Environmental DNA sampling provides new management strategies for vernal pool branchiopods in California.

California's vernal pools are declining ecosystems that support valuable native plant and animal diversity. Vernal pool branchiopods are particularly at risk from vernal pool habitat loss and conservation efforts have targeted their long-term protection through the establishment of preserves and conservation banks. These conservation strategies require repeated, perpetual monitoring of preserved habitat, which is currently carried out through dip-net surveys and visual identification of specimens. Dip-netting may be destructive and frequently requires some sacrifice of protected species. Environmental DNA offers a new, modern method to monitor many protected freshwater organisms. We designed qPCR-based species-specific assays for four of California's vernal pool branchiopods: The Vernal Pool Fairy Shrimp Branchinecta lynchi (BRLY), the Midvalley Fairy Shrimp Branchinecta mesovallensis (BRME), and the Conservancy Fairy Shrimp Branchinecta conservatio (BRCO), and the Vernal Pool Tadpole Shrimp Lepidurus packardi (LEPA). We tested these assays using eDNA sampling protocols alongside traditional dip-net surveys to assess their viability as an alternative method to monitor vernal pool branchiopods. Based on occupancy modeling, each of our assays achieved a 95% or higher detection rate when using optimized sampling protocols.

Increasing salinity drastically reduces hatching success of crustaceans from depression wetlands of the semi-arid Eastern Cape Karoo region, South Africa.

Salinity is an important factor affecting freshwater aquatic species distribution and diversity. The semi-arid Eastern Cape Karoo region of South Africa has been earmarked for shale gas development through hydraulic fracturing. The process uses large amounts of water and produces briny wastewater. When not managed properly, these wastewaters may lead to salinisation of surface freshwater bodies in the region. Therefore, the effect of salinity on the hatching success of crustacean resting eggs was examined using sediments from four depression wetlands found in the region. The sediments were exposed for 28 days to salinity levels of 0.5 g L-1, 2.5 g L-1, 5 g L-1 and 10 g L-1. Control aquaria in which no salt was added were also set up. There was a significant decrease in the emerged taxa richness and abundances at salinities of 2.5 g L-1 and above. Anostraca, Notostraca and Spinicaudata hatchlings were abundant at salinities of 0.5 g L-1 and below, while Copepoda, Daphniidae (Cladocera) and Ostracoda were observed in the highest salinity, but their densities were still lower with increased salinities. Given the importance of large branchiopods in the trophic balance of depression wetlands, their loss may alter the ecological balance and function of these ecosystems.

Thamnocephalus chacosaltensis, a new species of Anostraca (Crustacea: Branchiopoda) from Salta province (Argentina).

Thamnocephalus chacosaltensis, a new species of fairy shrimp, was found in a temporary turbid pond in the Rivadavia Department, Salta province, Argentina (24º13'19.3''S; 62º 52'14.3''W), belonging to the Chaco salteño. The males present a well developed frontal appendage. Their First (FB) and Third (TB) branches show features diagnostic for the species. FB shows three sub-branches; the most proximal one is coiled, lacks spines all along, gradually thins in distal direction and flattens in the distal half; distally, the flattened portion is folded and ends blunt, bearing a small spine at the tip. TB is a broad-based triangular, thin, much flattened and folded outgrowth, with a small spine at the apex. Male genital and abdominal segments lack medio-ventral spines near their posterior margins. Comparisons with the other species of the genus are established.

Morphometric and preliminary genetic characteristics of Branchinecta orientalis populations from Iran (Crustacea: Anostraca).

Branchinecta orientalis is a fairy shrimp endemic to the Palearctic region, from Mongolia to Spain. The patchy nature of its habitat is thought to result in a high degree of subdivision among populations, potentially promoting speciation. We combined morphometric characteristics with molecular phylogeny of cytochrome c oxidase I (COI) to test whether B. orientalis could be a species complex and whether there is any correlation between the genetic variation, morphometric characteristics and geographical variables. We studied six populations from Iran based on the comparison of morphometric and molecular datasets, we confirmed that the Aigher Goli (AIG) population is biometrically well separated from the Akh Gol, Hassar, Rashakan, Khaslou and Garagojanlou populations in northwestern Iran. The relatively high genetic divergence in the AIG from the other populations and its congruence with morphometric data were observed in B. orientalis populations. However, as these results were generated using a small sample size and on a limited sampling range, they should be considered as preliminary.

