A comparison of methods for incubating zooplankton diapausing eggs from sediment of endorheic pans in the Free State, South Africa

Liefferink, SL; Tate, RB; Vuren, J.H.J. van; Ferreira, Maryke L.; Malherbe, Wynand

doi:10.2989/16085914.2014.975778

Cited by 4 publications

(5 citation statements)

References 24 publications

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“…Isolation increased the overall hatching success and lowered activation time (the time needed for the emergence of hatchlings). In a similar study, hatching rates were also found to be significantly higher when the sugar flotation method was applied in the case of cladocerans and ostracods, while the overall number of anostracan hatchlings was higher in untreated samples (Liefferink et al, 2014). The latter two studies indicate that there can be pronounced differences between the hatching successes of zooplankton groups related to the applied incubation method.…”

Section: Introductionmentioning

confidence: 67%

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

2016

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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, Daphnia magna, Moina brachiata, Branchinecta orientalis, and Triops cancriformis. 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.

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Section: Introductionmentioning

confidence: 67%

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

2016

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“…; Liefferink et al . ), taxon accumulation curves had not plateaued when the experiment was terminated (Fig. ).…”

Section: Resultsmentioning

confidence: 92%

“…() and Liefferink et al . (). Each wetland comprised of two subsamples for both burned and control treatments.…”

Section: Methodsmentioning

confidence: 97%

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The negative impacts of fire on the resurrection ecology of invertebrates from temporary wetlands in Cape Flats Sand Fynbos in the Western Cape, South Africa

et al. 2019

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Fire is an important environmental disturbance in Mediterranean-climate regions; however, its intensity and frequency are predicted to increase under climate change scenarios with unknown implications for ecosystems in these regions. Temporary wetlands, with their periodic wet and dry phases, are considered one of the most productive systems in the world and their invertebrate communities form a crucial diet component for higher trophic levels. The effect of fire on the hatching success of invertebrate propagules from temporary wetlands in the Cape Flats Sand Fynbos (Cape Town, South Africa) was investigated. Homogenised soil samples from these wetlands were either experimentally subjected to vegetation fires (treatment samples) or were left as is (control samples). The results revealed that fire had a significant negative impact on invertebrate hatching success, as revealed by analyses of the different diversity measures (e.g. taxon richness, Shannon diversity and Pielou's evenness) and community composition. Proper management of fire, especially in the Mediterraneanclimate regions, which replicates the natural fire intervals typical of the area (10-15 years) and avoids unregulated or accidental fires, is essential to ensuring future protection of these critical biodiversity hotspots created by the temporary wetlands.

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“…Hatching experiments (dry phase). Hatching assays followed the standard methods described [32,33], and were conducted in a controlled environment (± 12˚C with 24 hours light cycle) at the Department of Biological Sciences, University of Cape Town, South Africa. About 300 g of the dry soil sediments were transferred into a 3 litres non-transparent polyethylene plastic containers (n = 3) and filled with 2 litres of deionised water, sufficient to completely inundate the soil.…”

Section: Data Collectionmentioning

confidence: 99%

Protected and un-protected urban wetlands have similar aquatic macroinvertebrate communities: A case study from the Cape Flats Sand Fynbos region of southern Africa

et al. 2020

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Rapid urbanisation has led to major landscape alterations, affecting aquatic ecosystems' hydrological and biogeochemical cycles, and biodiversity. Thus, habitat alteration is considered a major driver of aquatic biodiversity loss and related aquatic ecosystem goods and services. This study aimed to investigate and compare aquatic macroinvertebrate richness, diversity and community structure between urban temporary wetlands, located within protected and unprotected areas. The latter were found within an open public space or park with no protection or conservation status, whereas the former were inaccessible to the public and had formal protected, conservation status. We hypothesised that; (1) protected urban wetlands will harbour higher aquatic macroinvertebrate biodiversity (both dry and wet) as compared to unprotected urban wetlands, and (2) that the community composition between the two urban wetlands types will be significantly different. Contrary to our hypothesis, our results revealed no major differences between protected and unprotected urban wetlands, based on the measures investigated (i.e. taxon richness, Shannon-Weiner diversity, Pielou's evenness and community composition) during the dry and wet phase. The only exception was community composition, which revealed significant differences between these urban wetland types. These results suggest that human activities (potential littering and polluting) in the unprotected urban wetlands have not yet resulted in drastic change in macroinvertebrate richness and composition, at least from the dry phase. This suggests a potential for unprotected urban wetlands suffering from minimal human impact to act as important reservoirs of biodiversity and ecosystem services.

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A comparison of methods for incubating zooplankton diapausing eggs from sediment of endorheic pans in the Free State, South Africa

Cited by 4 publications

References 24 publications

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

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

The negative impacts of fire on the resurrection ecology of invertebrates from temporary wetlands in Cape Flats Sand Fynbos in the Western Cape, South Africa

Protected and un-protected urban wetlands have similar aquatic macroinvertebrate communities: A case study from the Cape Flats Sand Fynbos region of southern Africa

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