Influence of Microalgae Diets on the Biological and Growth Parameters of Oithona nana (Copepoda: Cyclopoida)

Several species of the planktonic free-living genus Oithona have been successfully used in the larviculture of marine fish and shrimp. However, few studies have been published that allow us to estimate the potential of Oithona nana culture under controlled conditions. This work evaluated the effect of the microalgae Isochrysis galbana and Chaetoceros calcitrans as single (200,000 cells/mL) and mixed diets (100,000 + 100,000 cells/mL) on population and individual growth, ingestion rate, number of spawnings, fertility, development time by stage, and sex ratio of O. nana. We cultured this copepod at 28 ± 0.5 °C, 35 PSU salinity, 125 lux, and 12:12 photoperiod. Results showed that diet had no effect on the final population level (6273–7966 ind/L) or on individual growth, nor on sex ratio, with less males than females. With C. calcitrans, O. nana had a higher filtration rate (57 ng C/ind/day). On the other hand, a mixed diet induced a higher number of spawns (0.4 events/day) and nauplii per spawn (23 ind). Similarly, a single or mixed diet, containing I. galbana, accelerated the development rate by 6.33–7.00 days. We concluded that O. nana can be cultured with both microalgae, indicating its potential use in an intensive system for production. However, more research is required to improve the productivity of O. nana rearing.

Lactobacillus strains isolated from oysters improve the production of Crassostrea gigas larvae

One of the main problems in laboratories of oyster seed production occurs in the stage of settlement or fixation and metamorphosis of the larvae. The organisms develop drastic morphological and physiological changes at this stage, exposing them to attack by pathogenic microorganisms. Numerous studies indicate that before larval settlement to a substrate, they require bacteria to stimulate and induce the process. In this study, Japanese oyster (Crassostrea gigas) larvae were fed with combinations of microalgae and bacteria previously selected for their probiotic potential; their impact on survival, growth, and settlement was evaluated. Larvae D of 12 days old were provided by a private company and transported to the laboratory under controlled conditions. Probiotic bacteria Lactobacillus plantarum 69Cr, L. fermentum 101Cc, and L. casei 43Cg were reactivated on MRS and applied at a concentration of 1×104 CFU mL-1. Microalgae Isochrysis galbana and Chaetoceros calcitrans were grown in F2 medium and supplied at a concentration of 3×104 cells mL-1. Results showed, in all treatments, a survival range of 39-53%, growth of 300-310 μm, and 34-56.5% settlement. However, the best bacteria combined with I. galbana and C. calcitrans was L. plantarum 69Cr with a 54% survival, 310 μm growth, and 56.5% settlement. It is concluded that the combination of L. plantarum 69Cr with I. galbana and C. calcitrans has the potential to be used in the production of Japanese oyster larvae.

Effect of pluronic block polymers and N-acetylcysteine culture media additives on growth rate and fatty acid composition of six marine microalgae species

The efficiency of microalgal biomass production is a determining factor for the economic competitiveness of microalgae-based industries. N-acetylcysteine (NAC) and pluronic block polymers are two compounds of interest as novel culture media constituents because of their respective protective properties against oxidative stress and shear-stress-induced cell damage. Here we quantify the effect of NAC and two pluronic (F127 and F68) culture media additives upon the culture productivity of six marine microalgal species of relevance to the aquaculture industry (four diatoms-Chaetoceros calcitrans, Chaetoceros muelleri, Skeletonema costatum, and Thalassiosira pseudonana; two haptophytes-Tisochrysis lutea and Pavlova salina). Algal culture performance in response to the addition of NAC and pluronic, singly or combined, is dosage- and species-dependent. Combined NAC and pluronic F127 algal culture media additives resulted in specific growth rate increases of 38%, 16%, and 24% for C. calcitrans, C. muelleri, and P. salina, respectively. Enhanced culture productivity for strains belonging to the genus Chaetoceros was paired with an ~27% increase in stationary-phase cell density. For some of the species examined, culture media enrichments with NAC and pluronic resulted in increased omega-3-fatty acid content of the algal biomass. Larval development (i.e., growth and survival) of the Pacific oyster (Crassostrea gigas) was not changed when fed a mixture of microalgae grown in NAC- and F127-supplemented culture medium. Based upon these results, we propose that culture media enrichment with NAC and pluronic F127 is an effective and easily adopted approach to increase algal productivity and enhance the nutritional quality of marine microalgal strains commonly cultured for live-feed applications in aquaculture. Key points • Single and combined NAC and pluronic F127 culture media supplementation significantly enhanced the productivity of Chaetoceros calcitrans and Chaetoceros muelleri cultures. • Culture media enrichments with NAC and F127 can increase omega-3-fatty acid content of algal biomass. • Microalgae grown in NAC- and pluronic F127-supplemented culture media are suitable for live-feed applications.

