Intracolonial Variation in Coral Bleaching: Thermotolerance Variability of the Algal SymbiontsEPA Grant Number: U915820
Title: Intracolonial Variation in Coral Bleaching: Thermotolerance Variability of the Algal Symbionts
Investigators: Smith, Robin T.
Institution: Florida International University
EPA Project Officer: Broadway, Virginia
Project Period: August 1, 2000 through August 1, 2002
Project Amount: $80,463
RFA: Minority Academic Institutions (MAI) Fellowships for Graduate Environmental Study (2000) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Earth Sciences
The objective of this project is to investigate the thermal limits of intracolonial coral symbionts. The specific objectives of this project are as follows: (1) develop a molecular tool for the identification and quantification of intracolonial symbiont populations; (2) investigate differences in the physiological thermal limits of multi-species symbionts within a host colony; and (3) assign a relative "fitness" level (degree of adaptation) to the various symbionts with respect to thermal tolerance.
The host species chosen for this project is Montastraea faveolata, an ecologically important reef-building coral of the Caribbean. Five samples separated by <1 cm shall be taken from three distinct regions of the same colony. Replication will involve sampling from three spatially separate coral colonies. Once acclimation in the aquaria has been visually confirmed, two of each of the five sample sets will be used to quantify pre-bleached algal composition. The method that is being developed to quantify the algal clade composition within a sample is outlined: (1) digest total DNA using the restriction enzymes TaqI and DpnII; (2) use ?universal eukaryotic? primers (ss5 and ss3) of ssRNA genes (Medlin et al, 1988) by PCR to make a probe from pure algal cloned DNA; (3) end-label the probe with dye; (4) hybridize the probe to the restriction enzyme digested DNA; (4) run on auto sequencer using native (non-denaturing) gel; (5) identify clade types by peak comparison with known standards; and (6) quantify peak volumes as area under the curve. The ratio of identified peak areas will equal the ratio of abundance of symbionts clades within a sample. Experimental treatment of the remaining samples will involve an increasing temperature gradient over time as determined by the preliminary study. Samples will be processed as described above to quantify existing clade composition. Comparative analysis of pre- and post-bleached samples will be used to assess thermal tolerance of the symbiont clades.
Information gained by this project will contribute to understanding the bleaching mechanism and will offer a useful molecular tool for predicting how coral communities might adapt to the potential consequences of global change.