Freshwater Crayfish Cherax Research Articles

Color quality improvement of Cherax quadricarinatus with dragon fruit peel meal utilization

This study aims to determine the effect of dragon fruit peel meal utilization in the diet to improving the color quality of freshwater crayfish (Cherax quadricarinatus). This research was done from May to June 2022 at the Lampung State Polytechnic Fisheries Laboratory. The test animals used were freshwater crayfish with an average weight of 6.7 – 6.8 g/crayfish and a stocking density of 7 crayfish/aquarium. Feeding with a feeding rate of 3% twice a day. The experimental design used was a completely randomized design with 5 treatments and 3 repetitions. The treatments were A = commercial feed (control), B = 5% dose, C = 10% dose, D = 15% dose, E = 20% dose. The parameters observed in this study were an increase in color quality and water quality. The results of this study indicate that the difference in the dose of red dragon fruit peel meal in the diets can have a significant effect on the color brightness of freshwater crayfish (86.01 in claws and 87.59 in Chepalotorax to teslon). The conclusion of this research is that supplementation of red dragon fruit peel meal mainly at a dose of 10% in the feed can improve the color quality of freshwater crayfish from brown to bluish color.Keywords:Dragon fruit peel meal UtilizationDietColor qualityCherax quadricarinatus

Utilization of Chitosan from Fresh Water Lobster (Cherax quadricarinatus) Shells in Anti-Acne Gel Preparations

Cutibacterium acnes is one of the bacteria that cause acne on the face. Freshwater crayfish (Cherax quadricarinatus) shells have been abandoned and are not used by the community; thus, their shells are processed into economically valuable compounds such as chitosan. Chitosan has antibacterial characteristics that can inhibit acne bacterial development. The purpose of this study is to see if chitosan derived from crayfish shells may be stable in the form of an anti-acne gel and has antibacterial action against Cutibacterium acnes. Anti-acne gel was made from crayfish shells at concentrations of 2, 4 and 6 %, then gel formulations were evaluated and antibacterial efficacy against Cutibacterium acnes germs was tested. Chitosan produced by freshwater lobster shells was 68.75 %. The results of the test of freshwater crayfish shells against Cutibacterium acnes revealed that the average diameter of the inhibition was 6.34 mm at a concentration of 2 %, 6.57 mm at a concentration of 4 % and 6.90 mm at a concentration of 6 %; thus, a concentration of 6 % has the best inhibition. According to the organoleptic test, there was no change in shape or color. According to the homogeneity test, there are no lumps or coarse grains. According to the spreadability test, all preparations were within a 56 cm range. The adhesion test shows a satisfactory adhesion time of more than 1 s. The pH test revealed that all preparations were within the normal skin pH range, indicating that the recipe satisfied the specifications. Anti-acne gel prepared from the shell of a freshwater crayfish displays antibacterial action against Cutibacterium acnes as a cause of acne, with an inhibitory diameter of 6.11 mm at 2 % concentration, 6.8 mm at 4 % concentration and 7.11 mm at 6 % concentration. The diameter of the inhibitory zone in the positive control was 11.9 mm. HIGHLIGHTS Freshwater crayfish shells against Cutibacterium acnes revealed that the average diameter of the inhibition was 6.34 mm at a concentration of 2 %, 6.57 mm at a concentration of 4 %, and 6.90 mm at a concentration of 6 %; thus, a concentration of 6 % has the best inhibition Anti-acne gel prepared from the shell of a freshwater crayfish displays antibacterial action against Cutibacterium acnes as a cause of acne, with an inhibitory diameter of 6.11 mm at 2 % concentration, 6.8 mm at 4 % concentration, and 7.11 mm at 6 % concentration. The diameter of the inhibitory zone in the positive control was 11.9 mm GRAPHICAL ABSTRACT

Acoustic Signals and Behavior of the Invasive Freshwater Crayfish Cherax destructor (Clark, 1936)

