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

Abstract

Copepods are the main prey for fish and other crustacean larvae in the marine environment compared to other preys (Støttrup 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 (Støttrup 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 (Støttrup 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 (Støttrup 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.