Dry Cysts Research Articles

New bacilli-based probiotic for aquaculture: efficacy study on Macrobrachium rosenbergii

The data on the study of the effectiveness of a new probiotic based on strains B. toyonensis B-13249 and B. pumilus B-13250 when growing shrimps are presented. The experiments were carried out on a private farm in Kazakhstan. The control group of shrimps, which did not receive the probiotic, completed the molting process on the 28th day of the experiment, and the experimental group – 10 days earlier. It was also found that the probiotic has a positive effect on the hydrochemistry of water in recirculating aquaculture system (RAS). The concentration of ammonium (NH3/NH4 +), nitrite (NO2) and nitrate (NO3-) nitrogen in the experimental group did not reach the limit value, in contrast to the control. Based on the obtained results, this probiotic can be recommended for greening aquaculture. The dosage of the probiotic when applied with brine shrimp as feed for shrimp is 1 g/100 g of dry cysts. The dosage of the probiotic when the RAS is added to the water is 5 g/600 l of circulating water once a week.

Production performance and nutritional quality of the fairy shrimp Dendrocephalus brasiliensis Pesta, 1921 (Crustacea, Anostraca) cultured with fish effluent in recirculation system

The lack of information of the nutritional profile and technology in the rearing of Dendrocephalus brasiliensis in intensive systems of aquaculture limits its using in larval rearing. We investigated the effects of the stocking density in both biomass and cyst productions, as well as the centesimal composition and biochemical profile of D. brasiliensis. To evaluate the biomass production of fairy shrimps, larvae were distributed randomly into three densities of 25, 50 and 100 individuals L−1 in 5-L net tanks (NT). The D. brasiliensis were reared for 30 days using effluent from tilapia recirculation systems. The results showed that the different stocking densities affected both biomass and cyst productions as well as survival of D. brasiliensis. The highest biomass production (2.6 g L−1) was obtained in high density (HD) stock (100 ind L−1). The fairy shrimp reared in HD (20 females and 20 males L−1) produced more cysts (82.57 mg NT−1), with the highest amount reaching 4 mg of dry cysts L−1. Thus, for intensive production of D. brasiliensis, we suggest its rearing in HD (100 ind L−1) and 20 pairs L−1 or 4 mg of dry cysts L−1 at the same conditions used in this study. Nauplii and juveniles of D. brasiliensis had high concentrations of protein (605.0 ± 3.0 g kg ms−1 for nauplii and 704.3 ± 3.5 g kg ms −1 for juveniles) and lipids (181.0 ± 3.0 g kg ms −1 for nauplii and 86.0 ± 3.5 g kg ms −1 for juveniles), as well as high amounts of amino acids and highly unsaturated fatty acids (18:2n-6, 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3). The nutritional profile of D. brasiliensis and its zootechnical characteristics make of it a species with great potential as a live food resource for species of economic interest in aquaculture.

Gamma Radiation Tolerance and Protein Carbonylation Caused by Irradiation of Resting Cysts in the Free-living Ciliated Protist Colpoda cucullus

The ciliate Colpoda cucullus forms resting cysts to survive unfavorable environmental stresses. In this study, we have shown that Colpoda resting cysts survived exposure to a gamma radiation dose of 4000 Gy, although vegetative cells were killed by 500 Gy. After 4000 Gy irradiation, more than 90% of resting cysts and approximately 70% of dry cysts could excyst to form vegetative cells. In both cases, the excystment gradually increased after the induction of excystment. In addition, we also showed that protein carbonylation level was increased by gamma irradiation, but decreased by incubation in the cyst state. These results indicated that cell damage was repaired in resting cysts. Colpoda probably developed tolerance to gamma radiation by forming resting cysts as a strategy for growth in terrestrial environments, as part of contending with the stress due to reactive oxygen species caused by desiccation.

