Optimum Growth Parameters for Both Indoor and Outdoor Propagation of Microalgae,Chlorella Vulgaris and Isochrysis Galbana

Chlorella vulgaris and Isochrysis galbana were grown under different growth conditions both in indoor and outdoor cultures. Best culture conditions such as light intensities, photoperiods, salinities and nutrient concentrations were determined as well as the biochemical compositions. Indoor cultures of C. vulgaris and I. galbana, when continuously illuminated, grew optimally at 100 μmolm-2s-1 and 40 μmolm-2s-1, respectively. However, under 12 hour light, C. vulgaris grew optimally at 200 μmolm-2s-1. The chlorophylla concentrations in both algae were lower at higher light intensity and higher at lower light intensity. Total protein and total lipid contents of both species were also significantly higher (p<0.05) at lower light intensity. I. galbana contained more lipid than C. vulgaris in those conditions. In contrast to protein and lipid, carbohydrate content increased with increasing light intensity. Similar to C. vulgaris, the lowest carbohydrate content of I. galbana was obtained at l0 μmolm-2s-1 conditions for both photoperiods. Although the protein contents of C. vulgaris varied under different light intensity and photoperiod, the relative proportions of constituent amino acids were found to be almost similar. Total essential amino acids under continuous illumination was significantly higher (p<0.05) at the lowest and the highest intensities while in I. galbana, it was significantly higher (p<0.05) only at the lowest intensity. It was surprising that C. vulgaris contained high proportions of ω-3 highly unsaturated fatty acids at continuous illuminations although both eicosapentaenoic acid (20:5ω-3) and docosahexaenoic acid (22:6ω-3) were absent at 12 hours light. EPA in I. galbana, was absent at 12 hours light, while the DHA was present in relatively smaller quantities than in continuous light. In indoor conditions, at full media concentration, the best salinity for C. vulgaris was at 30 ppt and 25 ppt for I. galbana. C. vulgaris grown in full media concentration contained more chlorophylla relative to that in half media concentration. For I. galbana grown in full media concentration, chlorophylla increased as salinity increased. Protein contents decreased as salinity increase both at full and half strength media for C. vulgaris and I. galbana. The cellular lipid contents of both algae were significantly higher (p<0.05) in half media concentration. In full media concentration, total lipid contents in C. vulgaris decreased at higher salinity but in I. galbana no clear trend in lipid contents in relation to salinity observed. As salinity increased, higher carbohydrate contents were found in C. vulgaris in full media concentration, while in half media concentration an inverse trend was detected. I. galbana also revealed higher proportions of total carbohydrates in half media concentration compared to full media concentration. The amino acid profile of both algae exhibited minor differences at different salinity and media concentrations. Most of the essential amino acid in C. vulgaris and I. galbana were significantly higher (p<0.05) at lower salinity. In C. vulgaris, the EPA was absent while only trace amount of DHA were detected in cells grown under full media concentration. However in I. galbana the amount of EPA was very high at higher salinity and in contrary the, DHA was higher at lower salinity. The growth performances of C. vulgaris outdoor cultures were relatively better than I. galbana under all growth conditions studied. C. vulgaris grown both in unsheltered and sheltered areas demonstrated rapid increased in cell density after four days of culture with no lag phases observed. Unlike C. vulgaris, cultures of I. galbana grown under unshaded conditions demonstrated increase in cell numbers for 2 days but cells under sheltered place demonstrated no increased at all. The highest specific growth rate in C. vulgaris was in lower salinity at half media concentration while the maximum cell density was achieved by cells in full media concentration of the same salinity. For I. galbana cells density of half media concentration was higher then in full media concentration. The highest total protein content of C. vulgaris was obtained in culture under shaded conditions and generally total lipid and carbohydrate were found to be higher in unshaded conditions. However, it was unexplainable why less carbohydrate was found in older cells at both conditions. I. galbana was a fast growing algae and the protein as well as lipid contents were significantly higher (p<0.05) at sheltered condition while no significant changes to carbohydrate content was recorded. The carbohydrate content in C. vulgaris was higher in older cultures in full and half media concentration while at early culture age, the lipid content was higher. In the early culture age of I. galbana, protein content was insignificantly affected (p>0.05) by salinity and media concentration. However, total lipid and carbohydrate were found higher at 15 ppt compared to higher salinity in half media concentration. In the bioeconomic study the production cost of C. vulgaris was found to be directly influenced by labour cost. From the production forecast, it was discovered that the high production cost was due to underutilized labour force which can be reduced by having bigger scale production. In order to break-even for one cycle of 100 L cultures, the minimum culture volume should be 1,902 litres

