EXPERIMENTAL OIL EXPOSURE OF ASCOPHYLLUM-NODOSUM (L) LEJOLIS

The effect of weathered, crude oil on Ascophyllum nodosum was tested i n an outdoor experiment and in a laboratory experiment. Adult A. nodos um plants which were exposed to oil in an outdoor basin for 3 days sho wed reduced growth for a certain period of time, after which growth re covered. Also, some necrotic damage was observed. Three-week-old and 1 -year-old germlings placed under the adult plants showed no significan t reduction in number compared to control plants. In the laboratory ex periment some of the 1-month-old germlings were initially exposed to o il for 6 min, some for 1 h, some for 3 h and some for 5 h. After 3 wee ks in running, filtered water oil-exposed germlings had reached the sa me length as those in the control groups, and no effect of exposing th e germlings to oil for different lengths of time at the start of the e xperiment was found. The results indicate that a limited oil pollution of weathered, crude oil may reduce growth and biomass of adult plants for a certain period of time. However, this need not be detrimental t o a population with good recruitment from germlings or vegetative shoo ts growing under a dense canopy layer.