Shifts in phytoplankton community structure in response to hydrological changes in the shallow St Lucia Estuary

Nunes, Monique; Adams, Janine B.

doi:10.1016/j.marpolbul.2018.01.035

Cited by 17 publications

(8 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most dinoflagellate species are marine, and about 10% of freshwater origin (Hoppenrath et al, 2009). Therefore, these findings agree with the overall trend of increasing dinoflagellate species richness from the upper to the lower reaches of estuaries found in other studies (Quinlan and Phlips, 2007;Nunes et al, 2018;Paerl, 1988). This trend suggests that dinoflagellate species richness in this estuary may be associated with proximity to the ocean.…”

Section: Discussionsupporting

confidence: 92%

“…Phytoplankton community composition varied spatially between the different reaches of the estuary, with salinity as the main determinant. A typical pattern with chlorophytes dominant at the upper reaches characterised by low salinity, and dinoflagellates and diatoms at the lower reaches at higher salinities (Nunes et al, 2018;Bazin et al, 2014;Jendyk et al, 2014;Nursuhayati et al, 2013;Muylaert et al, 2009;Valdes-Weaver et al, 2006;Tomas, 1997) was apparent in this study.…”

Section: 42: Phytoplanktonsupporting

confidence: 56%

“…14) supports the finding that chlorophytes occur mainly at lower salinities. This is true for other South African estuaries (e.g., St. Lucia Estuary (Nunes et al, 2018;Nche-Fambo et al, 2015), Sundays Estuary (Kotsedi et al, 2012)), and other coastal water bodies worldwide (Tragin and Vaulot, 2018;Hamilton et al, 2000;Flameling and Kromkamp, 1994). The phytoplankton community responds to different environmental parameters in different ways, ensuring its diversity and persistence throughout the changing environment, thereby a continued presence of energy at the bottom of the food chain.…”

Section: 42: Phytoplanktonmentioning

confidence: 97%

See 2 more Smart Citations

Microplankton community structure in the subtropical Mlalazi estuary.

Fru Azinwi

View full text Add to dashboard Cite

In a country like South Africa that is prone to drought, achieving good quality of water is necessary to ensure the nation's water resource sustainability in the interest of all water users (National Water Act (No. 36 of 1998). River flow and rainfall influence the estuarine environment and biological indicators (phytoplankton (chl a)), system variables (salinity, turbidity, dissolved oxygen, and temperature), and nutrients (phosphate, nitrate, and nitrite) are some of the core water quality variables considered in ecological reserve assessments. Globally, microplankton (phytoplankton and ciliate) community structure (composition, abundance, and biomass) varies with physico-chemical parameters, making them good bioindicators of water quality. Phytoplankton are one of the main primary producers in estuaries, forming the basis of trophic webs. Ciliates are a valuable tool for indicating hydrological conditions and trophic status and can be used as an additional bioindicator to phytoplankton. Characteristics that make ciliates potential bioindicators include very high metabolic rates, short generation times, broad geographic distribution, and their rapid response to changing environmental factors. Ciliates dominate the microzooplankton abundance in coastal water bodies and graze on phytoplankton directly, making ciliates ecologically crucial in transferring energy to higher trophic levels, and controllers of phytoplankton community structure, through top-down pressure on phytoplankton. The main attributes of ciliates used for water quality monitoring are feeding habits (bactivores, carnivores, omnivores, and algivores), species composition, abundance, and biomass.For each water quality variable, a concentration range (minimal ('excellent') to severely modified ('poor') within the water resource should be determined. This emphasises the importance of studying these variables in near-pristine water resources to determine the minimally modified concentrations. There are few microplankton community composition studies in South African oligotrophic or non-eutrophic systems that are important in determining reference conditions and community structures for possible future changes in 'Nazario' and his lovely wife Immaculata 'Ma Peng', Swiri 'Prof', Lum 'Maitre Spiritus', Njitse 'Njitse Made It' and Adamu 'Eidey' who always cheered me on. Lastly my love and thanks to my UKZN friends

show abstract

Section: Discussionsupporting

confidence: 92%

Section: 42: Phytoplanktonsupporting

confidence: 56%

Section: 42: Phytoplanktonmentioning

confidence: 97%

See 1 more Smart Citation

Microplankton community structure in the subtropical Mlalazi estuary.

