Abiotic and biotic responses to the 2016/2017 restoration project at the St Lucia Estuary mouth, South Africa

Jones, Salome; Carrasco, Nicola K.; Perissinotto, Renzo; Fox, Caroline H.

doi:10.2989/16085914.2019.1680340

Cited by 8 publications

(24 citation statements)

References 46 publications

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“…Restoration would enhance the provision of estuarine ecosystem services that are estimated to contribute R 4.2 billion to the national economy annually [36]. Most estuary restoration interventions have addressed hydrological or hydrodynamic issues such as the reconnection of the iMfolozi/uMsunduze and St. Lucia estuaries [37] and the active management of the Zandvlei Estuary mouth to maintain water quality [38]. Some physical habitat restoration has been carried out at the Knysna and Keurbooms estuaries by deploying artificial structures to prevent bank erosion, which, in turn, provides alternative habitats for estuarine fauna [39].…”

Section: Introductionmentioning

confidence: 99%

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

2021

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Restoration of salt marsh is urgent, as these ecosystems provide natural coastal protection from sea-level rise impacts, contribute towards climate change mitigation, and provide multiple ecosystem services including supporting livelihoods. This study identified potential restoration sites for intervention where agricultural and degraded land could be returned to salt marsh at a national scale in South African estuaries. Overall, successful restoration of salt marsh in some estuaries will require addressing additional pressures such as freshwater inflow reduction and deterioration of water quality. Here, we present, a socio-ecological systems framework for salt marsh restoration that links salt marsh state and the well-being of people to guide meaningful and implementable management and restoration interventions. The framework is applied to a case study at the Swartkops Estuary where the primary restoration intervention intends to route stormwater run-off to abandoned salt works to re-create aquatic habitat for waterbirds, enhance carbon storage, and provide nutrient filtration. As the framework is generalized, while still allowing for site-specific pressures to be captured, there is potential for it to be applied at the national scale, with the largest degraded salt marsh areas set as priorities for such an initiative. It is estimated that ~1970 ha of salt marsh can be restored in this way, and this represents a 14% increase in the habitat cover for the country. Innovative approaches to restoring and improving condition are necessary for conserving salt marshes and the benefits they provide to society.

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Section: Introductionmentioning

confidence: 99%

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

2021

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“…In the late 1960s, a back channel was dredged from the Mfolozi River through the mangroves of the St Lucia Narrows to allow for the reconnection of the two systems (Whitfield and Taylor, 2009;Taylor 2013). A link channel was later created in the early 1980s (Jones et al 2020) to combat the drought conditions within the St Lucia Estuary. Due to severe drought conditions from 2002 until 2007/08, the iSimangaliso Wetland Park authority attempted to reopen and widen the back channel again to allow for a brief relinkage of the two systems (Whitfield and Taylor, 2009;Taylor and Adams, 2013;Cyrus et al 2020;Schutte et al 2020).…”

Section: Tarebia Granifera: a Prominent Threat In South African Aquat...mentioning

confidence: 99%

“…In 2012, a new channel called the Mfolozi spillway or beach channel was dredged, allowing for freshwater input from the Mfolozi River (Cyrus et al 2020). In late 2015/early 2016, the St Lucia Estuary had become highly fragmented due to low water levels and decreased rainfall (Jones et al 2020). However, in June 2016, the iSimangaliso Wetland Park Authority initiated a Global Environment Facility (GEF) restoration project (Jones et al 2020).…”

Section: Tarebia Granifera: a Prominent Threat In South African Aquat...mentioning

confidence: 99%

“…In late 2015/early 2016, the St Lucia Estuary had become highly fragmented due to low water levels and decreased rainfall (Jones et al 2020). However, in June 2016, the iSimangaliso Wetland Park Authority initiated a Global Environment Facility (GEF) restoration project (Jones et al 2020). This project aided in removing artificial dredger spoil at the mouth area that was historically placed to prevent the two systems from reconnecting (Whitfield et al 2013;The World Bank 2017).…”

Section: Tarebia Granifera: a Prominent Threat In South African Aquat...mentioning

confidence: 99%

“…The GEF project ended in June of 2017 and increased freshwater input from the Mfolozi River to the St Lucia Estuary. Increased rainfall combined with the freshwater input ultimately resulted in the estuary shifting state from dry hypersaline to a predominantly freshwater system in 2017 (Whitfield et al 2013;Miranda et al 2017;Jones et al 2020).…”

Section: Tarebia Granifera: a Prominent Threat In South African Aquat...mentioning

confidence: 99%

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Feeding dynamics of invasive (Tarebia granifera) and native (Melanoides tuberculata) freshwater gastropods.

Naidoo

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Tarebia granifera has invaded several South African estuaries, outnumbering native gastropods such as Melanoides tuberculata. Comparative feeding dynamics can aid in estimating and understanding invasion impacts. This study aimed to explore the feeding dynamics of these gastropods with the use of two different approaches. Stable Isotope Analyses (SIAs) were used to investigate the dietary preferences and niche overlaps in the St Lucia Estuary, while Functional Response Experiments measured the relationship between the consumption rate of a food resource and its availability. These experiments were run both with and without the presence of heterospecific chemical cues (secondary metabolites secreted by either species) to determine whether chemical cues influence the functional responses of T. granifera and M. tuberculata. Mixed species experiments were also conducted to observe individual behaviour (active, inactive and feeding) over time and measure resource consumption when both species are placed together under high and low food availability. The SIA showed that both gastropods exhibited generalist diets, however, due to niche partitioning, there was no significant difference in their dietary niche overlap. In the FR experiments, both species exhibited Type II FRs and had similar feeding rates. However, in the presence of heterospecific chemical cues, M. tuberculata exhibited a higher feeding rate at high food availabilities, whereas T. granifera showed efficient feeding dynamics under limited food resources. In the mixed species experiments, T. granifera spent more time feeding under low food availability while M. tuberculata spent more time feeding under high food availability. This study showed that in certain conditions (e.g. high resource availability) the alien species did not always have a feeding advantage. A multiple method approach is recommended when assessing ecological impacts of invasive species. iv ACKNOWLEDGEMENTS First and foremost, I would like to express my sincere gratitude to my supervisor Dr Nicola K.Carrasco and co-supervisor Dr Nelson A.F. Miranda, for giving me this opportunity. I would like to thank my supervisors for always having faith in me and for always providing me with invaluable guidance throughout my project. It was a great privilege to work and study under two proficient supervisors. I would like to extend my gratitude to Professor André Vosloo, for his valuable input towards my project.A special thank you to Caroline Fox from Ezemvelo KZN Wildlife for logistical support and for providing us with the helpful information in the field. Dr Grant Hall of the Stable Isotope Laboratory at the Mammal Research Institute (University of Pretoria) is also acknowledged for processing and analysing the stable isotope samples.A sincere thank you to Jamila Janna for providing valuable data for this study. I would also like to thank my research colleagues, Merusha Govender, Merrisa Naidoo, Njabulo Mdluli, Natleen Govender and Mandy Jones, for their assistance and continuous support in the fi...

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Zooplankton dynamics during a regime shift in the St Lucia Estuary, South Africa.

Govender

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Abiotic and biotic responses to the 2016/2017 restoration project at the St Lucia Estuary mouth, South Africa

Cited by 8 publications

References 46 publications

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

Feeding dynamics of invasive (Tarebia granifera) and native (Melanoides tuberculata) freshwater gastropods.

Zooplankton dynamics during a regime shift in the St Lucia Estuary, South Africa.

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