116
M. Cintia Piccolo· Gerardo M.E. Perillo
tidal water movements. However, the largest fall in mud temperature occurred during
a late afternoon flooding. Power spectra of air, water and soil temperature showed
maximum peaks at 3.6, 4.3 and 5.3 h, respectively.
Tidal and wind records from two stations located one on an estuarine bank and
another offshore the Bahia Blanca Estuary were analysed by Piccolo and Perillo (1989)
to establish the atmospheric forcing on the subtidal fluctuations for a four month
period. Although the residual tidal records for both stations have large coherences at
all scales, the phase relationships may indicate that forcing is produced first at the left
bank for time scales shorter than 16 days. It is then evident that the continental winds,
which are strongly prevailing in the area, are the main factor to produce variations in
the tides. Wind forcing is also influenced by the geomorphologic characteristics of
the particular setting of both stations. The left bank of the estuary has faster response
to wind forcing than the offshore one because the tide is channelized at least part of
the time and the NW -SE winds are more effective in producing the water level set up/
set down.
Numerous studies have been performed about the different species and zones that
characterize the estuary. A brief resume of some of the results will be presented here.
Macrobenthic intertidal associations in the estuary are described by Elias (1985) presenting the first delimitation of infaunal communities in the mud flats. Physiographically the estuary corresponds to a salt marsh, where two communities are conspicuous: the "espartillar" (Spartina sp. - Salicornia sp.) and the cangrejal (Chaemagnathus
granulata). Besides two communities were found: Laeonereis acuta - etone sp. and
Axiotella sp. - Ninoe sp. Wagner et al. (1991) studied the intertidal communities in
Ingeniero White harbour. At present, Balanus glandula and Balanus a. amphitrite inhabit that zone (Fig. 6.8). Seasonal pulses of Balanus larvae from Bahia Blanca are
observed in annual cycles. Balanus glandula is dominating with high biomass values
at the middle intertidal zone. On the other hand, Barria de Cao (1986, 1992) analysed
the numerical abundance and seasonal cycles of tintinnines species in the estuary. She
identified 25 species of Tintinnina (Protozoa, Ciliophora) belonging to 11 genera.
Hoffmeyer (1983, 1994) studied the faunistic composition of the zooplankton of the
inner part of the estuary. She identify 35 taxa corresponding to 8 phyla being the most
common (A. tonsa, Paracalanus parvus, Euterpina acutifrons etc.)
The waters of the estuary are characterized by the presence of Scyphomedusae. Three
species were found: Chrysaora lactea, Aurelia aurita and Drymonema gorgo in summer
and efirae of the two former from October to January. These species are commonly
found in the Brazilian waters. Their occurrence in higher latitudes may be due to influence of warm waters coming from the north or the heating of local waters which could
maintain their populations temporarily during spring and summer (Mianzan 1989).
6.4
Estuaries of the Patagonia
Rivers in the Patagonia are allochthonous with source of water provided by the precipitation and/or the melting of the snow on the Andes. They flow across the arid and
desert Patagonia region practically no tributaries are received. Several of the river are
some of the largest in the country in valley size and river discharge such as the Colorado, Negro and Santa Cruz Rivers. Rio Gallegos is probably the one that has the larg-
M. Cintia Piccolo· Gerardo M.E. Perillo
tidal water movements. However, the largest fall in mud temperature occurred during
a late afternoon flooding. Power spectra of air, water and soil temperature showed
maximum peaks at 3.6, 4.3 and 5.3 h, respectively.
Tidal and wind records from two stations located one on an estuarine bank and
another offshore the Bahia Blanca Estuary were analysed by Piccolo and Perillo (1989)
to establish the atmospheric forcing on the subtidal fluctuations for a four month
period. Although the residual tidal records for both stations have large coherences at
all scales, the phase relationships may indicate that forcing is produced first at the left
bank for time scales shorter than 16 days. It is then evident that the continental winds,
which are strongly prevailing in the area, are the main factor to produce variations in
the tides. Wind forcing is also influenced by the geomorphologic characteristics of
the particular setting of both stations. The left bank of the estuary has faster response
to wind forcing than the offshore one because the tide is channelized at least part of
the time and the NW -SE winds are more effective in producing the water level set up/
set down.
Numerous studies have been performed about the different species and zones that
characterize the estuary. A brief resume of some of the results will be presented here.
Macrobenthic intertidal associations in the estuary are described by Elias (1985) presenting the first delimitation of infaunal communities in the mud flats. Physiographically the estuary corresponds to a salt marsh, where two communities are conspicuous: the "espartillar" (Spartina sp. - Salicornia sp.) and the cangrejal (Chaemagnathus
granulata). Besides two communities were found: Laeonereis acuta - etone sp. and
Axiotella sp. - Ninoe sp. Wagner et al. (1991) studied the intertidal communities in
Ingeniero White harbour. At present, Balanus glandula and Balanus a. amphitrite inhabit that zone (Fig. 6.8). Seasonal pulses of Balanus larvae from Bahia Blanca are
observed in annual cycles. Balanus glandula is dominating with high biomass values
at the middle intertidal zone. On the other hand, Barria de Cao (1986, 1992) analysed
the numerical abundance and seasonal cycles of tintinnines species in the estuary. She
identified 25 species of Tintinnina (Protozoa, Ciliophora) belonging to 11 genera.
Hoffmeyer (1983, 1994) studied the faunistic composition of the zooplankton of the
inner part of the estuary. She identify 35 taxa corresponding to 8 phyla being the most
common (A. tonsa, Paracalanus parvus, Euterpina acutifrons etc.)
The waters of the estuary are characterized by the presence of Scyphomedusae. Three
species were found: Chrysaora lactea, Aurelia aurita and Drymonema gorgo in summer
and efirae of the two former from October to January. These species are commonly
found in the Brazilian waters. Their occurrence in higher latitudes may be due to influence of warm waters coming from the north or the heating of local waters which could
maintain their populations temporarily during spring and summer (Mianzan 1989).
6.4
Estuaries of the Patagonia
Rivers in the Patagonia are allochthonous with source of water provided by the precipitation and/or the melting of the snow on the Andes. They flow across the arid and
desert Patagonia region practically no tributaries are received. Several of the river are
some of the largest in the country in valley size and river discharge such as the Colorado, Negro and Santa Cruz Rivers. Rio Gallegos is probably the one that has the larg-