Fru Azinwi

View full text Add to dashboard Cite

show abstract

“…Recent research has reported on the presence of HAB species in the Narrows of St Lucia, a UNESCO World Heritage site. Conditions are fresh, silty and nutrient rich, as a result of agricultural inputs from the iMfolozi system and a prolonged closed mouth state (Nunes et al 2018;Nunes et al 2019). The presence of HABs alter the functioning of closed estuaries, because entire foodwebs might become dysfunctional or impaired in a relatively short period of time (Table 5).…”

Section: Ecological Consequences ('Impact')mentioning

confidence: 99%

Nutrient enrichment as a threat to the ecological resilience and health of South African microtidal estuaries

Adams

Taljaard

Niekerk

et al. 2020

African Journal of Aquatic Science

View full text Add to dashboard Cite

Journal of Aquatic Science is co-published by NISC (Pty) Ltd and Informa UK Limited (trading as Taylor & Francis Group) water and to the quality of the water concerned' (OSPAR 2003). Eutrophication is characterised by a surge in primary production in response to nutrient loading that results in a loss of submerged aquatic vegetation, oxygen depletion, harmful algal blooms, imbalanced food webs, lower biodiversity, altered biogeochemical cycling and fish-kills (Conley et al. 2009; Ferreira et al. 2011; Lemley and Adams 2019a; Van Niekerk et al. 2019a). Depending on the scale of nutrient enrichment and the type of estuary, these impacts can cause the state of an estuary to change from one dominated by macrophytes to another dominated by phytoplankton and/or macroalgae (Dahlgren and Kautsky 2004; Smith and Schindler 2009; Nunes and Adams 2014; Lemley et al. 2018c). South Africa has a range of estuary types that occur across four biogeographic regions; cool temperate, warm temperate, subtropical and tropical (Whitfield 1992; Van Niekerk et al. 2020). Nutrient enrichment is a serious concern not only in temporarily closed estuaries (e.g. Groot Brak), but also in large permanently open systems

show abstract

“…Therefore, the nutrient input from the Mfolozi River needs to be monitored to detect any potential change in the ecological integrity of the estuary. The Mfolozi River catchment's potential for eutrophication was validated by the long-term water quality data that indicated an increased occurrence of nutrient-enriched conditions (of between 20 and 50%) (Nunes et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

The use of epilithic diatoms grown on artificial substrata to indicate water quality changes in the lower reaches of the St Lucia Estuary, South Africa

Nunes

Adams

Bate

2019

WSA

Self Cite

View full text Add to dashboard Cite

In shallow estuaries, artificial substrates provide a means of assessing the response of the diatom community to water chemistry. The shallow St Lucia Estuary was historically connected to the Mfolozi River at the mouth. This connection was severed during the early 1950s due to sediment input from the agriculturally impacted Mfolozi River. A connection has recently been re-established and the potential impact of dissolved inorganic nutrients from the Mfolozi River needs to be determined, as it may alter the ecological integrity of the St Lucia Estuary which forms part of a UNESCO World Heritage Site. This study found that the epilithic algal biomass and diatom species composition grown on glass slides were good indicators of nutrient enrichment in the estuary. Over a 28-day study period an above-average rainfall event resulted in an increase of nutrient-enriched freshwater flow into the estuary. No significant biomass differences were recorded in either the natural phytoplankton or microphytobenthos communities because of high variability. By contrast, the epilithic algal biomass accumulation on the glass slides was highest following the freshwater input. Statistical analyses indicated that the accumulation of the epilithic community on the glass slides was mostly affected by DIN and salinity. Diversity index scores for both the natural phytoplankton and microphytobenthos were variable, while the epilithic diatom index scores consistently declined from Day 7 (H’ = 1.2) to Day 28 (H’ = 0.7). These data indicate that epilithic algae grown on glass slides can be used as an effective monitoring tool to detect nutrient-induced changes as a supplementary method in this highly variable estuary.

show abstract

Shifts in phytoplankton community structure in response to hydrological changes in the shallow St Lucia Estuary

Cited by 17 publications

References 44 publications

Microplankton community structure in the subtropical Mlalazi estuary.

Microplankton community structure in the subtropical Mlalazi estuary.

Nutrient enrichment as a threat to the ecological resilience and health of South African microtidal estuaries

The use of epilithic diatoms grown on artificial substrata to indicate water quality changes in the lower reaches of the St Lucia Estuary, South Africa

Contact Info

Product

Resources

About