Gavin Rishworth

A multi-tracer approach was employed to investigate the age and origin of groundwater resources in a data-scarce, hydrogeologically complex area with mixed land-use in South Africa. The focus of this study is on nearshore groundwater discharge (NGD) but includes boreholes and springs in a catchment to coast approach. Tritium results indicate that the groundwater recharge for the region occurred pre-1955s to within the past decades. Generally, more recent recharge signatures are observed along the coast, indicating groundwater derived from or mixed with younger groundwater from unconfined coastal aquifers. Eleven organic micropollutants were detected in quantifiable concentrations in the groundwater samples and were predominantly made up of wastewater indicators. Where detected in the NGD, the highest concentrations were observed at sites proximal to coastal peri-urban areas. Dissolved inorganic nitrogen concentrations of NGD also reflected land-use cover with samples from sites down gradient from coastal villages having higher concentrations than those not proximal to human occupation. Contamination signatures were not directly related to the tritium concentration in water and, as such, older groundwater systems may also be vulnerable to water quality degradation where, e.g., direct contamination of boreholes is possible. Our study shows that applying an integrated multi-tracer approach is applicable and delivers useful information even in a data-scarce region. Finally, NGD sites along the South African coast can be useful as alternative groundwater monitoring sites where access to boreholes can be challenging and/or detailed borehole information might not be available, which can make the interpretation of, e.g., water quality data, difficult.

Tidal marshes offer multiple ecosystem services, but are some of the most threatened coastal ecosystems worldwide. One of these valued services is their ability to sequester and store large amounts of carbon. Bioturbating macrofauna are ecosystem engineers that can influence the geomorphology and biogeochemistry of tidal marshes. Bioturbators can influence accretion and erosion processes in tidal marshes by either stabilizing or destabilizing sediment. Through this reworking of sediment, they can also influence the amount of carbon that can be stored. The impact of bioturbation on tidal marshes depend on a number of factors, such as, species composition, burrow morphology, diet, behaviour and habitat type. This review assesses the current knowledge on the role benthic bioturbators play in shaping sediment processes in tidal marshes and identifies key knowledge gaps for future research. For example, the impact of individual benthic species on sediment dynamics is mostly unknown. Bioturbation effects cannot be generalised and predicting when and where these effects will be most prominent is challenging. Future studies should investigate family and species specific effects on sediment properties, such as erodibility or texture, under controlled laboratory conditions and in the field. This should be compared across different habitat types such as ecotones, mudflats, salt marshes and mangroves. Furthermore, the role of consumers, as bioturbators, remains an understudied driver of the carbon cycle because it is complex. In order to better predict how tidal marshes may persist in the face of future climate change, such as sea level rise, it is important to understand the role of bioturbators on sediment and carbon dynamics to enable better mitigation of global change effects through conservation and restoration of tidal habitats.

Tidal marshes offer multiple ecosystem services, but are some of the most threatened coastal ecosystems worldwide. One of these valued services is their ability to sequester and store large amounts of carbon. Bioturbating macrofauna are ecosystem engineers that can influence the geomorphology and biogeochemistry of tidal marshes. Bioturbators can influence accretion and erosion processes in tidal marshes by either stabilizing or destabilizing sediment. Through this reworking of sediment, they can also influence the amount of carbon that can be stored. The impact of bioturbation on tidal marshes depend on a number of factors, such as, species composition, burrow morphology, diet, behaviour and habitat type. This review assesses the current knowledge on the role benthic bioturbators play in shaping sediment processes in tidal marshes and identifies key knowledge gaps for future research. For example, the impact of individual benthic species on sediment dynamics is mostly unknown. Bioturbation effects cannot be generalised and predicting when and where these effects will be most prominent is challenging. Future studies should investigate family and species specific effects on sediment properties, such as erodibility or texture, under controlled laboratory conditions and in the field. This should be compared across different habitat types such as ecotones, mudflats, salt marshes and mangroves. Furthermore, the role of consumers, as bioturbators, remains an understudied driver of the carbon cycle because it is complex. In order to better predict how tidal marshes may persist in the face of future climate change, such as sea level rise, it is important to understand the role of bioturbators on sediment and carbon dynamics to enable better mitigation of global change effects through conservation and restoration of tidal habitats.

Tidal marshes offer multiple ecosystem services, but are some of the most threatened coastal ecosystems worldwide. One of these valued services is their ability to sequester and store large amounts of carbon. Bioturbating macrofauna are ecosystem engineers that can influence the geomorphology and biogeochemistry of tidal marshes. Bioturbators can influence accretion and erosion processes in tidal marshes by either stabilizing or destabilizing sediment. Through this reworking of sediment, they can also influence the amount of carbon that can be stored. The impact of bioturbation on tidal marshes depend on a number of factors, such as, species composition, burrow morphology, diet, behaviour and habitat type. This review assesses the current knowledge on the role benthic bioturbators play in shaping sediment processes in tidal marshes and identifies key knowledge gaps for future research. For example, the impact of individual benthic species on sediment dynamics is mostly unknown. Bioturbation effects cannot be generalised and predicting when and where these effects will be most prominent is challenging. Future studies should investigate family and species specific effects on sediment properties, such as erodibility or texture, under controlled laboratory conditions and in the field. This should be compared across different habitat types such as ecotones, mudflats, salt marshes and mangroves. Furthermore, the role of consumers, as bioturbators, remains an understudied driver of the carbon cycle because it is complex. In order to better predict how tidal marshes may persist in the face of future climate change, such as sea level rise, it is important to understand the role of bioturbators on sediment and carbon dynamics to enable better mitigation of global change effects through conservation and restoration of tidal habitats.

