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The vegetation of the Blackwood River estuary, southwest Australia

Congdon, R.A. and McComb, A.J. (1981) The vegetation of the Blackwood River estuary, southwest Australia. Journal of Ecology, 69 (1). pp. 1-16.

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(1) The standing crop and productivity of the main primary producers (the sources of autochthonous detritus) were measured in a West Australian estuary which has a shallow estuarine basin, two small lagoons and a tidal river, and which has marked seasonal changes in salinity.
(2) Standing crops of phytoplankton (mainly diatoms) are small in the open water; no blooms were observed during 3 yr. In sporadic sampling the highest concentration of chlorophyll 'a' was 1-98 jig I -1. Sediments contain more chlorophyll (as microscopic algae) per unit area than does the water column. Small phytoplankton stocks are attributed to low nutrient concentration when light flux and temperature are high and water-residence time low.
(3) Macroscopic algae (twenty species) are most prominent in the summer marine phase. Their distribution is very patchy, and they have a small total biomass.
(4) There are four benthic angiosperms in the estuary. The greatest contributor to production in open water is Ruppia, which is the most widely distributed of these, and has a peak dry-weight standing crop of 503 g m-2.
(5) The fringing marshes are mainly dominated by Juncus kraussii, which reaches a dry-weight standing crop of about 5 kg m-2.
(6) Based on general distribution, standing crops and published seasonal data, it is estimated that Ruppia produces about 700-1900 tonnes (dry weight) yr- 1, Juncus about 1000-4500, and the paperbark trees (Melaleuca spp.) of the marsh about 800 tonnes yr- 1 in leaf litter. Most of this organic material must become available as detritus, as only Ruppia is grazed appreciably.

Publication Type: Journal Article
Publisher: Blackwell Publishing
Copyright: 1981 Blackwell Scientific Publications
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