Rotifer Production Research Articles

Nannochloropsis sp phytoplankton culture technique laboratory scale

Nannochloropsis sp is a phytoplankton often used in marine fish hatchery activities as feed for the mass production of rotifers, and its availability is very much needed for rearing marine fish larvae. This activity aims to study pure culture techniques for Nannochloropsis sp on a laboratory scale. The method used is a literature study method and a direct practical method regarding Nannochloropsis sp phytoplankton culture techniques laboratory scale and conducted interviews with employees at the BPBL Batam Phytoplankton Live Food Production Unit Laboratory. Based on observations, it was found that the peak growth or optimum cell density of Nannochloropsis sp. occurred on the sixth day in a 1000 mL Erlenmeyer, namely 60.95 - 62.10 million cells/mL with an initial density of 10.15 - 10.55 million cells/mL and in a 2000 mL Erlenmeyer, namely 58.75 - 60, 25 million cells/mL with an initial density of 8.25 – 8.45 million cells/mL.

Plankton community’s production in the water area of the Volga-Kama Biosphere Reserve (Russia)

The quantitative and production characteristics of planktonic community were assessed in the water area of the Volga Carbon Polygon (Saraly, Volzhsko-Kamsky State Nature Biosphere Reserve during the growing season of 2023. The Saralinsky section of Volga-Kama Reserve was characterized by high values of algae biomass, chlorophyll-a concentration and, accordingly, primary production of 110.6 ± 36.7 mgC/m3 and characterized this area as hypereutrophic. Zooplankton production was 120.2±48.0 kcal/m3/day or 12.0±4.8 mgC/m3. The values of the P/B coefficient of the zooplankton community varied from 17 to 69, and are determined mainly by the production of small rotifers and cladocerans. These values indicate the eutrophic state of studied area.

Effects of chicken manure extract on the directed cultivation of bio-bait Chlorella vulgaris-rotifer (Brachionus plicatilis) and their fatty acid content

Chicken manure is rich in various nutrients, and it is used to improve the nutritional status of microalgae, which subsequently affects the production and nutrition of rotifers. The investigation of the effect of chicken manure on Chlorella and rotifer cultivation is therefore critical for practical production. Here, to investigate the effects of chicken manure extract (CME) on the continuous culture of the biological bait “Chlorella-rotifer”, different concentrations of CME (Groups 1–5: 0, 5, 10, 15, and 20 mL·L−1, respectively) were added to the culture medium for cultivating Chlorella vulgaris, assessed the growth of C. vulgaris, and the optimal amount of CME for culturing Chlorella was determined; and the effects of the cultured Chlorella as food for rotifer cultivation and fatty acid composition of Chlorella and rotifers were analyzed. In 12 days of continuous culture, no significant difference in Chlorella population density was noted among G3, G4, and G5 (P > 0.05). Following completion of the culturing period, the specific growth rate of Chlorella in G3 (0.14 ± 0.01) and G5 (0.14 ± 0.01) showed no significant difference (P > 0.05), and chlorophyll a (Chl a) content in G3 (3.79 ± 0.06 mg·mL−1) was significantly higher than that in G5 (3.30 ± 0.12 mg·mL−1) (P < 0.05). Hence, we chose G3-cultured Chlorella for rotifer cultivation. In the 120-h rotifer cultivation period, the longevity of G3-bred rotifers (G-CME) (15.06 ± 0.82 d) was significantly more than that of the control group (G-BG11) (13.13 ± 1.27 d) (P < 0.05), and the offspring number of rotifer in G-CME (24.75 ± 3.45) was significantly higher than that in G-BG11 (17.75 ± 3.06) (P < 0.05). Rotifer population density and fecundity were significantly improved by G-CME than by G-BG11. Regarding fatty acid composition, the principal component analysis showed that Chlorella cultured by CME (CME-C) and BG11 (BG11-C) and rotifers that used them as diet (CME-R and BG11-R, respectively) exhibited a variation in principal components, with LC-PUFAs (12.66% ± 0.42%) and n-6 LC-PUFAs (3.99% ± 0.17%) being significantly higher in CME-R than in BG11-R (LC-PUFAs: 9.76% ± 0.81%, n-6 LC-PUFAs: 2.17% ± 0.32%) (P < 0.01). In conclusion, CME can promote the growth and alter the fatty acid composition of Chlorella, thus indirectly improving the growth condition and fatty acid content of rotifers; the optimal amount of CME for the continuous cultivation of the bio-bait “Chlorella-rotifer” was 10 mL·L−1.

