138
P. Lana et al.
Algal blooms in Paranagua Bay are probably influenced by nutrient
input from continental runoff during rainy periods, inflow of nutrientrich, subtropical coastal waters during winter (Fernandes 1992), and nutrient release into the water column during advective transport associated
with frontal systems (Marone and Camargo 1994; Lopes 1997). Most of the
636 pelagic and benthic diatom species identified for Parana State occur in
the bay (Brandini and Fernandes 1996) and centric diatoms and phytoflagellates are the dominant algal component. The diatom Skeletonema
costatum is abundant throughout the year but reaches peak densities at
high nutrient levels and low salinity during rainy summers while Chaetoceros, Rhizosolenia and Leptocylindrus are usually less abundant. Dinoflagellates and silicoflagellates are a minor component of the local phytoplankton standing-stock (Brandini 1985; Fernandes 1992; Brandini and
Thamm 1994). Chlorophyll-a concentrations (up to 49 jlg Chl-a l- 1 ) in the
meso- and oligohaline sectors (Brandini et al. 1988; Machado et al. 2000)
and the polyhaline mid bay ( 4-20 jlg 1- 1 ) depend on optimal nutrient concentration, water transparency, and salinity for diatom growth. In euhaline
areas (0.1-8 jlg Chl-a l- 1 ), concentrations are influenced by the adjacent sea
(Brandini 1985; Brandini et al. 1988; Brandini and Thamm 1994; Lopes
1997) and maxima are associated with large (>200jlm) diatoms (Coscinodiscus, Palmeria; Lopes 1997). Benthic macroalgae (approximately 100 species) occur mainly on exposed rocky shores. The macroalgal community
(Bostrychietum sensu Post) of mangrove swamps is composed of different
red algae (i.e., Bostrychia, Caloglossa, Catenella), which dominate in different areas along the estuarine gradient. Occasionally, extensive mats of
Acanthophora spicifera are a conspicuous feature of intertidal flats.
The zooplankton assemblages are dominated by copepods (up to 90 o/o
of total standing stock), followed by tintinids and appendicularians as the
major subdominant taxa, and by cladocerans and chaetognaths (Montu
and Cordeiro 1988; Lopes 1997). Highest densities (up to 82,000 org. m- 3 )
occur in poly- and mesohaline sectors of the bay, approximately corresponding with areas of peak chlorophyll concentrations. High densities of
meroplankton larvae occur during larval recruitment in tidal mangrove
creeks and at the mouth of small rivers in the euhaline area. The distribution of zooplankton (i.e., copepod associations) follows a salinity gradient
(Lopes 1997). The calanoid Pseudodiaptomus richardi represents the dominant holoplankton of oligohaline areas and is the only"true" estuarine species below salinities of 15. Acartia tonsa and Oithona oswaldocruzi occur
mainly in the mesohaline sector, together with other estuarine-marine
species adapted to strong salinity variations, such as Acartia lilljeborgi,
Pseudodiaptomus acutus and Oithona hebes. Although marine-euryhaline
copepods (Tern ora turbinata, Paracalanus spp., Oithona simplex, Euterpi-
P. Lana et al.
Algal blooms in Paranagua Bay are probably influenced by nutrient
input from continental runoff during rainy periods, inflow of nutrientrich, subtropical coastal waters during winter (Fernandes 1992), and nutrient release into the water column during advective transport associated
with frontal systems (Marone and Camargo 1994; Lopes 1997). Most of the
636 pelagic and benthic diatom species identified for Parana State occur in
the bay (Brandini and Fernandes 1996) and centric diatoms and phytoflagellates are the dominant algal component. The diatom Skeletonema
costatum is abundant throughout the year but reaches peak densities at
high nutrient levels and low salinity during rainy summers while Chaetoceros, Rhizosolenia and Leptocylindrus are usually less abundant. Dinoflagellates and silicoflagellates are a minor component of the local phytoplankton standing-stock (Brandini 1985; Fernandes 1992; Brandini and
Thamm 1994). Chlorophyll-a concentrations (up to 49 jlg Chl-a l- 1 ) in the
meso- and oligohaline sectors (Brandini et al. 1988; Machado et al. 2000)
and the polyhaline mid bay ( 4-20 jlg 1- 1 ) depend on optimal nutrient concentration, water transparency, and salinity for diatom growth. In euhaline
areas (0.1-8 jlg Chl-a l- 1 ), concentrations are influenced by the adjacent sea
(Brandini 1985; Brandini et al. 1988; Brandini and Thamm 1994; Lopes
1997) and maxima are associated with large (>200jlm) diatoms (Coscinodiscus, Palmeria; Lopes 1997). Benthic macroalgae (approximately 100 species) occur mainly on exposed rocky shores. The macroalgal community
(Bostrychietum sensu Post) of mangrove swamps is composed of different
red algae (i.e., Bostrychia, Caloglossa, Catenella), which dominate in different areas along the estuarine gradient. Occasionally, extensive mats of
Acanthophora spicifera are a conspicuous feature of intertidal flats.
The zooplankton assemblages are dominated by copepods (up to 90 o/o
of total standing stock), followed by tintinids and appendicularians as the
major subdominant taxa, and by cladocerans and chaetognaths (Montu
and Cordeiro 1988; Lopes 1997). Highest densities (up to 82,000 org. m- 3 )
occur in poly- and mesohaline sectors of the bay, approximately corresponding with areas of peak chlorophyll concentrations. High densities of
meroplankton larvae occur during larval recruitment in tidal mangrove
creeks and at the mouth of small rivers in the euhaline area. The distribution of zooplankton (i.e., copepod associations) follows a salinity gradient
(Lopes 1997). The calanoid Pseudodiaptomus richardi represents the dominant holoplankton of oligohaline areas and is the only"true" estuarine species below salinities of 15. Acartia tonsa and Oithona oswaldocruzi occur
mainly in the mesohaline sector, together with other estuarine-marine
species adapted to strong salinity variations, such as Acartia lilljeborgi,
Pseudodiaptomus acutus and Oithona hebes. Although marine-euryhaline
copepods (Tern ora turbinata, Paracalanus spp., Oithona simplex, Euterpi-