pmuller at jaws.marine.usf.edu
Mon Mar 18 15:40:33 EST 1996
Two papers were published in late 1995 on bleaching in larger foraminifera with
Talge, HK and Hallock, P. 1995. Cytological examination of symbiont loss in a
benthic foraminifer, Amphistegina gibbosa. Marine Micropaleontology 26:107-113.
Hallock, P., Talge, HK, Cockey, EM, and Muller, RG. 1995. A new disease in
reef-dwelling foraminifera: Implications for coastal sedimentation. Journal of
Foraminiferal Research 25:280-286.
"Bleaching" in Amphistegina in the Florida Keys began in summer 1991 and has
continued since, increasing in the population each spring, peaking near the
summer solstice, and with recovery in progress by late summer and continuing
through winter months. Mottling and bleaching in individual forams are caused
by progressive digestion of diatom endosymbionts, accompanied by progressive
deterioration of the foram's cytoplasm (Talge and Hallock). Associated
"symptoms" include anomalous shell breakage, shell-surface lesions that permit
invasion by microborers and epibionts, and reproductive damage including
deformed young and sometimes failure to calcify (Hallock et al.). Similar
symptoms have been observed in Amphistegina spp. from the Bahamas; Jamaica;
Heron Island, Australia; the western Australian shelf; and, to a lesser extent,
in Belau, and Hawaii.
If you are interested in looking for similar symptoms in Amphistegina on your
reefs, please let me know and will send you a color photocopy of normal, mottled
and bleached Amphistegina, collection instructions, and a copy of the Hallock et
This problem is not insignificant. Amphistegina is normally an abundant
reef-dwelling organism that is found nearly circumtropically (except the eastern
tropical Pacific). Its shells account for substantial proportions of the
sand-sized sediments in the coastal zones of Indo-Pacific islands (e.g., 20+% of
Hawai'i's beach sands and 90+% of Kapingimarangi's). Loss of Amphistegina
populations could have serious implications for coastal sedimentation in such
areas if populations sustain long-term damage of the magnitude seen in Florida
Keys populations over the past 5 years.
Pamela Hallock, Professor
Department of Marine Science
University of South Florida
140 Seventh Avenue S.
St. Petersburg, FL 33701 USA
pmuller at seas.marine.usf.edu
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