STATUS OF PLANKTON AND BENTHOS IN THE AQUACULTURE FIELD OF BANGLADESH

Phytoplankton is a key food item in both aquaculture and mariculture. Phytoplankton is utilized as food for the animals in aquaculture directly. The plankton are collected from a body of water or cultured. Phytoplankton is used as a food stock for the production of rotifers and also used to feed molluscs, pearl oysters and giant clams. Plankton is divided into two groups belonging to phytoplankton and zooplankton. Phytoplankton has chlorophyll to capture sunlight, and they use photosynthesis to turn it into chemical energy. Zooplankton is a small floating or weakly swimming organism. Zooplankton moves vertically in the water column each day, feeding on the phytoplankton, small floating plants such as algae. Zooplankton serves as an intermediary species in the food chain, transferring energy from planktonic algae to the larger invertebrate predators and fish. Benthos is the community of organisms that live on, in, or near the seabed, river, lake or stream bottom, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environment, from tidal pools along the foreshore, out to the continental, and then down to the abyssal depths.

Automated system of tubular filtration for rotifer production

AbstractThis study developed an automated filtration system for a selected rotifer, Brachionus ibericus. This system is controlled by a programmable logic controller, and it enables the high‐density cultivation of marine rotifers and the selection of rotifers for palatability. We tested seven mesh sizes (300, 200, 100, 50, 20, 5, and 1 μm) for commercial 10‐inch (25.4‐cm) stainless steel tubular filters in the proposed system, after which we selected the optimal mesh size for filtering impurities, separating rotifers, eliminating wastewater, and minimizing the rotifer loss rate. The results indicated that a combination of the 5‐ and 200‐μm meshes produced optimal filtration efficiency. After every 120 s of filtration followed by a 30‐s flushing process, a rotifer density of 3170 ± 101 individuals/ml, a mesh blocking loss rate of 4.95 ± 3.62%, and impurity‐free rotifer volume of 45.18 ± 1.2 L were obtained. Our study verified that tubular filters can be used in commercial aquaculture.

Culturing live foods for fish larviculture using non‐microalgal diet: The role of waste‐generated bacteria and selected commercial probiotics—A review

AbstractCondensed suspension of live microalga cells, for example, Chlorella vulgaris, Nannochloropsis oculata and Tetraselmis tetrathele is often utilized as diets for mass production of live food resources, that is, rotifers, copepods, cladocerans and Artemia. These live food resources are essential for fish larviculture in hatcheries. However, the production of sufficient microalgae is costly, laborious and fragile, and thus require cost‐effective and stable production technologies, especially for the emerging countries. Studies have shown that locally available biowastes such as fish wastes and chicken manure provide substrates for generating billions of heterotrophic bacterial cells and microparticles as well as growth hormones, which can be used in propagating live food resources. The fish wastes contain essential nutrients that are important for the growth of both live foods and fish larvae. With single feeding of fish wastes, the culture condition of live foods may become unstable, and thus bacterial isolates and selected probiotics, for example, genus Pseudomonas, Moraxella and Micrococcus are needed to stabilize the culture conditions to increase reproduction capacity of the cultured live foods. This article consolidates the results and conclusions of our recent studies on the culture of live food resources, that is, Proales similis de Beauchamp, Brachionus rotundiformis Tschugunoff, Tigriopus japonicus Mori and Diaphanosoma celebensis Stingelin, using waste‐generated bacteria from fish waste diet (FWD) and selected probiotics. The non‐algal materials reviewed in this article are important to ensure constant supply of cheap live foods to improve aquaculture, especially in the developing countries, which lack sophisticated technology for production of high‐density microalgae.

