A. Shenbaga Devi

Effect of different dosages of zinc on the growth and biomass in five marine microalgae

Marine environment often restrain toxic heavy metals that may enter into the food web via uptake by microalgae and eventually cause severe poisoning problems at higher tropic levels. The effects of Zinc cations upon growth of five native microalgal species, Chlorella marina, Isochrysis galbana, Tetraselmis sp., Nannochloropsis sp., and Dunaliella salina were evaluated. Growth inhibition of the microalgal cells were determined by exposing them to different concentrations of aqueous solutions of zinc metal for 15 days. A major reduction in cell density was observed in all the five cultures in the concentration of 50 ppm. Among the five micro algal species tested, Tetraselmis sp. alone showed growth up to 250 ppm concentration of zinc metal till the final day (15th day) of experiment. Key words: Zinc, microalgae, heavy metal, Chlorella marina, Tetraselmis sp.

Isolation and Culture of Microalgae

Marine microalgae or phytoplankton are the floating microscopic unicellular plants of the seawater which are generally free living, pelagic with the size range of 2–20 μm. The important components of microalgae are the diatoms, dinoflagellates, green algae, blue-green algae, and coccolithophores. Most microalgae have got immense value as they are rich sources of essential fatty acids, pigments, amino acids, and vitamins. They play a critical role in the coastal aquaculture of fish, molluscs, shrimps, and oysters, especially to meet the nutritional requirement of the larvae as well as for bioencapsulation. It is an established fact that the success of any hatchery operation mainly depends on the availability of the basic food, the phytoplankton. The maintenance and supply of the required species at appropriate time form a major problem being encountered by the algal culturists. The procedure for the phytoplankton culture involves aspects such as the isolation of the required species, preparation of the suitable culture media, and maintenance of the culture in the laboratory scale, as well as large scale under controlled conditions of light, temperature, and aeration, and their constant supply to the aqua farmers in different phases of growth. A culture may be defined as an artificial environment in which the microalgae grow. The culture of phytoplankton is an important aspect of planktonology, and the mass culture of phytoplankton is achieved under laboratory-controlled conditions and under field/outdoor conditions. Under laboratory conditions, sterilized or thoroughly cleaned containers are filled with filtered/sterilized seawater (28–34‰) and enriched with the addition of fertilizers, i.e., Guillard and Ryther’s F medium, Walne’s medium, or TMRL medium. The culture containers are inoculated with pure strains of the desired phytoplankton previously cultured in the laboratory. They are provided with heavy aeration and light using aerators and fluorescent bulbs respectively in a controlled laboratory with temperature of 25 ± 2 °C. The exponential growth phase is generally observed in 36 h to 3 days after inoculation. Cell density of 1.5–4.5 million cells per ml could be recorded. As a sufficient quantity of phytoplankton inoculums usually is present in the coarsely filtered seawater when the nutrients are added, a phytoplankton bloom develops in a course of few days under substantial sunlight. However, it happens sometimes that diatom bloom is inhibited by lack of sunlight or due to the nature of seawater in the tank. In such cases, the addition of new seawater and/or addition of ferric chloride in small amounts may stimulate instant resumption of the diatom in culture.

Preliminary study on the dye removal efficacy of immobilized marine and freshwater microalgal beads from textile wastewater

Discharge of textile wastewater containing toxic dyes can adversely affect aquatic organisms and human health. The objective of the study was to investigate the potential of immobilized marine microalgae ( Chlorella marina, Isochrysis galbana, Tetraselmis sp . Dunaliella salina and Nannochloropsis sp.) and freshwater microalga ( Chlorella sp.) in removing dye from textile wastewater (TW). The present study incorporated the use of 2% sodium alginate matrixes for decoloration. Among the algal species tested, the highest colour removal was noticed in Isochrysis galbana (55%) followed by freshwater Chlorella sp. (43%). The present method is easy to use, cost effective and devoid of technical problems. Keywords: Marine microalga, immobilization, textile wastewater, Chlorella marina, Isochrysis galbana, Dunaliella salina, biosorption, bioremediation. African Journal of Biotechnology , Vol 13(22) 2288-2294

