Creating an ecosystem - Aquarium La Rochelle

Each aquarium is designed to meet the needs of the species it houses. Their development is a complex process requiring a solid knowledge of marine biology in order to reconstitute the ecosystem in which the species evolves.

But what criteria do the caretakers take into account?

Geographical area and habitat

The first criterion studied is geographical location. At the Aquarium La Rochelle, five regions are highlighted: the Atlantic Ocean, the Mediterranean Sea, the oceanic zone, the Caribbean Sea and the Indo-Pacific region. The ecosystems presented in the aquariums must be consistent with these different areas.

Once the geographical area has been determined, the scientists look at the characteristics of the habitat where the species lives: luminosity, substrate and hydrodynamics.

Is the environment rocky, sandy, muddy, occupied by algae or seagrass? Is it agitated or rather calm?

A distinction is made between ” weathered mode ” and ” sheltered mode “. The weathered mode defines coasts exposed to the wind, where the waves are strong. These are the points or islands. The sheltered mode, on the other hand, refers to coasts that are less exposed to the wind, where the water is calmer, such as bays.

Caves, for example, are a special habitat. They have characteristics similar to those found in the deep sea: darkness, low water renewal and constant temperature. They are home to organisms that do not depend on light energy for their survival. This is the case of the red coral, Corallium rubrum.

Discover the red coral

Adequate water

The water in the tanks is adapted to the species it contains. This is why the Aquarium obtains its water in two ways. A borehole, located under the building, allows seawater to be taken in at a salinity of 28 g/L. This level is suitable for local species (Atlantic and Mediterranean) but is less suitable for tropical species. To meet the needs of these animals, the site uses water from claires located on the Ile de Ré, whose salinity is around 35 g/L. Richer in minerals, it is particularly suitable for invertebrates such as corals, which draw on it for the elements essential to the development of their calcareous structure.

The temperature of each tank is similar to that encountered by the species in their natural environment. The coldest aquarium is home to the langoustines, which live on the continental shelf and at depths of up to 200 metres. The average water temperature is 12°C.

As in the natural environment, this temperature must be varied in order to reproduce the rhythm of the seasons, which is often a determining factor in the species’ reproduction cycle.

In addition to temperature and salinity, oxygen and pH are important parameters to consider.

Discover the langoustines

How to populate aquariums?

When populating aquariums, the relationships between species must also be taken into account. Their diet and behaviour must be known.

Some animals live in schools (jacks), others are solitary (octopus) or territorial and rather aggressive (angelfish). Thus, their presence could easily hinder the development of other more fragile animals. Knowing the characteristics of each one allows the acclimatisation of the animals and the sustainability of the ecosystem.

Discover Golden Trevally

Discover Common octopus

Discover French Angelfish

The importance of balance

It is sometimes necessary to introduce species that limit certain proliferation. For example, herbivores (surgeonfish) help to contain the growth of algae. Detritus feeders (often invertebrates such as sea stars and sea urchins) limit the waste associated with excess food. Others, by their behaviour, clean the sand (like the red mullet), the rocks (butterfly fish) or their fellow fish (cleaner fish).

Together, they allow the ecosystem to function properly, which can then be said to be “in balance”.

Discover Blue Tang

Discover Common Sea Star

Discover Hatpin Urchin

Discover Beaked Coral fish

Discover Bluestreak Cleaner Wrasse

Size and shape of the tanks

The size and shape of the tanks are designed according to the lifestyle and needs of the individual animals.

Active or schooling species need a maximum of space. The decor must therefore be limited so as not to impede their movement. This is the case for sardines, sea bass and sea bream, but also for planktonic animals like jellyfish. On the other hand, moray eels and crustaceans, which are more active at night, prefer rocky areas where they can hide during the day.

Before a species is introduced into a tank, its adult size should be considered. The development of the animal and its acclimatisation will depend on the size of the aquarium.