Brief description
The sea urchin Echinometra mathaei exists in high densities on intertidal rock platforms at Rottnest Island, Western Australia. In terms of both numbers and biomass, it is the dominant species in the benthic community. From November, 1984 to November, 1986 experiments were carried out to see if this numerical dominance also had functional significance, specifically in the determination of the species composition and the patterns of distribution and abundances in the surrounding benthic community.Lineage
Maintenance and Update Frequency: annually
Statement: At each site, six contiguous 5 x 5 m plots were marked out with concrete markers cemented to the limestone in a line parallel to the shore, about two-thirds of the way towards the edge of the platform. Two plots at each site were selected for each of the following three treatments: uncleared, half cleared, and completely cleared of urchins. The allocation of treatments was systematic, as there was only two replicate plots for each treatment (Hurlbert, 1984), and so at each site, plots 1 and 4 were left uncleared, plots 2 and 6 completely cleared and plots 3 and 5 half cleared. Within each plot, the central 2 x 2 m2 was marked by smaller concrete markers into four 1 m2 quadrats. At each sampling, these quadrats were scored for numbers of urchins and gastropods, distinguishing new recruits from resident adults, and for the percentage cover of algae, which was estimated with a 50 x 50 cm grid of fishing line tied to a metal frame to make 100 intersection points. This was placed haphazardly within the quadrat, and the type of algae or other substrate beneath each intersection point recorded. A representative sample of algae was taken from each quadrat to determine species composition. Recordings were taken at ~3-monthly intervals over 2 yr, from November, 1984 to November, 1986. Total counts of the turbinid gastropod Turbo intercostalis in each 5 x 5 m plot at Radar were also taken at irregular intervals. The treatments were maintained by periodic removal of migrant urchins.
**Hurlbert, S.H., 1984. Pseudoreplication and the design of ecological field experiments. Ecol. Monogr., Vol. 54, pp. 187-211.**
Created: 25 01 2008
Data time period: 1984-10 to 1986-10
text: westlimit=115.4; southlimit=-32.05; eastlimit=115.6; northlimit=-31.95
Subjects
25247003 |
BIOSPHERE |
Biosphere | Ecological Dynamics | Competition |
Biosphere | Ecological Dynamics | Life History |
COASTAL PROCESSES |
COMMUNITY DYNAMICS |
Community Structure |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
Echinometra mathaei |
Intertidal Zone |
OCEANS |
Oceans | Marine Biology | Marine Invertebrates |
Rocky Coasts |
environment |
oceans |
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Identifiers
- global : a94b4aa0-cafe-11dc-82dd-00188b4c0af8