Distribution of Phytoplankton in Selected Salt Pans of Tamil Nadu, Southeast Coast of India

Salt is one of the world’s best-known minerals and the chemical substances most related with the history of human civilization (Korovessis and Lekkas 2009). Solar evaporation is a process that has been profitably used for salt production for millennia. However still, the biology of a saline ecosystem in relation with the salt production process has not been well studied. Recently many countries have shown interest in maintaining and manipulating the hypersaline ecosystem for aquaculture and other related activities. Salt pan ecosystem is highly dynamic where the organisms are subjected to vulnerable physico-chemical disturbances. Salt pans are unique enclosed ecosystem that is characteristically exposed to a wide range of environmental stress and perturbations manifest mainly through salinity changes. In the extreme astatic physico-chemical conditions of these hypersaline habitats, only a few plant and animal species can live. Salt pan ecosystem offers a number of unique ecological niches having a strange combination of environmental factors. The nutrient-rich seawater in saltworks favours algal blooms in reservoirs and evaporators.

A Method of Analysis of Pigments in Phytoplankton

Phytoplankton (phyto, plant; plankton, wandering) are the free-floating microscopic plant cells, which contain photosynthetic pigments found in both terrestrial and marine environments. They contribute nearly 25% of the total vegetation of the plant. Pigments are chemical compounds which reflect only certain wavelengths of visible light. Because they interact with light to absorb only certain wavelengths, pigments are useful to plants and other autotropic organisms which make their own food using photosynthesis. Its value as a biomass indicator of oceanic microscopic marine plants has been recognized over the years. The inventory of pigments is a key characteristic of phototrophic organisms which is used as a criterion in the classification of autotrophic bacteria. Knowledge of phytoplankton dynamics in the World Ocean is central to the study of marine ecology and biogeochemical processes involved in climate change. Phytoplankton biomass can be estimated by the photosynthetic pigment. Phytoplankton pigment quantification is an integral part of inland water monitoring and general experimental research involving phytoplankton. Chlorophyll a (chl a) concentrations are widely used by plankton ecologists as an alternate for phytoplankton biomass and for estimating primary productivity. Photosynthetic and photoprotective pigments and their relative concentration can provide valuable taxonomical and physiological information of phytoplankton. Because pigment composition can be a reflection of taxonomic composition, presence or absence of certain marker pigments can be used to identify phytoplankton community composition. Pigment composition is an important physiological parameter. The environmental factors such as illumination and nutrient availability are influencing the relative pigment concentration. Phytoplankton pigments were analysed by spectrophotometry and HPLC methods. Both techniques were significant advances because of their sensitivity and ease of measurement.

Isolation, Culture, and Application of Marine Microalga Dunaliella salina (Volvocales, Chlorophyceae) as an Aqua Feed Additive

Microalgae are microscopic unicellular organisms capable to convert solar energy to chemical energy via photosynthesis. They contain numerous bioactive compounds that can be harnessed for commercial use. The potential of microalgal photosynthesis for the production of valuable compounds or for energetic use is widely recognized due to their more efficient utilization of sunlight energy as compared with higher plants. Microalgae can be used to produce a wide range of metabolites such as proteins, lipids, carbohydrates, carotenoids, or vitamins for health, food and feed additives, cosmetics, and energy production (Adams et al. 2009). However, microalgal biotechnology only really began to develop in the middle of the last century. Nowadays, there are numerous commercial applications of microalgae such as microalgae can be used to enhance the nutritional value of food and animal feed owing to their chemical composition; they play a crucial role in aquaculture. Moreover, they are cultivated as a source of highly valuable molecules. For example, polyunsaturated fatty acid oils are added to infant formulas and nutritional supplements, and pigments are important as aqua feed additive.

