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Nitrogen uptake by size-fractionated phytoplankton in mangrove waters
| Content Provider | Semantic Scholar |
|---|---|
| Author | Dham, Vivek V. Wafar, M. V. M. Heredia, Anjali Menezes |
| Copyright Year | 2005 |
| Abstract | Seasonal changes in the uptake of nitrogenous nutrients (nitrate, nitrite, ammonium and urea) in 2 size fractions (netplankton: 20 to 200 µm; and nanoplankton: 0.8 to 20 µm) were studied in relationship to the phytoplankton species composition in mangrove waters on the west coast of India. Seasonal changes in particulate organic nitrogen in the nano- and netplankton fractions were simi- lar, whereas those of chlorophyll a varied, showing high values in nanoplankton in pre-monsoon and in netplankton in monsoon and early post-monsoon months. Nitrogen uptake as the sum of all 4 nutrients was similar between net- (150 nmol N l -1 h -1 ) and nanoplankton (184 nmol N l -1 h -1 ), but differed substantially according to the N compound. Netplankton were responsible for >90% of the nitrate taken up, and nanoplankton for >80% of the ammonium uptake. Netplankton also took up ammonium (31 nmol N l -1 h -1 , 20% of the total N taken up), whereas nitrate uptake (3 nmol N l -1 h -1 ) in the nanoplankton amounted to only about 2% of the total N uptake. The size-dependent differ- ences in the utilisation of nitrate and ammonium appear to be further enhanced by a reduction in nitrate uptake through increased water temperatures and a greater repression of nitrate uptake in the nanoplankton than in the netplankton at ambient ammonium concentrations of >0.5 µmol N l -1 . The proportions of nitrite and urea uptake in the 2 size classes were similar to those of nitrate and ammonium, indicating size-dependent uptake of these 2 compounds as well. Pennate diatoms and flagellates were dominant during high nitrate uptake, and centric diatoms and blue green algae dur- ing high ammonium uptake. Species succession, however, is probably related to changes in salinity. |
| Starting Page | 281 |
| Ending Page | 291 |
| Page Count | 11 |
| File Format | PDF HTM / HTML |
| DOI | 10.3354/ame041281 |
| Volume Number | 41 |
| Alternate Webpage(s) | https://www.int-res.com/articles/ame2005/41/a041p281.pdf |
| Alternate Webpage(s) | https://doi.org/10.3354/ame041281 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