Large branchiopod (Crustacea: Branchiopoda) egg morphology of Western Ghats, Maharashtra, India.

The eggs of many large branchiopods have taxonomic value and are commonly used as traits in species and/or generic descriptions. In this paper we present detailed descriptions and SEMs of resting eggs of seven of the eight species of large branchiopods found in the Western Ghats of Maharashtra, India. We highlight the inter- and intrapopulation egg morphological variation in Streptocephalus.

A new species of Branchinecta (Crustacea: Anostraca) from Uruguay.

Branchinecta uruguayensis, a new species of fairy shrimp, is described from a single seasonally astatic aquatic habitat in coastal Uruguay. This is the first record of an anostracan from the nation of Uruguay. Male B. uruguayensis n. sp. are separated from other Branchinecta species by the form of the second antennae. Branchinecta uruguayensis n. sp. share the distal antennomere lobiform projection with B. papillata Rogers, De los Rios, & Zúñiga, 2008 and B. achalensis César, 1985. Branchinecta uruguayensis n. sp. females are readily separated from all other Branchinecta by the presence of posteriolateral thoracic spines and lateral crenulations on the first abdomen segment margins. A key is provided to the Branchinectidae of South America.

Morphological variation in males of Dendrocephalus orientalis (Anostraca: Thamnocephalidae): Implications for species identification.

The genus Dendrocephalus Daday, 1908 consists of 17 described species. The morphology of the frontal appendage and the first pairs of thoracopods of males are the main characteristics used for species identification. The objectives of this study were to increase knowledge of the morphology of Dendrocephalus orientalis and to propose a new identification key for the species occurring in Brazil. Specimens were collected in temporary ponds within the conservation unit Monument Natural Grota do Angico (MNGA), which straddles the borders of the municipalities of Poço Redondo and Canindé de São Francisco, State of Sergipe, Brazil. During the study period, 560 male individuals of D. orientalis were sampled. The specimens showed variations in the number of spines on the eyes and the proximal surface of the male frontal appendage. On the eye, the number of spines ranged from 0 to 2; morphotypes with 1 and 2 spines predominated in the samples, with 50.5% and 46.2%, respectively. The number of spines on each eye was the same within each individual. On the proximal surface of the males frontal appendage the following numbers of spines on each arm were recorded: 1 and 1 (57.86%); 2 and 1 (30.89%); 2 and 2 (9.46%); 1 and 0 (1.25%); 3 and 2 (0.36%); 2 and 0 (0.18%). Based on these variations, we conclude that the number of spines on the eyes and the frontal appendage arms cannot be used as a diagnostic character for species identification. On the other hand, the first pairs of thoracopods and sub-branches 1V and 2A of the frontal appendage should be included in keys, since these structures did not show significant intraspecific morphological variation. 

LETHAL EFFECTS OF PESTICIDES ON THE NAUPLII FAIRY SHRIMP, BRANCHINELLA THAILANDENSIS.

During agricultural activities, large amounts of insecticides and herbicides are used for controlling pests. The overspraying of pesticides may contaminate freshwater bodies, as well as having a significant effect on aquatic animals. To determine the potential risk of pesticides, the acute toxicity of insecticides and herbicides on the nauplii fairy shrimp, Branchinella thailandensis were evaluated. The organisms were exposed to different concentrations of insecticides (chlorpyrifos and carbaryl), and herbicides (paraquat and 2,4-D) for 24 h, after which the LC50 values were compared. The acute toxicity tests determined that the LC50 values of chlorpyrifos and carbaryl after 24 h were 0.00186 mg/L and 0.21 mg/L, respectively. For herbicides, paraquat and 2,4-D, the LC50 values were 0.11 mg/L and 27.91 mg/L. Therefore, chlorpyrifos insecticides were found to be more toxic than herbicides (2,4-D and paraquat) with regard to the nauplii fairy shrimp. The high toxicity of pesticides has a long-term, and potentially damaging effect on aquatic organisms in the application areas.

A new species of Streptocephalus (Crustacea: Anostraca: Streptocephalidae) from the Western Ghats, India, with a key to the Asian species.

