ORCID Profile
0000-0003-0449-6042
Current Organisation
Murdoch University
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Publisher: Elsevier BV
Date: 05-2023
Publisher: National Inquiry Services Center (NISC)
Date: 11-11-2022
Publisher: National Inquiry Services Center (NISC)
Date: 10-02-2020
Publisher: MDPI AG
Date: 19-12-2021
DOI: 10.3390/D13120680
Abstract: 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.
Publisher: National Inquiry Services Center (NISC)
Date: 02-01-2020
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.SCITOTENV.2022.156955
Abstract: Halophytes in estuaries are effective sinks of carbon, nitrogen, and phosphorus. Blue carbon (BC) is carbon stored in coastal habitats such as mangroves, salt marshes and seagrass. The objectives of this study were to firstly assess the biomass and sediment C stocks in salt marsh (Spartina maritima and Salicornia tegetaria) and seagrass (Zostera capensis) habitats of the Swartkops Estuary, South Africa. Secondly, we applied the nutrient pollutant indicator (NPI) to assess the nutrient status of the estuary. Six replicate sediment cores of 1 m (summer) and 0.5 m (winter) per plant species were collected at six sites. Six replicates for biomass of each species were harvested at each site during summer and winter. Biomass and nutrient dynamics showed that there were distinct seasonal differences in the magnitude of C, N, and P stored in the plants. The sediment was the dominant C pool and differed spatially with creek sites storing more C. Out of the three species, S. maritima stored the most C (224 ± 19.1 Mg C ha
Publisher: Wiley
Date: 07-10-2023
DOI: 10.1002/EDN3.365
Abstract: The effective management of rare and threatened species, especially in areas where population sizes have diminished, relies on knowledge of their population size, threats, and distribution. Robust mapping of distribution presents a particular challenge in aquatic environments for cryptic species, especially those with low abundance. Environmental DNA (eDNA) approaches can offer improved detection rates of many rare and threatened species when compared with traditional s ling approaches. In this study, we developed and optimized a targeted eDNA assay for the critically endangered estuarine pipefish ( Syngnathus watermeyeri ). eDNA s ling and seine netting were undertaken at 39 sites across the historical range of S. watermeyeri in the Eastern Cape of South Africa in 2019. At each site, five water s les were collected for eDNA analysis ( n = 195) along with three seine netting hauls ( n = 117). Habitat and environmental data were collected at each location to explore what physical and biotic parameters might correlate with pipefish presence/absence. We successfully detected S. watermeyeri in two estuaries (Kariega and Bushmans) using both survey methods. Importantly, the positive detection rate of eDNA (66.7%) was four times that of seine netting (16.7%), highlighting the value of eDNA as a monitoring tool for rare and cryptic species. Null detections in the Kasouga, East Kleinemonde, and West Kleinemonde estuaries add to the growing body of evidence that the estuarine pipefish has been extirpated from these locations and is now only found in two estuarine systems. The occurrence of S. watermeyeri was found to be highly dependent on the cover of submerged macrophytes such as Zostera capensis (eelgrass). By providing a more complete picture of the conservation status of this critically endangered species, this work facilitates the development of a long‐term monitoring program and the identification of priority conservation areas.
Publisher: National Inquiry Services Center (NISC)
Date: 07-06-2022
Publisher: National Inquiry Services Center (NISC)
Date: 04-02-2020
Publisher: Wiley
Date: 05-12-2022
DOI: 10.1002/AQC.3742
Abstract: The identification and development of locally significant conservation actions require comprehensive and current ecological species information. Logistically this can be difficult, especially when studying rare and cryptic species which are at greater risk of becoming extinct. This study investigated the current distribution and density of the estuarine pipefish Syngnathus watermeyeri , the only Critically Endangered pipefish in the world, and the commonly found longsnout pipefish Syngnathus temminckii . Pipefish were surveyed using a seine net in the Kariega, Bushmans, Kasouga and Kleinemonde East and West estuaries, located on the south coast of South Africa, in October 2019, March 2020 and July 2020. The habitat and physico‐chemical characteristics of each site were measured to determine whether these factors had an effect on the presence of S. watermeyeri . In addition, available habitat extent within the Bushmans and Kariega estuaries was mapped. Pipefish were only detected in two of the five estuaries within the historical range of S. watermeyeri and a total of 59 S. watermeyeri and 45 S. temminckii were found across all three surveys. Zostera capensis and Codium sp. were the dominant submerged vegetation within the Bushmans and Kariega estuaries and the presence of pipefish was positively associated with the availability of vegetation, especially Codium sp. This is the most extensive targeted survey for S. watermeyeri to date, both temporally and spatially, and provides important insights into what threatens this species. This information should be used to inform future IUCN Red List assessments and the development of locally significant conservation actions.
Publisher: Elsevier BV
Date: 06-2022
No related grants have been discovered for Johan Wasserman.