Microalgal culture and maintenance in marine hatcheries

Unicellular marine microalgae are widely used as food in the hatchery production of fish and shellfish. Molluscs like oysters, mussels and clams filter them from the seawater in all stages of life. Rotifers and brine shrimp also ingest algae, and these are then used as food for fish and prawn larvae. In hatchery systems algae are added to the larval rearing tanks to improve ‘quality’ of water as green water systems. The production of algae is very critical in successful hatchery management

Microalgal Culture and Maintenance in Marine Hatcheries

Marine algae are single-celled plants and like all plants, contain chlorophyll, which traps the energy from light and uses it to convert nutrients and carbon dioxide dissolved in the sea water into organic matter. Microalgae are the primary producers of the sea. Among microalgae, flagellate and diatom species, are primary producers at the base of the marine food chain. They are cultured in hatcheries in suitably treated seawater enriched with nutrients, which include nitrates, phosphates, essential trace elements, vitamins and carbon dioxide. Synthetic seawater may be used but it is expensive except for small laboratory scale cultures. The culture microalgae arise because the natural phytoplankton content of seawater is insufficient to support growth of high densities of larvae and juveniles reared. Particularly in the hatchery, the water treatments will remove almost all of the natural phytoplankton which then needs to be replaced from cultures of preferred, high food value species. In this context, few of the naturally occurring algae of good food value are amenable to artificial culture

Growth pattern of stock cultures of five selected species of marine microalgae maintained under indoor controlled environment and under outdoor conditions

Growth pattern of five species of microalgae viz., Chaetoceros calcitrans, Dunaliella sp., Isochrysis galbana, Tetraselmis tetrahele and Nannochloropsis salina were studied under indoor controlled conditions (at 230C) and under outdoor (at 28-30°C) conditions. The variations in ammonia and pH levels in the culture flasks over a period of 90 days were also studied. Results revealed that the pattern of growth of all five species of algae were significantly different (p<0.05) in the two different conditions. The results clearly showed that the growth of all the five species of algae were faster in outdoor conditions and outdoor cultures were able to maintain only for a maximum period of three months. Ammonia and pH levels recorded were higher in outdoor cultures which indicated higher physiological activities and growth. Ammonia and pH levels were found to increase gradually in all the cultures, upto 30 days under both conditions and subsequently found almost constant throughout the study. Even though ammonia levels were found to rise with increase in pH and temperature, it did not increase to a level that is detrimental to the microalgal cultures

Breeding and larval rearing of three species of damselfishes (family: Pomacentridae)

The annual world ornamental fish trade is to the tune of around 4.5 billion dollars (1995) with a growth rate of about 8%. Nearly 50% of the revenue from the trade is contributed by marine ornamental fishes. With the spread of scientific knowledge on marine aquarium management and development of an array of aquarium gadgets, there is an Increased demand for tropical marine aquarium fishes in recent years and this opens up the possibility of developing a lucrative marine ornamental fish trade the worldover

Effect of Feeding Frequencies on Growth and Profit of Asian Seabass (Lates calcarifer) in Cage Culture Systems

Cage culture is one of the most advanced aquaculture production systems where fishes are held in floating enclosures like net cages, moored in the open water systems, and allow free water flow. The open water cages developed by Central Marine Fisheries Research Institute (CMFRI) during the last decade are becoming very popular in coastal waters. One of the major problems faced by farmers at all stages of culture is fish feed and feeding. A suitable feeding strategy is important to improve fish growth and reduce feed costs and environmental pollution. The study was conducted to investigate the effect of feeding frequency from sea bass cultured in cages on water quality, growth parameters, survival rate, economic return and bottom characters in Moothakunnam (N10011.478’ E076011.901’+ 4m) in Ernakulam district. Water and sediment samples and growth parameters were collected and analyzed monthly from inside and outside of the cages for a period of one year. Significant differences were found in growth parameters like weight gain (1.04±0.03-1.78±0.008), Specific growth rate (1.2±0.03-1.48±0.005), Survival rate (40%-61.53%) and FCR (4.3-4.56). The water quality parameters DO, Nitrate, Nitrite, Ammonia and Orthophosphate in the cage and reference sites did not show many significant variations indicating a healthy growth condition in the cages. Therefore it could be concluded that the growth performance of sea bass is increasing by feeding frequency, but the economic analysis indicated that net profit is negatively related to feeding frequency

Studies on the diversity and impact of macro biofouling organisms in brackish water finfish cage

Biofouling refers to accumulation of organisms on submerged surfaces. In case of open water cage culture, fouling organisms attached to cage nets block water flow and reduces waste removal resulting in increased stress levels on stocked fishes and reduces the rate of intake of feed and growth. It also increases weight of the nets leading to its damage. The quantity and diversity of biofouling organisms and their effects on the growth and survival of stocked fishes were studied

A burst search for gravitational waves from binary black holes

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarisation for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios, and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated CBC waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.Comment: 12 pages, 4 figures, 2 tables, submitted for publication in CQG in the special issue for the conference proceedings of GWDAW13; corrected some typos, addressed some minor reviewer comments one section restructured and references updated and correcte

Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors

Gravitational waves deliver information in exquisite detail about astrophysical phenomena, among them the collision of two black holes, a system completely invisible to the eyes of electromagnetic telescopes. Models that predict gravitational wave signals from likely sources are crucial for the success of this endeavor. Modeling binary black hole sources of gravitational radiation requires solving the Eintein equations of General Relativity using powerful computer hardware and sophisticated numerical algorithms. This proceeding presents where we are in understanding ground-based gravitational waves resulting from the merger of black holes and the implications of these sources for the advent of gravitational-wave astronomy.Comment: Appeared in the Proceedings of 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

Stock assessment of coastal tunas in the Indian seas

Tuna and billfish production from the Indian coastal waters, Lakshadweep and Andaman and Nicobar islands during the period 1985-'99 averaged 40,204 t. The contribution by E.affinis, Athazard, T.tonggol, K.pelamis and T.albacares (young ones) were 18,5041,6,8521,3,093 t, 3,3921 and 2,2111 respectively. Drift gill net was the major gear employed in the coastal tuna fishery. The length frequency data collected on the above species during 1990-'98 at seven centres along the Indian coast were analysed employing FiSAT programme to estimate their growth and mortality parameters, exploitation rates and relative yield per recmit

Status of exploitation of coastal tunas in the Indian seas

Tuna and billfish production from Indian seas during the period 1985-'99 evinced an increasing trend and the landings fluctuated between 24,287 t (1987) and 53,6621 (1992). The average annual production during the said period was 40,2041, contributing to 3.6% of the total pelagic fish landings and 1.8% of the total marine fish landings. On an average, 24% of the total tuna and billfish production during 1991-'99 was contributed by northwest coast, 2% by Andaman and Nicobar islands and 14.9% by Lakshadweep. Among the maritime states, Kerala (36 %), Gujarat (18.1%) Tamilnadu (11.6%), Maharashtra (5.9%), Kamataka (5%), Andhra Pradesh (4.4 %) and Goa (2%) were the prime tuna producing states