Biology of aquaculture animals - learning from nature to manage culture

Understanding of aquatic ecosystems and the fundamental aspects of the biology of aquatic animals is vitally important in managing aquaculture on a sustainable basis. The paradigm shift that is taking place in twenty-first century aquaculture is borne out of the compulsion of integrating environmental perspectives and biological attributes of target species in farming systems. There is an overwhelming amount of data highlighting the practical ways that several aspects of research on ecology can be applied to improve aquaculture production. Basic information on the biology of fish or shellfish has helped in designing rearing conditions and with more comprehensive information it is possible to optimize growth of captive animals and efficiency of production per unit area without adverse environmental implications. Aquaculture faces many challenges and at every stage a thorough understanding of the processes that regulate the biological systems of the cultured animals is required for an informed interpretation and for improving rearing methods. Since species selected for aquaculture and their farming systems are diverse, our knowledge should also be comprehensive enough to address the issues that arise in the planning and operation stages of aquaculture

Harvesting of the microalga nannochloropsis sp. by bioflocculation with mung bean protein extract

Harvesting microalgae from medium is a major challenge due to their small size and low concentrations. In an attempt to find a cost-effective and eco-friendly harvesting technique, mung bean (Vigna radiata) protein extract (MBPE) was used for flocculation of Nannochloropsis sp. The effects of parameters such as pH, flocculant dose, algae concentration, and mixing time were used to study the flocculation efficiency (FE) of MBPE. Optimum parameters of MBPE dosage of 20 mL L−1 and a mixing rate of 300 rpm for 6 min achieved a FE of >92% after 2 h of settling time. MBPE-aggregated microlga flocs were characterized by microscopy. Zeta potential values decreased with increasing flocculant dose, and the values obtained were −6.93 ± 0.60, −5.36 ± 0.64, and −4.44 ± 0.22 for doses of 10, 20, and 30 mL L−1, respectively. In conclusion, MBPE flocculants used in this study are safe, nontoxic, and pollution free, so they could be used for an effective, convenient, and rapid harvesting of microalgae in an eco-friendly approach. These methods are sustainable and could be applied in industrial scale for aquaculture nutrition

Reproductive Pattern of Sea Cucumber, Holothuria scabra at Two Different Sites in Sabah, Malaysia

Holothuria scabra is one of valuable sea cucumber in Sabah as it can give a high quality of beche-de-mer that can be source of income for the fisherman. High demand of this species has led to overexploitation and overfishing, thus production in hatchery is crucial to overcome this problem since this species able to be reared in captivity. The presence study was conducted for 14 months started from July 2015 until August 2016 at two places Kudat (N06°49’24.4”, E116°51’42.0”) and Kunak (N04°39’52.05”, E118°15’49.01”) Sabah, Malaysia. Gonad index (GI) and microscopic examinations were used to evaluate monthly variations of gonad maturation. Annual reproductive pattern was observed at Kudat where the highest peak of GI was in July 2015 (1.678 ± 1.079%) and the lowest in July 2016 (0.00 ± 0.00%) whereas in Kunak continuous pattern recorded with the highest peak in September 2015 (3.491 ± 1.699%) and the lowest GI in Feb 2016 (0.184 ± 0.097%). Size at first sexual maturity in Kudat and Kunak were approximately 99 g and 101 g, respectively and in length approximately 174 mm for both places. Keywords: Holothuria scabra, reproductive pattern, gonad index, Kudat, Kuna

Effects of pH and water turbulence on the growth of harmful algae pyrodintum bahamense var. compressum