An Intensive Culture Techniques of Marine Copepod Oithona rigida (Dioithona rigida) Giesbrecht

Copepods are the main prey for fish and other crustacean larvae in the marine environment compared to other preys (Stottrup 2000; Ostergaard et al. 2005; Sampey et al. 2007). Their dietic value to fish larvae is known to be greater than the rotifer, Brachionus spp. and brine shrimp Artemia spp., they are the main live prey presently used in aquaculture hatcheries widely (Stottrup 2000; Lee 2003). Using rotifers and Artemia during the early fish larval rearing periods of life history not always enhances finest larval growth since these live prey usually have an inadequate fatty acid report and, in some instances, inappropriate size (Kahan et al. 1982; Sargent et al. 1999; Holt 2003; Faulk and Holt 2005). Thus, alternative food sources that do not have these inadequacies and promote larval growth are required. Copepods, copepodites, and naupliar stages are good nominees (Holt 2003), and studies on their mass production have been developed to investigate their efficiency on novel diets in aquaculture (Drillet et al. 2006). The small cyclopoid copepod genus Oithona is one of the most prevalent and copious in temperate, tropical, and polar oceans (Gallienne and Robins 2001; Hopcroft et al. 2005; Castellani et al. 2007); Oithona sp. can be used as feed transition between Rotifera and Artemia, or as a substitution of Artemia, recently. The calcium content of Oithona sp. is higher than that of Artemia (Castellani et al. 2008). The content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is also higher than that of Artemia and Rotifera. The high content of EPA/DHA will be helpful for growth improvement and survival rate and to reduce the occurrence of abnormality on shrimp and fish larvae. Oithona sp. contains immunostimulant; attractant and some significant digestive enzyme given the importance of Oithona sp. as a substitute for Artemia in the aquaculture, and also the sustainable availability of Oithona sp., were significant (Diana and Suminto 2015). Furthermore, owing to limitations of mouth gape, newly hatched larvae of some warmwater marine fish species have complexity ingesting Rotifera and Artemia nauplii but are able to feed upon copepod nauplii (Stottrup 2003). Optimizing copepod diets to meet their inclination can result in growth, egg production, and successful egg hatching (Milione and Zeng 2008; Rahman and Meyer 2009; Rahman and Verdegem 2010). Based on the commercial availability and production, the aquaculture industry is dominated by rotifers and Artemia, even though without enrichment of Artemia nauplii and rotifers did not fulfill the HUFA level required by the fish larvae (Raju 2012). The fast growth and higher survival of larvae were noticed when the fish larvae are fed with copepod alone or in combinations with other live feeds (Stottrup 2000, 2003; Payne et al. 2001; Ananthi et al. 2011; Santhanam and Perumal 2012a; Jayaraj 2012; Kathiresan 2013; Nandakumar 2015; Ananth 2015; Dinesh Kumar 2015). For the successful rearing of larvae, nutrition-rich, small-sized feed should be used. Copepods can work on it and considered as a promising live feed for larval stages of shrimp and fish (Santhanam 2002). Temperature, pH, and salinity are the main key factors that ruled the growth and reproductive potential of copepod in aquaculture systems followed by food and food concentration (Sun et al. 2008; Rhyne et al. 2009; Santhanam and Perumal 2012a; Santhanam et al. 2013; Nandakumar et al. 2015). Temperature plays a main role throughout the life cycle when the food factor is satisfactory. When pH is low in water, the skeptical damage was found in crustacean (Whiteley 2011), and growth and reproductive success were also affected (Whiteley 2011; Engstrom-Ost et al. 2014). Most of the marine invertebrates including copepods are weak during early developmental and reproductive stages (Kurihara 2008). Previous studies also suggested that the when the pH decreases, egg production, egg-hatching success, and nauplius survival also decreased (Mayor et al. 2007; Kurihara 2008). Only few reports are available on the culture of Oithona rigida with reference to environmental condition (Santhanam and Perumal 2012b; Vasudevan et al. 2013). Kahan (1979) optimized the copepod diet with vegetable juice as remedy for algal feed shortages. Though their diet depends on microalgae, we may have reinstated the algal diet with some other edible waste materials (Kahan 1979). The culture materials with various shapes will be given to troubleshoot the various physical barriers such as stable humidity, swimming activity behaviors, etc.; the type of vessels and their shape have been used since the copepod culturing mechanism begins (De Lepiney and Lionelle 1962; Santhanam et al. 2015). Light is also a complex external and ecological factor which includes spectrum of colors, intensity, and periodicity. It is considered to be a critical abiotic factor, influencing biological functions of any organism. With the above merits and demerits, the present study has been focused on optimization, and culturing O. rigida with a series of experiments was conducted to know the effect of temperature, salinity, pH, diets, and diet concentration on the survival, nauplii production rate, population density, development time, generation time, alternate diets, shape of the culture vessels, nature of the culture vessels, different light intensities, and different photo periods which have been analyzed under controlled and sophisticated laboratory condition. The main intention of this study is to develop the intensive culturing technology for copepod O. rigida to achieve greater population density of species.

