A LOW-VOLUME FLOW TANK FOR MEASURING NUTRIENT-UPTAKE BY LARGE MACROPHYTES

A recirculating pow-tank was designed and tested to measure inorganic nutrient uptake by, and visualize the movement of seawater around, lar ge macrophytes. The tank volume was small (46 L), and a propeller driv e produced unidirectional mean flow A turbulence reduction section dam pened turbulence in the test section to a low bevel, so that water mov ement within this region was virtually laminar. The test section of th e tank was wider than that of previous designs, allowing whole blades of Macrocystis integrifolia Bory and juvenile plants of Nereocystis lu etkeana (Mert.) Post. et Rupr. to be placed in the flow, away from the influence of velocity boundary layers associated with the tank walls. The tank's use in macroalgae nutrient uptake and flow visualization e xperiments was demonstrated.