Drowned reefs and carbonate platforms: reef-community disruption by nutrients provides a clue to the paradox
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-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
Similar Records
Holocene reef associated carbonate sediments and their Pleistocene counterparts, Miyako Islands, Ryukyus, southwest of Japan
Cenozoic cool-water limestones, Eucla platform, Southern Australia
Related Subjects
REEFS
AQUATIC ECOSYSTEMS
BIOGEOCHEMISTRY
GEOLOGIC HISTORY
GROWTH
ALGAE
BRYOZOA
CORALS
FEEDING
GEOLOGIC MODELS
MINERAL CYCLING
MOLLUSCS
NUTRIENTS
QUATERNARY PERIOD
SEA LEVEL
ANIMALS
AQUATIC ORGANISMS
CENOZOIC ERA
CHEMISTRY
CNIDARIA
ECOSYSTEMS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC STRUCTURES
INVERTEBRATES
LEVELS
PLANTS
580100* - Geology & Hydrology- (-1989)
580400 - Geochemistry- (-1989)