The effects of light intensity and blu, green and red wavelengths on mating strategies in the snow alga, Chloromonas sp -d, from the Tughill Plateau, New York State

In this study, four strains of the snow alga, Chloromonas sp.-D, were isolated from the Tughill Plateau, Whetstone Gulf State Park, NY, to study mating strategies under different light conditions. Experiments were conducted in white acrylic test tube holders that were placed in growth chambers with controlled light, temperature and photoperiod. Two light sources were used, Wide-Spectrum (WS) and CooI-White (CW), and the effects of blue, green and red light were tested by covering the holders with corresponding cellophanes. Cells were fixed with OsO4 and observed and tabulated using Zeiss phase-contrast microscopes. Using similar light intensities, blue light regimes produced more matings than green light regimes in four of four trials (two were significantly different, P<0.05), and blue light regimes produced more matings than red light regimes in seven of eight trials (three were significantly different, P<0.05). There were no trends in mating when green and red light regimes were compared in three trials. A photon light intensity of 200 I'mol m-2 S-I produced the most mating under both WS and CW regimes, but more mating occurred under CW in all intensities tested. When red light regimes of higher photon intensity (180 I'mol m-2 S-I) were compared to those of blue light regimes of lower intensity (60 I'mol m.2 S-I), more mating occurred under red light in four of four trials, but none were significantly different. Mating pairs of three types were observed: oblong-oblong (o-o), oblong-sphere (o-s) and sphere-sphere (s-s). Cell packs that produced mating types and o-o mating pairs diminished with time. However, o-s and s-s mating pairs and quadriflagellate zygotes produced from the mating pairs increased with time.