We present and describe the fairy shrimp Streptocephalus sahyadriensis sp. nov. from the Western Ghats of India. This species is most similar to S. simplex Gurney, 1906 and S. dichotomus Baird, 1860 sharing similar basic antennal appendage morphology. However, S. sahyadriensis sp. nov. differs in the form of the ornamentation on the peduncle and the arrangement and form of spines on the antennal appendage. The three species also have different egg surface morphologies. The Asian species of Streptocephalus are discussed and a key to species is provided.

A new fairy shrimp Phallocryptus tserensodnomi (Branchiopoda: Anostraca) from Mongolia.

A new species of Phallocryptus Biraben 1951 (Branchiopoda, Anostraca) from Mongolia is described. Phallocryptus tserensodnomi sp. nov. is close to P. spinosa (Milne-Edwards 1840), but both morphological and molecular analyses (Cytochrome Oxidase I, COI) indicate that they represent separate species. Most relevant differential features of the new species include: (1) frontal appendage provided with small ventral conical outgrowths; (2) second antennamere evenly curved, sickle-shaped; (3) distal fleshy process on labrum evenly curved forwards and tapering; (4) short stout acute spine-like projections present at each side of basal portion of gonopods; (5) female second antennae shorter and wider than in P. spinosa, tapering. Based on morphological comparisons the new species appears to be a Mongolian endemic, although some genotypes of presumed P spinosa from Africa are similar to the new species, suggesting P. tserensodnomi might have a wider distribution.

Annotated Checklist of the large branchiopod crustaceans of Idaho, Oregon and Washington, USA, with the "rediscovery" of a new species of Branchinecta (Anostraca: Branchinectidae).

We present a checklist of the large branchiopod crustaceans of Idaho, Oregon and Washington, USA. New distributional records are presented for most species, including the first records of Branchinecta constricta Rogers, 2006 and Lepidurus cryptus Rogers, 2001 from Idaho, the first record of B. oriena Belk & Rogers 2002 from Oregon, the first record of B. mackini Dexter, 1956 and Artemiafranciscana Kellogg, 1906 co-occurring, and the first record of L. cryptus from Washington. Furthermore, we present the first record of Eulimnadia diversa Mattox, 1937 from west of the continental divide, which we interpret as an accidental introduction. In 1959, Lynch collected a new fairy shrimp species from Washington, deposited that material in the US National Museum, labeled "muddy fairy shrimp, Branchinecta lutulenta", but never described it. Numerous efforts have been made to rediscover extant populations since 1999. We rediscovered this species in 2011, from two small pools from the vicinity of Lynch's original collection site, which appears to have been destroyed. Branchinecta lutulenta sp. nov. is most closely related to B. lindahli Packard, 1883 and B. oterosanvicentei Obregón-Barboza et al., 2002. Branchinecta lutulenta sp. nov. is readily separable from all other Branchinecta species by the form of the male second antennal distal antennomere and the ornamentation of the female dorsum.

Tanymastigites lusitanica sp. nov. (Crustacea: Branchiopoda: Anostraca) from Portugal, first representative of the genus in Europe.

Tanymastigites lusitanica sp. nov., a new species of fairy shrimp, is described from puddles in unpaved roads in the Alentejo region, Portugal. The males of Tanymastigites lusitanica sp. nov. are readily separated from the rest of the species of the genus by the morphology of antennae, antennal appendages and penes. T. lusitanica sp. nov. is closely related to T. perrieri but differs from it by the presence of a proximal ventrolateral short ridge in the distal segment of the antenna, and by the absence of a big thorn-like outgrowth in the distal lateral "lip" of the basal part of the penis. T. lusitanica sp. nov. presents a simple lateral branch in the antennal appendage of males, instead of the bifurcated lateral branch present in T. brteki, T. cyrenaica and T. mzabica. The finding of this new species represents the first citation of this genus in Europe. An identification key is provided to separate the males of the different species of the genus.

Evaluation of surface water quality using an ecotoxicological approach: a case study of the Alqueva Reservoir (Portugal).

