Re-use of aquaculture wastewater in cultivating microalgae as live feed for aquaculture organisms

Culturing microalgae using commercial media is expensive. Proliferation of aquaculture is generating high amount of wastewater containing nitrogen and phosphorus and this could be a source of nutrient for cultivating microalgae thereby reducing the production costs. This study compared the growth, productivity, and proximate composition of Chaetoceros calcitrans, Nannochloris maculate, and Tetraselmis chuii cultured in aquaculture wastewater and Conway medium. Results indicated that selected microalgae cultivated in wastewater and Conway medium did not show any significant differences (p > 0.05) in terms of cell density, optical density, and biomass. Further, volumetric and areal productivity showed similar trend for all the three species. But lipid productivity (LP) in N. maculate was significantly higher (p 0.05) for C. calcitrans and T. chuii in terms of LP when cultivated in the two media. N. maculate and T. chuii had significantly higher (p 0.05) in terms of carbohydrate content when cultured either in wastewater or Conway medium. The results indicate that aquaculture wastewater can be re-used as a possible source of low-cost nutrient for culturing selected microalgae for live feed utilization in aquaculture

Testis maturation stages of mud crab (Scylla olivacea) broodstock on different diets

The aim of this study was to investigate how various diets influence testis maturation stages in mud crab (Scylla olivacea) broodstock. Morphological and histological assessments were performed in triplicate (10 male crabs each). Daily, subject crabs were fed a squid (Loligo sp.) and a fish (Decapterus sp.) diet at 5-10% of body weight. Diets were analyzed following methods from the Association of Analytical Communities (AOAC). In comparison to control (wild) crabs, the two diets generally did not cause significant differences (p>0.05) in body weight, carapace width and gonadosomatic index (GSI), except in the GSI of squid-fed crabs (p<0.05). At the end of the experiment, crabs that reached Stage 3 testis maturation included were 6 fish-fed individuals and 23 squid-fed individuals. Additionally, differences in crude protein and fat levels across diets influenced the nature of male gonadal development. In conclusion, a squid diet was sufficient to induce Stage 3 testis maturation in Scylla olivacea within 60 days of culture. Our results prove the usefulness in developing appropriate feeding regimes for male Scylla olivacea broodstock

Dataset for the morphological and erythrocytes parameters of Clarias gariepinus, Pangasianodon hypophthalmus, and their reciprocal hybrid

Discrimination of different fishes can be done through different means which includes morphological appearance. When two fishes are successfully hybridized, they produce progenies that have shared morphology between their pure parent, hence, making morphometric characterization an important aspect of hybrid discrimination. However, erythrocyte characterization is also a simpler method for characterization. The dataset presented in this article represents the traditional morphological data, truss network data and erythrocyte data of pure and novel hybrids from reciprocal crosses of African catfish Clarias gariepinus and Asian catfish Pangasianodon hypophthalmus. Breeding of the broodstocks was done to produce pure and hybrid progenies which were maintained for a period of four to six months. Based on the cross combinations and morphotypes, traditional measurement of twenty-five morphological characters and five meristic counts were recorded. Thereafter pictures of the different fish groups were used to determine values of thirty-six distances between ten landmark points. The morphological abnormality of the hybrids at market size is also presented in this data article for the very first time. Blood was then collected from the caudal peduncle of ten fish per group and smeared on a slide for observation under a compound microscope (at 100 × magnification). Data gotten included erythrocytes parameters such as cell major axis, cell minor axis, nucleus major axis, nucleus minor axis cell area, nucleus area, cell volume, and nucleus volume. Data recording was through the Microsoft excel spreadsheet; which was also used to process the data to get the exclusive ranges of values for paired progenies. The data as presented is associated with the research article “Morphological characterization of the progenies of pure and reciprocal crosses of Pangasianodon hypophthalmus (Sauvage, 1878) and Clarias gariepinus (Burchell,1822)” [1].The dataset presented in this article can be used for easy identification of the novel hybrid progenies of the African Catfish and Asian Catfis

