School of Engineering and Science - Jacobs University

More documents

Recommendations

Info

CHAPTER II application, the alternative funnel-transfer technique (FTT) (Figure 1C) while setting up dilution experiments. Here, we report the effects of both filling techniques on microzooplankton abundance and Margalef diversity (dinoflagellates, ciliates) of North Sea samples. We concentrate on in situ grazing experiments, but the results are equally applicable to any situation where zooplankton communities containing physically fragile species are to be manipulated in the laboratory. Figure 1: Illustration of the different filling techniques: (A) A simple, more destructive pouring process producing a lot of air bubbles. (B) Siphoning the water via a tube into a container without air bubbles. (C) Our new, more gentle approach to fill incubation bottles: Combination of a funnel and tube (FTT). MATERIAL AND METHODS Two different methods of filling experimental bottles for grazing experiments were tested in two separate experiments using water taken from the North Sea. Sampling site Helgoland is located in the German Bight (Southern North Sea) approximately 50 km off the German coast. It is subject to both coastal influences from the shallow Wadden Sea as well as marine influences from the open North Sea. Since 1962 bucket water samples are taken as part of a long term monitoring program at the “Kabeltonne” site at Helgoland Roads (54°11.3’N; 7°54.0’E) (Wiltshire et al., 2008). Water samples for the experiments were taken here. 42
CHAPTER II Filling techniques We compared two filling techniques: Siphoning and FTT. Siphoning is believed to be conservative for sensitive species as it avoids bubbling when the flow-end of the tube is kept under the water surface (Stelfox-Widdicombe et al., 2004, Strom et al., 2007, Paterson et al., 2008). Water is transferred only via hydrostatic pressure through a tube from one container to another when both containers have different water levels relative to geodetic height (Figure 1B). The FTT consists of a funnel mounted on a tube. For the transfer to a container, water is filled gently into the funnel keeping the tube compressed completely until the funnel is half-full. Thereafter water flow to the container is adjusted via the internal diameter by compressing the flexible tube compartment (Figure 1C). This technique also avoids air bubbles that could harm sensitive species. Experiment 1 Experiment 1 (July 2007) was conducted to compare the two filling techniques using the experimental set-up of dilution grazing experiments. During the experiment both techniques were tested with a 200 µm net for pre-screening. Pre-screening is routine in dilution experiments and excludes mesozooplankton grazers ensuring that only the microzooplankton grazing is measured (Liu & Dagg, 2003, Fonda Umani et al., 2005, Sakka Hlaili et al., 2007). Containers, bottles, tubing and other material used for the experiments were acid washed (10% HCL) and rinsed with deionised water. Approximately 50 L of surface seawater were sampled at Helgoland Roads using a bucket and poured without bubbling into a wide-necked carboy. The samples were brought to the laboratory immediately. The homogeneous distribution of the plankton in the initial seawater was ensured by gentle mixing. After homogenisation, 10 L were gently transferred into a 10 L carboy (as usually used for the set-up of a dilution series) with the FTT (Figure 1C). Special care was taken during the filling process that no air bubbles were produced. When the carboy was filled, the flow was terminated by compressing the tube. In parallel to the FTT method 10 L of seawater were siphoned off with a silicone tube into a separate carboy (Figure 1B). 2.3 L narrow-necked polycarbonate incubation bottles were filled with water from each corresponding 10 L carboy using both methods in three replicates. Before each filling step gentle mixing was carried out. In both approaches a 200 µm mesh was fixed at the end of the tube. All incubation bottles were filled to the top, closed and stored cool in the dark until sampling for microzooplankton and chlorophyll a. 43