Comparison of the morphology and viability of gamma irradiated vegetative cells, wet cysts, and dry cysts of the soil ciliate Colpoda cucullus

Comparison of the morphology and viability of gamma irradiated vegetative cells, wet cysts, and dry cysts of the soil ciliate <i>Colpoda cucullus</i>

Effects of an alternative diet of Artemia cysts on the development and reproduction of Nesidiocoris tenuis (Hemiptera: Miridae)

The small green mirid Nesidiocoris tenuis Reuter (Hemiptera: Miridae) preys on pest insects such as whiteflies and serves as a biological control agent in many greenhouses. However, this mirid is limited in its application, because individuals tend to escape from agricultural fields and soon die due to a lack of available food sources. In addition, the food traditionally used to culture N. tenuis is expensive. Thus, identifying low-cost foods for N. tenuis would help to increase the species’ further utilization. Brine shrimp (Artemia spp., Anostraca: Artemiidae) cysts are potentially useful as a low-cost alternative diet to sustain populations of predatory natural enemies. We evaluated the developmental and reproductive performance of N. tenuis when reared on Artemia salina L. cysts supplied in dry or wet form. The dry cysts showed a similar performance to that of Mediterranean flour moth (Ephestia kuehniella Zeller, Lepidoptera: Pyralidae) eggs, which are often used as a nutritional diet for mass rearing of N. tenuis. Although the wet cysts contributed to growth, compared to other diets, they were inferior in nymphal development time and longevity. These results suggest that relatively inexpensive Artemia dry cysts can be used to successfully breed N. tenuis and sustain populations in crop fields.

Analysis of survival and hatching transcriptomes from potato cyst nematodes, Globodera rostochiensis and G. pallida

Potato cyst nematodes (PCNs), Globodera rostochiensis and G. pallida, cause important economic losses. They are hard to manage because of their ability to remain dormant in soil for many years. Although general knowledge about these plant parasitic nematodes has considerably increased over the past decades, very little is known about molecular events involved in cyst dormancy and hatching, two key steps of their development. Here, we have studied the progression of PCN transcriptomes from dry cysts to hatched juveniles using RNA-Seq. We found that several cell detoxification-related genes were highly active in the dry cysts. Many genes linked to an increase of calcium and water uptake were up-regulated during transition from dormancy to hydration. Exposure of hydrated cysts to host plant root exudates resulted in different transcriptional response between species. After 48 h of exposure, G. pallida cysts showed no significant modulation of gene expression while G. rostochiensis had 278 differentially expressed genes. The first G. rostochiensis significantly up-regulated gene was observed after 8 h and was coding for a transmembrane metalloprotease. This enzyme is able to activate/inactivate peptide hormones and could be involved in a cascade of events leading to hatching. Several known effector genes were also up-regulated during hatching.

Artificial and factitious foods support the development and reproduction of the predatory mite Amblyseius swirskii

The generalist predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was reared on Ephestia kuehniella Zeller eggs (Lepidoptera: Pyralidae), decapsulated dry cysts of the brine shrimp Artemia franciscana Kellogg (Anostraca: Artemiidae), and on meridic artificial diets (composed of honey, sucrose, tryptone, yeast extract, and egg yolk) supplemented with pupal hemolymph of the Chinese oak silkworm Antheraea pernyi (Guérin-Méneville) (Lepidoptera: Saturniidae) (AD1), with E. kuehniella eggs (AD2) or with A. franciscana cysts (AD3). Development, reproduction and predation capacity of the predatory mites were assessed in the first (G1) and sixth generation (G6) of rearing on the different diets. Immature survival rates in G1 were similar on all diets (96.8-100 %). After six generations, however, survival of A. swirskii was significantly reduced on all diets except on A. franciscana cysts. Oviposition rates did not differ between generations when females were fed on E. kuehniella, AD2 or AD3. The total number of deposited eggs was similar among diets except in G6 where the females fed on A. franciscana cysts produced more eggs than those maintained on E. kuehniella eggs. On most diets the intrinsic rates of increase in G1 were superior to those in G6, except for predators supplied with A. franciscana cysts where no differences were observed among generations. Female mites did not lose their capacity to kill first instar Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) after six generations on the different diets, but predation rates in G6 on E. kuehniella were lower than in G1. In conclusion, the different factitious and artificial diets tested in the present study supported the development and reproduction of A. swirskii for a single generation but fitness losses occurred to a varying degree after several generations on E. kuehniella eggs or the artificial diets. Artificial diet enriched with A. franciscana cysts yielded better results than the other artificial diets. Amblyseius swirskii performed best on decapsulated Artemia cysts indicating their potential for use in the mass production of the predator or to sustain its populations in the crop after release.

