Streptocephalus Dichotomus Research Articles

Streptocephalus diversity in Myanmar, with description of a new species (Branchiopoda, Anostraca).

The diversity of anostracans in Myanmar is poorly known. A series of biodiversity surveys had been conducted in Myanmar, and two species of Streptocephalus were collected in the central dry zone. Streptocephalus sirindhornae Sanoamuang et al., 2000 is reported in Myanmar for the first time, and Streptocephalus shinsawbuae sp. n. is described as new. Streptocephalus shinsawbuae sp. n. belongs to the S. dichotomus group and is similar to S. simplex Bond, 1934 and S. sahyadriensis Rogers & Padhye, 2014, but can be distinguished by the form of the male antennal posterior primary ramus and anterior primary ramus apex and egg ornamentation. Streptocephalus dichotomus has been reported from Myanmar in the past but was not found in this survey.

Ultrastructure of Spermatozoa in a Freshwater Fairy Shrimp, Streptocephalus dichotomus (Crustacea: Anostraca)

Ultrastructure of spermatozoa in fairy shrimp Streptocephalus dichotomus revealed that they are amoeboid type with no acrosome and flagella. Surface topography of the spermatozoon is smooth with occasional pseudopodial projections. Transmission electron micrographs of spermatozoa show organelle and the mitochondria which is not fused to form the so called ‘Nebenkern’. The testicular lumen reveals spermatozoa in varying sizes and shapes.

Observations on the hatching dynamics and phenology of co-occurring large branchiopods from a small temporary pool in western India usingex situsediment rehydration

Sediment rehydration is a useful technique to study various ecological aspects of resting egg banks of many aquatic invertebrates, but there is a paucity of such studies from the Asian region as compared with other regions. Hence, using a tropical temporary pool as a study system, and with successive, ex situ hydrations of sediments, we studied (1) the hatching phenology and dynamics of co-occurring Notostraca and Anostraca, and (2) the effects of cyclical hydroperiods on these dynamics. Ten species of different aquatic taxa emerged from the sediments. Among the large branchiopods, the primary consumer Streptocephalus dichotomus (Anostraca) was more numerous than the predatory Triops granarius (Notostraca). However, while differing in ecological roles, the two species exhibited similar phenology and hatching strategies, with nauplii emerging in similar proportions across hydration treatments, peaking at the first hydration (∼90%), and decreasing through the third. Hatching began on day 1 in all hydrations and peaked on days 2–3. Hatching duration decreased with successive hydrations, being the longest for the first hydration. These species are important to the food chain associated with temporary aquatic habitats, which are relatively understudied in the Indian context. Laboratory-based studies, in combination with field data can help understand the ecology of the associated community. We highlight the need for such studies that can prove important for conservation of such habitats, when their destruction is rampant and undocumented.

Distribution and assemblages of large branchiopods (Crustacea: Branchiopoda) of northern Western Ghats, India

The present study is a report on the distribution and assemblages of large branchiopods from the Western Ghats of Maharashtra. Different types of water bodies were sampled including pools on lateritic outcrops. Eight species of large branchiopods were found in 72 samples collected over a period of 4 years. We found 7 large branchiopod species in rock pools, while the cyclestheriid Cyclestheria hislopi was observed only in rivers and water reservoirs. In twenty-five percent of the samples multiple species co-occurred with a maximum of 4 species in a single sample. Streptocephalus dichotomus was the most commonly observed species while Streptocephalus sahyadriensis was noted only in rock pools. Altitude and aquatic vegetation were identified as important factors for the distribution of large branchiopods in the studied area. Triops granarius was the species most commonly found to be co-occurring with other species, followed by S. sahyadriensis. Cyclestheria hislopi and Eulimnadia indocylindrova always occurred alone.

EFFECT OF TWO ORGANOPHOSPHORUS PESTICIDES ON THE REPRODUCTIVE BIONOMICS OF FRESHWATER FAIRY SHRIMP STREPTOCEPHALUS DICHOTOMUS (BAIRD, 1860) (CRUSTACEA: ANOSTRACA)

