Produção Nacional
Primary Production and Effects of Enrichment with Nitrate and Phosphate on Phytoplankton in the Barra Bonita Reservoir (State of São Paulo, Brazil)
1985; Wiley; Volume: 70; Issue: 4 Linguagem: Inglês
10.1002/iroh.19850700409
ISSN0020-9309
AutoresRaoul Henry, Kozo Hino, José Geraldo Gentil, José Galazia Tundisi,
Tópico(s)Marine and coastal ecosystems
ResumoAbstract Primary productivity of the phytoplankton was evaluated by the 14 C and dissolved oxygen methods in December 1981 at the Barra Bonita Reservoir (São Paulo State, Brazil). The primary production varied between 0.17 to 14.51 mg C m −3 h −1 at 4 and 0 m depth, respectively. About 57 to 94% of the photosynthetic activity was due to phytoplankton > 50 μm. The highest value of assimilation rate (3.36 mg C mg Chl −1 h −1 ) was found in the surface water. Dissolved nutrient concentrations were very high and consisted mainly of nitrate. Light penetration was low, the aphotic zone accounting for about 90% of the water column. Enrichment with nitrate and phosphate showed that both N and P stimulated the production of biomass (chlorophyll a ), mainly due to the addition of phosphate. The enrichment experiment also indicated that phosphate addition has a significant stimulatory effect on the growth of Melosira sp. The limiting effect of light penetration on photosynthetic activity is more severe than that of nutrients.
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