Ecophysiology of the Mediterranean mussel Mytilus galloprovincialis L; effect of different microalgae diets and ration on broodstock conditioning

Three diets based on three microalgae species (Tetraselmi ssuecica, Isochrysis galbana, and Chaetoceros calcitrans) and three feeding rations (1%, 2%, and 3%) were used to understand the ecophysiology of the Mediterranean mussel Mytilus galloprovincialis during Broodstock conditioning. Generally, mussels increase their consumption regarding food availability for all diets, and it is evident that the highest consumption was recorded with a feed ratio of 3%. During the study, I. galbana and C. calcitrans strains show the high consumption (1.58 µg. g-1. h–1 ±0.00) and (1.58µg. g-1. h–1 ±0.00) compared with T. suecica (1.542 µg. g-1. h–1 ±0.023) recorded at 3% food ration of monospecific diets. Same results were recorded for ingestion but with great learning for I. galbana in triscpecific diet (0.70 µg. g-1. h–1 ±0.052) compared to C. calcitrans(0.36 µg. g-1. h–1 ±0.037) and T. suecica (0.25 µg. g-1. h–1 ±0.126), respectively.The analysis of ANOVA has shown that both diet and food availability affect significantly the ingestion (F = 30.9, df = 2, p < 0.001 and F = 4.4, df = 6, p < 0.001) during mussel conditioning.

Growth performance and nutritional quality enrichment of Phronima pacifica by Chlorella vulgaris and Chaetoceros calcitrans as natural feed

Herawati VE, Nailulmuna Z, Rismaningsih N, Hutabarat J, Pinandoyo, Elfitasari T, Riyadi PH, Radjasa OK. 2020. Growth performance and nutritional quality enrichment of Phronima pacifica by Chlorella vulgaris and Chaetoceros calcitrans as natural feed. Biodiversitas 21: 4253-4259. Phronima pacifica as a natural feed has the potential to replace Artemia sp. because of its high nutritional content. The purpose of this study was to determine the effects of different types of feed for P. pacifica during its culture on its population density, growth rate, and nutritional content because of its potential use as a natural feed for fish. The test animals in this study consisted of P. pacifica at a stocking density of 3 ind/L, which were cultured for 18 d. Then, Chlorella vulgaris and Chaetoceros calcitrans were introduced as enrichment feed for P. pacifica. This study used a completely randomized design with three treatments and three replications. The treatments were as follows: A (100% Chlorella vulgaris), B (100% Chaetoceros calcitrans), and C (50% Chlorella vulgaris and 50% Chaetoceros calcitrans). The results showed that treatment increased the population density of P. pacifica by up to 54.67 ± 0.0038 ind/L by the 12th day. Based on the results of proximate analysis for amino acid and fatty acid profiles, the highest values for proteins and fats were in P. pacifica enriched with Chlorella vulgaris (A) and consisted of 45.45% protein, 7.57% fat, 5.95% eicosapentaenoic acid, and 39.23% lysine. Based on an ANOVA, feeding of P. pacifica with Chlorella vulgaris and Chaetoceros calcitrans had a significant effect on population density, relative growth rate, biomass production, and nutrient value of proteins and fats of P. pacifica (P < 0.05). The best results, including population density, growth rate, weight of biomass, and nutrient content of P. pacifica, occurred after feeding with Chlorella vulgaris.