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

Lukić, Dunja; Vad, Csaba F.; Horváth, Zsófia

doi:10.4081/jlimnol.2016.1385

Cited by 9 publications

(7 citation statements)

References 34 publications

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“…Therefore sucrose flotation of Triops eggs used in the isolation hatching method had no effect upon hatching rates of resting eggs, as recently supported by Lukic, Vad & Horváth (2016). Our results from the hatching methods suggest that the Caerlaverock T. cancriformis populations exhibit a low level of bet-hedging.…”

Section: Discussionsupporting

confidence: 78%

A new molecular diagnostic tool for surveying and monitoring Triops cancriformis populations

Sellers

Griffin

Hänfling

et al. 2017

PeerJ

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The tadpole shrimp, Triops cancriformis, is a freshwater crustacean listed as endangered in the UK and Europe living in ephemeral pools. Populations are threatened by habitat destruction due to land development for agriculture and increased urbanisation. Despite this, there is a lack of efficient methods for discovering and monitoring populations. Established macroinvertebrate monitoring methods, such as net sampling, are unsuitable given the organism’s life history, that include long lived diapausing eggs, benthic habits and ephemerally active populations. Conventional hatching methods, such as sediment incubation, are both time consuming and potentially confounded by bet-hedging hatching strategies of diapausing eggs. Here we develop a new molecular diagnostic method to detect viable egg banks of T. cancriformis, and compare its performance to two conventional monitoring methods involving diapausing egg hatching. We apply this method to a collection of pond sediments from the Wildfowl & Wetlands Trust Caerlaverock National Nature Reserve, which holds one of the two remaining British populations of T. cancriformis. DNA barcoding of isolated eggs, using newly designed species-specific primers for a large region of mtDNA, was used to estimate egg viability. These estimates were compared to those obtained by the conventional methods of sediment and isolation hatching. Our method outperformed the conventional methods, revealing six ponds holding viable T. cancriformis diapausing egg banks in Caerlaverock. Additionally, designed species-specific primers for a short region of mtDNA identified degraded, inviable eggs and were used to ascertain the levels of recent mortality within an egg bank. Together with efficient sugar flotation techniques to extract eggs from sediment samples, our molecular method proved to be a faster and more powerful alternative for assessing the viability and condition of T. cancriformis diapausing egg banks.

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Section: Discussionsupporting

confidence: 78%

A new molecular diagnostic tool for surveying and monitoring Triops cancriformis populations

Sellers

Griffin

Hänfling

et al. 2017

PeerJ

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“…This procedure, as stated by Lukić et al (2016), should have neither a negative nor positive effect on Daphnia hatching; thus, this difference in experimental procedures is unlikely to have affected the hatching rates in our research.…”

Section: Experimental and Sampling Proceduresmentioning

confidence: 78%

Different thermal stimuli initiate hatching of Daphnia diapausing eggs originating from lakes and temporary waters

2017

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The simultaneous hatching of Daphnia resting eggs from a number of different lakes and ponds using one set of hatching cues can be difficult to achieve as environmental conditions differ considerably between water bodies. Therefore, optimal hatching conditions for ephippial eggs originating from shallow temporary waters may differ from those found in large lakes. The aim of our study was to compare the optimal thermal conditions for hatching ephippial eggs of Daphnia found in permanent lakes and those from shallow temporary ponds. We used ephippial eggs of Daphnia from the longispina species complex originating from two temporary city ponds and two deep lakes in Poland. The ephippia were protected against overheating at all stages of the field and laboratory work to prevent activation or killing of the eggs. After a refractory period (imposed storage in cool and dark conditions), ephippia were incubated at six different temperatures (6, 9, 12, 15, 18 and 21°C) under a 16:8 L:D light regime. Our results indicate that hatching of resting eggs of Daphnia that inhabit lakes or ponds may require different thermal conditions. The hatching success of ephippial eggs originating from temporary waters was relatively high (30-56%) at all tested incubation temperatures, while for the ephippial eggs from the deep lakes it was lower (7-37%) and inversely related to water temperature. The divergent hatching responses of the ephippial eggs originating from temporary pools and lakes may reflect the typical thermal conditions during hatching in their native habitats. While in the deep lakes of the temperate zone Daphnia hatching typically occurs during the low water temperatures of early spring, in shallow ponds Daphnia hatching may occur throughout the year at varying water temperatures, from a few to over a dozen degrees Celsius.

