Coral bleaching and mortality in Panama and Ecuador during the 1997-1998 El Niño-Southern Oscillation event : Spatial/temporal patterns and comparisons with the 1982-1983 event

摘要: Bleaching and mortality of zooxanthellate corals during the 1997-98 El Nino-Southern Oscillation (ENSO) event are documented for eastern equatorial Pacific localities in Panama (Gulf Chiriqui Gulf Panama) Ecuador (Galapagos Islands mainland coast). Overall, very strong 1982-83 ENSOs were similar magnitude duration, but varied spatially, resulting different patterns elevated sea temperature stress coral responses two disturbance events. Two bleaching episodes occurred Chiriqui, each coincident with high (≥30°C) situ temperatures warm water filaments visible NOAA/NCEP SST fields. Coral was significantly among localities: Galapagos (26.2%) > (13.1%) coastal (7.0%) (0%). notably higher (52-97%) than 1997-98. most sites within also different. Highest mortalities at offshore compared nearshore Panama, Ecuador. Although species localities, tissue death especially Millepora spp., Pavona Pocillopora Porites spp. Corals present relatively deep (12-18 m), inter-reef habitats suffered lower rates shallow (1-10 m) habitats. Bleached tissues demonstrated a significant increase zooxanthella density, only slight chlorophyll concentration over 5 mo respite, from end first (October 1997) to beginning second (March 1998). The use molecular DNA techniques compare algal symbionts bleached healthy colonies revealed correlation between severity symbiont genotype, regardless depth. In particular, one genotype (commonly found scleractinian genus Chiriqui) particularly resistant bleaching, indicating that diversity can play an important role explaining spatial host systematic bleaching. Extreme reductions abundance some populations have resulted local extirpations. It is possible boschmai, endemic hydrocoral, now extinct. Remnant patches Gardineroseris planulata survived ENSO disappeared following event, causing extinctions. Marked declines external bioerosion corallivore abundances before after should less effect on surviving when such effects continued degrade reefs long initial disturbance. Surviving still subject heavy grazing pressure by abundant echinoid populations. response Nino cannot be fully understood without appreciation spatial/temporal variability historical stresses which these been past 25+ yrs.