Rates of spread of Spartina anglica and sediment accretion in the New River Estuary, Invercargill, New Zealand

Abstract

Rates of spread of Spartina anglica and associated accretion of sediment on sand and mud flats were measured by re-examining transects and a permanent quadrat that were set up 9 years earlier (1973) in the New River Estuary, Invercargill. Spread is slowest where the species nears its lower tidal limit, and where there is erosion of sediment. In recently colonised areas the maximum spread of vegetation is 5.3 m/a. Sediment accretion rates varied from 12 mm/a in dense swards on muddy substrate, to 3 mm/a on sand in areas of turbulent water. One area of erosion is reported.

Keywords:

• Spartina anglica
• colonisation
• growth rates
• sedimentation
• estuaries
• New River Estuary, New Zealand
• Leptocarpus similis