This study evaluates the effects of the two organophosphorus pesticides (malathion) and (glyphosate), on the reproductive bionomics of the freshwater fairy shrimp Streptocephalus dichotomus . The sublethal effects at 1/5 th of 96 h LC 50 of malathion, 2.0 ppm, and glyphosate, 0.0011 ppm on cyst production of the pre-adults were also studied. The 24 and 48 h LC 50 values of malathion for nauplius were found to be 14 and 12 ppm; for glyphosate they were 0.026 and 0.014 ppm, respectively. The 24, 48, 72 and 96hr LC 50 values of malathion for juveniles were 9.6, 8.0, 7.1 and 6.4 ppm; for pre-adults were 26.0, 16.8, 12.1and 9.1 ppm, respectively. Similarly the 24, 48, 72 and 96 hr LC 50 values of glyphosate for juveniles were 0.097, 0.052, 0.032 and 0.017 ppm; for pre-adults were 0.013, 0.010, 0.007 and 0.005ppm , respectively. Animals treated with malathion (2.0 ppm) produced 41.2±12.7 cysts/female/day whereas the glyphosate exposure at 0.0011ppmresulted 95.5±12.6 cysts/female/day when compared to control (118.7±10.21cysts/female/day). An overall significant effect of pesticides on the cyst production between control and pesticide treated fairy shrimps was revealed (P<0.001). Of the two organophosphorus pesticides tested, glyphosate was found to be significantly more (1000 times) toxic to fairy shrimp nauplius, juveniles and preadults than malathion. However, at the sub lethal level, malathion showed higher reproductive toxicity than glyphosate.

Histopathological changes in the ovaries and muscle tissues of freshwater fairy shrimp Streptocephalus dichotomus (baird), exposed to malathion and glyphosate

Possible impact of organophosphorus pesticides namely malathion and glyphosate on the ovaries and muscle tissues of the freshwater fairy shrimp Streptocephalus dichotomus were reported here for the first time. Preadult fairy shrimps were exposed to sub lethal concentration (1/5th of 96hrs LC50) of malathion (2.0 ppm) and glyphosate (0.0011 ppm) for a period of 30 days. Histological observations revealed a few marked pathological lesions such as mild destruction of epithelial layer, follicle cells, nurse cells, necrosis and degeneration of oocytes in the ovaries. Similarly degeneration of muscles, necrosis of muscle fibers, haemorrhages and appearance of pigmented cells in the muscle tissues were evident compared to control. The structural alterations observed in the ovaries and muscle tissues of the freshwater fairy shrimp are suggestive that malathion and glyphosate caused tissue damage at the tested concentrations. Therefore, the findings of this investigation can be taken as biomarkers for monitoring pesticides contamination in aquatic biota.

Does gender really matter in contaminant exposure? A case study using invertebrate models

Exposure to contaminants in the environment is indiscriminate and multiple species/populations of all sexes are potentially at risk. In this paper we examine the current information available on gender specific differences in invertebrates following exposure to environmental contaminants. Because of their close association with the environment and diversity of habitats, invertebrates are uniquely at risk for adverse responses to pollutants. Since 97% of all animal species are invertebrates, it would be impossible to cover each of the phyla in this review. Instead, this paper discusses major invertebrate species including insects ( Periplaneta americana, Panorpa vulgaris, Lycosa hilaris, Haematobia irritans irritans (L.), and Drosophilia melanogaster), nematodes ( Caenorhabditis elegans), crustaceans ( Streptocephalus dichotomus, Amphiascus tenuiremis, Microarthridion littorale, Tisbe bulbisetosa, Acartia tonsa, and Palaemonetes pugio), mollusks ( Pinctada fucata martensii, Ilyanassa obsoleta, Nucella lapillus, Hinia reticulata, Thais clavigera, and Mercenaria mercenaria), corals ( Euphyllia ancora and Montipara capitata), and echinoderms ( Asterias rubens) that have been used in studies examining the differences between males and females. Our discussion focuses on gender differences that occur in both toxicokinetic mechanisms (uptake and elimination, metabolism and physiology) and other toxicological endpoints (survival and behavior as well as morphology and development). It will become evident that the endocrine systems of invertebrates have many traits and/or pathways that are comparable to those observed in higher organisms. Yet the sensitivity of some elements of the invertebrate endocrine system, e.g., disruption of neuropeptide hormone signaling following TBT exposure, highlights the uniqueness of their systems and their potential for disruption.

Scanning electron microscope study of the development of mandibular structure and the molar surface morphology ofBranchinella maduraiensisandStreptocephalus dichotomus(Crustacea, Anostraca)

In the present study, the molar surface morphology of Streptocephalus dichotomus Baird, 1860 and Branchinella maduraiensis Raj, 1961 is analyzed and correlated with the distribution of these species in ephemeral pools. The larval stages of S. dichotomus are characterized by scanning electron microscopy in relation to their feeding physiology, which shows their morphological complexity during developmental stages. The larval mandible consists of a coxa with a three-segmented palp, and further development leads to its gradual transition into the adult mandible. Muscles involved in mandibular movement exhibit rotatory and counter-rotatory movement, which enhances the grinding of food materials. Analysis of the molar surface morphology of B. maduraiensis and S. dichotomus reveals that the mandibles are asymmetrical. Detailed analysis of the topography of the molar illustrates specific structural differences between the species. Gut content analysis also perfectly matches the molar morphology of these species, confirming that B. maduraiensis handles zooplankton more preferentially than S. dichotomus. Our investigation of these fairy shrimps provides information on their molar surface morphology and feeding biology, which increases the understanding of their coexistence.