Pyrodinium, a red tide causing dinoflagellates are often related to toxicity cases particularly paralytic shellfish poisoning (PSP). Study on the effects of specific parameter on the growth it fy*ai"iin is essential to determine the potential factors r-esponsible for thek occurrences. The effects or iH ana turbulence on the growth of Pyrodinium bahamense var. compressun was conducted in laboratory under controlled conditions. P bahamense was cultured in nine different pH levels under two conditions; with and without water turbulence. The experiments were conducted under constant light intensity 100 pmolm-2s{ at 25"C with photoperiod of 12h'light:12 h dark bycle. Cells were incubated for two weeks'and **pri"gr *";;;;" for growth deterrnination every day at interval. This study shows thatP bahamenseattained the highest cell density (616 cells mT:t; when grown at pH 8-5 without water motion. However, in the presence of Ilow water turbulence or water motion, the cell density is relatively low (128 cells ml,-r) at pH 8.5. These different outcomes might be due to the growth inhibitory effect of water motion to P bahameise. Celldensities of p. bahamensewere also found significantly lower at acidic conditions ( 9.0

Temporal and spatial distribution of nutrients and HABs at coastal water of Kota Belud, Sabah

A study was carried out to determine the temporal and spatial distribution of nutrients and Harmful Algal Blooming species (HABs) to establish the relationship between nutrient concentrations and HABs density in the coastal water of Kota Belud, Sabah, Malaysia. Eight stations were set up in four transects (each transect had two stations; one 500 meters seawards from shoreline, and another five kilometers seawards from shoreline) along the Kota Belud coastal area. Phytoplankton samples, water samples and in situ environmental parameters were collected during dry and wet seasons. Altogether nine HABs species were identified from the study area, where six species (Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus) belonged to Dinophyceae and three species (Thalassionema nitzchoioides, Chatoceros affinis, Rhizosolenia sp.) belonged to Bacillariophyceae. Among nine species, Chatoceros affinis was the most abundance composed of 80.6% of total species recorded from all stations during study period. Among the toxic producing Dinoflagellate, Pyrodinium bahamense bloom (>103 cells/l) was observed during study period. Trong linear relationship (r2 = 0.80) was observed between the cell density and concentration of nitrate nitrogen. Relationship between cell density and phosphate phosphorus was poor (r2 = 0.51). The study showed that increasing in nutrient concentrations resulted in the increasing of HABs density. Nitrate was seen to be more important than phosphate in Kota Belud water as limiting factor of the growth of HABs

RNA/DNA ratio in milkfish (Chanos Chanos) larvae reared at different stocking densities

Stocking density can induce stress in fish in an aquaculture system if not handled properly, and the chronic stress may lead to mortality. Several studies have reported that the capability to deal with a range of stocking densities differs among fish species and maturity stage. Hence, fish larvae may have different resilience to stress from the adult fish. Milkfish larvae were reared in hatchery for 50 days using a recirculating culture system at four different stocking densities (8,12,16 and 20 larvae/liter). The growth performance was not significantly different (P>0.05) except at stocking density of 20 larvae/liter. The highest survival rate (88.04%) was recorded in the system with 8 larvae/liter while the lowest (55.44%) in the culture tank where stocking rate was 20 larvae/liter. The stocking density also influenced the RNA / DNA ratio of the milkfish larvae. The RNA/DNA ratio showed a pattern that was identical with that of sigmoid growth where stocking rate of 8, 12, and 16 larvae/liter gained weight until 30 days of rearing. Highest RNA/DNA ratio was recorded at 16 larvae/liter (2.85±0.004), while the lowest was at 20 larvae/liter (2.25±0.217). Food availability might play a limiting factor that leads to the lower RNA/DNA ratio of larvae reared at a high density due to competition

First Report on The Occurrence of Cochlodinium Blooms in Sabah, Malaysia

Harmful algal blooms (HABs) resulting in red discoloration of coastal waters in Sepanggar Bay, off Kota Kinabalu, Sabah, East Malaysia, were first observed in January 2005. The species responsible for the bloom, which was identified as Cochlodinium polykrikoides, coincided with fish mortalities in cage-cultures. Determinations of cell density between January 2005 and June 2006 showed two peaks that occurred in March–June 2005 and June 2006. Cell abundance reached a maximum value of 6 × 106 cells L−1 at the fish cage sampling station where the water quality was characterized by high NO3–N and PO4–P concentrations. These blooms persisted into August 2005, were not detected during the north–east monsoon season and occurred again in May 2006. Favorable temperature, salinity and nutrient concentrations, which were similar to those associated with other C. polykrikoides blooms in the Asia Pacific region, likely promoted the growth of this species. Identification of C. polykrikoides as the causative organism was based on light and scanning microscopy, and confirmed by partial 18S ribosomal DNA sequences of two strains isolated during the bloom event (GenBank accession numbers DQ915169 and DQ915170)