Page 1 and 2: The role of heterotrophic dinoflage
Page 3: “What we know is a drop, what we
Page 7 and 8: INTRODUCTION INTRODUCTION Understan
Page 9 and 10: INTRODUCTION flagellates) and metaz
Page 11 and 12: INTRODUCTION The remaining species
Page 13 and 14: INTRODUCTION Figure 4: Diplopsalis
Page 15 and 16: INTRODUCTION compared to dinoflagel
Page 17: INTRODUCTION “seawater dilution t
Page 20 and 21: RESEARCH AIMS Apart from the pure g
Page 22 and 23: OUTLINE OF THE THESIS the two diffe
Page 25 and 26: CHAPTER I CHAPTER I Dinoflagellates
Page 27 and 28: CHAPTER I Dinoflagellates and cilia
Page 29 and 30: CHAPTER I INTRODUCTION Marine resea
Page 31 and 32: CHAPTER I counted out at 200-fold m
Page 33 and 34: CHAPTER I Dinoflagellates closely f
Page 35 and 36: CHAPTER I Figure 3: Biomass [µgC L
Page 37 and 38: CHAPTER I prevents confusion with o
Page 39 and 40: CHAPTER I Figure 6: Comparison of c
Page 41: CHAPTER I should therefore occur on
Page 44 and 45: CHAPTER II 38
Page 46 and 47: CHAPTER II ABSTRACT Grazing experim
Page 50 and 51: CHAPTER II Experiment 2 Experiment
Page 52 and 53: CHAPTER II Ciliates The three most
Page 54 and 55: CHAPTER II Experiment 2 Microzoopla
Page 56 and 57: CHAPTER II Asterisk * 1 symbolizes
Page 58 and 59: CHAPTER II DISCUSSION Transfer tech
Page 60 and 61: CHAPTER II bottles when siphoning w
Page 62 and 63: CHAPTER II ACKNOWLEDGEMENTS This st
Page 64 and 65: CHAPTER III 58
Page 66 and 67: CHAPTER III ABSTRACT Mesocosm exper
Page 68 and 69: CHAPTER III the prey (Cowles et al.
Page 70 and 71: CHAPTER III The mesocosms were stir
Page 72 and 73: CHAPTER III Net growth of plankton
Page 74 and 75: CHAPTER III prior to the experiment
Page 76 and 77: CHAPTER III incubation bottles with
Page 78 and 79: CHAPTER III Data analysis To monito
Page 80 and 81: CHAPTER III General development of
Page 82 and 83: CHAPTER III Ciliate community After
Page 84 and 85: CHAPTER III Other microzooplankton
Page 86 and 87: CHAPTER III Microzooplankton Experi
Page 88 and 89: CHAPTER III Figure 6: (6a) General
Page 90 and 91: CHAPTER III Table 3: Temora longico
Page 92 and 93: CHAPTER III Table 4: Temora longico
Page 94 and 95: CHAPTER III The comparison of mesoc
Page 96 and 97: CHAPTER III Flagellates contributed
Page 98 and 99:
CHAPTER III The effort to capture,
Page 100 and 101:
CHAPTER III in words and deeds. Man
Page 102 and 103:
CHAPTER III Table 2 Microzooplankto
Page 104 and 105:
CHAPTER III Table 3b Temora longico
Page 106 and 107:
CHAPTER III Table 4b Temora longico
Page 108 and 109:
CHAPTER IV 102
Page 110 and 111:
CHAPTER IV ABSTRACT The intra-speci
Page 112 and 113:
CHAPTER IV Hansen, 1997). In turn,
Page 114 and 115:
CHAPTER IV out in F/2 medium over 7
Page 116 and 117:
CHAPTER IV the same patterns in G.
Page 118 and 119:
CHAPTER IV Figure 1: General develo
Page 120 and 121:
CHAPTER IV Favella ehrenbergii (Fig
Page 122 and 123:
CHAPTER IV (24, 48, 72 hours of inc
Page 124 and 125:
CHAPTER IV Growth response of G. do
Page 126 and 127:
CHAPTER IV due to pre-conditioning
Page 128 and 129:
CHAPTER IV This was also confirmed
Page 130 and 131:
124
Page 132 and 133:
DISCUSSION described by competition
Page 134 and 135:
DISCUSSION to know who they are. Th
Page 136 and 137:
DISCUSSION Microzooplankton grazers
Page 138 and 139:
DISCUSSION Figure 1: A rather simpl
Page 140 and 141:
DISCUSSION 1986, Tillmann, 2004) co
Page 142 and 143:
DISCUSSION To my knowledge similar
Page 144 and 145:
DISCUSSION transported around the w
Page 146 and 147:
140
Page 148 and 149:
SUMMARY by its larger competitor. T
Page 150 and 151:
REFERENCES Buskey, E.J. & Stoecker,
Page 152 and 153:
REFERENCES Gentsch, E., Kreibich, T
Page 154 and 155:
REFERENCES Jeong, H.J., Yoo, Y.D.,
Page 156 and 157:
REFERENCES Montagnes, D.J.S., 2003.
Page 158 and 159:
REFERENCES Rose, J.M. & Caron, D.A.
Page 160 and 161:
REFERENCES Teixeira, I.G. & Figueir
Page 162 and 163:
156
Page 164 and 165:
158
show all

School of Engineering and Science - Jacobs University

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?