Drowned reefs and carbonate platforms: reef-community disruption by nutrients provides a clue to the paradox

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6863755

Hallock, P

Growth rates of corals on Holocene reefs indicate that carbonate platforms should easily keep pace with long-term subsidence and sea-level changes, yet drowned reefs and platforms are common in the geologic record. Recognition of the influence of nutrients in reef communities provides a clue to that paradox. Coral reefs are ecosystems adapted to nutrient-deficient environments. Input of nitrates and phosphates stimulates growth of plankton and, in the benthos, of fleshy algae and suspension-feeding animals such as bryozoans, barnacles, boring bivalves, sponges and tunicates. These fast-growing organisms not only displace the hermatypic algae and corals that produce most of the carbonate, but many are bioeroders that actively destroy the reefal structure. Nutrient enrichment can result from either runoff or upwelling. Thus, not only are terrigenous sediments detrimental to reefs, but suppression of reef development by nutrients carried in runoff from land can extend well beyond the range of sediment influx. Understanding that increased organic productivity disrupts reefal communities and curtails carbonate production provides important new insights for paleoenvironmental interpretations. Carbonate platforms that have succumbed to upwelled nutrients may include those whose drownings coincide with times of increasing deep-ocean circulation.

• Research Organization: Univ. of South Florida, St. Petersburg (USA)
• OSTI ID: 6863755
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
580400 -- Geochemistry-- (-1989)
ALGAE
ANIMALS
AQUATIC ECOSYSTEMS
AQUATIC ORGANISMS
BIOGEOCHEMISTRY
BRYOZOA
CENOZOIC ERA
CHEMISTRY
CNIDARIA
CORALS
ECOSYSTEMS
FEEDING
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GROWTH
INVERTEBRATES
LEVELS
MINERAL CYCLING
MOLLUSCS
NUTRIENTS
PLANTS
QUATERNARY PERIOD
REEFS
SEA LEVEL