BACKGROUND, AIM, AND SCOPE: Freshwater reservoirs can be impacted by several hazardous substances through inputs from agricultural activity, sewage discharges, and groundwater leaching and runoff. The water quality assessment is very important for implementation of the monitoring and remediation programs to minimize the risk promoted by hazardous substances in aquatic ecosystems. Evaluation of the degree of contamination of aquatic environments must not take in account only its chemical characterization but it must be complemented with biological assays, which determine potential toxic effects and allows an integrated evaluation of its effects in populations and aquatic ecosystem communities. The application of this type of strategy has clear advantages allowing a general evaluation of the effects from all the water components, including those due to unknown substances and synergic, antagonistic, or additive effects. There are only a few studies that reported ecotoxicological acute end points, for the assessment of surface water quality, and the relationship among toxicity results and the anthropogenic pollution sources and the seasonal period. The aim of this study was to assess the ecotoxicological characterization of the surface water from Alqueva reservoir (South of Portugal) and to evaluate the influence of anthropogenic sources of pollution and their seasonal variation in its toxicity. The construction of Alqueva reservoir was recently finished (2002) and, to our knowledge, an ecotoxicological assessment of its surface water has not been performed. Because of that, no information is available on the possible impact of pollutants on the biota. The surface water toxicity was assessed using acute and chronic bioassays. The results are to be used for developing a monitoring program, including biological methods. MATERIALS AND METHODS: Water samples were collected during 2006-2007, at each of the nine sampling sites selected in Alqueva reservoir. These sampling points allow an assessment at the upstream (Sra. Ajuda, Alcarrache, Alamos-Captação), at the middle (Alqueva-Montante, Alqueva-Mourão, Lucefecit), and at the downstream of the water line (Alqueva-Jusante; Ardila-confluência; Moinho das Barcas). The campaigns occurred in February, March, May, July, September, and November of 2006 and February, March, and May of 2007. The rainy season comprised November, February, and March, and the dry season included May, July, and September. A total of 81 samples were collected during the study period. The physical-chemical parameters were analyzed following standard and recommended methods of analysis (APHA et al. 1998). The pesticide analyses were performed using gas chromatography according to DIN EN ISO 6468 (1996). Surface water ecotoxicity was evaluated using the following bioassays: Vibrio fischeri luminescence inhibition, Thamnocephalus platyurus mortality, and Daphnia magna immobilization and reproduction assay. The Spearman rank correlation coefficients were used to evaluate the associations between the water sample physicochemical properties (from each sampling station in each season) and the acute and chronic toxicological effects, with a level of significance p < 0.05. RESULTS: In the acute toxicity study, the species that was found to be the most sensitive was T. platyurus. T. platyurus detected a higher number of toxic water samples during the dry season. Concerning the luminescent inhibition of V. fischeri, the results showed that this organism detected a great number of toxic water samples in rainy seasons. The water samples, which promoted higher toxic effects towards this species, were from the north and from the middle of the reservoir. The correlation analysis showed that V. fischeri luminescent inhibition (%) was positively correlated with total phosphorus, chlorpyrifos, iron, and arsenic. T. platyurus mortality (%) was positively correlated with the water pH, 5-day biochemical oxygen demand (BOD(5)), chlorides, atrazine, simazine, terbuthylazine, and endosulfan sulfate contents. Although the surface waters did not promote acute toxicity to the crustacean D. magna, in the chronic exposure, a significant decrease in the number of juveniles per female was observed, mainly at the dry period. The number of juveniles per female, in the reproduction test of D. magna, was negatively correlated with pH, temperature, BOD(5), chloride, atrazine, simazine, terbuthylazine, and endosulfan sulfate. The water toxicity of the Alqueva water might be due principally to the intensive agriculture activities surrounding the reservoir and to the municipal wastewater discharges. DISCUSSION: The physicochemical parameters and the pesticide concentrations indicated that the water quality was worse in the north part of the reservoir system. These results are characteristic of the majority of reservoirs, once the construction of the dam promoted, by itself, the impounding of water flow and the increase of compound residence time. The toxicity tests corroborate with the chemical characterization. Acute toxicity of Alqueva water may be a result of the effect promoted by chlorpyrifos, endosulfan sulfate, phosphorus, and iron. Chronic toxicity may be a result of the effect of herbicides, arsenic, organic matter, endosulfan sulfate in mixture. Hence, the water toxicity of the Alqueva might be due principally to the intensive agriculture activities surrounding the reservoir and to the municipal wastewater discharges. CONCLUSIONS: This study has shown that a large number of samples from different sites of the Alqueva reservoir contained potentially toxic contaminants. The sites with impaired water quality were those located at the north of the reservoir and in the surrounding areas of intensive agricultural activity. The results demonstrated that the use of a screening of acute and chronic toxicity tests with organisms from different trophic levels and with distinct sensibilities allowed the detections of several patterns of toxicity from spatial and temporal variability promoted by natural or anthropogenic sources. The chronic responses showed, especially in the dry season, that some of the species belonging to this aquatic ecosystem might be at risk. RECOMMENDATIONS AND PERSPECTIVES: The V. fischeri and T. platyurus are two species that should be used in the acute bioassays for the ecotoxicological monitoring programs of this reservoir. It is recommended that other species, such as a productive organism (algae), be included in the next study, once the water reservoir had high levels of herbicides. Ecotoxicological assessment of surface water must integrate initial screening based on acute tests followed always by chronic bioassays. The results implicitly suggest that the implementation of processes of remediation by reducing pollutant input into the reservoir and by the implementation of water treatment processes is important and necessary.

