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Type: Journal article
Title: Changes in biofilms induced by flow regulation could explain extinctions of aquatic snails in the lower River Murray, Australia
Author: Sheldon, F.
Walker, K.
Citation: Hydrobiologia: the international journal on limnology and marine sciences, 1997; 347(1-3):97-108
Issue Date: 1997
ISSN: 0018-8158
Abstract: Notopala sublineata, Notopala hanleyi (Viviparidae) and Thiara balonnensis (Thiaridae) are prosobranch gastropods that were once abundant in the lower River Murray. These and other snail taxa have declined markedly over the last 50 years, coinciding with increased flow regulation by dams and weirs. In this paper we speculate that the decline may be linked to changes in the nature of food resources. Before regulation, most of the biofilm biomass in the lower Murray probably was microbial, as fluctuating water levels and high turbidity would have maintained these communities in a state of early succession. By stabilising seasonal water levels, we suggest that regulation has promoted the growth of filamentous algae, perhaps at the expense of bacteria. Evidence from gut and faecal pellet analysis, and from analysis of carbon stable-isotopes, suggests that the gastropod taxa are detritivores, feeding mainly on amorphous organic detritus. Algae have a relatively high C:N ratio (low nutritional value) and may be an inadequate food to maintain female growth and reproduction, especially in viviparous snails. © 1997 Kluwer Academic Publishers.
DOI: 10.1023/a:1003019302094
Appears in Collections:Aurora harvest
Zoology publications

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