Population dynamics and lifecycle of the brown shrimp Crangon crangon (Caridea, L. 1758). Experimental, biochemical and theoretical aspects Dissertation zur Erlangung des Doktorgrades des vorgelegt von: Marc Hufnagl aus Ulm beim Department für Biologie der Fakultät für Mathematik, Informatik und Naturwissenschaften der Universität Hamburg Hamburg, Dezember 2009 To explain a phenomenon is to find a model that fits it into the basic framework of the theory and that thus allows us to derive analogues for the messy and complicated phenomenological laws which are true of it. (Nancy Cartwright, 1983) Table of Content Table of Content 1 SUMMARY.................................................................................................................. 1 2 ZUSAMMENFASSUNG............................................................................................. 3 3 OUTLINE OF PUBLICATIONS............................................................................... 7 4 GENERAL INTRODUCTION .................................................................................. 9 REFERENCES..................................................................................................................... 16 5 DETERMINING GROWTH RATES OF THE BROWN SHRIMP CRANGON CRANGON (L.): REVIEW AND LABORATORY APPROACH. ............................... 21 ABSTRACT ........................................................................................................................ 21 INTRODUCTION ................................................................................................................. 22 MATERIAL AND METHODS................................................................................................ 23 Marking method and growth determination................................................................ 23 Preliminary feeding trials............................................................................................ 24 Growth experiments..................................................................................................... 25 Sampling area.............................................................................................................. 25 Preliminary treatment.................................................................................................. 25 Feeding during the growth experiments...................................................................... 26 Water supply and setup ............................................................................................... 26 Experimental design: marked shrimps May ................................................................ 27 Experimental design: unmarked shrimps May ............................................................ 28 Experimental design: unmarked shrimps July............................................................. 28 Literature review ......................................................................................................... 29 Growth function........................................................................................................... 29 Model fitting to subsets of data ................................................................................... 30 Application of the growth model ................................................................................. 31 Moult intervals and moult increments......................................................................... 31 RESULTS........................................................................................................................... 32 Preliminary trials: food effect ..................................................................................... 32 Mortality growth experiments ..................................................................................... 33 Growth rates from laboratory trials............................................................................ 33 Literature review ......................................................................................................... 35 Growth models............................................................................................................. 37 Application of the model.............................................................................................. 38 Moult intervals and moult increments......................................................................... 39 DISCUSSION...................................................................................................................... 41 Laboratory experiments of the actual study ................................................................ 41 Sources for variability in growth rates........................................................................ 43 Moult intervals and moult increments......................................................................... 46 Application of the growth model ................................................................................. 48 REFERENCES..................................................................................................................... 49 APPENDIX......................................................................................................................... 54 I Table of Content 6 IS CRANGON CRANGON (L. 1758, DECAPODA, CARIDEA) FOOD LIMITED IN THE WADDEN SEA?................................................................................................. 57 ABSTRACT........................................................................................................................ 57 INTRODUCTION................................................................................................................. 58 MATERIAL AND METHODS ............................................................................................... 59 Field samples and collection of the animals for the starvation experiments.............. 59 Length, weight, sex...................................................................................................... 60 Caloric content............................................................................................................ 60 Length weight relation and dry weight condition ....................................................... 61 Water content, ash-, ash-free-dry weight and protein content.................................... 61 RNA·DNA-1 analysis.................................................................................................... 61 Starvation experiments................................................................................................ 62 Starvation-times in the field ........................................................................................ 63 RESULTS........................................................................................................................... 64 Field data .................................................................................................................... 64 Starvation experiments................................................................................................ 68 Estimating starvation time .......................................................................................... 72 DISCUSSION...................................................................................................................... 73 Starvation experiments................................................................................................ 73 Field observations....................................................................................................... 74 Conclusions ................................................................................................................. 78 REFERENCES .................................................................................................................... 78 7 ARE RNA·DNA-1 AND DRY WEIGHT SUITABLE GROWTH PROXIES FOR CRANGON CRANGON (L., CRUSTACEA) ?................................................................ 83 ABSTRACT........................................................................................................................ 83 INTRODUCTION................................................................................................................. 84 MATERIAL AND METHODS ............................................................................................... 85 Growth experiments .................................................................................................... 85 Dry weight condition................................................................................................... 85 RNA·DNA-1 analysis.................................................................................................... 86 Correlation of RNA·DNA-1 and dry weight with growth............................................. 86 RESULTS........................................................................................................................... 86 Dry weight condition index ......................................................................................... 86 RNA·DNA-1 ratio ......................................................................................................... 86 Variability of RNA·DNA-1 and dry weight condition for similar sized animals.......... 89 DISCUSSION...................................................................................................................... 90 Dry weight condition