| Summary: | Dissertation (Ph.D.) University of Alaska Fairbanks, 1970 A collection of essays is presented that are a contribution toward a biology of eelgrass (Zostera marina L.) in Alaska. Eelgrass is the most abundant seagrass on the coast of Alaska. The distribution of the plant in Alaska is disjunct and extends from Kotzebue Sound to the southern border of the state. The present circumboreal distribution is thought to be the result of dispersal from a west Pacific origin around the Pacific rim and through the Arctic into the Atlantic. Ten widely scattered eelgrass populations in Alaska have been sampled for quantitative comparison. The highest standing stocks (1510 g dry wt/m²) were found in Kinzarof and Izembek lagoons on the Alaska Peninsula. The caloric content, chlorophyll a concentration, turion density, and leaf size varied greatly among the populations. The eelgrass in Safety Lagoon survives the arctic winter under one meter of sea ice in conditions of extremely low light intensity and anoxic water. In chemical composition, eelgrass is similar to other angiosperms, but it also reflects adaptation to the marine environment. Trace elements are accumulated in the plant in proportion to their concentration in the sea. The roots as well as the leaves function as the sites for the uptake of phosphate. Using radioactive phosphate it was shown that phosphate was absorbed greatest in the light and transported throughout the plant; a portion of the phosphate removed from solution by the roots was lost across the leaves. The metabolism of eelgrass in the dark is extremely dependent on temperature. Physiological differences exist between shallow water and deep water plants and between summer and winter plants. A depressed rate of respiration in winter is an adaptation enhancing survival in high latitudes.
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