Learn how we have solved one of the major limitations of land rehabilitation projects; the availability of sufficient quantities of native seeds.
[Reading time: 2 min 20 seconds]
One of the difficulties in sampling temporary aquatic habitats is sampling when the system is dry; when there is no surface water present we can’t use traditional aquatic sampling methods.
Many crustaceans produce drought-resistant eggs, with some species in Western Australia having evolved to survive several years without rainfall, because their eggs can lie dormant without drying out (or ‘desiccating’). These desiccation-resistant eggs accumulate in the sediment, forming an egg bank that allows the population to re-establish when the rains return.
Would this species be picked up in a survey during those dry periods? Probably not.
A giant ostracod
Aquatic Ecologist with Biologic, Mahabubur Rahman, studied giant ostracods (subfamily Mytilocypridinae) for three years, as part of his PhD with Murdoch University, collecting sediment from salt lakes which contained ostracod (seed shrimp) eggs. He and his team conducted two rehydration trials and found that even after 27 months of dry storage at room temperature, the viability of these eggs was not affected. Mahabubur’s work takes us a step closer to understanding more about giant ostracods, and their ability to survive in a range of conditions.
His second trial found some species can tolerate a very wide salinity range, but others require specific salinity levels to hatch, meaning they would not show up in a survey of a water body outside their salinity range.
“In WA there are a few areas that don’t receive rainfall for a long period of time,” he said. “Each species requires different conditions to hatch – in a period of lower rainfall, the lake can have water with high salinity so species that prefer less salt won’t show up – and vice versa.”
So, what is it like spending three years with these little survivors?
Mahabubur’s rehydration trial
“I love these small creatures. They each exhibit different behaviours in the water. Typically, they are very active swimmers, but when there’s any movement in the water, some hide under the sediment, while others stop moving and trap air inside their shell to float away faster as a defence mechanism,” he said.
If you are interested in learning more about the importance and value of ephemeral aquatic systems, and how to better characterise baseline condition for a development or Project, contact us.
To find out more about Mahabubur’s PhD finding read the full report here Mahabubur’s paper “Using desiccation-resistant eggs to explore the ecology of giant ostracods (subfamily Mytilocypridinae) in Australian salt lakes” was published this month in the esteemed journal Hydrobiologia.
Citation:
Rahman, M., Chaplin, J., Lawrie, A. et al. (2024) Using desiccation-resistant eggs to explore the ecology of giant ostracods (subfamily Mytilocypridinae) in Australian salt lakes. Hydrobiologia.
Photography Credits: Mahabubur Rahman