The study of acoustic signals in aquatic animals contributes to developing new monitoring systems based on passive acoustics and improves our knowledge of their behaviors and ecology. Here, the sounds produced by the invasive species crayfish Cherax destructor and their possible role in intraspecific interactions are analyzed. Synchronized acoustic and video monitoring systems were used in a tank to record acoustic signals and associated behavioral events (tail flips, number of encounters, number of fights) and states (velocity and distance moved, angular velocity, duration of fighting and proximity). The crayfish were monitored in seven layouts combining males (M) and females (F) (F, M, FF, MM, MF, MMF, FFM). Both males and females produced two types of acoustic signals (high- and low-frequency sounds). Grouped animals produced fewer low-frequency sounds than single animals. In a grouped layout, more sounds were recorded when animals were in proximity (distance between two specimen less than 6 cm). In a single layout, sounds were not associated with a specific event or behavioral state. The number of signals emitted in the FF group and single M group were significantly higher than those in other layouts. Our study indicates that low-frequency sounds are produced non-accidentally and provide a baseline for future tests on intraspecific acoustic communication on this species. This study could help implement low-cost passive acoustic monitoring able to identify this species and the possible negative effect of its dispersion in a non-native environment.

Effectiveness of different dosages of vitamin E on the maturation of freshwater lobster (Cherax quadricarinatus)

This study aims to determine the effectiveness of different doses of vitamin E on the maturation of freshwater crayfish (Cherax quadricarinatus). The method used was a Randomized Block Design (RAK) with 4 treatments and 3 replications. The treatments in this study were P1 (control), P2 (vitamin E 150 mg/kg feed), P3 (vitamin E 300 mg/kg feed), and P4 (vitamin E 450 mg/kg feed). Parameters observed in this study were Gonad Maturity Index (GIC), fecundity, and egg diameter.The results of Duncan's analysis showed that the increasing vitamin E to feed was significantly different (P<0.05) with treatment without increasing vitamin E to LAT maturation such as gonadal maturity index, fecundity, and egg diameter. However, administering different doses of vitamin E (150 mg/kg of feed, 300 mg/kg of feed, and 450 mg/kg of feed) had no significant effect on LAT maturation. The treatment without the increasing vitamin E did not show maturity, which was indicated by the value of all parameters 0, while the treatment with the increasing vitamin E to the feed resulted in a range of IKG values, fecundity, and egg diameter respectively was 8.28 - 9.84%, 230.66 - 30.66 eggs and 0.46 – 0.48 mm. The best treatment in this study was treatment with a dose of vitamin E 450 mg/kg feed because it had the highest reproductive performance and could accelerate gonadal maturity in LAT.Keywords: Egg Diameter; Fecundity; Freshwater Lobster; Maturation; Vitamin E

Effectiveness of different dosages of vitamin E on the maturation of freshwater lobster (Cherax quadricarinatus)

This study aims to determine the effectiveness of different doses of vitamin E on the maturation of freshwater crayfish (Cherax quadricarinatus). The method used was a Randomized Block Design (RAK) with 4 treatments and 3 replications. The treatments in this study were P1 (control), P2 (vitamin E 150 mg/kg feed), P3 (vitamin E 300 mg/kg feed), and P4 (vitamin E 450 mg/kg feed). Parameters observed in this study were Gonad Maturity Index (GIC), fecundity, and egg diameter. The results of Duncan's analysis showed that the increasing vitamin E to feed was significantly different (P<0.05) with treatment without increasing vitamin E to LAT maturation such as gonadal maturity index, fecundity, and egg diameter. However, administering different doses of vitamin E (150 mg/kg of feed, 300 mg/kg of feed, and 450 mg/kg of feed) had no significant effect on LAT maturation. The treatment without the increasing vitamin E did not show maturity, which was indicated by the value of all parameters 0, while the treatment with the increasing vitamin E to the feed resulted in a range of IKG values, fecundity, and egg diameter respectively was 8.28 - 9.84%, 230.66 - 30.66 eggs and 0.46 – 0.48 mm. The best treatment in this study was treatment with a dose of vitamin E 450 mg/kg feed because it had the highest reproductive performance and could accelerate gonadal maturity in LAT.Keywords: Egg Diameter; Fecundity; Freshwater Lobster; Maturation; Vitamin E

Growth performance of freshwater crayfish (Cherax quadricarinatus) as the effect of prebiotic-feed from sweet potato

