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BROODSTOCK CONDITIONING and LARVAL REARING of the GEODUCK CLAM (Panopea Generosa GOULD, 1850)

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BROODSTOCK CONDITIONING and LARVAL REARING of the GEODUCK CLAM (Panopea Generosa GOULD, 1850) BROODSTOCK CONDITIONING AND LARVAL REARING OF THE GEODUCK CLAM (Panopea generosa GOULD, 1850) by Robert Marshall B.Sc.(hons), Dalhousie University, 1993 M.Aq., Simon Fraser University, 1997 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in The Faculty of Graduate Studies (Animal Science) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) March 2012 © Robert Marshall, 2012 Abstract The aim of this thesis was to identify conditions that optimize Panopea generosa broodstock conditioning and larval growth and survival in a hatchery setting. A series of experiments subjected broodstock (adults) to various levels of key factors [i.e. temperature (Ch. 2), salinity (Ch. 3) and nutrition [ration (Ch. 4) and feed type (Ch. 5)]. A larval experiment examined the effects of stocking density and feed level combinations on growth and survival (Ch. 6). Broodstock responses were quantified using gravimetric (condition and gonadosomatic indices) and histological techniques (development classification, volume fractions and oocyte diameter). Survival and spawning rates were also examined. Of the temperatures tested (7, 11, 15 and 19˚C) 11˚C had the highest spawning rates (% individuals) and more oocytes follicle-1, than 15 and 19˚C. At 7˚C gonadosomatic indices were highest but this temperature did not produce spawning clams. Gonads degenerated at 19˚C. Among salinities of 17, 20, 24, and 29 gonad sheath thickness and area occupied by gametes increased at 29 but not at 24. Salinities of 17 and 20 were associated with fungal infection and had high mortality rates after 26 d exposure. With higher ration treatments (up to 7.2 × 109 cells clam-1 d-1 [Isochrysis sp. (TISO) and Chaetoceros muelleri, 50:50 by cell count] clams became more spawned. Very high rations (10.0 × 109 cells clam-1 d-1) increased mortality. Algal type [Dunaliella tertiolecta, (TISO), C. muelleri and TISO + C. muelleri) had no measurable impact on gonad development based on any of the response variables used. The larval experiment showed that there was a significant interaction between stocking density and feed level with respect to growth and survival. The most efficient treatment was 10 larvae ml-1 fed ii 5,000 cells larva-1 (TISO) as it had among the highest growth (3.75 μm day-1) and survival (42%) rates but low algal requirements. These findings illustrate reproductive responses of P. generosa that can be applied to a hatchery management strategy. iii Preface For this thesis I contributed to the development of the experimental protocols, conducted the research, collected the data, performed the statistical analysis, interpreted the data and prepared the various chapters. My committee members (Dr. Abayomi Alabi, Dr. Anthony Farrell, Dr. Claudio DiBacco, Dr. Marina von Keyserlingk, Dr. Christopher M. Pearce, and Dr. Robert Scott McKinley) helped to conceive the design of the original experiments and provided valuable feedback on the results. Drs. McKinley and Pearce provided overall supervision and guidance and ensured that the experiments and the data analyses were correctly performed. My co-authors, Drs. McKinley and Pearce, reviewed and provided critical comments on all of the manuscripts submitted based on this dissertation. A version of Chapter 2 has been accepted for publication [Marshall, R., McKinley, R.S., Pearce, C.M., 2012. Effect of temperature on gonad development of the Pacific geoduck clam (Panopea generosa Gould, 1850). Aquaculture, in press]. A version of Table 1.1 has been published as part of a review paper [Marshall, R., McKinley, R.S., Pearce, C.M., 2010. Effects of nutrition on larval growth and survival in bivalves. Reviews in Aquaculture 2, 33-55. Dr. Pearce provided funding (through an NSERC Discovery grant) and provided laboratory space at the Pacific Biological Station and ensured that the experiments were conducted in with the approval of the DFO Pacific Region Animal Care Committee and the guidelines of the Canadian Council on Animal Care (CCAC). The DFO PRACC Animal Use Protocol approval numbers were 06-016, 07-007a and 08-011. iv Table of Contents Abstract ...........................................................................................................................ii Preface ........................................................................................................................... iv Table of Contents ............................................................................................................ v List of Tables ...............................................................................................................viii List of Figures ................................................................................................................ ix List of Abbreviations ....................................................................................................xiii Acknowledgements ...................................................................................................... xiv 1 Introduction ................................................................................................................. 1 1.1 General introduction .............................................................................................. 1 1.2 General biology and ecology of Panopea generosa ................................................ 4 1.3 Geoduck aquaculture and potential ........................................................................ 7 1.4 Factors influencing the gonad development and larval growth and survival of molluscan bivalves ...................................................................................................... 8 1.4.1 Effects of physical and biological factors on broodstock conditioning of bivalve molluscs ...................................................................................................................... 9 1.4.1.1 Introduction ................................................................................................. 9 1.4.1.2 Temperature ................................................................................................. 9 1.4.1.3 Salinity ...................................................................................................... 11 1.4.1.4 Water quality ............................................................................................. 12 1.4.1.5 Nutrition .................................................................................................... 14 1.4.1.6 Conclusions ............................................................................................... 21 1.4.2 Effects of stocking density and ration on larval growth and survival ................. 22 1.5 Thesis objectives and hypotheses ......................................................................... 27 1.5.1 Experiment 1: Effect of temperature on the gonad development of the geoduck clam....................................................................................................................... 28 1.5.2 Experiment 2: Effect of salinity on the gonad development of the geoduck clam....................................................................................................................... 29 1.5.3 Experiment 3: Effect of food ration on the gonad development of the geoduck clam....................................................................................................................... 31 1.5.4 Experiment 4: Effect of food type on the gonad development of the geoduck clam....................................................................................................................... 33 1.5.5 Experiment 5: Effects of stocking density and algal feed ration on growth, survival, and ingestion rate of larval geoduck clams ............................................... 34 2 Effect of temperature on gonad development of the Pacific geoduck clam (Panopea generosa Gould, 1850) .................................................................................................. 36 2.1 Introduction ......................................................................................................... 37 2.2 Materials and methods ......................................................................................... 38 2.2.1 Algal culture ................................................................................................. 38 2.2.2 Broodstock collection and initial maintenance ............................................... 38 2.2.3 Broodstock conditioning: experimental design .............................................. 39 2.2.4 Sampling ....................................................................................................... 41 2.2.5 Mortality rate and spawn events .................................................................... 42 2.2.6 Condition and gonadosomatic indices ........................................................... 42 GSI is the gonadosomatic index..................................................................................... 43 v 2.2.7 Ash-free dry weight ...................................................................................... 44 2.2.8 Histological sampling ................................................................................... 44 2.2.9 Statistical analyses ........................................................................................ 46 2.3 Results ................................................................................................................
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