Long-term Lethal Toxicity Test with the Crustacean &lt;em&gt;Artemia franciscana&lt;/em&gt;

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish water and sediment. The choice of biological indicators must be based on reliable scientific knowledge and, possibly, on the availability of standardized procedures. In this article, we present a standardized protocol that used the marine crustacean Artemia to evaluate the toxicity of chemicals and/or of marine environmental matrices. Scientists propose that the brine shrimp (Artemia) is a suitable candidate for the development of a standard bioassay for worldwide utilization. A number of papers have been published on the toxic effects of various chemicals and toxicants on brine shrimp (Artemia). The major advantage of this crustacean for toxicity studies is the overall availability of the dry cysts; these can be immediately used in testing and difficult cultivation is not demanded1,2. Cyst-based toxicity assays are cheap, continuously available, simple and reliable and are thus an important answer to routine needs of toxicity screening, for industrial monitoring requirements or for regulatory purposes3. The proposed method involves the mortality as an endpoint. The numbers of survivors were counted and percentage of deaths were calculated. Larvae were considered dead if they did not exhibit any internal or external movement during several seconds of observation4. This procedure was standardized testing a reference substance (Sodium Dodecyl Sulfate); some results are reported in this work. This article accompanies a video that describes the performance of procedural toxicity testing, showing all the steps related to the protocol.

Long-term Lethal Toxicity Test with the Crustacean &lt;em&gt;Artemia franciscana&lt;/em&gt;

Our research activities target the use of biological methods for the evaluation of environmental quality, with particular reference to saltwater/brackish water and sediment. The choice of biological indicators must be based on reliable scientific knowledge and, possibly, on the availability of standardized procedures. In this article, we present a standardized protocol that used the marine crustacean Artemia to evaluate the toxicity of chemicals and/or of marine environmental matrices. Scientists propose that the brine shrimp (Artemia) is a suitable candidate for the development of a standard bioassay for worldwide utilization. A number of papers have been published on the toxic effects of various chemicals and toxicants on brine shrimp (Artemia). The major advantage of this crustacean for toxicity studies is the overall availability of the dry cysts; these can be immediately used in testing and difficult cultivation is not demanded. . Cyst-based toxicity assays are cheap, continuously available, simple and reliable and are thus an important answer to routine needs of toxicity screening, for industrial monitoring requirements or for regulatory purposes. The proposed method involves the mortality as an endpoint. The numbers of survivors were counted and percentage of deaths were calculated. Larvae were considered dead if they did not exhibit any internal or external movement during several seconds of observation. This procedure was standardized testing a reference substance (Sodium Dodecyl Sulfate); some results are reported in this work. This article accompanies a video that describes the performance of procedural toxicity testing, showing all the steps related to the protocol.

Mechanisms Associated with Cellular Desiccation Tolerance in the Animal ExtremophileArtemia

Using differential scanning calorimetry, we demonstrated the presence of biological glasses and measured the transition temperatures in dry encysted embryos (cysts) of the brine shrimp, Artemia franciscana. Cysts from the following three geographic locations were studied: San Francisco Bay (SFB); the Great Salt Lake, Utah (GSL); and the Mekong Delta, Vietnam (VN; these cysts were produced from previous sequential inoculations of SFB cysts into growth ponds). Values for the glass transition temperature, T(g), were highest in VN cysts. This study indicates that the composition and properties of these biological glasses can be altered by natural selection and thermal adaptation. To our knowledge, T(g) values for all three kinds of cysts were significantly higher than those for any other desiccation-tolerant animal system. To gain insight into the significance of T(g), we examined the thermal stability of these dry cysts at 80 °C. GSL cysts were the least tolerant, by far, with VN cysts being extremely tolerant and SFB cysts not far behind. Those results correlated with the thermal transition values. Also measured were alcohol-soluble carbohydrates, ~90% of which is the disaccharide trehalose, a known component of biological glasses. Amounts in the GSL cysts were significantly less than those in the other two kinds of cysts. Several stress proteins were measured in the three groups of cysts, with all of them being in lesser amounts in GSL cysts compared with the SFB and VN cysts. We interpret the data in terms of mechanisms involved with desiccation tolerance and thermal conditions at the sites of cyst collection.

