| Summary: | Estuarine systems are the most important
aquatic natural resources of the nation from various
perspectives; fisheries use them mainly through studies
that allow the detection and evaluation of the areas of
concentration of adults on reproduction phase and potentially
exploitable species. This present paper analyzes
the spatial and temporal variation of the abundance
of zooplankton groups in the Estuary El Salado, Puerto
Vallarta, Jalisco. Eight zooplanktonic trawls were
conducted during diurnal periods from spring to winter
2001, trawls were superficial, lasting ten minutes,
by using a standard “Zeppelin” net with a mesh size of
505 μm with a length of 1.50 m mouth width of 0.60 m
which was equipped with a digital flow meter to calculate
the volume of filtered water, abundance data were
normalized to a volume of 1000 m3. The total catch was
101,968.4 organisms, represented in eleven groups, the brachyurans were the most important group in the order
of abundance accounting for 44.5 %, followed by 24.1
% in chaetognaths, decapod with 6.78 %, euphausiids
with 11.84 %, and less abundant copepods with 6.18 %,
3.37 % siphonophores small jellyfish, stomatopods 2.83
%, 0.22 % amphipods, cladocerans with 0.33 %, 0.08 %
gastropods and finally rare organisms with 0.02 % (appendicular,
polychaetes and cumaceans). Variations in
both spatial and temporal abundance were influenced
by tidal conditions as well as variations in temperature
and salinity. All registered major zooplankton groups
abundances were homogeneous in the four seasonal
periods, however spring was characterized by low
abundance, while for summer and winter, the highest
values recorded were represented mainly by the Brachyura
order, and those abundances were associated
with two reproductive periods in both seasons.
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