After four years of frog hunting and intense experimenting, Jane Reniers defended her doctorate on amphibian life history strategies. The title of her doctorate was Managing Reproductive Challenges in Time Constrained Environments. Amphibian life history variation from clutch to landscape. I believe PhDs are all about managing challenges in a time constrained environment. And just like the amphibians she studied, Jane managed to overcome a lot of challenges and bad luck but still defended succesfully after just more than four years. A great job with a nice booklet to show for it… and a lot of great manuscripts still waiting to be published!
While she is moving on to new challenges, we will miss Jane’s spirit and laughter in the lab. But no doubt we will continue to collaborate to publish the remaining chapters of her PhD. We wish you all the very best Jane!
In a side-project of his PhD Falko Buschke published a new paper in Journal of Nature Conservation on how different decision making strategies affect the exploitation of natural habitat. He shows that taking into account cumulative costs (e.g. earlier developments of an area and associated costs in terms of habitat loss) in different ways (not at all/ higher cost for additional developments / equal-division of costs among early and late developers) will have profound effects on how much habitat will be destroyed in the end. But this is just a start…
Falko explains the story behind the paper and the consequences of his findings in detail on his blog: The Solitary Ecologist
In freshwater zooplankton, that survive unfavorable periods of winter cold or drought as dormant eggs in the sediment, light is an important cue that may activate the embryo to hatch. If no light is detectable then the egg is probably buried and it would be a bad idea to hatch. We investigated the light-activation process of zooplankton resting eggs using a rock-pool fairy shrimp as a model. We showed that light activation entails a relatively simple mechanism involving a light-energy threshold. These results illustrate the potential adaptive value of light activation but also highlighted the possible role of variation in eggshell pigmentation as a risk-spreading strategy. How does this work?
Much like a pair of sunglasses, the egg shell modulates how much light is absorbed. Consequently embryos in eggs with a darker egg shell should be less responsive to light. This is exactly what we found. In darker eggs, the embryo responds later, presumably because the light energy threshold is reached later. Given that there is often strong variation in the color of eggs in populations and in clutches of eggs, this simple ‘sunglasses effect’ can ensure that not all eggs will hatch at the same time. As a result the emerging larvae that use different food sources when they get older are less likely to compete with one another. As such, it could represent a simple, yet potentially effective risk spreading strategy.
While the effectiveness of this strategy within inundations was demonstrated, its potential role in spreading hatching over different inundations remains unknown. Tests are needed to assess whether degradation of pigments over time may be an adaptive mechanism that prevents resting eggs from becoming locked in diapause. Additionally, given the similarities in observed responses to light activation in both crustacean resting eggs and plant seeds, parallel patterns in these taxonomically distant groups might possibly reflect an old evolutionary mechanism tapping the same biochemical pathways, but this hypothesis also remains to be confirmed.
The paper is accessible via this link:
Pinceel et al 2013_light induced dormancy termination
A joint inter university collaboration was set up between the Flemish universities and the Nelson Mandela institute of Science and Technology in Arusha, Tanzania. The project was officially launched in September 2013. Within the project, which will run for at least six years, I will be supervising a PhD student working on the ecology of wetlands in the Pangani floodplain. The aim is investigate the impact of variation in hydrology and anthropogenic disturbance on wetland functioning and biodiversity, quantify ecosystem services and formulate more effective management strategies.
- Picture of an adult male fairy shrimp of the species Branchipus schaefferi taken by Aline Waterkeyn
Fairy shrimp re-discovered in Belgium
Fairy shrimps (Crustacea, Anostraca) are specialized inhabitants of inland water bodies that periodically dry or freeze over. Tipped of by local conservationists we traveled to Hainaut and were able to confirm the first observation since 1997 of a member of this basal crustacean order in Belgium and the first sighting of the species Branchipus schaefferi Fischer, 1834 since 1930. Nineteen populations were found in a restricted area. The current study illustrates that populations of fairy shrimp can remain undetected, although individuals are relatively large (1 – 4 cm) and conspicuous and often characterized by bright coloration, and even in relatively well-studied and monitored regions, such as Belgium. Large branchiopods are threatened in many parts of the world and notably in Western Europe. The main reason for this is the loss of temporary aquatic habitats as a result of intensive agriculture and urbanisation, and the few remaining habitats are often degraded.
Fairy shrimp wheel track habitat
While public incentive to conserve a rare group of crustaceans may be limited, it is important to realize that temporary ponds not only house a unique crustacean fauna, but are also of vital importance for other endangered species of plants and animals (Williams, 2006). These include macrophytes, dragonflies and amphibians specifically linked with temporary waters. Substantial efforts and financial support have been directed at protecting certain endangered amphibians that use temporary ponds for breeding, such as the natterjack toad (Bufo calamita) and the fire bellied toad (Bombina bombina). Temporary pond restoration and construction projects performed for these ‘flagship’ species (e.g. EU life project Bombina) are likely to be beneficial for other typical temporary pond organisms too. For instance, different rare macrophytes were shown to re-emerge from old seed banks during pond restoration projects (Hilt et al., 2006). Due to the prolonged viability of their dormant eggs (Brendonck, 1996), it is not unlikely that large branchiopods may emerge from old egg banks present in the sediment. Consequently, a habitat oriented conservation strategy protecting the few remaining high quality temporary ponds and increasing temporary pond densities in the landscape is likely to be most beneficial as a large number of organism groups, including large branchiopods, will benefit from them.
Checking out wheel tracks and farmland ponds in the Binche area in Hainaut
Low predation pressure in combination with plenty of nutrients ensure that fairy shrimps can reach high population densities in temporary pools
Read more about the ecology of fairy shrimp and the remaining populations in Belgium in these publications:
Vanschoenwinkel et al. 2013 Natuurfocus 2013-2- Oerkreeftjes duiken opnieuw op in België
Vanschoenwinkel et al 2013 BJZ_kleur
Sunset at our campsite at Walga Rock
Where we are going we don’t need roads
During the 2013 expedition we sampled a total of 600 rock pools from 50 inselbergs in Western Australia. The dataset wil be used to get more insight in the drivers of diversity patterns across spatial scales.
Sampling a rock pool community on Baladgie Rock overlooking a salt lake
A typical example of a West Australian inselberg in the Cue area in Western Australia