Intertidal simulation chamber
Overview
This is a self-contained, automatic experimental system that simulates the intertidal environment. It’s like a PCR machine for the intertidal, with the added advantage of being accessible online! Multiple machines can be used to create “virtual common garden experiments” across large geographic spans. The system plugs to a regular power outlet and then controls 220 V devices (such as pumps and heaters) and 12 V devices (such as fans and lights).
This system pairs well with our autonomous temperature sensors (Envloggers) as it can replicate whatever temperature profiles they collected in the field, and pairs well with our cardiac performance logger (PULSE V2), which can be used to monitor the thermal stress of animals inside the experimental unit.
Features
- Capable of simulating the complex thermal conditions characteristic of the intertidal environment.
- Configurable tide timings, which can be regular or change from one tide to the next.
- The unit has two chambers: a top experimental chamber where organisms live, and a bottom chamber that holds the seawater during low tide.
- During low tide, heating is provided by six 50 W infra-red lamps, which simulate natural solar heating. These lamps do not produce visible light, only heat.
- Wired EnvLoggers inside the chamber provide temperature feedback during low tide. IR is continuously and automatically adjusted to follow even the most complex thermal profiles.
- Cooling is provided by computer-controlled fans which swap inner hot air by colder exterior air.
- Inside the chamber, air circulating fans contribute to temperature homogenisation during low tide.
- During low tide, seawater moves to the lower chamber and is pre-heated or cooled to the exact temperature that will be required at the start of the next high tide.
- During high tide, water temperature is continuously monitored and adjusted.
- Regular seawater changes can be programmed and done in an automated way.
- Visible light is independently provided by LED strips, producing 1130 lumens each. LED strips are easily swapped if needed. The number of strips is also configurable, in order to keep algae happy.
- Intertidal chambers can be connected to WiFi, and experimental conditions can be remotely monitored and changed at any moment through a dedicated webpage. The web interface is being continuously improved and will receive new features in the future.
- It is possible to coordinate simultaneous experiments running in geographically-separated labs anywhere in the world.
- The machine also stores programmed profiles (i.e., what it should do) and sensor data (i.e., what it actually did) in an SD card for offline data transfer if WiFi is not available.
- The footprint of the unit is 80 x 60 x 100 cm for the tank, 30 x 20 x 40 cm for the controlling unit, and 60 x 40 x 60 cm for the chiller. Reserving some extra room is advisable.
Manual and web-based monitoring and controlling
- The control unit has a colour LED screen which shows the current status of the system (e.g., which pumps or heaters are working and at which rate) as well as all temperatures currently being measured.
- The screen also shows the history of the set-points (i.e., what should have happened), as well as the actual logged data (i.e., what really happened).
- The screen also shows (and allows to change) the next experimental set-points.
- The control panel has a series of switches to manually override the current experimental settings at any given moment. They allow, for example, to force a quick low tide so as to manipulate a sensor or an animal. The automatic control can be resumed as easily as it was interrupted.
- The physical control system is mirrored in a remote server. The entire unit can be monitored online and the experimental conditions can be updated or changed remotely, on the fly.
- Data from sensors is stored in an SD card and can always be used as a "black box" in case something goes wrong.
- The remote server also works as a "black box", storing all logged data.
Sensors and safety
- Electric circuits are protected by a circuit breaker.
- Power cables that run near the heat lamps are heat-resistant.
- Fans are IP69K rated (i.e., withstand high water pressure and high temperature).
- The system has redundant sensors to monitor the presence of water in the upper and bottom chambers. In the unlikely event of a pump failure, they warn the controller which notifies the user while protects organisms from over-stressing.
- Temperature feedback is provided by three redundant waterproof/shockproof sensors in the experimental chamber (on top) and by two redundant waterproof/shockproof sensors in the water reservoir (low chamber). In the unlikely event one fails, the controller notifies the user while protects organisms from over-stressing.
