I had for many years, as a marine biologist, attempted to photograph marine rockpool organisms in their natural habitat. The photographs, although good record shots, were not particularly spectacular. It is very difficult to achieve a low angle of view out in the field without immersing the camera and lens in the water. I found out the hard way that camera equipment and salt water do not mix! Having worked in an aquarium, I used my knowledge of setting up native marine aquariums to create a temporary aquarium in my study. The aquarium allowed me to observe the organisms from close quarters and get a low angle of view on them.

In a natural rockpool the water is replenished, cooled and reoxygenated every time the tide comes in, a new supply of food is brought to the rockpool, and any toxic waste products are washed away. This natural balancing of the rockpool conditions does not happen in the artificial set-up and therefore has to be carried out manually. It is not an easy task to get all the conditions just right so that no distress in inflicted on the rockpool organisms, something that is imperative when creating an artificial environment in which to photograph wildlife.

Continual testing and cleaning the seawater in the aquarium is paramount, and the filtration system is at the heart of this. I use a combination of chemical, biological and mechanical filtration to keep a high level of water quality. Firstly a protein skimmer (pictured in the left hand side of the aquarium opposite) is uses to remove much of the nitrogen based waste products so that pressure is taken off the filtration system. The water is drawn out of the tank and is passed through a powerful canister filter (shown opposite) where it flows through a number of filtration layers, filter wool (mechanical), charcoal (chemical) and ceramic tubes covered in bacteria (biological). The water is then pumped through a filter plate at the base of the aquarium and up through layers of coarse then fine gravel. The many bacteria contained in this substrate help in breaking down waste products in the water. Water is pumped up through the filter bed rather than down through it so that any rotting particles of food can be forced out of the fine gravel bed. Through this filtration ammonia is broken down to nitrites and then nitrates before being broken down into nitrogen that can then escape into the air.

Seawater testing kits (pictured opposite) can be used to make sure that the levels of ammonia, nitrite and nitrate are within acceptable levels. Water salinity is tested using a hydrometer and adjusted by adding salt or fresh water. Water pH (acidity or alkalinity) can be controlled by adding pH buffers. The water is cooled by taking approximately 5 litres of it out each day and freezing it, and then reintroducing the ice back into the aquarium. Nutrients can be replenished by adding them to the water. Seawater is made up from aquarium salt and tap water and then left for a few days to allow any chlorine to escape into the air. Water can be taken from the sea in clean sea areas, however care must be taken as to where the water is taken from. Any pollutants or toxins in the water will be concentrated when in the aquarium. The water is aerated using a couple of powerful air pumps pumping air through wooden blocks.

In order to provide food as close as possible to the food the organisms would receive in the wild I liquidised whole prawns, white fish and spinach (for the herbivores) along with seawater and then froze the liquid in ice cube trays (pictured opposite). In this way I could feed the organisms the food they required by dropping a couple of food cubes into the water which when melted left the food in suspension.

A range of rockpool organisms can be kept for short periods of time (up to 10 weeks) in this way, although consideration needs to be given to the feeding relationships between the various competing animals. Unlike freshwater aquariums, it is important in native marine aquariums not to introduce any algae that can cause problems as it rots. A number of rocks and empty shells were introduced to the aquarium to provide the rockpool habitat (pictured opposite).

It is paramount when creating an artificial environment in which to photograph animals, that the welfare of the animal is kept a priority at all times. The set-up should closely resemble that of the animal's natural habitat as much as possible. No photograph is ever worth putting any animal under stress for. On completion of my photo shoot, the organisms were returned to the same location as I found them.