EELGRASS (ZOSTERA-MARINA L) TRANSPLANTS IN SAN-FRANCISCO BAY - ROLE OF LIGHT AVAILABILITY ON METABOLISM, GROWTH AND SURVIVAL

Survival, metabolism and growth of Zostera marina L. transplants were examined along depth gradients in Keil Cove and Paradise Cove in the e xtremely turbid San Francisco Bay estuary. Water transparency was unus ually high throughout 1989-1990 for San Francisco Bay. Transplant surv ival was strongly depth-dependent at Paradise Cove but not at Keil Cov e. All transplants were lost below - 1.0 m depth within 1 year at Para dise Cove, but survived to depths of - 1.5 m at Keil Cove. Half the tr ansplants growing in shallow water survived the first year at both sit es. Shoot photosynthesis, respiration, growth, and sugar content did n ot differ between sites. Daily periods of irradiance-saturated photosy nthesis (H-sat) were over 6 h all year. Seasonal photosynthetic acclim ation to light availability maintained long H-sat periods and high rat ios of daily whole-plant production to respiration through the winter, indicating a potential for net carbon gain throughout the year. Winte r growth was 50% of the summer rate, Despite high initial losses, surv iving transplants have persisted at both sites through 1994. Although eelgrass transplants can succeed in San Francisco Bay given sufficient light availability, the role of carbon reserves and transplant timing may influence transplant survival.