Impacts of Water Column Turbidity on the Survival and Growth of Vallisneria americana Winterbuds and Seedlings

ABSTRACT

Survival and growth of Vallisneria americana winterbuds was significantly related to both initial winterbud size and to the water column turbidity under which the plants were grown. Larger winterbuds showed better survival and better growth than did smaller ones. Turbidity likewise significantly impacted the survival and growth of the plants. Over the turbidity range of 0.2–45 NTU (53–7% total incident light), the plants were shown to have progressively poorer survival and to produce fewer rosettes and total number of leaves. Vallisneria americana seedlings were likewise influenced by turbidity. Under high turbidity conditions the seedlings had significantly higher mortality, while surviving plants produced fewer rosettes and accumulated less biomass than seedlings grown under low turbidity conditions. In addition, under turbid conditions the seedlings had to invest proportionally more energy into above-ground tissues.

Key Words:

• turbidity
• light
• aquatic macrophytes
• Vallisneria americana
• winterbud