Validation of parameters and protocols derived from chlorophyll fluorescence commonly utilised in marine ecophysiological studies.

This study documents the first validation of the suitability of the most common parameters and protocols used in marine ecophysiology to characterise photosynthesis by means of chlorophyll a fluorescence tools. We demonstrate that the effective yield of PSII (ΔF /F m ') is significantly underestimated when using short inductions times (≤1 min) following the rapid light curve protocol (RLC). The consequent electron transport rates (ETR) underestimations are species-specific and highly variable with irradiance and the photoacclimatory condition of the sample.

Photosynthetic responses of (Chlorophyta, Bryopsidales) to interactive effects of temperature, pH, and nutrients and its carbon pathways.

In this study, we evaluated the interactive effects of temperature, pH, and nutrients on photosynthetic performance in the calcareous tropical macroalga . A significant interaction among these factors on gross photosynthesis ( ) was found. The highest values of were reached at the highest temperature, pH, and nutrient enrichment tested and similarly in the control treatment (no added nutrients) at 33 °C at the lowest pH.

Absorptance determinations on multicellular tissues.

The analysis of the variation of the capacity and efficiency of photosynthetic tissues to collect solar energy is fundamental to understand the differences among species in their ability to transform this energy into organic molecules. This analysis may also help to understand natural changes in species distribution and/or abundance, and differences in species ability to colonize contrasting light environments or respond to environmental changes. Unfortunately, the challenge that optical determinations on highly dispersive samples represent has strongly limited the progression of this analysis on multicellular tissues, limiting our knowledge of the role that optical properties of photosynthetic tissues may play in the optimization of photosynthesis and growth of benthonic primary producers.

Coralline algal physiology is more adversely affected by elevated temperature than reduced pH.

In this study we analyzed the physiological responses of coralline algae to ocean acidification (OA) and global warming, by exposing algal thalli of three species with contrasting photobiology and growth-form to reduced pH and elevated temperature. The analysis aimed to discern between direct and combined effects, while elucidating the role of light and photosynthesis inhibition in this response. We demonstrate the high sensitivity of coralline algae to photodamage under elevated temperature and its severe consequences on thallus photosynthesis and calcification rates.