Toxicity of nanosized and bulk ZnO, CuO and TiO2 to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus.

As the production of nanoparticles of ZnO, TiO2 and CuO is increasing, their (eco)toxicity to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus was studied with a special emphasis on product formulations (nano or bulk oxides) and solubilization of particles. Our innovative approach based on the combination of traditional ecotoxicology methods and metal-specific recombinant biosensors allowed to clearly differentiate the toxic effects of metal oxides per se and solubilized metal ions. Suspensions of nano and bulk TiO2 were not toxic even at 20 g l(-1). All Zn formulations were very toxic: L(E)C50 (mg l(-1)) for bulk ZnO, nanoZnO and ZnSO4.7H2O: 1.8, 1.9, 1.1 (V. fischeri); 8.8, 3.2, 6.1 (D. magna) and 0.24, 0.18, 0.98 (T. platyurus), respectively. The toxicity was due to solubilized Zn ions as proved with recombinant Zn-sensor bacteria. Differently from Zn compounds, Cu compounds had different toxicities: L(E)C50 (mg l(-1)) for bulk CuO, nano CuO and CuSO4: 3811, 79, 1.6 (V. fischeri), 165, 3.2, 0,17 (D. magna) and 95, 2.1, 0.11 (T. platyurus), respectively. Cu-sensor bacteria showed that toxicity to V. fischeri and T. platyurus was largely explained by soluble Cu ions. However, for Daphnia magna, nano and bulk CuO proved less bioavailable than for bacterial Cu-sensor. This is the first evaluation of ZnO, CuO and TiO2 toxicity to V. fischeri and T. platyurus. For nano ZnO and nano CuO this is also a first study for D. magna.

Early Distal-less expression in a developing crustacean limb bud becomes restricted to setal-forming cells.

Distal-less (Dll) plays a well-known role in patterning the distal limb in arthropods. However, in some taxa, its expression even during early limb development is not always limited to the distal limb. Here, I trace the expression of Distal-less in a crustacean (Thamnocephalus platyurus) from the early limb bud to later stages of limb development, a period that includes differentiation of juvenile and adult morphology. During early development, I find two distinct types of DLL expression: one correlated with proximal distal leg patterning and the other restricted to setal-forming cells. Later in development, all the DLL expression is restricted to setal-forming cells. Based on the particular cells expressing DLL, I hypothesize an ancestral role for Dll function in the formation accessory cells of sensilla.

Improving the fatty acid profile of fairy shrimp, Streptocephalus dichotomus, using a lipid emulsion rich in highly unsaturated fatty acids.

Fatty acids are the largest component of lipids and have become a useful tool in the determination of live feeds to a variety of cultured species. Bioencapsulation is a technique which allows high-level incorporation of desired components (i.e., fatty acids, vitamins, antibiotics, etc.) in live feeds, which in turn can be supplemented to the consumer organisms. The procedure described in the present study serves as a platform of technology for enriching the Streptocephalus dichotomus. Uptake of two enrichment diets (ALGAMAC2000 and DHA-SELCO) by adult S. dichotomus was investigated. The fatty acid profile supports the hypothesis that the enrichment diet increases the level of essential fatty acids, such as linolic, linolenic, eicosapentenoic, and docosahexaenoic acids. The average content (percent of total fatty acids detected) of the enriched organism by different highly unsaturated fatty acid (HUFA) products were as follows: ALGAMAC2000 showed 14-22% saturated fatty acid (SFA), 17-18% monounsaturated fatty acid (MUFA), 28-41% polyunsaturated fatty acid (PUFA), 23-34% n-3, and 4.9-7.5% n-6, whereas DHA-SELCO showed about 20-23% SFA, 20-26% MUFA, 38% PUFA, 28-31% n-3, and 7.5-10% n-6. Our present investigation proves that both HUFA-rich diets appear to be an appropriate enrichment diet, and further provides an additional rationale for using fairy shrimp as a maturation diet for any cultivable freshwater organism.

