Branching and Massive Corals: Does Morphology Matter in Response to Changing Environments?

Coral species in the Tropical Eastern Pacific are subjected to environmental conditions which are marginal for coral reef development. Among these are coastal wind-driven upwellings and the episodic occurrence of sea-warming due to El Niño Southern Oscillation (ENSO). This study examined the possible effects of varying water temperature and dissolved nutrient scenarios on the coral-zooxanthellae symbiosis in two common coral species from the Tropical Eastern Pacific (Gulf of Panama). The branching coral species Pocillopora damicornis and the massive coral species Porites lobata were exposed for 30 days to different temperatures and nitrate concentrations. Results suggest that the slow-growing, massive species Porites lobata is able to cope better with changing environmental conditions than the fast-growing, branching coral Pocillopora damicornis. This indicates that the effect of temperature and nitrate enrichment on the coral-zooxanthella symbiosis varies according to the coral morphology. This biological monograph is a useful manual for university students involved in coral research.