Marine Photosynthesis

A 10-day course. The course includes lectures, labs, demonstrations and research projects.

About half of the photosynthetic production in the world takes place in the oceans. Despite this fact, very little of the mechanisms involved in marine photosynthesis and the environmental conditions that drive these processes, are presently taught at universities in Israel. The course aims towards furthering the understanding of marine photosynthesis through lectures, demonstrations and laboratory as well as field measurements of photosynthetic rates and group projects. A variety of marine organisms are dealt with, including macroalgae, seagrasses, phytoplankton and photosymbiont-containing invertebrates such corals and sponges, and a variety of measurement methods related to primary marine production are applied and compared. Key questions being addressed during the course include:

• The light environment: Light penetration into oceanic waters; qualitative and quantitative attenuation of light;
• The carbon cycle and inorganic carbon sources in seawater;
• Characteristics of marine photosynthetic organisms: Cyanobacteria, algae (both macro- and micro-algae including photosymbiotic zooxanthellae) and seagrasses;
• Photosynthetic light-capturing processes specific to aquatic environments: High-light and shade adaptations, complementary chromatic adaptations with depth;
• Photosynthetic use of marine inorganic carbon sources: HCO₃ utilisation, CO₂ concentrating mechanisms;
• Various marine environments and their impact on the primary producers: Open water (for phytoplankton), benthic communities (for macroalgae, seagrasses and photosymbionts), the intertidal, mangroves;
• Photosynthetic adaptations to various environments and "stresses"; evolution of photosynthesis; photosynthetic acclimation of angiosperms to the marine environment, adaptations to the intertidal;

Emphasis is placed on projects in which the students measure photosynthetic rates in a variety of marine organisms both in the sea and in the laboratory. These projects include measurements of marine photosynthesis as:

1. O₂ evolution (with metabolic chambers and O₂ electrodes, for benthos.
2. CO₂ uptake, including the use of ¹⁴CO₂ radioactive carbon fixation by phytoplankton, ¹²CO₂ (with infrared gas analysis or mass spectrometry, for macrophytes), stable isotope gas exchange (with mass spectrometry, for all plants) and quantum yields and electron transport rates (with fluorometers, including in situ measurements using underwater pulse amplitude modulated fluorometers, the Diving-PAMs, for benthos).

Before the course students will receive three chapters dealing with basic concepts and the information in the chapters will serve as a basis for teaching in the course. To ensure that everyone knows the basic concepts of photosynthesis, a brief proficiency test (closed format, about 10 questions) will be conducted at the beginning of the course. This test will constitute 30% of the final exam score.