Barbara S. Labbe1,2, Pamela A. Fernández3 and Alejandro H. Buschmann2,3
1Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
2Master in Science, Postgrade Direction, University of Los Lagos, Chinquihue km 6, Puerto Montt, Chile
3Center i~mar, University of Los Lagos, Chinquihue km 6, Puerto Montt, Chile
The absorption of CO2 by the oceans is causing a reduction in pH (0.3-0.4 units), a process known as ocean acidification (OA). This, together with changes in the weather variables, impacts marine ecosystems in a complex way. Studies based on large brown seaweed forests show that there is a growing interest in knowing the functioning of Ci uptake mechanisms (CCM) in species such as Macrocystis pyrifera who plays a fundamental role as a primary producer in marine environments. The mechanisms of acquisition of Ci described in adult algae could vary from the mechanisms present in other stages of life such as gametophytes, depending on their energy requirements. Previous studies predict that early stages of macroalgae are vulnerable to OA and are considered critical for population survival. However, not many studies address what happens in these stages of their life cycle against environmental factors related to OA and Global Climate Change (GCC). This study evaluated the effect of pH, temperature, and light on the grow/metabolism of carbon in M. pyrifera gametophytes. This study included the analysis of physiological variables: growth, photosynthesis, photosynthetic pigments and Anhydrase Carbonic (CA) activity. This study establishes for the first time that the extracellular conversion of HCO3– to CO2 carried out by the enzyme CA is the main CCM in gametophytes of M. pyrifera. Our results show that the gametophytes of M. pyrifera respond in a differential way to experimental conditions of pH/light/temperature and, in general, M. pyrifera gametophytes would benefit from future OA and GCC conditions.