Embryonic development and hatching of chirocephalus diaphanus prévost (Crustacea: Anostraca) in nature

Khalaf, A. N.; Hall, R. E.

doi:10.1007/bf00036740

Cited by 13 publications

(9 citation statements)

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“…The few studies which did consider the pattern of egg distribution in fairy shrimps each recorded a different pattern (KHALAF and HALL, 1975;HILDREW, 1985;MURA et al, 1987), though giving a converging ecological explanation for the particular distribution observed. Among the factors which could explain the different distribution patterns, species biology and ethology, and environmental characteristics were considered as having the greatest influence (ERIKSEN et al, 1986;MURA, 1991MURA, , 1993aMURA, , b, 1997THIERY, 1997).…”

Section: Cyst Distribution and Abundancementioning

confidence: 99%

“…However, this subject has been rarely investigated and, unfortunately, the few studies available (KHALAF and HALL, 1975;HILDREW, 1985;THIERY, 1997;MURA, 1993b, unpublished observations) provide contrasting information about the preferences of mature females for egg-laying areas of the pools. The biological characteristics of a species, however, cannot provide the sole explanation for the observed distribution patterns.…”

Section: Cyst Distribution and Abundancementioning

confidence: 99%

“…A few workers provided information on cyst numbers and distribution in natural biotopes (KHALAF and HALL, 1975;ERIKSEN et al, 1986;MURA et al, 1987;THIERY, 1987;MURA, 1991, 1993a and, but their attention was focused mainly on the horizontal distribution of cysts in the upper few centimetres of sediment, and data collection was thus limited and mainly qualitative.…”

Section: Introductionmentioning

confidence: 99%

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Structure and Functioning of the “Egg Bank” of a Fairy Shrimp in a Temporary Pool: Chirocephalus ruffoi from Pollino National Park (Southern Italy) as a Case Study

Mura

2004

International Review of Hydrobiology

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To investigate their distribution and total numbers, resting eggs of the anostracan Chirocephalus ruffoi were collected from the bed of a temporary pool in southern Italy. Samples were taken at 0.5 m intervals along six transects oriented at 30°from each other, by means of a cylindrical core sampler. The horizontal distribution of intact resting eggs was extremely patchy, with cyst number per core ranging from 191 to 1,400 (CV = 32.7%), corresponding to a mean of between 0.8 and 4.3 cysts cm -3 . Differences observed were related to core position and transect orientation, total cyst numbers being markedly higher in the leeward area of the pool compared to the windward area. Marked variation was also evident in vertical distribution, a significant, though weak correlation was recorded between egg density and sediment depth. Cyst-bank size (± 95% confidence limits) of the pool bed, estimated from the mean cyst number cm -3 obtained for the 6 transects, ranged between 1.0 × 10 8 and 1.3 × 10 8 cysts.Hatching in the laboratory was very erratic. Despite significant differences in hatching, the observed variation was unrelated to most of the variables considered (position within sections, cores and transects, pre-incubation treatment) and was explained only by initial sediment conditions (moist/dry). In none of the experimental conditions tested was synchronous hatching obtained.Possible causal factors (mixing of the bottom sediments by cattle, egg age, storage conditions, differential exposure to environmental cues as well as variability in hatching response even at clutch level) are discussed. IntroductionMany residents of temporary pools produce long-lived resting eggs enabling survival during unfavourable conditions. The changing nature of these habitats requires adaptation to very different environmental regimes. Moreover, the predictability and the frequency of the wet/dry phases vary greatly among habitats, depending on factors like climate, latitude, altitude, nature of the sediment etc. Therefore population persistence requires local adaptations in life history traits and, particularly in the hatching behaviour of the resting stages (BELK and COLE, 1975;WIGGINS et al., 1980). The more unpredictable the local habitat, the higher the risk of extinction favouring the evolution of adaptations that "spread the risk" (see review in SIMOVICH and HATHAWAY, 1997;BRENDONCK et al., 1998). Not all of the eggs deposited at one time will hatch during the same subsequent inundation and thus an egg bank (sensu DE STASIO, 1989) forms in the sediment, acting as a reserve for the future. In addition to information about quantitative reproductive characteristics, understanding the behaviour and functioning of an egg bank is of fundamental importance in identifying any local adaptations to habitat uncertainty.Internat. Rev. Hydrobiol.

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Section: Cyst Distribution and Abundancementioning

confidence: 99%

Section: Cyst Distribution and Abundancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structure and Functioning of the “Egg Bank” of a Fairy Shrimp in a Temporary Pool: Chirocephalus ruffoi from Pollino National Park (Southern Italy) as a Case Study

Mura

2004

International Review of Hydrobiology

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“…Cyst numbers collected in the filters were a function of the amount of sediment pulled off the pothole sediment surface, but the relationship was not as strong as expected. This variation could be due to differences in the concentration of cysts in different parts of the pothole, which results from differential deposition of cysts (Khalaf & Hall, 1975;Mura, 2005;Hulsmans et al, 2006) and re-working of cysts and sediment by wind (Eriksen et al, 1986;Thiery, 1998). Another source of variation is the volume of sediment moved by wind.…”

Section: Discussionmentioning

confidence: 97%

Dispersal of large branchiopod cysts: potential movement by wind from potholes on the Colorado Plateau

