About This Item
Share This Item
Bahamian whitings, controversial patches of drifting mud-laden water, have been thought to be produced by fish. Observations over several 7-day periods show that whitings are long-lived phenomena (days and possibly weeks) and that the dozens which exist at any time on the Great Bahama Bank continually "rain" aragonitic sediment. Although chemical changes consistent with precipitation have not been detected in seawater near or within whitings, new data indirectly suggest that precipitation from seawater causes whitings.
Lime mud settled in approximately 6 hr in large (30 gal) containers of water taken from whitings, whereas in the sea, the "parent" whitings persisted for days. Sediment traps verified continual transport of sediment. Divers noted no fish stirring up the bottom nor any evidence of bottom feeding. Side-scan sonar failed to detect unusually large schools of fish, and a shrimper's net dragged in the whitings failed to catch any fish known to be bottom feeders. Dragging the net in clear water near active whitings created "artificial" whitings that settled back to the bottom in a few hours. Current measurements within and outside of whitings ruled out current eddies. Near the edge of the Bahama platform, whitings occur over bottom sediments too coarse-grained to be stirred into suspension, et the muddy bottom of the banks was miles away. These data suggest that natural whitings must be continually replenished with sediment.
Filtration of known volumes of water from 15 whitings and from clear seawater indicates that active-whiting water contains only a very small (10-12 mg/L) amount of suspended carbonate sediment, yet whitings are considered a potential major source of lime mud on the Great Bahama Bank. Inasmuch as nearly one-half the world's oil is pumped from limestone, knowledge of the origin and deposition of lime mud has implications for hydrocarbon exploration.
End_of_Article - Last_Page 307------------