Good growth of freshwater crayfish (Cherax quadricarinatus) is supported by an excellent intestinal digestion process in the absorption of feed nutrition. Implementing prebiotics from sweet potatoes is expected to maximize the nutrient absorption inside the digestive tract of freshwater crayfish. This research aims to evaluate the growth performance of freshwater crayfish in implementing sweet potatoes in feed. The research was conducted for one month, from March to April 2021, in the Laboratory of Hatchery and Cultivation Technology, Agriculture Faculty, Malikussaleh University. The experimental design was a non-factorial, completely randomized design (CRD) with four treatments and three replications. The experimental factor was different percentages of sweet potato in feed, namely A: 0% (Control), B: 1%, C: 2%, D: 3%. This research showed that prebiotic feed from sweet potatoes had a significant effect (p<0.05) on freshwater crayfish's growth and feed efficiency. The best result was demonstrated by treatment D, namely adding sweet potato 3% in feed at length growth of 2.64±0.035 cm and weight growth of 3.155±0.078 g. Meanwhile, the feed efficiency value of freshwater crayfish was 69.023±7.118%. The water quality parameters during the research were optimal for crayfish cultivation.

Cloning and expression of the thioredoxin gene in Cherax quadricarinatus (Von Martens, 1868) (Decapoda: Astacidea: Parastacidae) under bacterial stress

Abstract As a member of the thioredoxin (Trx) system, the Trx1 gene plays essential roles in the pathogenesis of various diseases. The function of Trx in bacterial infections in the freshwater crayfish Cherax quadricarinatus (Von Martens, 1868), however, has not been clarified. We cloned thioredoxin 1 (CqTrx1) from C. quadrangularis, and its expression was investigated. The results showed that the coding sequence of the CqTrx1 gene was 318 bp, encoding a polypeptide of 105 amino acids, contains the conserved motif CGPC (Cys-Gly-Pro-Cys), and was 75.24% and 66.67% identical to sequences of the shrimps Macrobrachium rosenbergii (De Man, 1879) and Fenneropenaeus chinensis (Osbeck, 1765), respectively. The CqTrx1 transcript existed in all organs tested, with the highest expression level in the intestinal tract and the lowest expression level in the gonads. Under the stress of Vibrio algolyticus, V. parahaemolyticus, or Aeromonas hydrophila, the expression level of CqTrx in the gills was 3.1, 4, and 7 times that in the control group at 3, 9, and 24 h, respectively, indicating that CqTrx1 plays an essential role in shrimp antibacterial immunity.

Zeolite mediated processing of nitrogenous waste in the rearing environment influences gut and sediment microbial community in freshwater crayfish (Cherax cainii) culture

Zeolite is known to uptake toxic metals and filter nitrogenous waste from aquaculture effluents. The present study aimed to investigate the impacts of zeolite in three different applications namely, dietary zeolite (DZ), suspended zeolite (SZ) in the water column, and a combination of both (DZSZ) relative to unexposed freshwater crayfish, marron (control). At the end of the 56-days trial, the impact was assessed in terms of characterization of microbial communities in the culture environment and the intestine of marron. Alongside the microbial communities, the innate immune response of marron was also evaluated. The 16S rRNA data showed that marrons exposed to the suspended zeolite had a significant increase of bacterial diversity in the gut, including the restoration of marron core operational taxonomic units (OTUs), relative to other forms of exposures (DZ, DZSZ) and the control. Suspended zeolite alone also increased the number of unshared OTUs and genera, and improved predicted metabolic functions for the biosynthesis and digestion of proteins, amino acids, fatty acids, and hormones. In the tank sediment, the shift of microbial communities was connected more strongly with the time of experiment than the type of zeolite exposure. In the second case, only control marron had a different microbial ordination in terms of rare taxa present in the community. Nevertheless, the modulation in the gut environment was found more prominent in DZ, relative to modulation in the tank sediments. The taxa-environment correlation identified Rhodoferax as the most potential bacteria in removing nitrogenous waste from the rearing environment. Further analysis showed that SZ resulted in the upregulation of genes associated with the innate immune response of marron. Overall results suggest that SZ can be used to enrich microbial communities in the gut and tank sediments and better immune performance of marron.

