Linkages between coral assemblages and coral proxies of terrestrial exposure along a cross-shelf gradient on the southern Great Barrier Reef

Jupiter, S., Roff, G., Marion, G., Henderson, M., Schrameyer, V., McCulloch, M. and Hoegh-Guldberg, O. (2008) Linkages between coral assemblages and coral proxies of terrestrial exposure along a cross-shelf gradient on the southern Great Barrier Reef. Coral Reefs, 27 4: 887-903. doi:10.1007/s00338-008-0422-3


Author Jupiter, S.
Roff, G.
Marion, G.
Henderson, M.
Schrameyer, V.
McCulloch, M.
Hoegh-Guldberg, O.
Title Linkages between coral assemblages and coral proxies of terrestrial exposure along a cross-shelf gradient on the southern Great Barrier Reef
Journal name Coral Reefs   Check publisher's open access policy
ISSN 0722-4028
1432-0975
Publication date 2008-12-01
Year available 2008
Sub-type Article (original research)
DOI 10.1007/s00338-008-0422-3
Open Access Status
Volume 27
Issue 4
Start page 887
End page 903
Total pages 7
Editor B. E. Brown
Place of publication Germany
Publisher Springer
Language eng
Subject C1
960808 Marine Flora, Fauna and Biodiversity
060205 Marine and Estuarine Ecology (incl. Marine Ichthyology)
Abstract Coral core records, combined with measurements of coral community structure, were used to assess the long-term impact of multiple environmental stressors on reef assemblages along an environmental gradient. Multiple proxies (luminescent lines, Ba/Ca, δ15N) that reflect different environmental conditions (freshwater discharge, sediment delivery to the nearshore, nutrient availability and transformations) were measured in Porites coral cores collected from nearshore reefs at increasing distance from the intensively agricultural region of Mackay (Queensland, Australia). The corals provide a record (1968–2002) of the frequency and intensity of exposure to terrestrial runoff and fertilizer-derived nitrogen and were used to assess how the present-day coral community composition may have been influenced by flood-related disturbance. Reefs closest to the mainland (5–32 km offshore) were characterized by low hard coral cover (≤10%), with no significant differences among locations. Distinct annual luminescent lines and elevated Ba/Ca values (4.98 ± 0.63 μmol mol−1; mean ± SD) in the most inshore corals (Round Top Island; 5 km offshore) indicated chronic, sub-annual exposure to freshwater and resuspended terrestrial sediment that may have historically prevented reef formation. By contrast, corals from Keswick Island (32 km offshore) indicated episodic, high-magnitude exposure to Pioneer River discharge during extreme flood events (e.g., 1974, 1991), with strongly luminescent lines and substantially enriched coral skeletal δ15N (12–14‰). The reef assemblages at Keswick and St. Bees islands were categorically different from all other locations, with high fleshy macroalgal cover (80.1 ± 7.2% and 62.7 ± 7.1%, respective mean ± SE) overgrowing dead reef matrix. Coral records from Scawfell Island (51 km offshore) indicated little exposure to Pioneer catchment influence: all locations from Scawfell and further offshore had total hard and soft coral cover comparable to largely undisturbed nearshore to middle shelf reefs of the southern Great Barrier Reef.
Keyword Porites
Luminescence
Barium
Nitrogen isotope
Coral assemblage
Disturbance frequency
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID LP050896
Institutional Status UQ

 
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Created: Wed, 15 Apr 2009, 23:42:43 EST by Peter Fogarty on behalf of Centre for Marine Studies