Graham

Wirth

2007

Hydrobiologia

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Wind is suspected to be a primary dispersal mechanism for large branchiopod cysts on the Colorado Plateau. We used a wind tunnel to investigate wind velocities capable of moving pothole sediment and cysts from intact and disturbed surfaces. Material moved in the wind tunnel was trapped in filters; cysts were separated from sediment and counted. Undisturbed sediment moved at velocities as low as 5.9 m s -1 (12.3 miles h -1 ). A single all-terrain vehicle (ATV) track increased the sediment mass collected 10-fold, with particles moving at a wind velocity of only 4.2 m s -1 (8.7 miles h -1 ). Cysts were recovered from every wind tunnel trial. Measured wind velocities are representative of lowwind speeds measured near Moab, Utah. Wind can move large numbers of cysts to and from potholes on the Colorado Plateau. Our results indicate that large branchiopod cysts move across pothole basins at lowwind speeds; additional work is needed to establish velocities at which cysts move between potholes.

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“…Although this behaviour has also occasionally been observed in the natural biotope, it deserves further observations in order to exclude the possibility that it was an effect due to the artificial conditions of the experimental pool. In fact, past studies (KHALAF and HALL, 1975;HILDREW, 1985;MURA, 1991MURA, , 1993aMURA, , b, 1997THIERY, 1997) on egg-laying behaviour in Anostraca, have not unanimously found resting eggs prevailing in the peripheral areas. Indeed, on some occasions (KHA- LAF and HALL, 1975;MURA, 1993aMURA, , b, 1997THIERY, 1997) the situation was the reverse, cysts being concentrated in the central or deeper areas of the waterbodies.…”

Section: Cyst Abundance and Distributionmentioning

confidence: 95%

Cyst Distribution and Hatching Pattern ofChirocephalus ruffoi (Crustacea, Anostraca) in an Experimental Undisturbed Pool

Mura

2005

Internat. Rev. Hydrobiol.

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The pattern of cyst distribution in the absence of turbation and their hatching behaviour were studied in an outdoor artificial pool, where just differentiated adults of the anostracan Chirocephalus ruffoi (sex ratio 1:3) lived until it dried up. The horizontal and vertical distributions of cysts in the pool bed were determined. The comparison between cyst bank estimate (MURA, 2004) and the actual number of cysts counted in the pool bed revealed an estimate error of 20.9%. Resting eggs occurred only in the upper 2.5 cm thick soil sections and decreased within this section as depth increased. Peripheral areas of the pool contained significantly larger numbers of cysts than the central area. Multiway analysis on the results recorded in hatching success (nested ANOVA) revealed that the differences were significantly affected by initial soil conditions, treatment and vertical distribution of cysts. Among these factors, vertical distribution (sections nested in cores) was the most influential. Hatching success was significantly inversely related to depth. Differences in the timing of hatching depending on the above considered factors were also noted. A nearly synchronous hatching pattern was observed only for cysts from initially dry sediment of the uppermost layers. In all successively deeper layers, hatching showed multiple peaks and was increasingly delayed and erratic (already mentioned). ANCOVA within each of the experimental conditions revealed significant differences in hatching frequencies (time as covariate) depending on sediment depth. Within any given layer, ANCOVA revealed a significant influence of initial sediment conditions and treatment on the timing of hatching. IntroductionPersistence in highly variable habitats such as those inhabited by the fairy shrimp, requires adaptations both in the reproductive characteristics of active populations and in the hatching behaviour of their resting stages (BELK and COLE, 1975;WIGGINS et al., 1980;WILLIAMS, 1985). One of the most conspicuous aspects of such adaptations is the fact that not all of the eggs deposited during active life, even within a single cohort, hatch during subsequent inundations. This leads to the formation of an egg bank in pool beds which buffers the risk of extinction of the population.The behaviour of an egg bank is thus of great importance for the persistence of a given species in highly variable habitats. In spite of this, and in contrast to the plethora of studies on the cyst banks of zooplankters from permanent waterbodies (see review in MARCUS, 1996;MURA, 2004), no information on the structure and functioning of anostracan cyst banks was available until recent years.The function of egg banks (sensu DE STASIO, 1989) is especially important in regions where the climate is extremely unpredictable, and this was recently investigated in two studies aimed specifically at evaluating the size and dynamics of the egg banks of the anostracan Branchipodopsis wolfi inhabiting some short lived desert rock-pools in Botswana Internat. Rev. Hyd...

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Embryonic development and hatching of chirocephalus diaphanus prévost (Crustacea: Anostraca) in nature

Abstract: The embryonic development and hatching of C . diaphanus under natural conditions were investigated . Most of the embryonic development takes place during the dry period of the pond . Thus eggs are ready to hatch as soon as the pond is filled with rainwater .

Cited by 13 publications

References 4 publications

Structure and Functioning of the “Egg Bank” of a Fairy Shrimp in a Temporary Pool: Chirocephalus ruffoi from Pollino National Park (Southern Italy) as a Case Study

Structure and Functioning of the “Egg Bank” of a Fairy Shrimp in a Temporary Pool: Chirocephalus ruffoi from Pollino National Park (Southern Italy) as a Case Study

Dispersal of large branchiopod cysts: potential movement by wind from potholes on the Colorado Plateau

Cyst Distribution and Hatching Pattern ofChirocephalus ruffoi (Crustacea, Anostraca) in an Experimental Undisturbed Pool

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