Evaluation of the Effect of Different Locally Available Manures on Planktonic Quality and Quantity

An experiment was conducted in out-door, circular cement tanks (1000 L) with soil base for one year to estimate the plankton productivity and microbial characteristics in relation to seasons and inputs. Effect of three locally available manures - Cow dung (CD), poultry manure (PM) and goat manure (GM), on plank.tonic quality and quantity was evaluated. CD, GM and PM were applied to freshly prepared triplicate tanks at isonitrogenous dose at fortnightly intervals. Water quality, plankton quality and quantity were estimated. The study revealed that irrespective of the treatment, the water quality parameters showed similar pattern during the study period. Though the ammonia levels remained almost similar throughout the study, after initial 3 months, drastic decrease in nitrate levels were noticed in all the tanks owing to higher growth of plank.tonic biomass. Significantly higher phosphate content in water was noticed in poultry manure applied tanks. Plankton biomass was higher in all seasons with poultry manure followed by goat manure and cow dung. Bacillariophyceae (diatoms), Chlorophyceae and Cyanophyceae were higher with CD followed by GM, PM and Control (CO-without inputs). Density of Crustaceans, Rotifers and Euglenophyceae was the highest with PM, while it was similar in CD and GM. Control recorded the least value. Further, there was variation in tanks with respect to density of lactobacillus group of bacteria (on MRS agar plates) with highest count in CD (3.9x104 CFU/ml of bacteria) followed by GM (5.1x103 CFU/ml), PM (5.1x102 CFU/ml) and CO (3.7x102 CFU/ml). The study revealed superiority of poultry manure as a nutrient source for higher production of rotifers and crustaceans at all seasons under the prevailing conditions.

Potential Applications of Native Cyanobacterium Isolate (Arthrospira platensis NIOF17/003) for Biodiesel Production and Utilization of Its Byproduct in Marine Rotifer (Brachionus plicatilis) Production

To achieve strong, successful and commercial aqua-biotechnological microalgae applications, screening, isolation, molecular identification, and physiological characterizations are needed. In the current study, a native cyanobacteria strain Arthrospira platensis NIOF17/003 was isolated from the surface water of El-Khadra Lake, a saline-alkaline lake located in Wadi El-Natrun, Egypt. The cyanobacterium was phylogenetically identified by 16S rRNA molecular marker and deposited in the GenBank database (accession number MW396472). The late exponential phase of A. platensis NIOF17/003 was reached at the 8th day of growth using Zarrouk medium, with a recorded dry weight (DW) of 0.845 g L−1. The isolated strain showed 52% of protein, 14% of carbohydrate, biomass productivity of 143.83 mg L−1 day−1, 8.5% of lipid, and lipid productivity of 14.37 mg L−1 day−1. In general, the values of cetane number, iodine value, cold filter plugging point (52.9, 85.5 g I2/100 g oil, and −2.2 °C, respectively) of the isolated fatty acid methyl esters are in accordance with those suggested by international standards. Besides, applying algal-free lipid (FL) as biodiesel byproduct in the production of rotifer (Brachionus plicatilis) revealed that a 0.6 g L−1 FL significantly increased the rotifer population females carrying eggs, confirming that FL can be used efficiently for B. plicatilis production. The current study concluded that the new isolate A. platensis NIOF17/003 is a promising strain for double sustainable use in biodiesel production and aquaculture feed.

Effects of Temperature on Population Growth and Resting Egg Production of Freshwater Rotifer (Brachionus calyciflorus)Effects of Temperature on Population Growth and Resting Egg Production of Freshwater Rotifer (Brachionus calyciflorus)