Electromagnetic field effects on Artemia hatching and chromatin state

Abstract The influence of magnetic fields on hatching and chromatin state of brine shrimp, Artemia sp., was investigated. Dry Artemia cysts were exposed to a magnetic field of intensity 25 mT for 10 min. The magnetic field was applied in different variants: constant field, rotating field of different directions (right-handed and left-handed) and different magnet polarization. The effect of ultra wideband pulse radiation and microwave radiation was also investigated. The energy density on the surface of object exposed to ultra wideband pulse radiation was 10−2, 10−3, 10−4, 10−5 and 10−6 W/cm2, the power of microwave radiation was 10−4 and 10−5 W/cm2, exposure time - 10 s. After incubation of the cysts for 48 hours in sea water the hatching percentage of Artemia from exposed cysts was higher than in controls. The number of heterochromatin granules was significantly higher in the nauplia (newborn larvae of Artemia) developed from cysts that had been exposed to magnetic and electromagnetic fields. The data obtained demonstrate an increase in percentage hatching of Artemia cysts after treatment with magnetic and electromagnetic fields and chromatin condensation in nauplia. We have also shown different effects of right-handed and left-handed rotating magnetic fields on these processes.

Comparison of the effects of freezing and thawing on the cysts of the two potato cyst nematode species, Globodera rostochiensis and G. pallida, using differential scanning calorimetry

AbstractDifferential scanning calorimetry was used to examine and to compare the effect of freezing and thawing on the eggs of the two potato cyst nematode (PCN) species, Globodera rostochiensis and G. pallida. No thermal events were recorded for either PCN species when dry cysts were cooled to –45°C and thawed to +5°C. The cyst walls of hydrated cysts of both species were found to contain ice-nucleating agents that significantly increased the temperature at which external and internal water in contact with the cyst wall froze compared with control water droplets. The freezing of hydrated eggs of both species of PCN eggs produced a very broad exotherm ranging from –30°C to –42°C. A significant positive correlation between cyst weight and supercooling point for G. pallida eggs was identified, indicating that cyst size and egg location within the cyst may influence the freezing of PCN eggs on an individual level. Integration of these egg exotherms identified a supercooling point of –37.45°C and –39.05°C for G. pallida and G. rostochiensis, respectively. The supercooling points of eggs of G. pallida but not G. rostochiensis were found to increase significantly on the second freeze cycle of a freeze-thaw-freeze programme. Rehydration of these G. pallida cysts restored the supercooling point to its original level when the cysts were re-analysed, indicating that water was lost from the egg complex of G. pallida during the initial freeze-thaw-freeze programme. The results of this study indicate that the ability of eggs of both species of PCN to supercool appears to be a trait that was developed prior to divergence of the two species.

Biochemical and biophysical aspects of the tolerance of anhydrobiotic crustacean embryos to very high temperatures

1. Heat tolerance of dry cysts of the fairy shrimp Branchipus schaefferi and the brine shrimp, Artemia franciscana was studied using rapid (∼100 °C/min) and slow (∼4 °C/min) heating. 2. Rapid heating caused much greater death than did slow, and we consider the possible causes. 3. Although these primitive crustaceans are closely related, the major stress proteins of Artemia cysts (artemin and p26) were not detected in Branchipus cysts. 4. The Arrhenius activation energy ( E a) for thermal killing of Branchipus cysts was found to be 5-fold higher than that of Artemia cysts over the range of 110–130 °C. 5. These major differences in stress proteins and E a are especially interesting because the thermal tolerance of both kinds of cysts is very similar.

Inbred Strains of Brine Shrimp Derived from Artemia franciscana: Lineage, RAPD Analysis, Life Span, Reproductive Traits and Mode, Adaptation, and Tolerance to Salinity Changes

Inbred strains of the brine shrimp were developed from dry dormant cysts of wild-type Artemia franciscana produced in the Great Salt Lake, U.S.A. The established strains were named GSL2, 4, and 7. They were raised in 2% natural sea salt solution at 28 degrees C under a long-day condition, and fed on food sold for Artemia. Ovoviviparous offspring (free-swimming nauplii) in each brood derived from full sib (sister x brother) matings were used for succeeding generations. The ordinal number of the filial generation increased at a rate of ten generations per year. The number was over 60, and the lineage was recorded. Random amplified polymorphic DNA (RAPD) analyses of the inbred strains revealed the uniqueness, homogeneity, and genetic similarity among them. Their life span, the time required to become sexually mature, brood size, mode of reproduction, and adaptation and tolerance to salinity changes were investigated. The inbred strains usually released free-swimming nauplii rather than spawning encysted gastrulae (dormant cysts). On the other hand, the opposite results were obtained from wild-type Artemia under the same conditions. Both adults and nauplii of the inbred strains appeared to be less adaptive and less tolerant to salinity changes compared to those of the wild type. The established inbred strains should provide a wider and deeper scope for Artemia biology in particular, and the life sciences in general.

