The improvement of copepods intensive culture protocols as live feeds for aquaculture hatcheries

Camus, Thomas (2012) The improvement of copepods intensive culture protocols as live feeds for aquaculture hatcheries. PhD thesis, James Cook University.

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Abstract

To date, aquaculture hatcheries are mostly dependent on the production of rotifers (Brachionus spp.) and brine shrimp (Artemia spp.) as a source of live prey for the rearing of early marine larvae. However, these traditional live feeds have been repeatedly proven inappropriate for an expanding list of marine species, including numerous important commercial and ornamental species. As a result, hatchery production of many marine larvae is uneconomical or impossible using either rotifers or Artemia, which puts significant limitations on commercial larviculture. The identification of alternative live prey items that do not have the inadequacies of traditional live feeds is hence of critical importance to increase the variety and survival of species cultured commercially and to insure the long-term growth and economic performance of the aquaculture industry.

Marine copepods are the most abundant metazoans throughout the world's ocean and constitute the majority of plankton biomass in the epipelagic zone. Their importance as natural prey items, in addition to their ubiquitous distribution in marine systems, makes them valuable live feeds candidates for marine hatcheries, and their superiority over traditional live feeds is well established in the literature. Among copepods, families from the genus calanoid possess fully pelagic developmental stages and are considered to have the best potential as live prey.

Although copepod culture technology has gained a great deal of interest over the last 30 years, most intensive culture protocols are still in their experimental phases and only a few species of calanoids are routinely mass cultured as food for larviculture. The present study focused on improving our knowledge of intensive culture techniques for calanoid copepods, in order to help realize their full potential as live feeds for commercial larviculture. A series of experiment was conducted with Acartia sinjiensis and Bestiolina similis, two calanoid copepods with excellent potential as live prey for marine larvae, and recommendations were made to optimize their intensive culture protocol.

This thesis consists of 8 chapters. Following a general introduction (chapter 1) and a general materials and methods section (chapter 2), the subsequent experimental chapters are comprised of two parts: Chapters 3, 4 and 5 focuses on improving culture techniques for Acartia sinjiensis, while Chapters 6 and 7 are focused on ameliorating culture methods for Bestiolina similis. The final chapter (Chapter 8) summarizes the main results from all of the data chapters and provides recommendations on potential application in aquaculture hatchery settings.

In Chapter 3, the influence of photoperiod on the productivity of the calanoid copepod Acartia sinjiensis was assessed. The effects of various photoperiod regimes (Light:Dark = 0:24; 6:18; 12:12; 18:6 and 24:0h) on important productivity-related parameters in cultures of Acartia sinjiensis were evaluated. Photoperiod significantly affected A. sinjiensis productivity overtime, and a clear trend of increasing daily egg production with longer illumination period was observed. Adult sex ratio was the only parameter that was not significantly influenced by photoperiod. Based on results from this chapter, a photoperiod of 18L:6D is recommended to improve A. sinjiensis intensive culture protocol.

In chapter 4, the effects of adult stocking density (125, 250, 500, 1000 and 2000 adults l⁻¹) over a wide range of parameters relating to Acartia sinjiensis productivity in culture were investigated in a series of laboratory experiments. A. sinjiensis adult cannibalism, population growth and 48h hatching success were all significantly affected by adult stocking density, while 96h hatching success and daily female egg output were not. A. sinjiensis was found to readily tolerate being cultured in important stocking density when compared to other calanoid species. A stocking densities as high as 2000 adults l⁻¹ is recommended for its intensive cultivation.

As cannibalism was determined to be a potential drawback in Acartia sinjiensis intensive cultivation in chapter 4, a detail assessment of cannibalism under intensive culture conditions was conducted in chapter 5. With respect to predators, cannibalism in adult males was negligible and significantly lower when compared to adult females cannibalism rates. With respect to prey, early nauplius stages (NI to NIII) were significantly more prone to cannibalism by adults than later stages (NIV to NVI). Cannibalism by adult females was significantly influenced by encounter rates between adults and prey, and was found to saturate at a prey concentration of 751 nauplii l-1 in the absence of microalgal food. Furthermore, factors such as adult starvation period and microalgae quantity were also found to significantly influence A. sinjiensis cannibalistic behaviour. Cannibalism can be significantly lessen under intensive culture conditions, providing some simple culture management techniques.

The Chapters 6 and 7 present data on investigations of both optimal quality and quantity of microalgal diets for the calanoid copepod Bestiolina similis. In chapter 6, an optimal microalgal diet for B. similis intensive cultivation was determined by conducting a range of laboratory experiments. The tri-algal diet T-Iso+Tet+Pav (at a 1:1:1 carbon ratio) was recommended to maximize B. similis productivity in culture, as it was responsible for the best egg production rate and the highest cumulative egg production during female lifespan, in addition to the shortest egg incubation time, the highest female longevity, the best 48h and 96h egg hatching rates, the highest naupliar survival and the best population increase over a 12 day culture period.

After having determined B. similis optimal food quality parameters in the previous chapter (Tiso+ Tet+Pav), the effects of various food concentrations (1800, 1500, 1200, 900, 600, 300 and 150 μg C l⁻¹) of this microalgal diet were investigated in chapter 7. Microalgae concentration significantly influenced B. similis egg production and faecal pellet production rates. Other parameters significantly affected by food concentration include population growth, egg hatching success, naupliar and copepodite survival as well as development time, adult female lifespan and cumulative egg production. A microalgae concentration of 664 μg C l⁻¹ was determined to saturate B. similis female cumulative egg production over their lifespan. Such a food ration should be implemented as part of B. similis culture protocol, as it will ensure that its productivity is not significantly limited by the quantity of microalgal food.

Item ID: 29905
Item Type: Thesis (PhD)
Keywords: marine copepods; copepod culture technology; culture techniques; Acartia sinjiensis; Bestiolina similis; live feed culture
Additional Information:

Publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 3. Camus, Thomas, and Zeng, Chaoshu (2008) Effects of photoperiod on egg production and hatching success, naupliar and copepodite development, adult sex ratio and life expectancy of the tropical calanoid copepod Acartia sinjiensis. Aquaculture, 280 (1-4). pp. 220-226.

Chapter 4. Camus, Thomas, and Zeng, Chaoshu (2009) The effects of stocking density on egg production and hatching success, cannibalism rate, sex ratio and population growth of the tropical calanoid copepod Acartia sinjiensis. Aquaculture, 287 (1). pp. 145-151.

Chapter 6. Camus, Thomas, Zeng, Chaoshu, and McKinnon, A. David (2009) Egg production, egg hatching success and population increase of the tropical paracalanid copepod, Bestiolina similis (Calanoida: Paracalanidae) fed different microalgal diets. Aquaculture, 297 (1). pp. 169-175.

Chapter 6. Camus, Thomas, and Zeng, Chaoshu (2010) Roles of microalgae on total egg production over female lifespan and egg incubation time, naupliar and copepodite survival, sex ratio and female life expectancy of the copepod Bestiolina similis. Aquaculture Research, 41 (11). pp. 1717-1726.

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Date Deposited: 25 Oct 2013 00:16
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070401 Aquaculture @ 34%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060808 Invertebrate Biology @ 33%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 33%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8301 Fisheries - Aquaculture > 830101 Aquaculture Crustaceans (excl. Rock Lobster and Prawns) @ 100%
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