A comparison of the fauna in eelgrass and erosion control structures in a warm temperate Southern African estuary

Villiers, N.M. de; Harasti, David; Hodgson, Alan N.; Claassens, Louw

doi:10.1016/j.rsma.2021.101757

Cited by 8 publications

(2 citation statements)

References 79 publications

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“…The seagrass-associated species concerned were mostly classic members of the southern African estuarine fauna as identified by Day ( 1981 ) and de Villiers et al ( 1999 ), but the superabundance of the Zostera -leaf associated Alaba pinnae appears most unusual. Alaba is also present, though by no means dominant, in the nearby Swartvlei estuary to the west (Whitfield 1989 ) but has not been recorded by surveys of other South African estuaries (Barnes and Claassens 2020 ), except sporadically in the St Lucia / iSimangaliso system (Perissinotto et al 2014 ), and apparently it does not occur in the Keurbooms/Bitou Estuary immediately to the east of Knysna (Duvenage and Morant 1984 ; Villiers et al 2021 ). Leaving aside the overwhelmingly dominant Alaba , with the exception of a single core sample containing large numbers of small nereid worms, compared to the natural channels the Thesen canals supported proportionately fewer polychaete individuals (11% of the total vs. 20%) and those of other gastropod taxa (28% vs. 37%), but more crustaceans (48% vs. 37%), bivalves (5% vs. 2%) and echinoderms (3% vs. 1%) (see Supplementary data).…”

Section: Resultsmentioning

confidence: 99%

Where ecologically ‘tis better to go brown than green: enhanced seagrass macrobenthic biodiversity within the canals of a brownfield coastal marina

2022

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At the start of the 21st century, a coastal residential-estate marina was developed on a previously degraded and polluted brownfield island site within Knysna estuarine bay, Garden Route National Park, South Africa, including the creation of 25 ha of new flow-through tidal canals. Canals near the larger entrance to this system now support permanently submerged beds of seagrass, which in turn support abundant macrobenthic invertebrates. In comparison with equivalent seagrass-associated assemblages present in natural channels around the island, those in the artificial marina canals were similarly structured and dominated by the same species, but the marina assemblages were significantly more species-rich (1.4 x on average) and were more abundant. Indeed, this area of marina supports the richest seagrass-associated macrofaunal biodiversity yet recorded from South Africa. The canals created de novo therefore now form a valuable addition to the bay’s marine habitat, in marked contrast to the generality that marinas developed on greenfield sites represent a net reduction in intertidal and shallow marine area and associated seagrass-associated benthos. If located and constructed appropriately, brownfield marina development and conservation of coastal marine biodiversity clearly need not be antithetical, and brownfield sites may provide opportunity for the location and management of ‘artificial marine micro-reserves’ or for the action of ‘other effective area-based conservation measures’ for soft-sediment faunas.

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Section: Resultsmentioning

confidence: 99%

Where ecologically ‘tis better to go brown than green: enhanced seagrass macrobenthic biodiversity within the canals of a brownfield coastal marina

2022

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“…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]. Targeted restoration against salt marsh loss was carried out to a limited extent at the Orange Estuary as part of a national payment for ecosystems services programme [40].…”

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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Conservation benefits of a marine protected area on South African chondrichthyans

Cortelezzi

Paulet²,

Olbers

et al. 2022

Journal of Environmental Management

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A comparison of the fauna in eelgrass and erosion control structures in a warm temperate Southern African estuary

Cited by 8 publications

References 79 publications

Where ecologically ‘tis better to go brown than green: enhanced seagrass macrobenthic biodiversity within the canals of a brownfield coastal marina

Where ecologically ‘tis better to go brown than green: enhanced seagrass macrobenthic biodiversity within the canals of a brownfield coastal marina

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

Conservation benefits of a marine protected area on South African chondrichthyans

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