Shifts in phytoplankton community structure in response to hydrological changes in the shallow St Lucia Estuary. (March 2018)

• Record Type: Journal Article
• Authors: Nunes, Monique; Adams, Janine B.; Rishworth, Gavin M.
• Is Part Of: Marine pollution bulletin. Volume 128(2018)
• Page Start: 275
• Page End: 286
• Publication Date: 2018-03
• Subjects: Mfolozi River -- Chlorophytes -- Euglenoids -- Reverse salinity gradient -- Flow season; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2018.01.035
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: Hydrological regimes are key in shaping the structure of phytoplankton communities in estuaries. Because anthropogenic disturbances often alter the quantity and quality of riverine inputs, this research focused on investigating phytoplankton dynamics in the St. Lucia Estuary, since being reconnected to the Mfolozi River. Due to the closed mouth state of the estuary, the input from the river resulted in oligohaline (≥5) conditions and the characteristic reverse salinity gradient to persist throughout the study (i.e. one year). Model results indicated that phytoplankton communities were structured by rainfall, light transmittance and depth, while shifts between dominant groups were driven by salinity and flow season. The persistence of chlorophytes and euglenophytes as the co-dominant functional group indicates the freshening and nutrient-enriched nature of the river. This study provides the first detailed account documenting the response of the phytoplankton community to recent restoration efforts in the St Lucia Estuary, a Ramsar Site. Highlights: Phytoplankton functional groups shifted in response to Mfolozi River input. River input facilitated system dynamics characteristic of the limnetic phase. Persisting oligohaline (≥5) conditions reduced habitat heterogeneity. Chlorophytes and euglenophytes were identified as co-dominant phytoplankton groups.