Coastal Living of the Future: Garden Route 2050

We have entered the Anthropocene and coastal communities in particular will face increasing environmental impacts ranging from climate change to biodiversity loss. Are coastal communities prepared to stand by and watch the deterioration of their environment, or will human ingenuity triumph? Coastal Living of the Future will develop a multi-disciplinary, community-based approach to investigate what the future holds, and what can and should be done now to achieve a sustainable future. Knysna, South Africa, will be used as a complex social-ecological coastal system where different futures will be envisioned by combining both scenario research and ecological modelling. Water will be used as an overarching theme linking all social, economic and environmental aspects common to coastal communities globally. The development of this approach in utilising the future to inform the present, will provide an actionable conservation roadmap for coastal communities across the globe.

Coastal Diversity Research

GOAL: Develop applied research and tools to determine the status, threats and conservation needs of coastal ecosystems to guide future biodiversity conservation, education and management.

Polychaete species used as bait: taxonomy, population structure, ecology and management

Description

Polychaetes are frequently used as bait by recreational and subsistence fishers. However, effective management of this resource is hampered by inadequate information related to actual identities of all species used, their distribution, biology, and population structure. Furthermore, Diopatra cf. aciculate that occurs in Knysna Estuary is an alien. Thus, more detailed information concerning the ecological impact that it may be having, its reproductive strategies, timing of recruitment and dispersal throughout the estuary (all information that can inform effective management) is not known.

This study will therefore:

1. Address the taxonomy and phylogeography of five widely distributed species in the genera Gunnarea and Marphysa, to increase our understanding of the population structures of the different species and consequently the vulnerability of individual populations to overexploitation;
2. Investigate the ecological impact of D. cf. aciculata as an ecological engineer, a resource and consumer, to determine how indigenous species in the estuary may be affected by the activity of the alien; and
3. Investigate the reproductive strategies and dispersal of D. cf. aciculata to identify times when the species might be most vulnerable to management, and possibly source and or sink subpopulations that may be targeted for management. This project proposes to use a combination of standard morphological, Sanger sequencing and histological techniques, and stable isotope and microsatellite analyses.

Period

2015-2024

Contact

Carol Simon at CSIMON@sun.ac.za

Past research outputs

Simon, C., du Toit, A.N., Smith, M.K.S., Claassens, L., Smith, F., Smith, P. 2019. Bait collecting by subsistence and recreational fishers in Knysna Estuary may impact management and conservation. African Zoology. 54(2): 91-103  https://doi.org/10.1080/15627020.2019.1608862

van Rensburg, H., Richoux, N.B. & Simon, C.A. 2023. The trophic position and isotopic niche of a cryptogenic tube-building polychaete in a protected clear-water estuarine bay. Estuarine, Coastal and Shelf Science 295: 108549. https://www.sciencedirect.com/science/article/pii/S0272771423003396?via%3Dihub

van Rensburg, H., Matthhee, C.A. & Simon, C. 2020. Moonshine worms ( Diopatra aciculata : Onuphidae, Annelida) in the Knysna Estuary, South Africa; taxonomy and distribution. Journal of the Marine Biological Association of the UK 100(6): 1-11. https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/abs/moonshine-worms-diopatra-aciculata-onuphidae-annelida-in-the-knysna-estuary-south-africa-taxonomy-and-distribution/FE6D3C64D4264D29FF9681B3FAF78129

Schoeman, S. & Simon, C.A. 2023. Live to Die Another Day: Regeneration in Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae) Collected as Bait in Knysna Estuary, South Africa. Biology 12(3): 483; https://doi.org/10.3390/biology12030483

 

Marine Debris Research

GOAL: Develop applied research and tools to determine the nature, extent and implications of the growing impact from marine debris on coastal ecosystems to guide future conservation, education and management.