Indonesia

Artemia is one of live feed needed in aquaculture as fishes and crustacean. Commercially, Artemia usually sold in dry cysts which can kept for years. The aim of this research were to know increasing quantity and quality A. franciscana cysts after exposing various concentration of fish silage as artificial food and to know optimal concentration of fish silage that can increase quantity and quality A. franciscana cysts. This research was done in Laboratory of Live Feed BBPBAP Jepara Central Java. This research was conducted by 5 treatments. Treatments were grouped based on amount of concentration given, i.e: control (coconut cake) with concentrate 10 g/m3, fish silage concentrate 10, 20, 30, and 40 g/m3. Parameter investigated were number of cysts produced by individual female A. franciscana, diameter of A. franciscana cysts, hatching percentage, and hatching rate of A. franciscana cysts. Data were analyzed using ANOVA and continued using Tukeys test at significant level 5%. The result of this research showed that exposing fish silage can increase quantity and quality A. franciscana cysts. They were increase number of cysts production by individual females, decrease cysts diameter, increase hatching percentage and hatching rate. Optimal concentration of fish silage on increase quantity and quality of A. franciscana cysts was 20 g/m3.

The brine shrimp Artemia sp. as alternative prey for rearing the predatory bug Macrolophus caliginosus

Abstract The predatory bug Macrolophus caliginosus , which is widely used in greenhouse crops, is limited in its application by its high price. An important factor in the cost is the high price of Ephestia kuehniella eggs, the prey used in their mass rearing. In order to reduce their price, alternatives to moth eggs are currently being investigated. The brine shrimp Artemia sp. is produced in large quantities in saline lakes and is fed as live food source to the larvae of a variety of marine and freshwater organisms. In this study, we tested Artemia sp. as prey for rearing M. caliginosus from two strains. We evaluated developmental and reproduction parameters of the predator when fed nauplii, enriched nauplii with a fatty acid, dry cysts and hydrated cysts, and were compared with those obtained when the predator was fed with E. kuehniella eggs. Nauplii had a significant reduction in survivorship, a delay in development of nymphs and a low reproduction of adults. Nauplii enriched with docosahexaenoic acid (DHA, 22:6 n − 3), a common practice for larviculture of some marine fish species, resulted toxic to M. caliginosus nymphs and survival was quite low. On the contrary, either dry or hydrated cysts from the two strains tested of the brine shrimp produced the same nymphal survivorship, nymphal development time and weight and fecundity of adults as those obtained with E. kuehniella eggs. Demographic parameters of the eighth generation of the predator reared with cysts of the two strains, either dry or hydrated, were as good as those of moth eggs. We concluded that Artemia sp. cysts were a good substitution prey for the mass rearing of M. caliginosus .

Lysozyme-like and trypsin-like activities in the cysts of Artemia franciscana Kellog, 1906

Lysozyme-like and trypsin-like activities were looked for in Artemia franciscana dry cysts to ascertain whether this inactive stage has a chemical protection against pathogens (in addition to the physical barrier represented by the cyst envelope). Both the biochemical activities were found either in the cyst content or in the cyst envelope. In particular, two protease activities were recognized. The two protease activities were found in the cyst content, but only one of them was also found in the cyst envelope. It has been supposed that the latter protease could be appointed, along with the lysozyme, to the chemical defence against aggressors of living origins. This is the first report of a lysozyme-like activity in the Artemia cyst, and the first report of trypsin-like protease in the cyst envelope.

Changes in the lipid content and fatty acid composition of 2nd-stage juveniles of Globodera rostochiensis after rehydration, exposure to the hatching stimulus and hatch.