Composition and nutritional efficacy of adult fairy shrimp Streptocephalus dichotomus as live feed

Success in aquaculture is based on various criteria, in which selection of a suitable feed and its potential use is important. The suitability and potential use of the adult fairy shrimp, Streptocephalus dichotomus, as a live feed was investigated. S. dichotomus contains 55% protein, 9% carbohydrate, 19% lipids, 10% ash and an energy value of 20 kJ/g, which is equivalent to Artemia sps. The amino acid composition of adult S. dichotomus was determined; the levels of essential amino acids in proteins were 7.7% lysine, 2.8% methionine, 1.6% histidine, 7.4% arginine, 4.6% isoleucine, 8.2% leucine, 4.9% valine, 4.3% glycine, and 5% threonine which are higher than those of the Artemia. Analysis of the carotenoids showed the presence of astaxanthin, canthaxanthin and β-carotene. Effective utilization of adult fairy shrimp was studied using the ornamental fish, Carassius auratus, which showed equivalent growth performance similar to Artemia. The biochemical analyses of whole tissue of the fish fed with live feeds showed their efficient utilization. Fatty acid and amino acid compositions of carcasses of fish fed live diets showed their efficient consumption. Energy budget analysis of fish fed on the fairy shrimp, S. dichotomus, revealed that about 99.6% of the consumed feed was assimilated with a conversion ratio of 1.59, similar to Artemia (99.4% assimilated with a conversion ratio of 1.44). The presence of carotenoids, high energy content and optimal nutritional value offers the advantages of fairy shrimp as live feed in freshwater aquaculture.

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.

Nutritional evaluation of decapsulated cysts of fairy shrimp (Streptocephalus dichotomus) for ornamental fish larval rearing

The suitability of decapsulated cysts of the fairy shrimp, Streptocephalus dichotomus as a sole diet was evaluated for the ornamental angelfish Pterophylum scalare larvae. Brine shrimp, Artemia sp., and microworms, Panagrellus redivivus, were used as comparison foods. The results indicate an appreciable weight gain of 15.22±1.69 mg and a growth (length) of 0.876±0.03 cm in experimental fish fed decapsulated fairy shrimp cysts compared with the growth and weight of fish fed other foods. The influence of the experimental diets was further reflected in the composition of fatty acid and amino-acid profiles of the experimental fish. Angelfish larvae readily consumed the decapsulated cysts and utilized them efficiently during the early days of exogenous feeding.

Carotenoprotein complexes in entomostracan crustaceans ( Streptocephalus dichotomus and Moina micrura)

The carotenoprotein complexes of a freshwater fairy shrimp ( Streptocephalus dichotomus) and a daphnid ( Moina micrura) were characterised and compared. Based on thin layer chromatography and mass spectral analysis, a variety of cartenoprotein complexes such as astaxanthin, canthaxanthin, antheraxanthin, lutein, β-cryptoxanthin and violaxanthin were found. Both crustaceans had astaxanthin and canthaxanthin as predominant prosthetic groups. Amino acid analysis of the complexes further revealed high levels of asparagine, glutamine and glycine in both species. Our study highlights the presence of naturally available carotenoid species in both crustaceans and their possible inter-conversion in anostracans.

Sex-linked differences in phenol oxidase in the fairy shrimp Streptocephalus dichotomus Baird and their possible role (Crustacea: Anostraca)

Phenol oxidase activity in the hemolymph of male Streptocephalus dichotomus is only 1/3rd of that of females. About 70% of this activity resides in cell lysate and 30% in plasma. Electrophoretic analysis revealed that male plasma has a single fraction of tyrosine hydroxylase, evidenced by positivity towards tyrosine methylester-PMS-NBT. Female hemolymph has as many as three isozymes showing diphenoloxidase activity. The significance of these results is discussed with reference to sex-linked enzyme activity and its possible role in longevity.

Unfertilized Oocytes in Streptocephalids: Resorbed or Released?

