Subtidal Benthic Macroinfauna in an Estuary of South Chile: Distribution Pattern in Relation to Sediment Types |
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| Authors: | E Jaramillo S Mulsow M Pino H Figueroa |
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| Institution: | Instituto de Zoologia, Universidad Austral de Chile, Valdivia, Chile.;Instituto de Geociencias, Universidad Austral de Chile, Valdivia, Chile;Instituto de Estadi'stica, Universidad Austral de Chile, Valdivia, Chile |
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| Abstract: | Abstract. A quantitative survey (18 stations) of the subtidal soft bottom macroinfauna in an estuary of the south Chilean coast was conducted during January, 1980. The map of sedimentological facies elaborated for the Queule River Estuary shows sandy bottoms in the outlet and upper part of the area studied, while the middle part is occupied by muddy sand. The ordination of stations by Principal Component Analysis is fundamentally defined by mud and gravel percentage and is, in general, concordant with the distribution of sediments in the facies map. A total of 17,405 animals was collected (16 taxa), Polychaeta being the dominant group in density (77.47%) and biomass (73.4%). The maximum number of species was obtained outside the mouth of the estuary, while maximum densities and biomass were obtained in the middle of the estuary.
The Factor Analysis performed with the abundances data of the most abundant species rendered the ordination of two groups of stations (concordant with a Cluster Analysis) in the Q-mode and two groups of species in the R-mode. One group of stations is restricted to sandy habitats of the outlet area and is dominated by suspension feeders. The other, in the middle and upper part of the estuary (muddy sand or sandy bottoms with a higher percentage of organic matter), is dominated by deposit feeders. Between these two groups, significant differences in sedimentological variables (sand, mud, and organic matter percentage) were detected. Each of the two delineated groups of species corresponds to the groups of stations, showing that most of the taxa can be combined in faunal assemblages with preference for different types of substrate. |
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| Keywords: | Macroinfauna soft bottom sediment subtidal estuary |
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