Methodologies for the Bioenrichment of Plankton

Aquaculture is expanding worldwide to meet the protein requirements of humans. The basic requirement in culture practice is seed production, while the major constraint is larval nutrition (Imelda 2003). Larviculture—specifically, the initiation of feeding in early larval stages—is a major bottleneck for the industrial scale-up of fish and shellfish cultures. Larval survival also varies with the type of organism, with a rate of <10% in finfish, <1% in mud crabs, <20–40% in shrimp and <20% in molluscs. Evolutionarily, most fish and crustacean larvae are motile prey organisms and encounter problems with the initiation of inert/dry diets. Even if they accept the diets, their poor enzymatic activity and non-functional stomachs will not allow them to digest the existing formulated diets (Pedersen et al. 1987; Pedersen and Hjelmeland 1988; Agh and Sorgeloos 2005). Thus, improving the acceptance of dry diets for fish larvae and formulating more digestible and less polluting diets are important tasks for aquaculturists. The challenge in larval nutrition lies in the fact that live feeds are not completely replaced in hatchery operations. Therefore, once this is achieved, live food (phytoplankton and zooplankton) will remain an important food source for the starting of feeding in the early larval stages. Among the important starter feeds used in larviculture are newly hatched nauplii of Artemia and rotifer Brachionus plicatilis. The successful development of commercial hatcheries and farms has been made possible by several improvements in the production techniques of this live food (Candreva et al. 1996; Dehasque et al. 1998; Agh and Sorgeloos 2005). When compared to rotifers and Artemia nauplii, the traditional live feeds provided to marine fish larvae, copepods can improve larval growth and survival and the ratio of normally pigmented juveniles when fed either alone or as a supplement (Kraul 1983; McEvoy et al. 1998; Nanton and Castell 1999). Thus, the ability to culture these organisms at a scale adequate for marine larviculture would present a major step forward for the production of many marine species that require a better suited diet nutritionally than that provided by the traditional live prey (Josianna and Stottup 2006). It is believed that the optimal formulations for the first feeding of larvae should simulate the yolk composition and, to some extent, reflect the nutrient requirements and metabolic capacities of pre-feeding finfish and shellfish of other organisms (Imelda 2003).

Diversity and Abundance of Marine Copepods in Muthupet Mangrove Waters, Southeast Coast of India

The aim of the study is to evaluate the diversity and relative abundance of copepods in Muthupet waters. Two years (January 2009 to December 2010) of investigation resulted in 75 species of copepods identified in Muthupet waters comprising 51 species of Calanoida, 14 Cyclopoida and 10 Harpacticoida. The copepod population showed a bimodal pattern of distribution, where the first peak was encountered during February and March 2009 and the second peak occurred during February and March 2010. The bulk of copepod population was contributed by species namely, Paracalanus parvus, Nannocalanus minor, Acartia spinicauda, A. danae, Acrocalanus gracilis and Oithona rigida. Generally, calanoid copepods were found to be dominant with 68 % followed by Cyclopoida (18.66 %) and Harpacticoida (13.33 %). Copepods population in Muthupet lagoon has been positively influenced by salinity. Population density, species diversity and species richness were found to be higher in summer due to the stable hydro-graphical conditions. However, high species evenness was observed during the monsoon season indicating that the species were equally distributed. It is concluded that the Muthupet mangrove wetland ecosystem is considered as a rich bio-diversity hot spot for marine copepods.