Resting egg production of rotifers provides critical advantages in larviculture of most fish species due to the reduction in the costs of labour and algae production. The study was conducted to investigate the effects of temperature on population growth and resting egg production of a freshwater rotifer, Brachionus calyciflorus, collected in Northern Vietnam. The rotifer was pre-cultured at 27ºC before being transferred to the cultures at 15 and 35ºC while the control was maintained at 27ºC. One-liter beakers filled with 500mL culture medium were used with three replicates for each temperature group. Stock rotifers were inoculated at an initial density of 200 ind ml-1 and fed with concentrated fresh algae. The results indicated that population growth rate (r) of rotifers cultured at 27 and 35ºC were significantly higher than that of rotifers at 15ºC while the highest density was attained from the treatment of 27ºC, at 608.3 ind mL-1, compared to 468.3 and 360.5 ind mL-1 at 35 and 15ºC, respectively. Transferring the cultures from 27 to 35ºC significantly increased the rate of resting egg carrying females with the maximum rate of 31.5% compared to 21.2 and 13.5% of the rotifers at 27 and 15ºC, respectively. The resting egg densities of the cultures at 35ºC were also significantly higher than those at 15 and 27ºC. The resting egg carrying females appeared and increased their rates in concurrence with increases in the population density. The present results are important information for resting egg induction and production of rotifer in larviculture.

RAS based culture system for continuous production of Rotifers (Brachionus calyciflorus) in mass

The present study was undertaken to find out preferred food type, minimum effective algal cell requirement, effective harvest rate of rotifers and to design and construct re-circulatory aquaculture system (RAS) based rotifer, Brachionus calyciflorus production system at Aquatic Rainbow Technology Park, Dr MGR Fisheries College and Research Institute, TNJFU, Madhavaram campus, Chennai during 2017–2019. In the first experiment, food types, viz. Chlorella vulgaris, Spirulina major, Scenedismus obliquus and Baker’s yeast were extensively fed to rotifers with control (5000 L). The highest rotifer count was observed with C. vulgaris food type (365.33±2.18 rotifers/ml) followed by Baker’s yeast (245.33±5.36 rotifers/ml) on 8th day which started declining gradually to 30th day because of lower water quality. Second experiment on algal consumption rate by rotifer postulated that 22,000–25,000 cells/day/rotifer was the minimum cell requirement. Third experiment on standardizing effective harvest rate (10%, 30%, 50% and 70%) suggested that daily harvest at 30% maintained the rotifer culture at its stationary phase (381±19.45 rotifers/ml). After the experiments, we have designed, built and operated RAS based live food production unit for 17 months where the harvested water was treated using series of filters (rapidsand, cartridge, UV filters) and reused for algal culture. The seasonal data showed that temperature plays a major role with the highest production during summer (404.43±24.33 rotifers/ml) and consequently lower in winter (301.21±14.33 rotifers/ml). The system opens a new perspective of commercial scale production of rotifers with standard culture and harvesting practices.

Influence of certain environmental parameters on mass production of rotifers: A review

Marine biology,marine ecology,Phytoplankton, marine algae, zooplankton, nekton, benthos, corals and coral reefs, ecology, zoogeography and systematics, primary production and experimental work on ecosystem including energy flow at different trophic levels, population dynamics and theoretical models, recycling of matter, influence of environmental factors on metabolic activity, marine microbiology, mariculture and experimental work on propagation of cultivable species, biology of fishes, marine reptiles, sea birds and mammals, physical, chemical, geological and meteorological features of the environments related to marine biology, marine environmental damage caused by pollution and engineering works, underwater observations, conservation of living resources, modifications in methodology and techniques and development of new apparatus related to marine sciences

Nutritional value and production performance of the rotifer Brachionus plicatilis Müller, 1786 cultured with different feeds at commercial scale

The rotifer Brachionus plicatilis is the first live feed in larviculture of marine fish species. Rotifer diets differ in their biochemical composition, physical properties, and production technology while feeding protocols largely vary among facilities. The objective of the present study was to determine the effects of two different forms of Nannochloropsis oculata and commonly used commercial diets on growth performance and biochemical composition of rotifers produced under commercial conditions. Rotifers were fed one of five different types of feed: Algome® (dried Schizochytrium sp.), Protein Plus® (PP), Inactive Baker’s Yeast® (INBY), spray-dried Nannochloropsis oculata (SDN), or freshly cultured Nannochloropsis oculata (FN). Rotifers fed SDN diet resulted in significantly higher rotifer biomass during 16 days of semi-continuous culture, with an increasing biomass trend that lasted 11 days, high egg production, and egg-carrying female numbers, whereas rotifers fed PP showed highest ∑n-3, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid contents. Amino acid profiles of rotifers were enhanced by utilization of both INBY and SDN diets. Overall, the results indicated that SDN is optimal for long-term biomass production of rotifers. However, their nutritional profile needs to be enriched by feeding PP (EFA source) and INBY (EAA source) once desired biomass production is obtained.

