Reeds as indicators of nutrient enrichment in a small temporarily open/closed South African estuary

  • LRD Human
  • JB Adams

Abstract

This study investigated the use of δ15N levels in Phragmites australis reeds as an indicator of nutrient input into the small temporarily open/closed East Kleinemonde Estuary, Eastern Cape, South Africa. Nutrient (NH4 and SRP) concentrations decreased from the bank towards the main estuary channel, suggesting that nutrients introduced into the estuary in groundwater and surface runoff were taken up by the fringe of reeds. The roots, rhizomes, stems and leaves of Phragmites at the site with the greatest Phragmites biomass and density had significantly higher ä15N (~20‰) than the leaves at a site with no groundwater input, consistent with nutrient enrichment by septic tank wastewater and stormwater runoff. This study suggests that the δ15N level in reeds can be used to detect enrichment in small estuaries threatened by changing land use and deteriorating water quality.

Keywords: East Kleinemonde Estuary, Phragmites australis, reed morphology, stable isotopes

African Journal of Aquatic Science 2011, 36(2): 167–179

Author Biographies

LRD Human
Department of Botany, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, South Africa
JB Adams
Department of Botany, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031, South Africa
Section
Articles

Journal Identifiers


eISSN: 1727-9364
print ISSN: 1608-5914