Effects of an oil-based substrate (The Water Cleanser\u2122) and bacterial additives on nitrogen and phosphorous dynamics in freshwater crayfish (Cherax cainii, Austin and\xa0Ryan 2002) aquaculture

Two experiments were conducted to evaluate the efficacy of an oil-based substrate, The Water Cleanser™ (TWC). The first experiment studied the effects two substrates of different oil composition (TWC, TWC +), and a commercial bacterial additive (Bio-Aid) on concentrations of nitrogen and phosphorous in indoor aquaria. The second experiment studied the effects of TWC, a bacterial additive, and a combination (TWC + B) on concentrations of nitrogen and phosphorous, phytoplankton abundance and diversity in outdoor freshwater crayfish (Cherax cainii, Austin and Ryan, Invertebr Syst 16:357–367, 2002) tanks. In the first experiment, the concentration of TAN decreased more rapidly with Bio-Aid, whilst the maximum concentrations of NO2-N and NO3-N were reduced with the substrates. The concentration of orthophosphate was reduced in aquaria with TWC + . In the second experiment, concentrations of TAN, NO2-N, NO3-N and total phosphate were not significantly affected by TWC. After addition of TWC + B, there was a significant decrease in the concentrations of nitrate and total phosphate, and a higher abundance of phytoplankton was maintained than with other treatments. Additionally, a population Bacillus sp. was found on the substrate surface. TWC had no adverse effects on phytoplankton abundance or diversity, or C. cainii physiology, weight gain or survival. TWC and TWC + were effective bioremediators of eutrophic water, whilst a combination of TWC + B was effective in short term bioremediation and in promoting phytoplankton abundance in C. cainii tank culture.

Pemberian minyak pala (Myristica fragrans) Houttuyn 1774 sebagai bahan anestesi dengan konsentrasi berbeda pada benih lobster air tawar (Cherax quadricarinatus) Von Martens 1868

This study aimed to examine the best concentration of nutmeg oil for anesthesia of freshwater crayfish (Cherax quadricarinatus) seeds and analyze the length of time to faint, the length of time to faint and the length of time to wake up for the seeds of freshwater crayfish (C. quadricarinatus) . This research was carried out at the Aquaculture Technology Laboratory, Faculty of Fisheries and Marine Sciences, Sam Ratulangi University, Manado. The time of the research was carried out from April 18, 2021 - May 18, 2021. This study used a completely randomized design (CRD) consisting of 5 treatments and 3 replications, thus there were 15 experimental units. Treatment A with a dose of nutmeg oil (0.7 mL), treatment B (1 ml), treatment C (1.3 mL), treatment D (1.6 mL) and treatment E (1.9 mL). Parameters observed during behavioral research, length of time to faint, length of time to faint and length of time to wake up. The results of the study using the ANOVA statistical analysis test and the BNT follow-up test (Least Significant Difference) showed that different doses of nutmeg oil had a very significant effect on the length of time to faint, the length of time to faint and the length of time to wake up. The length of time to pass out the fastest, the longest length of time unconscious and conscious longest duration was obtained in treatment E (1.9 mL).