Effect of nutritional status and concentration of Nannochloropsis gaditana as enrichment diet for the marine rotifer Brachionus sp

The development of strategies to improve the quality and to optimize the costs of rotifer production for fish larval feeding, particularly those related to microalgal supply, are highly desirable. In the present work, three different rations (80,000, 130,000 or 200,000 cells rotifer−1) of Nannochloropsis gaditana were assessed as enrichment diets for the marine rotifer Brachionus sp. The microalga was cultured in semi-continuous regime with two different daily renewal rates, 10% and 40%, which provided nutrient-depleted or nutrient-sufficient conditions respectively and resulted in strong differences in biochemical composition. Protein and arachidonic acid (ARA) content were twice higher and eicosapentaenoic acid (EPA) was three times higher in N. gaditana from nutrient-sufficient cultures. After 24-h enrichment, rotifers fed N. gaditana cultured in nutrient-sufficient conditions showed higher dry weight, as well as higher contents of protein, lipids and carbohydrates. Total polyunsaturated fatty acids (PUFAs) and ARA contents increased >50%, whereas EPA content doubled in rotifers fed N. gaditana from nutrient-sufficient conditions. As for feed ration, the increase from 80,000 to 130,000 cells individual−1 enhanced the accumulation of protein, lipids, carbohydrates, total PUFAs, ARA and EPA, but a further increase to 200,000 cells individual−1 only enhanced the accumulation of lipid content. Our results show that the nutritional quality of microalgae, rather than concentration, is the most important factor influencing biomass productivity and biochemical composition of rotifer cultures. Since microalgal biomass is in general a limited resource for aquaculture, the improvement of its nutritional value through the optimization of culture conditions should be considered as an adequate and cost-efficient strategy to produce high-quality live feed.

Production of the rotifer Brachionus plicatilis (Müller 1786) in closed outdoor systems fed with the microalgae Nannochloropsis gaditana and supplemented with probiotic bacteria Pseudoalteromonas sp. (SLP1)

In the present study, the mass production of the rotifer species Brachionus plicatilis was evaluated using closed outdoor algae culture systems in 450- and 1000-L polyethylene bags fed with the microalgae Nannochloropsis gaditana and supplemented with probiotic bacteria Pseudoalteromonas sp. (SLP1). These bacteria were previously isolated from the digestive tract of the commercially important fish Yellowtail kingfish (Seriola lalandi, Family: Carangidae) and their stimulatory activity on growth in the microalga N. gaditana was verified. In each treatment, a significantly greater production of organisms (P < 0.05) was shown when fed with the microalgae and supplemented with beneficial bacteria over 9 days compared to control treatments without the addition of beneficial bacteria. Using denaturing gradient gel rlectrophoresis analysis (DGGE), the permanence of the SPL1 bacteria was demonstrated in a B. plicatilis culture in a 1000-L outdoor system when they were incorporated into the diet. With these results, it is shown that the use of this microalgae-bacteria mixture is feasible to improve rotifer production in outdoor batch culture systems. This is a potential input vector for beneficial bacteria as well as nutritional elements into the digestive tract of larval and juvenile stages of fish of economic importance, especially S. lalandi.

The Effects of Microalgae as Live Food for Brachionus plicatilis (Rotifer) in Intensive Culture System.

