1. Introduction
The majority of the operational costs in a bivalve nursery are associated with algae culture and the maintenance feeding and water quality of seed stock
Castagna and Kraeuter, 1977; Coutteau et al., 1994. These costs can be reduced by increasing production per unit area or volume, minimizing labor requirements,
and utilizing cultured microalgae more efficiently. The technologies of computer- controlled operation, water recirculation, and fluidization offer the potential to
meet these objectives. These technologies offer the potential to reduce labor requirements, improve utilization efficiency of the algae produced, improve control
and monitoring of system operation, reduce the solids and metabolic wastes in the seed culture system, sustain water quality for optimum seed growth, and reduced
fouling of the culture units.
A recent development of shellfish aquaculture is the high-density nursery culture of clutchless oysters 2 – 25 mm by the use of water flowing upward at fluidization
velocities Ver and Wang, 1995. Under fluidized conditions, the bed of oysters is expanded due to the increased fluid flow. The oysters are suspended in the fluid
rather than lying on each other as in a packed bed under low flow conditions. The fluidization allows for a more uniform distribution of the food supply and better
transport of fecal material and other particulates out of the seed bed by the flowing water.
Typical land-based clam nursery systems utilize upwellers for seed culture in which ambient seawater or seawater with cultured algae is pumped upward through
the culture unit. The water flow through the upweller is too low for fluidization of seed to occur and as a result the density of seed is usually a single layer spread over
the bottom of the upweller unit.
In the last decade, the practice of culturing seed in a nursery system has flourished and the application of fluidized-bed technology coupled with computer-
control and recirculation technologies can potentially allow for the high-density culture of clam seed in a land-based nursery environment. An integrated system for
the production of algae and culture of northern quahog seed clams, Mercenaria mercenaria, was developed utilizing computer-control, fluidization, and recircula-
tion technologies. This paper presents 1 a description of the integrated system; 2 the computer-control strategy for the control and monitoring of the integrated
system; and 3 system performance of culturing northern quahog seed clams.
2. Materials and methods
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