ГЕМАТОЛОГИЧЕСКИЕ И БИОХИМИЧЕСКИЕ ПОКАЗАТЕЛИ ГЕМОЛИМФЫ АВСТРАЛИЙСКОГО КРАСНОКЛЕШНЕВОГО РАКА

The article describes Australian red claw crayfish, Cherax quadricarinatus, which is currently one of the most promising cultivation targets. However, to increase production volumes, it is necessary to improve cultivation technologies, which should be based on the data of physiological and biochemical parameters. An objective method for monitoring the physiological state 
 of Australian red claw crayfish in the artificial conditions is determining its hematological and biochemical indicators that complement the general characteristics of hemolymph and later define its physiological norm. When giving the objects the compound feed, which the authors produced by their own recipe, there was recorded a high level of total hemolymph protein of 40.8 ± 4.5 g/l. According to the results of biochemical research, the cholesterol content in the hemolymph of Australian crayfish was 3.2 ± 0.6 mmol/l, and the concentration of lipoproteins was 0.8 ± 0.2 g/l (levels within the reference values). When considering the hemogram of hemolymph there were found the dominant types and linear dimensions of native formed elements. The diameter of agranulocytes in Australian freshwater crayfish varied from 85 to 90 μm, semi-granulocytes - from 90 to 95 μm, granulocytes - from 65 to 78 μm, transparent cells differed by greater variability in size, which ranged from 85 to 120 μm. The part of granulocytes in relation to other shaped elements exceeded 50%, for transparent cells it turned out to be above 20%, for semi-granulocytes - about 15% and for agranulocytes - about 5%, which means that the latter form the rarest group. The established ratios are specific for Cherax quadricarinatus, its hemocytic characteristics greatly differs from Astacus leptodactylus, which is the main object of comparative research. The results of comparative analysis of the cellular composition of the hemolymph of the Australian freshwater crayfish Cherax quadricarinatus (Von Martens, 1868) demonstrate the taxonomic specificity of this representative of freshwater aquaculture

Monosex male formation of juvenile redclaw crayfish using natural steroid hormone from gamma sea cucumber and different doses of honey bee

In a new commercial commodity aquaculture, tropical freshwater crayfish Cherax quadricarinatus, it is known that female has a slower growth rate than male. One way to increase production rate is through monosex cultures comprising all-male population by using genital reversion technique. This biotechnology method can be applied by using hormones and natural products. The natural hormones extracted from gamma sea cucumber, Stichopus variegatus has bioactive substances including steroid compounds, while honey bee contains chrysin compounds that act as aromatase inhibitors. Therefore, the combination of both substances expected can increase in testosterone level and accelerate production in the male monosex population of juvenile crayfish. The purpose of the study is to determine the most effective dose of honey bee in masculinization of juvenile freshwater crayfish combined with 2 mg. L−1 steroid extract of gamma sea cucumber. Furthermore, a Completely Randomized Design (CRD) was designed in the experiment with five different dose of honey bee treatment and dipping method in 2 mg. L−1 steroid extract of gamma sea cucumber for 18 h. Each treatment with four replications. The highest male formation was found in the dose of 20 ml. L− 1 honey bee at 83.75% and the lowest was in control. The present of honey bee at different doses in 2 mg. L−1 of gamma steroid extract did not significantly give an effect on percentage of female, intersex formation, survival, and growth rate of juvenile redclaw crayfish.

Comparison of Morphological Characters of Freshwater Crayfish (Cherax quadricarinatus) from Different Ecosystems in Indonesia

Freshwater crayfish (Cherax quadricarinatus) as an invasive species has high capability to adapt in most waters in Indonesia. The extant distribution of this species in Indonesia causes observation of morphological characters is important to be established. This study purpose is to compare the morphological characters of Cherax quadricarinatus from several locations in Indonesia waters, such as the river in Bintan Island, Toba Lake, and Lido Lake. The total of morphological characters was measured in twenty-two characters. The result of the Kruskal-Wallis test represented nine different characters between Toba, Bintan, and Lido. Cluster analysis illustrated the highest level of similarities between Toba and Lido. The growth rate of the dactyls, and carapace width, and ocular carapace length between Toba and Lido were similar, meanwhile between Toba and Bintan were different. C. quadricarinatus originating from river waters in Bintan Island has a different morphological character from Lake Lido and Lake Toba. The differences in morphological characters between locations are caused by differences in habitat characteristics in rivers and lakes.

Фактологическое обеспечение практик повышения эффективности выращивания тропических пресноводных видов

The article describes the possibility to grow tropical freshwater crayfish Cherax quadricarinatus (Von Martens, 1868) and shrimp Macrobrachium rosenbergii (De Man, 1879) 
 in the climatic conditions of the Astrakhan region during 3-5 months, with further wintering in the ponds of fish farms. To achieve the maximum effect of the semi-intensive and intensive cultivation conditions it is necessary to apply additional feeding, observe the norms of seeding density and the diets of crustaceans. In two series of experimental works conducted in 2019-2020 on the base of Astrakhan State Technical University and a small innovative enterprise Modern Fishbreeding Complex Sharapovsky there was studied the method of increasing the biological and aquaculture potential of fast-growing tropical freshwater crayfish and shrimps by adjusting feed diets, chilled wet feed, and native formula feed based on feed components of local raw materials. Salicornia perennans Willd, a halophyte plant, was introduced into the formulation for the first time. As a result of experimental works the recommendations on semi-intensive and intensive cultivation of tropical freshwater species have been formulated, the possibility of increasing biological and aquaculture productivity of grown objects has been considered, which is recorded in the fish-biological standards and general management processes.

