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Seasonal variation in the biomass, tuber density, and photosynthetic metabolism of Hydrilla in three Florida lakes

Journal Article · · J. Aquat. Plant Manage.; (United States)
OSTI ID:6869714

Biomass, tuber densities and various water parameters were measured throughout 1977 in mats of hydrilla (Hydrilla verticillata Royle) in three Florida lakes: Jackson, Orange, and Trafford. In the northern lakes, Jackson and Orange, no mats were present in winter, and a maximum mat biomass of 0.24 Kg dry weight/m/sup 2/ was attained in the late fall. In the southern Lake Trafford, mats were present year round, and the maximum biomass of 0.89 Kg/m/sup 2/ occurred in the summer. In the hydrosoil of lakes Jackson and Orange, tuber densities reached a peak in the late fall, whereas in Lake Trafford they remained high throughout the year. The differences in mat biomass and tuber densities from north to south indicate that control techniques and costs may differ drastically, both seasonally and regionally. In all three lakes the presence of hydrilla mats substantially altered the local aquatic environment. During the day, stratification occurred in the mat but not in open water. High levels of O/sub 2/, pH, and temperature in the mat surface water, and low light penetration, produced unfavorable conditions for the plant growth. Hydrilla plants from all three lakes altered their photosynthetic metabolism from winter to spring, as demonstrated by a shift in the CO/sub 2/ compensation points from high to low values. In the spring, a reduction in potential photorespiratory and respiratory activity, and a concomitant increase in net photosynthesis, increased the potential productivity and growth of the plants. It is suggested that submersed aquatic macrophytes belong to a new photosynthetic category.

Research Organization:
Univ. of Florida, Gainesville
OSTI ID:
6869714
Journal Information:
J. Aquat. Plant Manage.; (United States), Journal Name: J. Aquat. Plant Manage.; (United States) Vol. 17; ISSN JAPMD
Country of Publication:
United States
Language:
English