University of Arizona Galapagos Marine Ecology (ECOL 496O/596O)
Monitoring for Species: Green and pencil urchins
Site: Loberia and Tijeretas
Design: A 50 m x 12 m study area was established at Loberia (see location map) and the area was sampled using a 1 m x 1 m PVC quadrat. There were no details for how the study area was sampled, i.e., where the quadrat was placed within the study area. However, the quadrat was placed at 32 separate locations and sampled (Figure 4); the number of urchins by species, % cover of algae (ocular estimate), and algae height on the rock were recorded/estimated within the quadrat. At Tijeretas, 2 rocks were sampled and the number of urchins by species, % cover of algae, and algae height was recorded for each rock. There is no location map for where these rocks were located or estimates of their size; thus, a density calculation was not possible for this survey.
Sampling Frequency: Although not explicitly indicated, the survey appears to have been conducted once at each site
Data Summary/Monitoring Parameter: number of urchins by species, percent cover of algae, and algae height.
Monitoring Protocol Design/Implementation: T. Lutz & C. Strauss
Year Sampled: 2004
Results:
Table 6. Number and density of urchins counted, mean cover and height of algae at Loberia and Tijeretas.
Site / No. green urchins / No. pencil urchins / Mean (+ SD) density green urchins (#/m2) / Mean (+ SD) density pencil urchins (#/m2) / Mean algae cover (%) / Mean algae height (mm)Loberia / 5700 a. / 2419 a. / 8.5 (+ 11.5) / 4 (+ 3) / 32 / 7
Tijeretas, Rock 1 / 104 / 55 / 44 / 20
Tijeretas, Rock 2 / 124 / 23 / 71 / 20
a. Estimated for study area from mean density values.
Sea Urchin Study Site Map
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