Biodiversity of nekton in Batangtoru River and its tributaries in North Sumatra, Indonesia

Abstract. Desrita, Muhtadi A, Leidonald R, Sibagaring RD, Nurfadillah 2020. Biodiversity of nekton in Batangtoru River and its tributaries in North Sumatra, Indonesia. Biodiversitas 21: 2344-2352. Batangtoru River which flows from the Tapanuli highlands (i.e., Sipirok, Tarutung, Siborong-borong, and Silangit) to the southwestern Indian Ocean is an important habitat for aquatic organisms in the western region of North Sumatra. This research was done to provide basic data on biodiversity of aquatic organisms in Indonesia, especially North Sumatra. The study was conducted in July-August 2019. Nekton was captured using backpack electrofishing units (12 volts and 9 Amperes), traps, nets, and bamboo trap. This study found 68 nekton species, consisting of fish (57 species), crab (3), shrimp (6), lobster (1), and 1 freshwater turtle (1). In general, nekton found in the Batangtoru River and its tributaries are native and economically valuable fish (Tor and eel), including the newly discovered species, which was, Hemibagrus caveatus. Invasive fish found consisted of 6 species, i.e., Cyprinus carpio, Oreochromis mossambicus, Oreochromis niloticus, Xiphophorus helleri, Hypostomus plecostomus, and Trichogaster pectoralis. The only invasive crustacean found was freshwater crayfish (Cherax quadricarinatus).

Ibis and spoonbill chick growth and energy requirements: implications for wetland and water management

Colonial-nesting waterbirds such as ibis and spoonbills (Threskiornithidae) can account for a significant proportion of energy flow through wetlands, particularly during large breeding events. However when food availability is reduced, chicks may starve and adults may abandon nests. If the energy required to rear chicks could be calculated, data quantifying prey energy value and availability could be used to develop landscape scale management targets to ensure that food requirements are met to support chicks until they attain independence, thereby maximising recruitment. We calculated ibis and spoonbill chick biometrics and energy requirements through (a) an international literature review, extracting and synthesising the best available growth and energy data; (b) new measurements of ibis and spoonbill chick biometrics for selected species; and (c) analysis of the resulting databases to construct growth curves and predict energy requirements for selected species. Here we present the first models of Royal Spoonbill growth and of Royal Spoonbill and Australian White Ibis chick energy requirements. The total energy estimated to raise a single Royal Spoonbill chick from hatching to independence was 71,290 kJ and for an Australian White Ibis chick was 67,160 kJ. Using prey energy values from the literature, extrapolations indicate that for either species, a nesting event of 1000 nests producing three chicks per nest would require an estimated ten tonnes of freshwater crayfish (Cherax destructor) or eight tonnes of invasive juvenile carp (Cyprinus carpio) to support chicks from hatching to independence. Effective water and wetland management is critical to optimise both energy availability in foraging sites and breeding success.

Truss Morphometric Approach for population kinship analysis of Cherax quadricarinatus (Von Martens, 1868) in West Java Waters

