Aquaria are a very important, but not essential, part of the study of
marine life. For non-divers it is the best
opportunity to see the behaviour of the smaller fish and invertebrates
in anything like their natural
environment.
The reasons for keeping aquaria vary from wanting to having a little
bit of natural life in the home to a
specialist study of one organism. However, the native marine aquarist
rarely keeps a tank solely as a
decoration, because although the sea anemones equal in colour anything
from tropical seas it is a much easier
option to keep almost all the other types of aquarium. This is because
50% of the species commonly kept
require temperature control, involving the use of a cooler to chill
the water by up to 10°C in summer.
Perhaps, the most valuable use of an aquarium is for the identification
of species in biological recording. The
aquarium has several advantages including:
1) It is likely to avoid the need of killing the animal as close observation
in captivity and enlarged
photographs (nowadays the pictures can be examined on a computer screen)
is usually sufficient, and in
the case of sea anemones may be the best method.
2) Enables observation to be undertaken over a period of time, which
has an advantage in identifying fish
and other animals that change their appearance over their life
span.
3) Behaviour in aquaria is often a useful clue with species that are
morphological very similar.
4) The specimen can be examined at greater leisure than in the field
and this is likely to produce more
accurate records.
The Real Reasons
I have no doubt that the real reason why some of our members go to the
considerable effort and work of
keeping aquaria, because it is good fun. At first, for me, it was almost
a compulsion. Certainly, taking a
decent photograph of the “strawberry” Beadlet Anemone, Actinia fragacea,
was a thing I had to do. This was
purely for aesthetic reasons.
Dynamic Systems
The aim of aquarist should be to provide conditions that mimic as far
as possible those found in the wild.
This has led to some aquarists contemplating a pond or rock pool type
of aquarium. It is certainly a
possibility but this type, especially if it is outside, actually makes
controlling the environmental conditions
more difficult, and viewing not so interesting. The large surface area,
in theory, should encourage gas
exchange at the surface keeping the dissolved oxygen levels up to saturation
point, but in practice this is best
achieved by disrupting the surface using water pumps (powerheads) or
diaphragm air pumps. Outside ponds
have only the one advantage, of high light levels of up to and over
50000 Lux in summer which may be the
cheapest method of providing sufficient light for Snakelocks
Anemones, Anemonia viridis, and other
anemones that have symbiotic algae in their tissues.
