The Benthic invertebrate community of a Southern Cape estuary : structure and possible food sources

Whitfield, A.K. (1989) The Benthic invertebrate community of a Southern Cape estuary : structure and possible food sources. Transactions of the Royal Society of South Africa, 47 (2). pp. 159-179. ISSN 0035-919X




Cluster analysis of invertebrate communities in the Swartvlei estuary revealed that vegetated (Zostera capensis) sites were distinct from unvegetated ones. `Indicator species' for the eelgrass group included Melita zeylinaca, Loripes clausus, Natica tecta and Palaemon pacificus, whereas those for the bare sand community were Urothoe pulchella, Callianassa kraussi, Iphinoe truncata and Pontogeloides latipes. Infaunal bivalves comprised >60 % of the invertebrate biomass at Zostera sites but <5 % at bare sand sites. Conversely the infaunal anomuran C. kraussi dominated the sandy sites (>80 %) and was a minor component (<5 %) at eelgrass sites. The supratidal invertebrate community was dominated by Orchestia spp. which live and feed on wrack detritus. Litterbag experiments revealed that degradation of Zostera leaf wrack was rapid during the first thirty days after deposition but slow between 40 and 140 days. Laboratory experiments indicated that Orchestia consumption of wrack material could not account for the rapid weight loss recorded in the natural environment. Preliminary diet analyses of intertidal and infratidal zoobenthos revealed that most invertebrate species feed on detritus and associated microorganisms. Filamentous algae and diatoms dominated the gut contents of only three out of 18 macrobenthic species, and living Zostera was not an important food item for any invertebrate examined.

Item Type:Article
Uncontrolled Keywords:invertebrata; invertebrates; Swartvlei estuary; Southern Cape; Benthic invertebrate communities; benthos; aquatic plants; substrates; sand; bivalves; stomach contents; ecosystems; cluster analysis; zostera capensis; indicator species; Melita zeylinaca; Loripes clausus; Natica tecta; Callianassa kraussi; Iphinoe truncata; Pontogeloides latipes; anomura; Orchestia; wrack detritus; zoobenthos; vegetated sites; unvegetated sites; Palaemon pacificus; Urothoe pulchella
Subjects:Y Unknown > Subjects to be assigned
Divisions:Research Institutes and Units > South African Institute for Aquatic Biodiversity (SAIAB)
ID Code:524
Deposited On:28 Feb 2007
Last Modified:06 Jan 2012 16:18
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