Brachionus plicatilis is used to feed fish and crustacean larvae in the aquaculture industry. It is well established that the type of microalgae may influence rotifer production. This experiment was conducted to determine the effect of five different locally available microalgae species at Fisheries Research Institute (FRI), Kampung Pulau Sayak, Kedah, Malaysia on the instantaneous growth rate (μ) of rotifer. Nannochloris sp., Tetraselmis sp., Isochrysis sp., Chlorella sp., and Nannochloropsis sp. were used as feed at different algae densities (0.1, 0.3, 0.7 and 1.5 × 106 cells/ml) and culture volumes (20, 70 and 210 ml). At algae densities ranging from 0.3 to 1.5 × 106 cells/ml, an average μ value of more than 0.90 per day were recorded for all algae species. However, at density of 0.1 × 106 cells/ml, only Tetraselmis sp. resulted in the significantly highest μ value compared with others (p < 0.05). In terms of volume, smaller culture volume of Tetraselmis sp. (20 ml) showed significantly higher μ compared with higher volume (70 and 210 ml cultures).

Nutritional enrichment of rotifer Brachionus plicatilis and its effect on clownfish larvae Amphiprion clarkii (Bennett, 1830)

The present study, evaluated the effect of enrichment of the rotifer Brachionus plicatilis with the microalga Nannochloroposis salina, amino acid derivative L-carnitine and commercially available S-presso (SELCO). The study also evaluated the effect of enriched rotifers in larval rearing of Amphiprion clarkii in terms of metamorphosis, pigmentation, growth and survival of larvae.. Rotifer production increased by 43, 39 and 54% respectively in B. plicatilis enriched with different concentrations of L-carnitine at 1, 10 and 100 mg l-1 on day 4 (p&lt;0.001) in comparison with the control group maintained on algal diet alone. Total unsaturated fatty acid (PUFA, HUFA and n-3 fatty acids) and the ratios of n-3/ n-6, DHA/EPA, EPA/AA were significantly higher (p&lt;0.05) in the L-carnitine treated rotifers compared with the S-presso enriched as well N. salina enriched groups. Larvae of A. clarkii, fed with L-carnitine enriched rotifer achieved maximum growth of 56.92±0.2 mg; whereas, those fed S-presso treated rotifers attained only 48.74±1 mg. In L-carnitine enrichment; metamorphosis of clown fish larvae took only 10 days, while it took 11 days and 10 days respectively in S-presso and N. salina enrichment. In L-carnitine and S-presso enrichments, initial pigmentation of larvae was observed within first 3-4 days of culture, whereas it took 4-5 days in N. salina enrichment. L-carnitine enrichment resulted in the highest survival of 70%, followed by N. salina with 68% and S-presso enriched group with 52%. The results indicate that L-carnitine could be a recommendable enrichment for increasing rotifer production as well as for clown fish larval culture.

Composting fishwastes as low-cost and stable diet for culturing Brachionus rotundiformis Tschugunoff (Rotifera): Influence on water quality and microbiota

The demand for the rotifers Brachionus spp., which is considered indispensable for larviculture, has increased considerably in the tropical countries. Although freshly cultured microalga is the common rotifer diet, the culture protocols are laborious and costly, thus limit sufficient production of rotifers, and consequently disrupt fish seedling production programs in the microalgae-based hatcheries. This study aimed at developing an alternative low-cost and stable fishwaste diet (FWD), for the rotifers. The diets i.e. FWD1 (fishwastes only), FWD2 (FWD1+carbon source) and control (Chlorella vulgaris only) were used to determine the population density, specific growth rate and dietary value of the rotifer Brachionus rotundiformis (SS-type) in 30l tanks of sea water (22ppt), in which 20rotifersml−1 were stocked and semi-continuously cultured for 18days at 28±1°C without aeration. The coefficient of variation (CV) of the mean specific growth rate was calculated to determine the stability of the cultures. The culture medium and rotifer gut were aseptically screened for bacteria, which were counted and reported as colony-forming units (CFUml−1). The rotifers and microflora were harvested and analyzed for total lipids. FWD2 produced significantly higher rotifer density than FWD1 and control diet (p<0.05), but no significant difference was detected between FWD1 and control cultures (p>0.05). Up to 1188±70rotifersml−1 were obtained on day 13day with FWD2. There was no significant effect of FWD on the CV of the cultures, which were 0.11±0.05, 0.07±0.02 and 0.08±0.04 for FWD1, FWD2 and control cultures, respectively (p>0.05). There was significantly higher DO in the control- than in the FWD-tanks, and higher NH3-N in the FWD- than in the control-tanks (p<0.05). There was no significant effect of FWD on the pH in the diets (p>0.05). However, the water quality values were within the acceptable limits for aquaculture. The FWD-rotifers ingested significantly higher CFUml−1 of bacteria (1.02±0.12×107) than the control-rotifers (8.25±2.19×106CFUml−1). About 0.35 and 0.39mg/g of DHA and EPA, respectively was obtained in the FWD2-fed rotifers, and both were under detectable limit in the control-rotifers. The FWD may have contained essential nutrients and probiotics, which explains the higher rotifer population density in the FWD cultures than in the control cultures. This study offers an opportunity to reduce or eliminate the need for the expensive on-site microalgal production, and rotifer enrichment emulsions, toward a more cost-effective aquaculture, especially in the tropical countries.