Tidal marshes offer multiple ecosystem services, but are some of the most threatened coastal ecosystems worldwide. One of these valued services is their ability to sequester and store large amounts of carbon. Bioturbating macrofauna are ecosystem engineers that can influence the geomorphology and biogeochemistry of tidal marshes. Bioturbators can influence accretion and erosion processes in tidal marshes by either stabilizing or destabilizing sediment. Through this reworking of sediment, they can also influence the amount of carbon that can be stored. The impact of bioturbation on tidal marshes depend on a number of factors, such as, species composition, burrow morphology, diet, behaviour and habitat type. This review assesses the current knowledge on the role benthic bioturbators play in shaping sediment processes in tidal marshes and identifies key knowledge gaps for future research. For example, the impact of individual benthic species on sediment dynamics is mostly unknown. Bioturbation effects cannot be generalised and predicting when and where these effects will be most prominent is challenging. Future studies should investigate family and species specific effects on sediment properties, such as erodibility or texture, under controlled laboratory conditions and in the field. This should be compared across different habitat types such as ecotones, mudflats, salt marshes and mangroves. Furthermore, the role of consumers, as bioturbators, remains an understudied driver of the carbon cycle because it is complex. In order to better predict how tidal marshes may persist in the face of future climate change, such as sea level rise, it is important to understand the role of bioturbators on sediment and carbon dynamics to enable better mitigation of global change effects through conservation and restoration of tidal habitats.

Tidal marshes offer multiple ecosystem services, but are some of the most threatened coastal ecosystems worldwide. One of these valued services is their ability to sequester and store large amounts of carbon. Bioturbating macrofauna are ecosystem engineers that can influence the geomorphology and biogeochemistry of tidal marshes. Bioturbators can influence accretion and erosion processes in tidal marshes by either stabilizing or destabilizing sediment. Through this reworking of sediment, they can also influence the amount of carbon that can be stored. The impact of bioturbation on tidal marshes depend on a number of factors, such as, species composition, burrow morphology, diet, behaviour and habitat type. This review assesses the current knowledge on the role benthic bioturbators play in shaping sediment processes in tidal marshes and identifies key knowledge gaps for future research. For example, the impact of individual benthic species on sediment dynamics is mostly unknown. Bioturbation effects cannot be generalised and predicting when and where these effects will be most prominent is challenging. Future studies should investigate family and species specific effects on sediment properties, such as erodibility or texture, under controlled laboratory conditions and in the field. This should be compared across different habitat types such as ecotones, mudflats, salt marshes and mangroves. Furthermore, the role of consumers, as bioturbators, remains an understudied driver of the carbon cycle because it is complex. In order to better predict how tidal marshes may persist in the face of future climate change, such as sea level rise, it is important to understand the role of bioturbators on sediment and carbon dynamics to enable better mitigation of global change effects through conservation and restoration of tidal habitats.

Tidal marshes offer multiple ecosystem services, but are some of the most threatened coastal ecosystems worldwide. One of these valued services is their ability to sequester and store large amounts of carbon. Bioturbating macrofauna are ecosystem engineers that can influence the geomorphology and biogeochemistry of tidal marshes. Bioturbators can influence accretion and erosion processes in tidal marshes by either stabilizing or destabilizing sediment. Through this reworking of sediment, they can also influence the amount of carbon that can be stored. The impact of bioturbation on tidal marshes depend on a number of factors, such as, species composition, burrow morphology, diet, behaviour and habitat type. This review assesses the current knowledge on the role benthic bioturbators play in shaping sediment processes in tidal marshes and identifies key knowledge gaps for future research. For example, the impact of individual benthic species on sediment dynamics is mostly unknown. Bioturbation effects cannot be generalised and predicting when and where these effects will be most prominent is challenging. Future studies should investigate family and species specific effects on sediment properties, such as erodibility or texture, under controlled laboratory conditions and in the field. This should be compared across different habitat types such as ecotones, mudflats, salt marshes and mangroves. Furthermore, the role of consumers, as bioturbators, remains an understudied driver of the carbon cycle because it is complex. In order to better predict how tidal marshes may persist in the face of future climate change, such as sea level rise, it is important to understand the role of bioturbators on sediment and carbon dynamics to enable better mitigation of global change effects through conservation and restoration of tidal habitats.