Ghost fishing impacts from shore-based angling

Description

Negative environmental impacts that result from discarded or lost fishing gear such as the entanglement of animals, are known as ghost fishing and has become a problem of increasing concern. Ghost fishing is, however, not only an ‘industry’ problem, but lost and/or discarded fishing gear that originate from shore-based angling can contribute significantly to ghost fishing. Even though ghost fishing and its impacts are well studied internationally, a dearth of information on this topic exists in South Africa. This project will conduct a baseline assessment of the occurrence and extent of ghost fishing gear within the Knysna estuary– focusing on popular shore-based angling sites. An attempt will be made to differentiate between types of angling gear (subsistence vs recreational) and which is the greatest source of ghost gear in the estuary.

As part of this project, we are working with the Strandloper Project (www.strandloperproject.org) to investigate the occurrence and impact from ghost fishing gear along the South African coast. The Knysna Basin Project participated in a 210 km coastal hike in May 2019 to document all ghost fishing gear found along the route and to help raise awareness of the threat from ghost fishing gear and marine debris. The Strandloper Project collaboration continues with regular diving surveys at selected sites along the Garden Route.

Period

Ongoing

Contact

Mark Dixon at ghostfishing@strandloperproject.org

 

Current projects

 

Project title: Past, present and future status, as well as the importance of the endangered white steenbras Lithognathus lithognathus to aquatic conservation in the Knysna Estuary

PhD Candidate: Jessica Seath 2025-2027 (Department of Ichthyology and Fisheries Science, Rhodes University)

Supervisors: Prof. Alan Whitfield, Prof. Nikki James, Prof. Amber-Robyn Childs

Project Description: This study will address the significant decline of the white steenbras (Lithognathus lithognathus) population, focusing on its status in the Knysna Estuary. The broad aims of this thesis are to determine the status of the white steenbras in the Knysna estuary through the review of our current knowledge on their recruitment patterns, habitat occupation and stock status, to determine their feeding ecology in Knysna estuary at different life stages and understand the potential competitive interactions with other sparids and to elucidate their vulnerability to fishing pressure and the potential effectiveness of an Estuarine Protected Area (EPA) approach to white steenbras long-term survival. For further information on this project see: The White Steenbras Project

 

Project title: Fish habitat associations in the marine bay region of the Knysna Estuary

MSc candidate: Lutholwethu Mabaleka (Department of Ichthyology and Fisheries Science, Rhodes University)

Supervisors: Prof. Nicola James, Dr Phakama Nodo, Prof. Amber Childs, Kyle Smith

Project description: The main aim of this project will be to examine the nature of habitat usage by juvenile fish in the marine bay region of the Knysna Estuary and to compare the nursery role of Zostera capensis and Asparagopsis taxiformis within the estuary. This aim will be achieved by quantifying fish assemblages (relative abundance, richness and size structure) across the different habitat types in the marine bay region using seine nets in each habitat type and using calibrated stereo Remote Underwater Video (sRUV) systems in Z. capensis and A. taxiformis beds.

The research objectives of the study include:
• To assess and determine fish assemblages (species richness and composition, relative abundance and size structure) in different habitat types in the marine bay region.
• To measure and compare the nursery function of seagrass Z. capensis and macroalgae A. taxiformis for juvenile fish (species richness and composition, relative abundance, size structure and behavior).

 

Project title: Macroinvertebrates associated with seagrass at point-source pollutant inputs in the Knysna Estuary

MSc candidate: Saudiqa Benjamin 2023-2024 (Zoology, Nelson Mandela University)
Supervisors: Dr Gavin Rishworth, Prof. Janine Adams, Dr Lucienne Human
Project description: Seagrasses provide many important ecosystem services e.g., habitat to macrofauna and regulating water quality, thereby maintaining ecosystem health. The aim of this study is to investigate how the endangered eelgrass Zostera capensis acts as a pollutant filter to reduce point-source watershed pollution at the Knysna Estuary, South Africa. Further aims include investigating other associated metrics such as sediment characteristics and how these influence the benthic macroinvertebrates associated with
seagrass habitat. Six polluted sites (point-sources) have been identified along the Knysna Estuary. The study will focus on how seagrass responds to nutrient input by primarily assessing concentration of nutrients (pollutants) within the seagrass tissue and sediment and additionally how the benthic macroinvertebrates vary in community composition at these point-sources sites. This research would contribute to providing conservation strategies for the protection of Z. capensis to improve water quality and ensure longevity of ecosystem services. It is funded by the MeerWissen SOMWAT Project: Nature based Solutions for Mitigation of Watershed Pollution.

