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Effect of Polarized UV-light on Zebrafish and Common Roach Larval Growth

Szakal, David (2017) BION01 20162
Degree Projects in Biology
Abstract
This pilot study suggests that addition of polarized ultraviolet (UV) light to the indoor rearing environment of Common Roach (Rutilus rutilus) and Zebrafish (Danio rerio) increases growth rate. A difference in body pigmentation after 20 days of rearing Zebrafish indicates that a small amount of UV-light is physiologically relevant. Future research has to clarify the mechanisms by which polarized and/or UV light enhance larval growth.
Popular Abstract
Shining light on the growth of fish

Aquaculture is practiced over the entire planet - today even on land, indoors. One of the problems that have occurred with this is that indoor lighting may not always mimic the natural conditions closely enough. In my project, I have been looking specifically whether a combination of white, ultraviolet, and polarized light has an impact on the growth rate during the first critical weeks after hatching.

Two aquaria were treated with white light (Control) and the other two grew up in tanks with polarized white and ultraviolet light (UV-pol). Larvae of two species known to have ultraviolet photoreceptors were used, Zebrafish (Danio rerio) and Common Roach (Rutilus rutilus) (figure 1). Both species... (More)
Shining light on the growth of fish

Aquaculture is practiced over the entire planet - today even on land, indoors. One of the problems that have occurred with this is that indoor lighting may not always mimic the natural conditions closely enough. In my project, I have been looking specifically whether a combination of white, ultraviolet, and polarized light has an impact on the growth rate during the first critical weeks after hatching.

Two aquaria were treated with white light (Control) and the other two grew up in tanks with polarized white and ultraviolet light (UV-pol). Larvae of two species known to have ultraviolet photoreceptors were used, Zebrafish (Danio rerio) and Common Roach (Rutilus rutilus) (figure 1). Both species were measured 10 days into each treatment. The second measurement was done on different days because the developmental rate is slower for Common Roach than Zebrafish. The effect of each treatment was estimated to be noticeable on day 30 for Common Roach and day 20 for Zebrafish, before the fish outgrow the larval/fry stage. After the last measurement, the fish were euthanized and weighed.

Figure 1 Adult specimen of the species used in the experiment were Zebrafish (Danio rerio), to the left, and Common Roach (Rutilus rutilus), to the right (Picture origin: Britannica ImageQuest, Encyclopædia Britannica).

When comparing the two treatments for Common Roach, UV-pol was 17 % heavier and 30 % longer than the control. Zebrafish reared in the UV-pol treatment was 12% heavier and 25 % longer than the control. In addition, two more things were observed during the experiment. Firstly, Zebrafish were contaminated with Vorticella sp., considered to be an opportunistic ectoparasite, resulting in increased mortality and presumably negative effect on growth rate. Despite this, the UV-pol treatment was still able to have a positive effect on growth. Secondly, there was a difference in pigmentation between the two treatments among zebrafish, further indicating an effect of the treatment.

This pilot study suggests that the addition of polarized UV-light to the indoor rearing environment of Common Roach and Zebrafish has a positive effect on growth rate. A similar pattern of increased growth rate occurs for both length and weight using the UV-pol treatment. The limited amount of UV-light being used, falling just within the UVB range, led to a noticeable difference in pigmentation for Zebrafish during their short period of exposure. The relative roles of polarization and UV-light in the underwater environment must be studied in the future. Increasing the yield of today’s aquacultures may reduce the fishing pressure on wild populations of fish resulting in a positive environmental impact as well as stimulate economic growth.

Master’s Degree Project in Biology 45 credits 2017
Department of Biology, Lund University

Supervisor: Ronald Kröger
Department of Biology (Less)
Please use this url to cite or link to this publication:
author
Szakal, David
supervisor
organization
course
BION01 20162
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
8902288
date added to LUP
2017-02-03 14:15:11
date last changed
2017-02-03 14:15:11
@misc{8902288,
  abstract     = {This pilot study suggests that addition of polarized ultraviolet (UV) light to the indoor rearing environment of Common Roach (Rutilus rutilus) and Zebrafish (Danio rerio) increases growth rate. A difference in body pigmentation after 20 days of rearing Zebrafish indicates that a small amount of UV-light is physiologically relevant. Future research has to clarify the mechanisms by which polarized and/or UV light enhance larval growth.},
  author       = {Szakal, David},
  language     = {eng},
  note         = {Student Paper},
  title        = {Effect of Polarized UV-light on Zebrafish and Common Roach Larval Growth},
  year         = {2017},
}