ABSTRACT Short interval monitoring of isolated females of Streptocephalus dichotomus Baird, S. proboscideus(Frauenfeld), and S. torvicornis (Waga) revealed no resorption of unfertilized oocytes in the lateral pouches of the oviducts or in the ovisac. Oocytes expelled by the female disintegrate in the medium. This finding is in disagreement with earlier studies on S. dichotomus and S. proboscideus, but corroborates findings on S. vitreus (Brauer) and S. rubricaudatus (Klunzinger). Light and electron microscopic studies of unfertilized and fertilized oocytes show polar-body extrusion, vitelline-membrane formation, and egg-shell deposition in fertilized oocytes only. The streptocephalids studied here differ, in this respect, from two other anostracans, Tanymastix and Artemia, where unfertilized oocytes develop a vitelline membrane, and sometimes an egg shell.

UNFERTILIZED OOCYTES IN STREPTOCEPHALIDS: RESORBED OR RELEASED?

ABSTRACT Short interval monitoring of isolated females of Streptocephalus dichotomus Baird, S. proboscideus(Frauenfeld), and S. torvicornis (Waga) revealed no resorption of unfertilized oocytes in the lateral pouches of the oviducts or in the ovisac. Oocytes expelled by the female disintegrate in the medium. This finding is in disagreement with earlier studies on S. dichotomus and S. proboscideus, but corroborates findings on S. vitreus (Brauer) and S. rubricaudatus (Klunzinger). Light and electron microscopic studies of unfertilized and fertilized oocytes show polar-body extrusion, vitelline-membrane formation, and egg-shell deposition in fertilized oocytes only. The streptocephalids studied here differ, in this respect, from two other anostracans, Tanymastix and Artemia, where unfertilized oocytes develop a vitelline membrane, and sometimes an egg shell.

Preliminary Studies on the Suitability of a Fairy Shrimp Streptocephalus dichotomus as Live Food in Aquaculture

AbstractA preliminary growth study was conducted with juvenile Oreuchromis mossambicus using a live‐food Streptocephalus dichotomus. Experimental fish showed better growth, survival and food conversion ratios, as well as a significant increase in protein (12%), free sugars (34.4%) and protein bound sugars (101%). However, there was a decline in the lipid content (‐3.99%). Energy budget analysis revealed that about 90% of the consumed energy (as live‐food) was assimilated by the experimental fishes. It is likely that the fish used 45% of the total energy assimilated for metabolic activities associated with growth.

Sexual and developmental differences in the protein pattern of haemolymph and body tissues of Streptocephalus dichotomus Baird (Crustacea: Anostraca)

The protein pattern of haemolymph and body tissues of the freshwater fairy shrimp Streptocephalus dichotomus has been investigated in both sexes, using polyacrylamide disc gel electrophoresis. The electropherograms of four developmental stages show variations in number and intensities of protein fractions. In Stage III, two female-specific proteins of glycolipoprotein nature appear. This stage corresponds to maturity: females begin to possess mature oocytes in the ovary. These two vitellogenic proteins are well represented in the female haemolymph, ovary and freshly laid eggs, but are absent in the male haemolymph. A heterosynthetic mode of yolk formation is thus evident in this anostracan. The two sex-limited proteins are only faintly represented in shelled eggs, suggesting an early utilization of these compounds in embryogenesis.

Studies On the Oviductal Secretion and Ovulation in Streptocephal Us Dichotomus Baird, 1860 (Anostraca)

In Streptocephalus dichotomus, the oviductal cells show the existence of a secretory cycle corresponding to each ovulation cycle. This secretory activity coincides with the passage of eggs from the lateral pouch of the oviduct into the ovisac. During ovulation the glandular cells of the oviduct become flattened and produce large numbers of secretory granules in the form of globules. Various phases of the secretory cycle are also described. The possible function and the type of secretion have been discussed with available information on other anostracans.

Egg envelopes of Streptocephalus dichotomus Baird: A structural and histochemical study

The origin, ultrastructure and histochemical properties of the egg membranes in the South Indian anostracan, Streptocephalus dichotomus have been studied. The egg morphology and the ultrastructure of the tertiary membrane of this phyllopod crustacean have been examined both by scanning and transmission electron microscopy. Scanning electron microscopic observations on the egg surface reveal the characteristic ridges on the egg surface with pores. Similarly, the tertiary egg shell of S. dichotomus consists of two distinct layers, an outer cortex and an inner alveolar layer. There are specific differences in the structure and in the relationship of one layer to the other. The alveolar layer is characterised by large lipid droplets and an alveolar mesh. These two layers termed as tertiary layers are secreted by maternal shell glands. The outer tertiary egg layers are phenolically tanned, the precursor materials for tanning being derived from shell gland secretions.

Nitrogen excretion in Streptocephalus Dichotomus Baird (Crustacea: Anostraca)

The total nitrogen excreted by Streptocephalus dichotomus is 1.5177 mg/g/day for males and 1.3875 mg/g/day for females at 30°C.