The total lipid content of the dry weight of whole cysts and 2nd-stage juveniles (J2) of Globodera rostochiensis was 17.1% in dry cysts, 20.9% in cysts soaked in distilled water (DW), 20.3% in cysts that had been in potato root diffusate (PRD) for 7 days, 7.3% in cysts that had been in PRD for 28 days and 29.2% for hatched J2. The fatty acid composition of the total lipid did not differ between dry cysts, cysts in DW and cysts in PRD for 7 days. However, major differences in the fatty acid composition of all lipid classes were found between rehydrated cysts in PRD and freshly hatched J2. After hatching, the degree of saturation and the percentage of monounsaturated fatty acids decreased and the percentage of polyunsaturated fatty acids increased considerably, especially in the free fatty acid fraction, where C20:1 showed an 8-fold decrease and C20:4 a 33-fold increase. There was a difference in the fatty acid composition of cysts in PRD for 7 days and cysts in PRD for 28 days (after most of the J2 had hatched); with increased time in PRD the percentage of polyunsaturated fatty acids increased and the percentage of monounsaturated fatty acids decreased in all lipid classes. Differences in the fatty acid profiles between cysts in PRD for 28 days and hatched J2 were found mainly in the free fatty acid and the non-acidic phospholipid fractions. The free fatty acid fraction of the cysts was dominated by monounsaturated fatty acids (52%), whereas the same fraction of hatched J2 contained large amounts of polyunsaturated fatty acids (60%). These polyunsaturated fatty acids, especially C20:4, might play an important part in nematode-plant interactions during infection.

The Influence of the Host Plant On Lipid Reserves of Globodera Rostochiensis

Up to 16 fatty acids were detected in total lipids from roots and leaves of two potato cultivars, Desiree and Maris Piper, and one tomato cultivar, Pixie. The fatty acid profiles from roots were similar for all three cultivars and were dominated by C18 : 2 (30-40%) and C 16 : 0 (about 22%). The fatty acid profiles from leaves were similar for all three cultivars and were dominated by C18 : 3 (about 52%). Both root and leaf lipids contained mainly C18 fatty acids. The lipid content found in dry cysts of Globodera rostochiensis rcared on different cultivars was 11.0%, 12.8% and 9.6% for potato cvs Desiree and Foremost and tomato cv. Pixie, respectively. The total lipid comprised 74-82% neutral lipid, 14-19% non-acidic phospholipid and 4-7% free fatty acid in the three samples. Hatched juveniles (J2) from cysts cultured on cvs Desiree and Foremost contained 26.1% and 24.3% lipid, respectively. The total lipid comprised 77% neutral lipid, 17-18% non-acidic phospholipid and 6-7% free fatty acid in the two samples. The fatty acid profiles of the main lipid classes of cysts of G. rostochiensis cultured on the three different cultivars were similar. The fatty acid composition of the main lipid classes of freshly hatched J2 from cysts of G. rostochiensis cultured on the two potato cultivars differed only in their free fatty acid fractions. A comparison of the fatty acid profiles of the total lipid of potato roots, cv. Desiree, and the total lipid of cysts of G. rostochiensis showed major differences. Root fatty acids and nematode fatty acids were 38% and 22% saturated, 10% and 44% monounsaturated and 52% and 35% polyunsaturated, respectively. The fatty acid profile of root lipids was dominated by C16: 0, C18: 2 and C18 : 3 but the nematode lipids consisted of mainly C18: 1, C20: 1 and C20: 4. The differences in the fatty acids of host and nematodes indicate that G. rostochiensis is capable of fatty acid chain elongation and/or desaturation.

VULNERABILITY OF BRANCHIOPOD CYSTS TO CRUSHING

Ephemeral wetlands, such as vernal pools and playas, have become increasingly threatened by a variety of destructive human practices, including off-highway vehicle (OHV) activity. Among the resident animals that may be adversely affected are the branchiopod crustaceans which produce desiccation resistant cysts to withstand the pools' dry periods. We report a quantitative investigation of the force required to crush individual branchiopod cysts of 8 species: Branchinecta lynchi, B. sandiegonensis, B. mackini, Streptocephalus woottoni, Thamnocephalus platyurus, Linderiella occidentalis, Lepidurus lemmoni, and Triops longicaudata. Very small forces of less than 1 newton crushed dry cysts. Wet cysts were even more fragile; many were crushed under less than 7 X 10-2 newtons. Differences in vulnerability were found within and between taxa and may be related to cyst morphology. Knowledge of these effects should be taken into consideration when developing management strategies for ephemeral wetlands.