P. Saravana Bhavan

Techniques in the Collection, Preservation and Morphological Identification of Freshwater Zooplankton

The word plankton (Greek for “wanderer” or “drifter”) was coined by the German Marine Biologist Victor Hensen (1887). The terminology “plankton” is plural (singular – plankter). Plankton community is a heterogeneous group of tiny plants (phytoplankton) and animals (zooplankton) adapted to suspension in the sea and fresh water. Their intrinsic movements, if any, are so feeble that they remain essentially at the mercy of every water current. It is a potentially functional community of similar organizational rank implicit in the terms forest or grassland communities. The terminology “plankton” included all organic particles, which float freely and involuntarily in the open water independent of shore and bottom. The dependence of plankton upon water movement for maintenance and transport is accurately implied in this definition (Greek word – planktos, meaning wandering). The term plankton refers to any small biota (from microns to centimeters) living in the water and drifting at the mercy of currents, ranging from bacteria to sea jelly.

Replacement of Fishmeal with Arthrospira (Spirulina) platensis and Its Use in Freshwater Prawn Macrobrachium rosenbergii Production

Next to agriculture, aquaculture plays a major role in food production around the world. Finfish and shellfish have a vital role in aquaculture operations. Among these, crustaceans, such as prawns, shrimps, crayfish, lobsters and crabs have vital role due to their nutritious delicacy for mankind. Macrobrachium rosenbergii is one of the important cultivable freshwater prawn species due to its wide variety of environment tolerances like temperature and salinity. M. rosenbergii is a candidate species in rural aquaculture for economic development (Tayamen 2007). In prawn culturing industries, about 40–60% of the operational expenditure is incurred towards the feeds used. Among the feed ingredients, fishmeal plays a major role due to the presence of high digestible protein, however, it is an expensive one due to low or unpredictable availability (Maliwat et al. 2016). Hence, there is a need to search the alternative protein sources to replace the fishmeal in prawn aquaculture. In regard to this, a number of studies have been conducted to find alternative source for replacing the fishmeal in the diets of prawns and shrimps (Sudaryono et al. 1999; Yang et al. 2004; Samocha et al. 2004; Muralisankar and Bhavan 2013).

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).