Nature and nurture in dormancy: dissolved oxygen, pH, and maternal investment impact Bythotrephes longimanus resting egg emergence and neonate condition

2008 ◽  
Vol 65 (8) ◽  
pp. 1692-1704 ◽  
Author(s):  
Meghan Elizabeth Brown
Keyword(s):  
Dissolved Oxygen ◽  
Hatching Success ◽  
Maternal Investment ◽  
Resting Eggs ◽  
Suitable Habitat ◽  
Bythotrephes Longimanus ◽  
Energy Investment ◽  
Resting Egg ◽  
Life Cycle Stages ◽  
Nature And Nurture

Bythotrephes longimanus (Onychopoda: Cercopagidae), an invasive zooplankter in North America, requires suitable habitat to satisfy its planktonic and resting stages, which occupy the pelagia and sediment of lakes, respectively. Thousands of resting eggs from hundreds of planktonic mothers were exposed to laboratory conditions that mimicked gradients observed in lake sediment (dissolved oxygen = 1.4–11.9 mg·L–1; pH = 3–11). Eggs hatched in all treatments, which confirms the utility of dormancy and the robustness of the resting egg in B. longimanus. However, hatching success and neonate condition were greatest when dormancy conditions were maintained at near-saturated dissolved oxygen and near-neutral pH; deviations from these conditions resulted in prolonged development, smaller neonates, and the failure of many eggs to hatch. In addition to the influence of environmental conditions, heavier mothers produced larger eggs that hatched more frequently and resulted in heavier neonates. These maternal effects are likely due to greater energy investment by healthier mothers. This study suggests that nature and nurture influence dormancy success, and the results underscore that both life-cycle stages of B. longimanus need to be considered to understand its range expansion.

scholarly journals Effects of chemical and physical conditions on hatching success of Bythotrephes longimanus resting eggs

2013 ◽  
Vol 58 (6) ◽  
pp. 2171-2184 ◽  
Author(s):  
Donn K. Branstrator ◽  
Lyle J. Shannon ◽  
Meghan E. Brown ◽  
Marte T. Kitson
Keyword(s):  
Hatching Success ◽  
Resting Eggs ◽  
Bythotrephes Longimanus ◽  
Physical Conditions

scholarly journals Isolation by sugar flotation has no direct effect on the hatching success of zooplankton resting eggs

2016 ◽  
Author(s):  
Dunja Lukic ◽  
Csaba F. Vad ◽  
Zsófia Horváth
Keyword(s):  
Hatching Success ◽  
Resting Eggs ◽  
Accurate Estimation ◽  
Temporary Waters ◽  
Large Branchiopods ◽  
Triops Cancriformis ◽  
Significant Difference ◽  
Flotation Method ◽  
Active Communities ◽  
Sugar Flotation

<p>Zooplankton in temporary waters produces resting stages to survive recurrent dry periods. Branchiopod crustaceans (i.e., cladocerans, large branchiopods) overcome these periods in the form of resting eggs buried in the sediment. Examining the diversity in the resting egg banks allows for a more accurate estimation of biodiversity of aquatic ecosystems than looking only at the active communities. The isolation of resting eggs from the sediment may be achieved by the sugar flotation method, which usually results in higher density and diversity than untreated samples (i.e., incubated in the sediment). We tested the effect of sugar isolation and centrifugation on the hatching success of resting eggs already isolated from sediment in order to reveal any direct effects on hatching success. We used four different branchiopod species, <em>Daphnia magna</em>, <em>Moina brachiata</em>, <em>Branchinecta orientalis</em>, and <em>Triops cancriformis</em>. Although we hypothesised that osmotic stress caused by sugar and centrifuging influence the hatching success either positively (e.g., faster activation as a response to osmotic changes) or negatively (destroyed by centrifugation), we found no significant difference either in the timing or rate of hatching between centrifuged and non-centrifuged eggs. Once the eggs are exposed to light and/or oxygen availability by being removed from the sediment, the centrifugation process does not have any additional effect on their hatching. Regardless of treatment, we found a significant difference in the hatching timing in the two major groups, with large branchiopods hatching earlier than cladocerans. We found that the sugar flotation method itself does not influence the hatching fraction of branchiopod resting eggs (implying no adverse effect on their viability) and its success in enhancing hatching can be attributed to its efficiency in removing eggs from the sediment.</p>

Heavy metal exposure reduces hatching success of Acartia pacifica resting eggs in the sediment

2007 ◽  
Vol 19 (6) ◽  
pp. 733-737 ◽  
Author(s):  
Xiao-dong JIANG ◽  
Gui-zhong WANG ◽  
Shao-jing LI ◽  
Jian-feng HE
Keyword(s):  
Heavy Metal ◽  
Hatching Success ◽  
Resting Eggs ◽  
Metal Exposure ◽  
Heavy Metal Exposure

scholarly journals The expression of virulence for a mixed-mode transmitted parasite in a diapausing host

Parasitology ◽  
2014 ◽  
Vol 141 (8) ◽  
pp. 1097-1107 ◽  
Author(s):  
ELHAM SHEIKH-JABBARI ◽  
MATTHEW D. HALL ◽  
FRIDA BEN-AMI ◽  
DIETER EBERT
Keyword(s):  
Hatching Success ◽  
Life Stage ◽  
Horizontal Transmission ◽  
Resting Eggs ◽  
Life Stages ◽  
Infected Female ◽  
Population Prevalence ◽  
High Virulence ◽  
Host Life ◽  
Adaptive Nature

SUMMARYMany parasites survive harsh periods together with their hosts. Without the possibility of horizontal transmission during host diapause, parasite persistence depends entirely on host survival. We therefore hypothesize that a parasite should be avirulent during its host's diapausing stage. In contrast, the parasite may express higher virulence, i.e. parasite-induced fitness reduction of the host, during host life stages with good opportunities for horizontal transmission. Here we study the effects of a vertically and horizontally transmitted microsporidium parasite, Hamiltosporidium tvaerminnensis, on the quantity and survival of resting eggs of its host Daphnia magna. We find that the parasite did not affect egg volume, hatching success and time to hatching of the Daphnia's resting eggs, although it did strongly reduce the number of resting eggs produced by infected females, revealing high virulence during the non-diapause phase of the host's life cycle. These results also explain another aspect of this system – namely the strong decline in natural population prevalence across diapause. This decline is not caused by mortality in infected resting stages, as was previously hypothesized, but because infected female hosts produce lower rates of resting eggs. Together, these results help explain the epidemiological dynamics of a microsporidian disease and highlight the adaptive nature of life stage-dependent parasite virulence.

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