11th ICRS Abstract book - Nova Southeastern University

Plenary
Photophysiology, Bleaching and Adaptation
Roberto IGLESIAS-PRIETO
Unidad Académica Puerto Morelos, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Apartado
Postal 1152, Cancún 77500 QR Mexico
During the last 200 million years scleractinian corals in symbioses with photosynthetic dinoflagellates have been responsible for the
formation and maintenance of coral reefs. In these organisms, algal photosynthesis can provide more that a 100% of the basal metabolic
requirements. The nutritional advantages that symbiotic invertebrates obtain from the translocation and consumption of algal
photosynthates can explain why symbiotic corals possess significantly larger calcification rates relative to non-symbiotic invertebrates. In
this context, algal photosynthesis is a key element in the formation of modern coral reefs. Considering the importance of algal
photosynthesis for the well being of symbiotic corals, the study of the photobiology of these organisms has attracted significant attention.
Symbiotic corals inhabit the entire photic zone and are subject to extraordinary variations in light intensity. I will review the characteristics
of the photosynthetic apparatus of dinoflagellates and the physiological mechanisms employed by corals and their symbiotic algae to
successfully harvest and utilize the available solar radiation. Based on comparative analyses of the differential responses of individual algal
species to variations in growth irradiance in culture, or intact associations in nature, it has been postulated that the differential utilization of
solar radiation is an important axis for niche diversification among reef-building corals. Recent analyses of the optical properties of intact
coral surfaces using transmittance determinations indicate that due to the multiple scattering of solar radiation on the highly reflective
aragonite skeleton, the specific absorption coefficients of the symbiotic algae are much higher that those obtained from freshly isolated
algae, making symbiotic scleractinians one of the most efficient solar collector in nature. This efficiency results in significant competitive
advantages, as symbiotic corals can collect the same amount of solar radiation as a green plant with approximately one order of magnitude
less photosynthetic pigments concentrations. The role of the animal skeleton in modulating the absorption properties of the symbiotic algae
has also profound implications for our understanding of the evolution of these organisms. Finally, I will discuss the role of multiple
scattering of coral skeletons in the propagation of thermal stress, leading to coral bleaching and mortality.
Population Connectivity Within and Among Reef Systems: Progress and Promising Directions
Robert COWEN
Marine Biology and Fisheries, University of Miami, RSMAS, Miami, FL
The study of population connectivity has evolved over the last decade to include a broad array of approaches to assess the scales and
mechanisms over which successful larval dispersal operates among reef systems. Strong interest in this topic has been stimulated by a need
to provide spatial management options to resource managers, often for resources that are in dire states. The major challenges in this effort
are to provide a quantitative understanding of the processes and scales controlling successful larval dispersal and how connectivity
influences the dynamics of the affected populations. Resolving the mechanisms controlling larval dispersal will involve a coherent
understanding of the relevant physical processes and how organisms mediate the physical outcome. Multiple scales will be important, and
therefore understanding how the processes are coupled across scales is essential. By the very nature of reef organisms initiating and ending
their larval life within nearshore waters, new focus must be extended on the bio-physical processes operating within this environment.
Identifying patterns will need to involve efforts that focus on a variety of species with different life histories across various environments.
In concert, the problem is multidisciplinary, but one requiring interdisciplinary research effort. This talk will evaluate our progress to date,
implications of mounting environmental challenges and suggest some promising new directions.
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