Analysis of Patterns of vertical and temporal distribution of phytoplankton using statistical tools: Lake Caviahue, Patagonia, Argentina.

BEAMUD, G., DIAZ, M. M., BACCALÁ N. B. AND PEDROZO, F. L

LIMNOLOGICA

Elsevier

Año: 2010 vol. 40 p. 140 - 147

0075-9511

Most existing studies on the algal communities of acid lakes are based on environmentsthat have been caused by anthropogenic disturbances. Such lakes have a different originfrom the natural acidic lakes and could be expected to differ also in the mechanismscontrolling phytoplankton and trophic status. Planktonic community in Lake Caviahueis somewhat diverse in spite of the low pH of the water. Algae have a distinctivevertical distribution: the values of phytoplankton biomass remain constant throughoutthe water column and at times were highest in the upper end of the hypolimnion,forming a maximum or a layer of chlorophyll a at depth. The goal of this work was toinvestigate the factors influencing the seasonal and vertical distribution ofphytoplankton. The lake was sampled between the years 2004-2006. Physical, chemicaland biological parameters at different depths throughout the water column weredetermined. The interrelationships between environmental variables at differentsampling dates were analyzed using an integration of multivariate matrices: MultipleFactor Analysis, to analyze any joint partnerships in the samples. We found thatphytoplankton biomass is dominated by Keratococcus rhaphidioides. With regard tozooplankton, we found a single species of rotifers (Philodina sp). The two arms of thelake and the depths have different behaviours showing differences in the arms´conductivity, dissolved oxygen and pH. The more superficial layers were characterizedby high values of phytoplankton and zooplankton biomass, organic and inorganiccarbon, dissolved oxygen and pH. The deeper layers showed high values of chlorophylla, ammonium and phosphorus (dissolved and particulate). From the multivariateanalysis it could be extracted the relationships of the each algal species with pH, as apossible indicator of the degree of "acidophilia".