Photoacclimation of Ventricaria ventricosa to a change in available light’s wavelength

A prominent process of photoacclimation accounts for the change in pigment concentration to improve photosynthetic performance. It occurs in algae due to their inherent characteristic of living underwater and receiving limited wavelength and irradiance of light from the sun. This process was investigated on the macroalga Ventricaria ventricosa, one of the largest known unicellular organisms. It contains a central liquid-filled vacuole that pushes the organelles towards the cell membrane. Upon perforation, the inner cell structure disassembles, facilitating pigment concentration analysis. On a first experimental stage, individuals at 8-10 m and 16-18 m deep were collected and analyzed for chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoids (Car) concentrations via spectrophotometry. The overall pigment concentration was not significantly different (ranging from 0.54-14.74 μg ml-1 Chl a, 0.36-19.29 μg ml-1 Chl b, 0.19- 4.09 μg ml-1 Car). The second stage included covering alga from the same depth belts with a green or transparent (control) filter cage for one week to then analyze pigment concentration. Control cages had pigment concentration values considerably lower from those of the first experimental stage (ranging from 0.02-3.38 μg ml-1 Chl a, 0.02-2.20 μg ml-1 Chl b, 0.01-1.44 μg ml-1 Car). Membrane perforation upon detachment from the reef, decreased water flow, and the cells’ size may have influenced this outcome. It is concluded that the depth gap used was not large enough to promote photoacclimation. It is also suggested that V. ventricosa prioritizes healing over photoacclimation, resulting in loss of pigment concentration while reestablishing turgor pressure.

This student research was retrieved from Physis: Journal of Marine Science XVI (Fall 2014)19: 74-80 from CIEE Bonaire.

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