EFFECTS OF TEMPERATURE ON PHOTOSYNTHESIS AND GROWTH OF SEAGRASSES

The effects of temperature on the photosynthesis and growth of seagrasses may be summarized by considering the ways in which temperature alters the characteristics of the photosynthesis.sbd.irradiance (P.sbd.I) curve of seagrasses. Within the limits of physiological tolerance (.apprx. 5-30.degree. C) temperature has little effect on the initial slope of the P.sbd.I curve. At 35-40.degree. C the photosynthetic capacity of seagrasses is reduced. Within the limits of physiological tolerance, the rate of photosynthesis at light saturation, the dark respiration rate and the light compensation point more than double as temperature increases. The optimum temperature for photosynthesis decreases from 25-35.degree. C at light saturation to as low as 5.degree. C as irradiance decreases. As a result of these effects of temperature on the P.sbd.I curve, growth of seagrasses in high (saturating) light environments increases with temperature, whereas growth of seagrasses in low (near the light compensation point) light environments decreases as temperature increases.