Lobster air tawar spesies Cherax quadricarinatus berasal dari perairan Australia dan Papua Nugini. Pengukuran morfometrik merupakan salah satu teknik dalam membedakan bentuk tubuh dari suatu populasi. Penelitian ini memiliki tujuan untuk menganalisis kekerabatan populasi pada lobster air tawar dari perairan Jawa Barat berdasarkan pendekatan truss morphometric. Beberapa karakter morfometrik dilakukan pengukuran dengan jumlah total sampel sebanyak 133 individu yang meliputi 20 individu dari Waduk Darma, 38 individu dari Situ Kemang, dan 75 individu dari Situ Kemuning. Hasil analisis kluster didapatkan bahwa populasi Cherax quadricarinatus yang berasal dari Situ Kemuning memiliki kekerabatan lebih dekat dengan Situ Kemang dibandingkan dengan Waduk Darma. Adanya perbedaan karakter morfometrik diduga terjadi karena perbedaan kondisi lingkungan pada ketiga populasi. Analisis diskriminan menunjukkan bahwa C. quadricarinatus yang beraal dari Waduk Darma, Situ Kemang, dan Situ Kemuning masing-masing terklasifikasi dengan tepat yaitu sebesar 100%, 63,2%, dan 76%. Sementara itu, terdapat 4 karakter utama yang dapat membedakan populasi dari semua lokasi (C4, B5, D6, dan A6).

Selective expression of a “correct cloud” of Dscam in crayfish survivors after second exposure to the same pathogen

Arthropod hypervariable Dscam (Down syndrome cell adhesion molecule) may be involved in adaptive-like immune characteristics, namely immune priming, enabling the host to “learn” and “remember” pathogens previously encountered in arthropods. However, expression of Dscam in immune-primed arthropods after a second challenge has apparently not been confirmed. Herein, working with Dscam of Australian freshwater crayfish (Cherax quadricarinatus, i.e. CqDscam), we further investigated whether immune priming is mediated by “clouds” of appropriate (or “correct”) CqDscam isoforms. In crayfish that survived a first WSSV challenge (immune priming), long-lasting CqDscam expression remained higher after a second WSSV challenge. Selective CqDscam isoforms were also induced after both challenges. Based on pathogen binding assays, these WSSV-induced CqDscam isoforms had a higher WSSV binding ability, perhaps mainly mediated by Ig3-spliced variants. We therefore hypothesized that in these crayfish survivors, an unknown selection process was generating a “correct cloud” of CqDscam against a previously encountered pathogen.

Study of patterns in the relationship of ecdysis with the age of freshwater crayfish Cherax quadricarinatus aged 76 Days

The purpose of this research study was to examine the growth pattern of ecdysis freshwater crayfish, especially crayfish type Cherax quadricarinaus aged 76 days to 116 days. The descriptive method was used. The data was collected through a direct observation. The data that was obtained consisted of an analysis done using simple linier regression. Because the weight of the crayfish was divergent, the data material was divided into 3 groups as a way to obtain data that was more accurate. For group 1, we obtained a linear regression with an equation of Y = 6,00 + 2,600X. For group 2, we obtained a linear regression with an equation of Y = 8,500 + 2,300X. Group 3 obtained a linear regression with equation of Y = 9,100 + 2,500X. The result explained a positive correlation between ecdysis with number of days. During the experiment, the water quality was still in the range of optimum, the DO ranged from 6,5 - 7 mg/l, the temperature was between 24o C – 27°C, the pH was about 7,5 – 8 and the ammonia was still at the range of normal <0,5.

Feed Enrichment with Amylolytic Lactic Acid Bacteria to Stimulate the Growth of Freshwater Crayfish (Cherax quadricarinatus)

The goal of feed enrichment with amylolytic Lactic Acid Bacteria (LAB) was to get an optimal feed formula in stimulating the growth of freshwater crayfish ( Cherax quadricarinatus ). The research design used a completely randomized block design, which consists of 2 groups (Group I = probiotic HS7 with inoculum density 10 8 and Group II = probiotic HS7 with density 10 10 ). Each group were given 4 different treatment (Feed A = protein 50%-carbohydrate 20%; Feed B= protein 40%-carbohydrate 30%; Feed C= protein 30%-carbohydrate 40%; and Feed D= protein 20%-carbohydrate 50%), with 2 repetition. The parameter observed in this study was daily growth rate and absolute growth. The result showed that Feed C, composed by protein 30%-carbohydrate 40% with LAB enrichment and inoculum density of 10 8 gives the best growth, with daily growth rate of ± 0.22-0.23 % each day and absolute growth of ± 13.10-13.20 gram in 75 days.