Primary Production and Effects of Enrichment with Nitrate and Phosphate on Phytoplankton in the Barra Bonita Reservoir (State of São Paulo, Brazil)

✍ Scribed by Dr. Raoul Henry; Kozo Hino; José Geraldo Gentil; José Galazia Tundisi

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 818 KB
• Volume: 70
• Category: Article
• ISSN: 1434-2944
• DOI: 10.1002/iroh.19850700409

✦ Synopsis

Primary productivity of the phytoplankton was evaluated by the 1% and dissolved oxygen methods in December 1981 a t the Barra Bonita Reservoir (SBo Paulo State, Brazil). The primary production varied between 0.17 t o 14.51 mg C m-3 h-1 a t 4 and 0 m depth, respectively. About 57 to 94 of the photosynthetic activity was due to phytoplankton =-50 pm. The highest value of assimilation rate (3.36 mg C mg Chl-1h-l) 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 o : o 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.