Publication Date:
2021-05-19
Description:
In order to produce a procedure for production of a natural food source for fish, amphipod Gammarus
(Crustacea) were noticed, which inhabits spring-brooks in wide areas of Fars province, especially in its cold
regions. Five typical habitats of these animals were firstly identified, and some of their important physical and
chemical factors, including depth, current velocity, width of habitat, dissolved oxygen concentration, pH and
electrical conductivity were measured monthly for one year, May 2000-April 2001. Some other factors of water
quality like calcium, magnesium, and total hardness, sulfate, chloride, and potassium ions concentration were
measured just once. Artificial culture were designed and conducted in three steps. At step 1, using 10 individuals
in four 1000 cc beakers, firstly the effect of three different sources of water, the city pipe water, ground water (a
well), and water from one of the typical springs were investigated measuring survival time in no-food
condition. Then, selecting spring water, the effect of three different diet including fresh lettuce leaves, decaying
willow leaves, and fish pellets on the specimen s survival were recorded. At step 2, using 400 individuals in four
40 liter glass tanks containing and supplied with fresh lettuce leaves as food source, firstly the probable effect of
artificial illumination, and then, introduction of microbial flora from the habitat spring were compared to a
control group. In both steps, water was aerated continuously. Finally at step 3, an experimental pond
(600cm×200cm, with 50cm depth) was made and 2000 adult amphipods were introduced. Animals were fed by
fish pellet. During the experiment, water temperature, dissolved oxygen concentration, and pH, along with the
new population density and total body length were measured in consequent repeated times. All the data were
processed by calculation of means, standard deviations, and statistical tests including Analysis of Variance and
Duncan test. Results showed that in natural habitats current velocity ranged 2.5-100cm/s (Mean=29.3), water
depth ranged 5-60cm (mean=25.3), water temperature ranged 11.2-18.4°C (Mean=14.4) dissolved Oxygen
ranged 3.45-13.33 ppm (Mean=7.5), pH ranged 6.5-8.8 (Mean7.6), and electrical conductivity ranged 200- 760µs/cm (Mean=357), in the period of our investigation. Range of variation between five habitats was 26.55- 56.64ppm (Mean=43.48) for Chloride ion concentration, 7.20-16.80ppm (Mean=12.77) for sulfate ion, 50.50- 85.77ppm (Mean=63.00) for Calcium hardness, 99.50-246.22ppm (Mean=138.59) for Magnesium hardness, 150-332ppm (Mean=201.6) for total hardness, and 0.15-0.30ppm (Mean=0.25) for Potassium ion concentration. Culture experiments showed that spring water is significantly the only reliable source compared to the well water
and city pipe water, and lettuce fresh leaves and decaying willow leaves had showed significant differences
compared to fish pellet in feeding amphipods in closed and limited spaces of laboratory containers. Also, artificial photoperiod had a significant negative effect in laboratory situations which their water temperature was
not controlled on low ranges, due to a rapid and huge algal growth. Adding microbial flora, which may has
benefits for amphipod s better growth, showed no significant effect on their survival in tanks. Culture in pond
proposed that the process of growth and reproduction acts continuously through the whole year, but it seemed
that new generations did not reach the adulthood and sexual maturation until the coming spring.
Description:
Iranian Fisheries Science Research Institute
Description:
Published
Keywords:
Amphiod
;
Gammarus
;
Culture
;
Live food
;
Cold spring ecology
;
Sexual
Repository Name:
AquaDocs
Type:
Report
,
Refereed
Format:
78pp.
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