Algae and Fishes: Benefits and Hazards
469
7. Maintenance workshop
It is used for keeping all the necessary tools/instruments and hardware used in the
project such as nettings, wood, supporters, robes, chains, and equipment.
8. Area of fish assortment and marketing preparations
It is used in fish sorting and preservation in ice. Floors are to be lined with ceramics.
2 Mariculture of Seaweeds
According to [5], algae whose life cycle does not involve alternation of generation
can be cultivated vegetatively. The vegetative culturing involves the excision of small
parts of the seaweed and cultivating them in either their natural marine environment
or in a suitable environment until reaching a suitable size. If placed in their natural
environment, the algal parts are tied to ropes or nets. Then either the whole alga
is removed or most of it, leaving a small part that will regrow into a whole thallus
once again. For hydrocolloid industry (agar and carrageenan), the vegetative method
is mostly used. On the other hand, cultivation of algae that involves alternation of
generations is difficult as it involves the transition between completely two different
phases such as Laminaria species. For this alga, the diploid sporophyte that is harvested as seaweed must first develop into a haploid microscopic gametophyte then
to a new sporophyte. The transition is performed in land-based facilities. The growth
rate can be increased by bubbling of air, CO 2 or pumping seawater. The latter can be
useful also for manipulating temperature and salinity. The pH of the tanks should be
in the range of 7.9–8.3 [5].
3 Natural Carotenoids as Nutrients and Colourants
for Fishes: Astaxanthin as an Example
According to [6] and references therein, aquatic animals cannot synthesise
carotenoids de novo whereas algae can. The latter represents main meal of those
animals. Carotenoids are fat-soluble natural pigments whose colour is attributed to
the conjugated double bonds in the hydrogen backbone [7]. The carotenoids have
several biological roles where they function as.
Vitamin A precursor [8]; antioxidants [9]; reproduction [10] and immune system
enhancers [11]. Their overall effects would lead to growth promotion [12]. Different carotenoids have different colours: astaxanthin (red), tunaxanthin (Yellow),
lutein (Greenish-yellow), beta-carotene (orange), alpha and beta-doradexathins (Yellow), canthaxanthin (orange-red), xeaxanthin (yellow-orange), eichinenone (red).
Carotenoids are being utilized in the ornamental fish feed as colourants [11]. The
coloured fishes as salmonids are considered quality fishes among the consumers.
469
7. Maintenance workshop
It is used for keeping all the necessary tools/instruments and hardware used in the
project such as nettings, wood, supporters, robes, chains, and equipment.
8. Area of fish assortment and marketing preparations
It is used in fish sorting and preservation in ice. Floors are to be lined with ceramics.
2 Mariculture of Seaweeds
According to [5], algae whose life cycle does not involve alternation of generation
can be cultivated vegetatively. The vegetative culturing involves the excision of small
parts of the seaweed and cultivating them in either their natural marine environment
or in a suitable environment until reaching a suitable size. If placed in their natural
environment, the algal parts are tied to ropes or nets. Then either the whole alga
is removed or most of it, leaving a small part that will regrow into a whole thallus
once again. For hydrocolloid industry (agar and carrageenan), the vegetative method
is mostly used. On the other hand, cultivation of algae that involves alternation of
generations is difficult as it involves the transition between completely two different
phases such as Laminaria species. For this alga, the diploid sporophyte that is harvested as seaweed must first develop into a haploid microscopic gametophyte then
to a new sporophyte. The transition is performed in land-based facilities. The growth
rate can be increased by bubbling of air, CO 2 or pumping seawater. The latter can be
useful also for manipulating temperature and salinity. The pH of the tanks should be
in the range of 7.9–8.3 [5].
3 Natural Carotenoids as Nutrients and Colourants
for Fishes: Astaxanthin as an Example
According to [6] and references therein, aquatic animals cannot synthesise
carotenoids de novo whereas algae can. The latter represents main meal of those
animals. Carotenoids are fat-soluble natural pigments whose colour is attributed to
the conjugated double bonds in the hydrogen backbone [7]. The carotenoids have
several biological roles where they function as.
Vitamin A precursor [8]; antioxidants [9]; reproduction [10] and immune system
enhancers [11]. Their overall effects would lead to growth promotion [12]. Different carotenoids have different colours: astaxanthin (red), tunaxanthin (Yellow),
lutein (Greenish-yellow), beta-carotene (orange), alpha and beta-doradexathins (Yellow), canthaxanthin (orange-red), xeaxanthin (yellow-orange), eichinenone (red).
Carotenoids are being utilized in the ornamental fish feed as colourants [11]. The
coloured fishes as salmonids are considered quality fishes among the consumers.