Behavioural data on instar crab movement at different thermal acclimation

This article investigated how crabs responded to different culture temperatures especially dislocation before molting using a combination of large recording files and computer software. In this novel approach of video recording portunid crab behavioral data, crab culture was recorded at five different acclimation temperatures of 20, 24, 28, 32 and 36 °C. Crabs were reared until the instar stage before being acclimatized for video recording. Large video files (MPEG-TS) were then analyzed using the latest version of Solomon Coder software developed by A. Peter and programmed with Embarcadero® Delphi® XE [1]. Recorded data was analyzed by calculating and marking movements of crabs using the time sequence tool. Additionally, a total movement was counted 30 min before crabs molted from instar stage 8 to instar stage 9. Part of the data is associated with the research article “Thermal tolerance and locomotor activity of blue swimmer crab Portunus pelagicus instar reared at different temperatures” (Azra et al., 2018) [2] and provided here as raw data of Supplementary materials. Keywords: Recorded video, Aquaculture, Water temperatur

Effect of Elevated Carbon Dioxide on Two Scleractinian Corals: Porites cylindrica (Dana, 1846) and Galaxea fascicularis (Linnaeus, 1767)

This study reveals the effect of elevated pCO2 on Porites cylindrica and Galaxea fascicularis. The corals responded differently under elevated pCO2. Zooxanthellae cell density, cell mitotic index, and photosynthesis rate of P. cylindrica decreased drastically under the elevated pCO2. At the end of the experiment, P. cylindrica suffered from a declining calcium carbonate precipitation rate. G. fascicularis increased its respiration rate and expelled 71% of its symbiotic zooxanthellae algae under elevated pCO2. Photosynthetic pigments in the remaining zooxanthellae algae increased from 1.85 to 11.5 times to sustain its photosynthetic outputs. At the end of the experiment, G. fascicularis managed to increase the rate of its calcium carbonate precipitation. Increase pCO2 in the atmosphere may affect species diversity of coral reefs

Ovarian maturation stages of wild and captive mud crab, Scylla olivacea fed with two diets

This study was aimed to determine the ovarian maturation stages of wild and captive orange mud crab, Scylla olivacea fed with different diets via gonadosomatic status, oocyte diameter and histological examinations. Captive crabs were fed with blood cockle, Anadara granosa, or fish, Decapterus spp. Through the histological examinations, ovarian maturation stages of wild and captive S. olivacea was classified into four stages: Immature (Stage 1), Early maturing (Stage 2), Pre-maturing (Stage 3) and Fully matured (Stage 4). Gonadosomatic Index of wild and captive crabs remained low during immature and 2 but increased significantly (p<0.05) in pre-maturing and 4 ovaries. Oocytes size were significantly different (p<0.05) in all ovarian maturation stages of wild and captive crabs. Follicle cells surround the oocyte of immature ovary and small yolk globules start to appear in early maturing ovary with large nucleus size. Oocyte size increased significantly (p<0.05) and yolk globule obviously appeared in pre-maturing ovary. Large and fused yolk globules appeared in the oocytes of fully matured ovary with nucleus was barely visible. The present study revealed that, ovarian maturation stages of S. olivacea are closely related to its morphological appearance and cellular development

Effect of different cryoprotectants and sperm densities of orange mud crab, Scylla olivacea (Herbst, 1796) for long-term storage of spermatozoa

The objectives of this study were to determine the effect of different cryoprotectants and sperm densities for long-term storage of orange mud crab, Scylla olivacea spermatozoa. Spermatozoa were obtained by homogenizing the spermatophores using a glass homogenizer in an ice-bath followed by centrifugation at 4°C. Spermatozoa were then suspended in calcium-free saline (Ca-F saline) containing 5% of the following cryoprotectants: Glycerol, dimethyl sulfoxide (DMSO) and methanol. Sperm which vibrated and rotated were counted as live during sperm viability assessment. Samples of spermatozoa were cooled to -196°C by two-step freezing, first to -80°C and then by plunging into liquid nitrogen (LN). Spermatozoa were gradually cooled at 1°C/min. Thawing was carried out in a 30°C water bath for 2 min. This yielded live sperm after storage in LN for 30 days. The best sperm viability was obtained from a density of 108 cells per mL in DMSO. There was no significant difference (p>0.05) among cryoprotectants toward sperm viability. However, sperm viability was significantly affected (p>0.05) by cell densities. In conclusion, DMSO gave the best protection to sperm cells of S. olivacea, but the effectiveness of DMSO as a cryoprotectant is influenced by sperm density