Analysis of proteins in conditioned medium that trigger monogonont rotifer mictic reproduction

The initiation, rate, duration, and termination of reproduction in the rotifer life cycle are tightly regulated, but the molecular mechanisms are poorly understood. Environmental signals are sensed and transduced to chemical signals within rotifers to integrate asexual and sexual reproduction. Crowding, diet, and photoperiod are environmental signals used by various rotifer species to initiate sexual reproduction, but most advances in the last 10 years have been in discovering how rotifer crowding is a case of quorum sensing. Female brachionids release a protein into their medium that acts as a pheromone and accumulates to trigger mictic reproduction. Candidates for this mixis-inducing protein (MIP) have been isolated from rotifer-conditioned medium and characterized biochemically. A N-terminal partial amino acid sequence of a particularly promising 39 kD protein was used to prepare a polyclonal antibody. This antibody immunoprecipitated a 22 kD protein from rotifer-conditioned medium and inhibited mixis induction. Future advances will benefit from the production of transgenic rotifers to confirm the mixis-inducing action of this putative MIP gene.

Technical and economic feasibility of adding pure oxygen for rotifer production (Brachionus plicatilis) spotted snapper (Lutjanus guttatus) larvae feeding

A study to technically and economically evaluate the addition of pure oxygen in a culture of rotifers for feeding marine fish in the Pacific Marine Park, Puntarenas, Costa Rica was performed. The results showed no significant differences (ANOVA P&amp;gt; 0.05) between the cultivation with addition of oxygen treatment and control, regarding the instantaneous growth rate, crop yield, doubling time, rotifers length and maximum densities reached. Concerning the economic analysis, control culture was 53% less expensive compared to the addition of oxygen system.

Cod Larviculture Using High‐density Rotifer Production with Different Enrichments

AbstractHigh‐density (HD) rotifer culture systems have been recently commercialized, but are not commonly used by the aquaculture industry. The aim of this study was to determine if HD systems could be used in cod hatcheries. An enrichment strategy using the commercial products, ArteMac and Protein Selco Plus (Com), was compared with the manufacturer's suggested enrichment, using Pavlova‐DHA (Pav). The Pav enrichment increased the eicosapentaenoic acid (EPA) levels in rotifers, but reduced the docosahexaenoic acid (DHA) and 22:5n‐6 (n‐6DPA, docosapentaenoic acid) levels. Larvae EPA levels in both polar and neutral lipids were relatively stable in the larvae fed with Com‐rotifers; while they were higher in early stages, they were progressively reduced through ontogeny in the Pav‐rotifers fed‐larvae. DHA levels in polar lipids decreased in larvae, particularly when fed with HD‐Pav rotifers. In all larvae, arachidonic acid (ARA) levels increased in the polar and neutral lipids, regardless of treatments. In both lipid fractions, the levels of ARA were quite stable in time, but still higher in larvae fed with Com‐rotifers. Bacterial load was lower in larvae fed with Pav‐rotifers. Denaturing gradient gel electrophoresis (DGGE) bacterial profiles of larvae and rotifers were all similar. This study shows the potential of using HD systems to produce rotifers, but highlights the necessity of adjusting the nutritional composition of rotifers prior to being fed to larvae.