Effects of growth factors and water source on laboratory cultures of a northern Asellus aquaticus (Isopoda) population
2008
Hasu, Tiina | Jokela, Jukka | Valtonen, E Tellervo
We tested whether two vitamin-based supplements, bright light or water from three different sources affected the survival and reproduction of Asellus aquaticus isopods, and the growth and survival of their laboratory-born juveniles. Isopods were sampled from the littoral zone of a lake in November (L:D = 6:18, temp. = 4°C) and brought to laboratory (L:D = 16:8, temp. = 21°C), where they started to breed after 5 weeks. None of the tested nutrient or light treatments significantly affected the time females started to carry the eggs in their marsupia, the duration of marsupial stage, the number of egg bearing females, the proportion of females producing live young, or the offspring growth measured as an increase in length. Generation specific survival effects of nutrient and light treatments were found in the two parent generations. However, the reproductive output of adult isopods measured as the mean number of surviving offspring per reproducing female was drastically reduced in tap water treatment, possibly due to the lethal effects of copper in the water for the newborn offspring. Survival of parent isopods did not differ among the water treatments. The lack of response to the tested growth factor treatments suggests that gut and/or endosymbiotic microbes may have an important role in A. aquaticus nutrition.
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