Memorial University – Multi-Stress System

Memorial University– Multi-Stress System

Institution:
Location:	St-John’s, Newfoundland & Labrador, Canada
Contact:	Dr. Annie Mercier
Equipment:	Two Multi-Stressor Units
Habitats:	Fresh water & Seawater;
Temperature:	5° to 30° C;
Description:	Control of water temperature between 5°C and 30°C; Generate hyperoxic conditions up to 110% saturation; Generate hypoxic conditions down to 30% saturation; While under hypoxic conditions: an automatic mix of air, oxygen and nitrogen provides constant degasing action, protecting the animals from buildup of CO2 gas; your animal are protected against accidental drop of dissolved oxygen below the set point by automatically raising the level of oxygen to 100% saturation when/if this happens; The rate of increase and decrease of water temperature can be adjusted; Provides automatized control over make-up water flow (incoming new water in each Multi-stressor unit); Provides manual control over the water flow to each row of rearing tanks. Constant protection against nitrogen super saturation (a constant risk in pressurized systems) by the use of a trickling biofilter operating at ambient pressure with air inflow. The biofilter media is pre-activated with live freshwater nitrifying bacteria before delivery.  This significantly reduces biofilter maturation time.
Water recirculation level:	99.7% (1 water exchange/5 to 6 days);
Work done:	Conception Fabrication On-site assembling, commissioning and training

Memorial University – Multi-Stress System

A Multi-stressor rack is composed of up to two independent water recirculating systems, one per shelf. Each system includes a Habitat Module (zebrafish tanks & plumbing for water inflow/outflow), and a Filtration Module (biofilter, cartridge filter, heat exchanger, controls) located on an adjacent rack). On each shelf runs a row of LEDs controlled by the Enviro-Monitron.

The Habitat Module is enclosed into opaque insulated cabinet to protect the animals for ambient room lighting and reduce chilling requirements. This unit is made to accommodate hypoxic control, as well as creating normoxic and hyperoxic conditions.  The Multi-stressor components are illustrated in the figures below.

Memorial University – Multi-Stress System : Flow circulation

The water flow through the unit is divided into two circuits, the Filtration circuit and the Circulation circuit.

Filtration Circuit

From the sump tank, the water is pumped through the 20 microns cartridge filter and the activated carbon filter. From the activated carbon filter, the water flows through the chiller & heater, the biofilter and trickles down back to the sump.

Circulation Circuit

The water coming from the biofilter is collected in the sump and then is pumped directly to the rearing tanks.  The effluent from each of the rearing tanks flows along a gutter and then back into the sump tank.

A double hydraulic circuit assures a constant flow to the rearing tanks, regardless of filter clogging.