11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 2: Biotic Response to Ancient Environmental Change in Indo-Pacific Coral Reefs
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Pleistocene Reefs Of The Egyptian Red Sea
Lorraine CASAZZA* 1
1 Dept. of Integrative Biology and UC Museum of Paleontology, University of California,
Berkeley, Berkeley, CA
Rifting of the Red Sea basin has resulted in eight emerged reef terraces along the
Egyptian coastline representing three cycles of reef growth during the middle to late
Pleistocene: Oxygen Isotope Stages 5 (75 - 127 ka BP), 7 (170 - 230 ka BP), and 9 (300 -
330 ka BP). This study compares three of those reef terraces: terraces I and III,
representing two distinct periods of reef growth during Oxygen Isotope Stage 5 and
Terrace V, representing Stage 7, in order to determine if and how these fringing reefs
have responded to environmental change over the last 230,000 years. Three locations
along the Egyptian Red Sea coast were chosen for 1) the presence of all three terraces and
2) good outcrop access at the mouths of wadis (dry riverbeds). For each terrace in each
location coral species were photographed and/or collected for identification every 1 m
along a 120 m line transect. An experimental method was also attempted for comparison.
This involved photographing 1m2 quadrats every 5 m along the same 120 m transect, and
percent coverage of total outcrop sampled calculated for each coral species. Visible
specimen of bivalves, echinoids and gastropods were collected for each quadrat, and
loose reef sediment was collected where it was found for identification of reef
foraminifera. Coral species composition and diversity for each terrace was combined with
presence /absence data for bivalve, gastropod and echinoid species to create a
characterization of each terrace community. Differences between the reef communities of
Stage 7 and Stage 5 may be due to a complete recolonization after hypersaline conditions
in the Red Sea during low sea level, or a result of differences in local paleoenvironment
during the two time periods.
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