Ecotoxicological study of Lithuanian and Estonian wastewaters: selection of the biotests, and correspondence between toxicity and chemical-based indices.

The toxicity of industrial and urban wastewater (WW) samples collected in Lithuania and Estonia was evaluated by using a suite of biological tests comprising the Algaltoxkit F with Selenastrum capricornutum, the Charatox with Nitellopsis obtusa, Daphtoxkit F with Daphnia magna, Thamnotoxkit F with Thamnocephalus platyurus, Protoxkit F with Tetrahymena thermophila and the Microtox with Vibrio fischeri. The Charatox and Thamnotoxkit F tests showed highest relative sensitivity, responding to 80-90% of samples, respectively, and both expressed good discrimination capacity between samples. Principal Component and pairwise correlation analysis allowed to select test-battery consisting of Charatox, Thamnotoxkit and Microtox. The WW toxicity was evaluated by means of cumulative indices such as average toxicity (AvTx) and two indices derived from the PEEP-index (Environ. Toxicol. Water Qual. 8 (1993) 115). In addition to these integrated evaluations of test-battery response, WW toxicity was evaluated according to the most sensitive test (MST) in the battery. The linear regression analysis between cumulative toxicity indices and chemical-based indices (derived from comparison of WW chemical concentrations and their respective maximum allowable concentration) revealed positive linear relationships (r(2)=0.7-0.8), while toxicity evaluation based on the MST was less positively related with chemical analysis data (r(2)=0.5-0.6). Although better coincidence between the toxicity and chemical-based assessments was achieved when information from all tests in the battery was assembled, the prediction of toxicity from chemical data was still limited. In search of suitable test-battery for the screening of certain type of WWs, a preliminary study comprising excessive suite of tests might be useful.

Eclosión de quistes en dos especies de Dendrocephalus (Anostraca: Thamnocephalidae) de uso potencial como alimento en acuacultura / Eclossion of cysts in two species of Dendrocephalus (Anostraca: Thamnocephalidae) in a potential use as food in aquaculture

The use of Artemia salina nauplii as live food has significantly aided culture of commercial fish and shrimps in recent years. However, reported deficiencies in the nutritional value of some strains originated the study of freshwater fairy shrimps as an alternative to Artemia. This study presents cyst biometry for Dendrocephalus geayi and D. spartaenovae (Anostraca: Thamnocephalidae), and the effects of some physicochemical variables on cyst hatching. The biometric characteristics of D. geayi and D. spartaenovae are within the size range of commercial Artemia strains. Favorable conditions to hatch D. geayi are 30 degrees C and conductivity near that of distilled water (<5 micromhos). For D. spartaenovae, these conditions are 28 degrees C and 280 micromhos. A very low salinity such as 1 per thousand inhibits hatching in both species.

[Eclossion of cysts of two species of Dendrocephalus (Anostraca: Thamnocephalidae) of potential use as food in aquaculture]. / Eclosión de quistes en dos especies de Dendrocephalus (Anostraca: Thamnocephalidae) de uso potencial como alimento en acuacultura.

The use of Artemia salina nauplii as live food has significantly aided culture of commercial fish and shrimps in recent years. However, reported deficiencies in the nutritional value of some strains originated the study of freshwater fairy shrimps as an alternative to Artemia. This study presents cyst biometry for Dendrocephalus geayi and D. spartaenovae (Anostraca: Thamnocephalidae), and the effects of some physicochemical variables on cyst hatching. The biometric characteristics of D. geayi and D. spartaenovae are within the size range of commercial Artemia strains. Favorable conditions to hatch D. geayi are 30 degrees C and conductivity near that of distilled water (<5 micromhos). For D. spartaenovae, these conditions are 28 degrees C and 280 micromhos. A very low salinity such as 1 per thousand inhibits hatching in both species.