Eakin, C.M., D.B. Smith, P.W. Glynn, L. D'Croz and J. Gil. Extreme tidal
exposures, cool upwelling and coral mortality in the eastern Pacific
(Panama). Association of Marine Laboratories of the Caribbean, 22nd Annual
Meeting Abstracts. 1989.

Panamanian (Pacific) reef flats were exposed by extreme low tides (-50 to -60
cm MLSW) on 7-10 February 1989 for approximately 2 hours at midday under
clear skies. Pocilloporid corals cover 6-37% of the reef flat at Uva Is.,
Gulf of Chiriqui and of these 97% by area experienced partial or complete
mortality due to exposure.  The dead coral tissues and crustacean symbionts
of Pocillopora sp. provided a windfall for opportunistic omnivorous fishes
immediately following the exposure.  Herbivorous fishes benefited later from
the algae that colonized the bare coral skeletons within a week following the
low tides.  Mortalities resulting from these exposures affected only the reef
flats above approximately -30 cm MLSW while the 1982-83 El Nino warming event
resulted in high mortality at all depths. Coral mortality associated with
this event was evident on coral reefs in the Gulf of Chiriqui and the 
Gulf of Panama.  The frequency of extreme low tidal exposure and patterns of 
colony survival indicate that these events are important in shaping reef flat
morphology.  Following the low tidal exposure, additional pocilloporid 
corals in the Gulf of Panama were bleached during cool upwelling events (16 
degrees C).  Samples of normal, bleached and algal-overgrown colonies are 
being analyzed for zooxanthellae densities, chlorophyll concentrations and 
tissue lesions.