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Who We Are

Knysna Basin Project is a scientifically based non-profit organisation focused on continued research in the Knysna Basin >>

Community Engagement

Knysna Basin Project aims to create and stimulate public and learner awareness and appreciation of the estuary >>

Public Involvement

Be part of an organization dedicated to the wellbeing of the Knysna Estuary, become a member of the Knysna Basin Project >>

Extent and impact of a macroalgal bloom in South Africa’s most important estuary

The Knysna Estuary is South Africa's top ranked estuary and remains permanently open to the sea. Recently a large bloom of opportunistic macroalgae (Ulva lactuca) has covered the lower reaches of the estuary. The occurrence of an opportunistic species is globally considered as a sign of eutrophication. This study will investigate some of the causes of the macroalgal bloom and the reasons for its persistence.

The study objectives are to:

1. Determine the distribution, biomass and canopy height of the macroalgal bloom.

2. Determine the effect of the macroalgal bloom on salt marsh and Zostera capensis cover abundance.

3. Measure water column and sediment nutrients with a focus on the Ashmead channel

4. Determine the flux of nutrients and DO between the sediment water interface using  a 12 h benthic chamber experiment.

5. Collect sediment cores to measure particle size, organic content and redox potential.

6. Measure the δ15N in macrophyte and algal material in order to trace the different sources of nitrogen discharged into the Ashmead channel.  

7. Determine the storage of nitrogen, phosphorus, as well as heavy metals within the macroalgae in order to evaluate their uptake of nutrients and suitability as fertilizers or compost.

Contact Person:  Lucienne Human (PhD)
Botany Department
Nelson Mandela Metropolitan University
Summerstrand Campus (South) Port Elizabeth 6031 PO Box 77000 South Africa
Tel office: (+27) 041 504 4605


Thesen Island Home Owners Association Barloworld Rhodes University
Knysna Marathon Club