 

 

Project title: Conservation and management of the endangered seagrass Zostera capensis and associated macroinvertebrates in the Knysna, Swartvlei and Keurbooms estuaries

MSc candidate: Minyonne Verster 2024-2025 (Zoology, Nelson Mandela University)
Supervisors: Dr Gavin Rishworth, Prof. Janine Adams, Prof. Richard Barnes
Project description: The dwarf eelgrass (Zostera capensis) occurs in the intertidal zone of permanently open estuaries but is severely fragmented. Due to localised threats and a fluctuating population, this species is listed as regionally Endangered. Conservation and management of the Zostera capensis is necessary. This project will investigate whether the current estuary management activities are adequate in the Knysna, Keurbooms and Swartvlei Estuary to protect the endangered seagrass Z. capensis and associated macroinvertebrates. The aims of this project are to determine the distribution, abundance, current status and threats of Z. capensis, as well as investigate the macroinvertebrate diversity associated with Z. capensis in the Knysna, Swartvlei and Keurbooms estuaries. Restoration measures to enhance ecosystem service provision will be identified as well as zonation of estuarine activities and other conservation strategies. This study will provide input to the larger MeerWissen funded SOMWAT Project (Nature based Solutions for Mitigation of Watershed Pollution) that is investigating seagrass as a buffer for land-based pollution. The results will aid in informing future estuary zonation and management plans.

 

 

Completed projects

• Reproductive and local dispersal patterns of Diopatra aciculata in the Knysna Estuary. (Stephanie Schoeman, Prof. Carol Simon – Stellenbosch University).
• Trophic ecology of Diopatra aciculata, a non-indigenous polychaete worm used as bait in South African estuaries. (Hendré van Rensburg, Prof. Carol Simon – Stellenbosch University).
• Spatial analysis of littoral and demersal fish assemblages within the Knysna Estuary system. (Andrew Meiklejohn, Prof. Amber-Robyn Childs, Kyle Smith, Ian Meiklejohn – Ichthyology and Fisheries Science, Rhodes University).
• The use of gabions as a tool for ecological engineering: evidence from a temperate estuary. (Jessica Seath, Dr Louw Claassens, Dr Louise Firth, Prof. William Froneman – Zoology and Entomology, Rhodes University).
• Ocean sprawl in the Keurbooms estuary: Ecological efficacy of different artificial structures used in erosion control. (Nina de Villiers, Dr Louw Claassens, Prof. Alan Hodgson – Zoology and Entomology, Rhodes University)
• Microplastic Pollution in the Knysna Estuary: Impacts on Syngnathids and Larval Fish (Merrisa Naidoo,
• The role of seagrass meadows in the accumulation of microplastics: Insights from a South African estuary (Bianca J. Boshoff, Tamara B. Robinson, Sophie von der Heyden – Stellenbosch University)
• Assessing the population dynamics of the Knysna Dwarf Chameleon, Bradypodion damaranum
• Conducting a baseline assessment of the occurrence and extent of ghost fishing gear in the Knysna estuary
• An investigation of ocean sprawl in the Garden Route Biosphere Reserve
• (Meta)barcoding of seagrass communities: comparative approaches for biodiversity planning
• The economic value of Zostera capensis in South Africa: desktop methods investigation
• Stormwater management using hydrological modelling and Sustainable Urban Drainage Systems