Seasonal variations of rotifers from the high altitude Llano reservoir (State of Mexico, Mexico)
Por:
Munoz-Colmenares, M. E., Sarma, S. S. S., Nandini, S.
Publicada:
1 nov 2017
Resumen:
Aim: Llano reservoir is a high altitude waterbody and is of recreational
importance in Mexico. It is also a source of revenue through fisheries.
Though the reservoir was constructed nearly 6 decades ago, quantitative
information on the zooplankton abundance is not available. The aim of
the present study was to present data on the seasonal variations of
rotifers from the high altitude waterbody Llano dam (State of Mexico)
during a one year period.
Methodology: Rotifer sampling was done monthly from 5 different littoral
zones for one year (August 2014 to July 2015). Eighty liters of
superficial water from the reservoir were concentrated to 200 ml through
a plankton net of 50 mu m pore size and fixed in 4% formalin. Selected
physico-chemical parameters (dissolved oxygen, temperature, pH,
conductivity and nutrients (NO3- and PO4-3) and Chlorophyll a were also
measured.
Results: Temperature varied from 10-20 degrees C and pH 5-8. The
reservoir had low turbidity (<3 NTU). nitrates (<60 mu g L-1),
phosphates (<5 mu g L-1) and chlorophyll a (6-8 mu g L-1). In all, 84
species of monogonont rotifers (from 18 families and 39 genera) and 13
cladoceran species (from 3 families) were recorded. Aspelta angusta,
Eosphora thoa, Trichocerca insulana and Lepadella punctata are new
records for Mexico. Polyarthra vulgaris had the highest frequency of
occurrence (98%), followed by Trichocerca bidens (90%) and Trichotria
tectractis (75%). During April, we recorded the highest density (825
ind. I-1) of all rotifer species together, meanwhile for the rest of
months, the density was low <300 ind. I-1. Shannon-Wiener index varied
from 1.0 to 4.2 bits ind. I-1, depending on the sampling period. The
Sladetek's Q(B/T) index in this reservoir was generally 1.
Interpretation: In addition to nutrient levels, Chla and Q(B/T), the
total rotifer density as a useful measure to determine the trophic
status of this waterbody was explored. Our data from nutrients and total
rotifer density showed that the Llano reservoir appeared to be
oligotrophic.
Filiaciones:
Munoz-Colmenares, M. E.:
Univ Nacl Autonoma Mexico, PCMyL, Circuito Exterior S-N,Ciudad Univ, Mexico City 04510, DF, Mexico
Sarma, S. S. S.:
Univ Nacl Autonoma Mexico, Lab Aquat Zool, Campus Iztacala,Av Barrios 1,AP 314, Tlalnepantla 54090, State Of Mexico, Mexico
Nandini, S.:
Univ Nacl Autonoma Mexico, Lab Aquat Zool, Campus Iztacala,Av Barrios 1,AP 314, Tlalnepantla 54090, State Of Mexico, Mexico
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