IADO   05364
INSTITUTO ARGENTINO DE OCEANOGRAFIA
Unidad Ejecutora - UE
artículos
Título:
Estuarine mesozooplankton dynamics at a short-term time scale: Role of semidiurnal tidal cycle
Autor/es:
MARÍA C. MENÉNDEZ; MARÍA C. PICCOLO; MÓNICA S. HOFFMEYER; MAXIMILIANO SASSI
Revista:
BRAZILIAN JOURNAL OF OCEANOGRAPHY
Editorial:
INST OCEANOGRAFICO
Referencias:
Lugar: San Pablo, Brasil; Año: 2010
ISSN:
1679-8759
Resumen:
The
objectives of the present study were to describe the influence of tidal cycle
on mesozooplankton variability and to compare the mesozooplankton distribution
between two zones in the main channel of the estuary: its northern margin and
the deeper central zone. Sampling was carried out on 12, May 2006, during a
transition from spring to neap tides. Zooplankton samples were collected during
the daytime every 3-h (from a boat in the central main channel), beginning at
high tide. Two submersible pumps were used to obtain simultaneous surface and
bottom samples and a PVC hose linked the pumps to 200 µm pore size plankton
nets. Water was filtered through the nets for 10-20 min, for a total sample
volume between 1.5 and 2.9 m3. The collected material was preserved
in a buffered solution of 4% formaldehyde. Vertical profiles of temperature and
salinity were obtained with a digital multisensor Horiba U-10 and additional
water samples were taken to determine suspended particulate matter (SPM).
Measurements of current velocity were made using a 1.5 MHz Acoustic Doppler
Profiler (ADP). A. tonsa abundances registered in the channel margin
were higher near the surface throughout the tidal. The abundance of this
species was markedly higher during ebb tide than during flood, low or high tide
events. Contrary to what occurs in the margin area, the abundances in the
central main channel were higher near the bottom during the entire tidal cycle
and no marked increase of the abundance was detected during ebb tide. These
results showed a daytime scenario in which the short-term temporal variability
of the dominant species A. tonsa was strongly affected by tidal
dynamics. This study presents a contribution to the knowledge of the
mesozooplankton dynamics over tidal time scales. The results highlight the role
of tides as forcing agents on the mesozooplankton community structure and
emphasize the importance of the biological-physical interactions at a
short-term time scale in coastal systems. In addition, and although this study
is restricted to samples collected during a short period of time, the results
show how variable the mesozooplankton community structure can be over short
time scales in mesotidal temperate estuaries. This variability should be
taken into account for any mesozooplankton monitoring program conducted in a
temperate system with a high-tidal regime.