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“…Anostracans can reach high densities in their habitats (Daborn, 1977;Horváth, Vad, Vörös, et al, 2013b;Vanschoenwinkel, Brendonck, Pinceel, Dupriez, & Waterkeyn, 2013; and they act both as competitors and predators of smaller zooplankton (Jocque, Vanschoenwinkel, & Brendonck, 2010;Lukić et al, 2018;Waterkeyn et al, 2011), which suggests a high impact on the zooplankton community. Even though B. orientalis hatches very early after inundation/ice break (Lukić, Vad, & Horváth, 2016;Petkovski, 1991), it is probably predominantly herbivorous in the early stages of its life (similar to other anostracans; Daborn, 1975;Fryer, 1983), which gives some time for zooplankton communities to establish at the beginning of the wet phase of their habitats. Moreover, anostracans disappear before temporary ponds dry out, while many zooplankton species occur throughout the whole wet season (Horváth, Vad, Vörös, et al, 2013a;Jocqué, Riddoch, & Brendonck, 2007;Tóth et al, 2014;Vanschoenwinkel, Waterkeyn, et al, 2010), which overall provides a temporal refuge for zooplankton (Kratina et al, 2012).…”

Section: Effect Of Anostracans On the Community As An Ig Predatormentioning

confidence: 99%

Environmental constraint of intraguild predation: Inorganic turbidity modulates omnivory in fairy shrimps

et al. 2019

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1. Omnivory is widespread in food webs, with an important stabilising effect.The strength of omnivorous trophic interactions may change considerably with changes in the local environment.2. Shallow temporary waters are often characterised by high levels of inorganic turbidity that may directly limit the food uptake of filter-feeding organisms, but there is little evidence on how it might affect omnivorous species. Anostracans are key species of temporary waters and recent evidence suggests that these organisms are omnivorous consumers of both phyto-and zooplankton.3. Using Branchinecta orientalis as a model species, our aim was to test how turbidity affects the feeding of an omnivorous anostracan. To do this, we used short-term feeding experiments and stable isotope analyses, with animals collected from soda pans in eastern Austria. In the feeding experiments, algae and zooplankton were offered as food either separately or in combination. The prey type treatments were crossed with turbidity levels in a factorial design.4. There was a pronounced decrease in the ingested algal biomass with increasing turbidity. Conversely, ingestion rates on zooplankton were less affected by turbidity. Stable isotope analyses from field material supported our experimental results by showing a positive relationship of the trophic position of anostracans and the trophic niche of the communities with turbidity. 5. Our results show that turbidity modulates the intraguild trophic relationship between anostracans and their prey by shifting the diet of anostracans from more herbivorous in transparent to more carnivorous in turbid waters. Thus, inorganic turbidity might also have a community-shaping role in plankton communities of temporary waters through altering trophic relationships. K E Y W O R D Sanostracans, phytoplankton, temporary ponds, trophic webs, zooplankton | 227 LUKIĆ et aL.

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

Cited by 9 publications

References 34 publications

A new molecular diagnostic tool for surveying and monitoring Triops cancriformis populations

A new molecular diagnostic tool for surveying and monitoring Triops cancriformis populations

Different thermal stimuli initiate hatching of Daphnia diapausing eggs originating from lakes and temporary waters

Environmental constraint of intraguild predation: Inorganic turbidity modulates omnivory in fairy shrimps

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