mg 0. mm2 * d-l under ice cover to a maximum of 205 mg 0 * rnp2 * d-l, which occurred well after the bloom. Respiration rates estimated from ETS activity agreed well with those estimated from zooplankton species abundance. Zooplankton community respiration never exceeded 60% of primary production in Lake Washington; however, in Findlcy Lake zooplankton community respiration rates exceeded primary production during the latter part of the ice-free growing season. Phosphorus regeneration rates calculated from zooplankton respiration appeared sufficient to supply most of the phytoplankton phosphorus reqtlirement during summer stratification in Lake Washington.
Limnology and Oceanography, 1979
The seasonal cycles of respiration of net zooplankton and microplankton were determined for euphotic zones of Lake Washington and Findlcy Lake. In Lake Washington net zooplankton respiration rates estimated from ETS activity ranged from 22.4 to 1,194 mg 0 * rnd2. d-l with the maximum occurring during the spring bloom. Net zooplankton respiration rates in Findlcy Lake ranged from 27 mg 0. mm2 * d-l under ice cover to a maximum of 205 mg 0 * rnp2 * d-l, which occurred well after the bloom. Respiration rates estimated from ETS activity agreed well with those estimated from zooplankton species abundance. Zooplankton community respiration never exceeded 60% of primary production in Lake Washington; however, in Findlcy Lake zooplankton community respiration rates exceeded primary production during the latter part of the ice-free growing season. Phosphorus regeneration rates calculated from zooplankton respiration appeared sufficient to supply most of the phytoplankton phosphorus reqtlirement during summer stratification in Lake Washington.