Diel growth in eelgrass Zostera marina

Abstract

Growth of eelgrass Zostera marina leaves was determined by sequential measurements of leaf length at time intervals of 4 to 12 h. Leaf growth rates at night were consistently lower (30 to 40%) compared to daytime rates, and night-time rates were highly correlated with growth during the previous day. Diel patterns of O sub(2) metabolism (measured at 2 to 4 h intervals) and leaf growth (at 4 h intervals) generally followed the daily irradiance cycle, with maximum growth and O sub(2) production rates both occurring near midday. It was demonstrated, however, that separate calibration studies relating root-rhizome growth to leaf growth can be conducted (over 1 to 2 wk) to allow estimates of short-term (4 to 12 h) responses of total plant growth to changes in environmental conditions.