Daphnia’s reaction to light
Posted by: Ming Leung in Uncategorized, tags: Daphnia, depth, light, sw13The gowth and reproduction of Daphnia lumholei, an an invasive species in the Southern United States, is highly influenced by temperature and abundance of food. In the absence of predators, Daphnia is faced with a trade off. They can either live in the epilimnion where development in the
warm water is fast, but food shortage causes low egg production, or in the hypolimnion, where food availability is high but development is slow because of low temperatures.
In this study, Kessler and Lampert test whether Daphnia is affected by light to choose the best depth of the water for reproductive or growth purposes. They also tested the depth preferences of varying Daphnia size classes and egg-bearing females . However, they found no direct correlation between light and Daphnia’s physical necessities. In fact, large and egg-bearing females, being forced into deeper layers by the residual light response during the day , experienced a lower average temperature during day than juveniles.
Kessler, K., and Lampert, W. 2004. Depth distribution of Daphnia in response to a deep-water algal maximum: The effect of body size and temperature gradient. Freshwater Biology 49(4): 392-401.
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April 19th, 2011 at 7:26 pm
This is a very interesting topic. I would have though just from my own conjecture that the Daphnia would have had a light preference for their ideal feeding and reproductive environments. I was surprised to see that there was no correlation. Perhaps this is a study that could be replicated? Maybe the results are a fluke or the methods weren’t up to par. What would a lack of light preference have to do with Daphnia lumholtzi’s invasive success I wonder?
April 19th, 2011 at 7:46 pm
I too read an article that discussed the affect temperature has on D. lumholtzi. Except it was not on the reproduction rate, but on the size length of the D. Lumholtzi’s helmet and spine. The article discussed how increased temperatures resulted in increased length of the Daphnia’s helmet and spine, thus consequently increasing their swimming abilities and survival rates from predators. I would have assumed that increased temperature would have also indirectly contributed to higher reproduction rates.
April 20th, 2011 at 9:07 pm
As you stated the Daphnia can live in either warm or cold water, but I think the issue of how and in what ways does the temperature negatively impact their development should be addressed. It would be ideal if the invasive species in a thermally stratified body of water attracts towards the layer of water between the epilimnion and hypolimnion; where both the food availability and temperatures are mediocre. Therefore, food helps egg production and development is neither fast nor slow in moderate temperatures. Is the temperature affecting development and reproduction in females only or is it males also?
April 21st, 2011 at 12:57 am
In my opinion, i think that the light dependecy would have an effect on any type of aquatic animal. If light is not able to reach the level at which algae, and other food sources for aquatic animals are located, then the prduction of these aquatic species would be problem, due to the fact of starvation, because the aqautic plants that serve as the food source, can not undergo photsynthesis for their production, which is food for aquatic animales. If the female daphnia have a shortage of food source, then the production of eggs will decrease in response to this shortage, because the energy needed to reproduce will decrese also, making it harder to produce an invasive species like the D. lumholtzi.
April 21st, 2011 at 8:22 am
Mike, Daphnia do indeed exhibit responses to different light treatments, but this experiment was conducted indoors using artificial lights (still, very sound methods, I think!) Work by others (e.g., Cooke et al. 2008) indicates that ultraviolet radiation may elicit a migratory response in Daphnia – when UV is excluded, the Daphnia prefer to remain in warmer, high-light waters. Of course, Jordan Lake is so turbid and icky that UV is not an important factor!
April 24th, 2011 at 9:59 am
1. The authors of this article suggested that to make up for the cold temperatures that egg bearing females are subjected to during day, the Daphnia spends time in warm waters during night longer. However, they have to yet test this hypothesis out.
2. The experiment was on a rather large scale, and unlikely to be just a fluke.
3. Since Daphnia can migrate up and down the water column, food source depth dependency is not such a large problem.
4. I doubt that this reaction to light has no relationship to Daphnia’s ideal feeding and reproductive environments. It’s just that there is no direct correlation between temperature and light. For example, it could be an adaptation against possible predators.
5. Moderation is often a disadvantage, especially when competing. Each individual is not only competing with native plankton to survive, but with each other to pass on its own genes.
Besides, some eggs can stay dormant for years. Remember, a specie’s objective is not just to propagate rapidly, but also to survive varying conditions.
April 24th, 2011 at 10:01 am
… sorry, scratch out #3
I got confused.
May 4th, 2011 at 5:48 pm
So does this apply to Daphnia magna?
And does this mean that light does not have an effect on survivorship, reproduction, and reproduction stress?