caa a22 4500 378872508 CHVBK 20180305123412.0 cr unu---uuuuu 161128e20030707xx s 000 0 eng 10.1515/BOT.2003.029 doi (NATIONALLICENCE)gruyter-10.1515/BOT.2003.029 Seasonal Variations in the Vertical Distribution of Benthic Microalgae in the Upper Sediment of the Mdloti Estuary, South Africa [Elektronische Daten] [S. Mundree, R. Perissinotto, C. Nozais] A 12-month survey investigated seasonal variations in the vertical distribution of benthic microalgal biomass in relation to major factors potentially controlling their dynamics in the subtropical temporarily-open Mdloti Estuary, KwaZulu-Natal, South Africa. Benthic microalgal chl-a concentrations in the upper 5 cm of sediment ranged from 259 mg m−2 to 977 mg m−2 during the closed phase, and from 6.7 mg m−2 to 305 mg m−2 during the open phase. Significant differences were obtained between sampling sites and among seasons. A distinctive trend of increasing chl-a biomass in the deeper layers of the sediment was noted from the upper reaches (head) to the lower reaches (mouth) of the estuary. Chl-a biomass was virtually homogeneously distributed throughout the upper 5 cm of sediment in the lower reaches. Results suggest that benthic microalgal cells not only exhibited diel rhythms of vertical migration but were actively re-suspended into the water-column of the Mdloti Estuary. While a decrease in salinity, temperature and Kd favoured an increase in benthic microalgal chl-a biomass in the upper 5cm sediment, nutrients in the overlying water had no significant impact on the biomass. Results further indicate a physiologically healthy community at all sites during the open phase, as compared to the closed phase of the estuary. During the closed phase, the pheopigment to chl-a ratio indicated an actively growing community in the upper reaches and a "stressed” community in the middle and lower reaches. Thus, the large amounts of "buried” benthic microalgal chl-a biomass found in the upper 5 cm of sediment may represent an important stock of potential primary producers in temporarily-open estuarine systems like the Mdloti. Copyright © 2003 by Walter de Gruyter GmbH & Co. KG Hydrobiology nationallicence Mycology, fungi nationallicence Botany & plant sciences nationallicence Mundree S. aut Perissinotto R. aut Nozais C. aut Botanica Marina Walter de Gruyter 46/4(2003-07-07), 323-331 0006-8055 46:4<323 2003 46 botm https://doi.org/10.1515/BOT.2003.029 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1515/BOT.2003.029 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mundree S. aut NATIONALLICENCE 700 1- Perissinotto R. aut NATIONALLICENCE 700 1- Nozais C. aut NATIONALLICENCE 773 0- Botanica Marina Walter de Gruyter 46/4(2003-07-07), 323-331 0006-8055 46:4<323 2003 46 botm CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter