University of Groningen
North Sea seaweeds: DIP and DIN uptake kinetics and management strategies Lubsch, Alexander
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Publication date: 2019
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Lubsch, A. (2019). North Sea seaweeds: DIP and DIN uptake kinetics and management strategies. University of Groningen.
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North Sea seaweeds:
DIP and DIN uptake kinetics and management strategies
The research reported in this thesis was carried out at the Department of Estuarine and Delta Systems (EDS) at the Royal Netherlands Institute for Sea Research (NIOZ), Texel, supported by the
Faculty of Science and Engineering at the University of Groningen.
Lay-out: Alexander Lubsch Cover design: Alexander Lubsch
Printed by: MünsterMedienXpress GmbH & Co. KG ISBN: 978-94-034-1688-5
North Sea seaweeds: DIP and DIN
uptake kinetics and management
strategies
Phd thesis
to obtain the degree of PhD at the University of Groningen
on the authority of the Rector Magnificus prof. E. Sterken
and in accordance with
the decision by the College of Deans. This thesis will be defended in public on
Friday 24 May 2019 at 14.30 hours
by
Alexander Lubsch
born on 14 October 1980 in Lengerich, Germany
Supervisors
Prof. K.R. Timmermans Prof. T.J. Bouma
Assessment Committee
Prof. K. Bischof Prof. A.G.J. Buma
i
Preface
The term ‘seaweeds’ is used here to describe multi-cellular marine macro-algae, although at some stage in their life-cycle seaweeds can be unicellular (spores, zygotes). One key component for survival and growth in seaweeds is the availability of (dissolved inorganic) nutrients. In this study the term ‘nutrients’ refers to the biologically available inorganic dissolved forms of nitrogen and phosphorus, two major constituents of living organisms. The focus in this thesis is on investigation of nutrient uptake kinetics, nutrient management, effects of nutrient limitation, growth, and composition in relation to nutrient availability in 4 ecologically and economically relevant (green, brown, and red) native North Sea seaweed species: Ulva lactuca (Chlorophyta),
Saccharina latissima, Laminaria digitata (Phaeophyta) and Palmaria palmata (Rhodophyta). Insight in
these major stimuli of production in seaweed biomass will allow better understanding of the ecophysiology of seaweeds, both under natural, as well as (large scale) production conditions.
It can be envisioned that nutrient availability will not only determine growth, but through the effects on composition it may also affect colour and texture. Hence, in addition to the analysis of the nutrient uptake kinetics and nutrient management strategies, 2 novel approaches with ecological and economical relevance on seaweeds with regard to nutrient availability are presented. Firstly, a combination of spectrophotometric measurements and colorimetric techniques was applied to determine the colour appearance of U. lactuca, resulting in a smartphone application ‘EyeOnUlva’. This application evaluates the nutritional value (total dissolvable protein content) of this opportunistic seaweed by digital imaging. Secondly, an approach was introduced that allows for standardised methods to infer to effects of nutrient availability and varying hydrodynamic forces on the texture of seaweed, using L. digitata individuals.
ii
Contents
Chapter 1 ... 1
1. General introduction ... 1
1.1 Seaweed... 1
1.2 The North Sea ... 2
1.3 Seaweed farming in Europe ... 5
1.4. Thesis outline ... 8
Chapter 2 ... 26
Uptake kinetics and storage capacity of dissolved inorganic phosphorus and corresponding N:P dynamics in Ulva lactuca (Chlorophyta) ... 26
2.1 Abstract ... 26
2.2 Introduction ... 27
2.3 Material and methods ... 29
2.4 Results ... 35
2.5 Discussion ... 41
2.6 Acknowledgements ... 46
Chapter 3 ... 47
Using a smartphone app for the estimation of total dissolvable protein concentration in Ulva lactuca Linnaeus (Chlorophyceae) ... 47
3.1 Abstract ... 47
3.2 Introduction ... 48
3.3 Material and methods ... 51
3.4 Results ... 57
3.5 Discussion ... 63
3.6 Acknowledgements ... 67
Chapter 4 ... 68
Uptake kinetics and storage capacity of dissolved inorganic phosphorus and corresponding dissolved inorganic nitrate uptake in Saccharina latissima and Laminaria digitata (Phaeophyceae) 68 4.1 Abstract ... 69
4.2 Introduction ... 69
4.3 Material and Methods ... 73
4.4 Results ... 80
4.5 Discussion ... 90
iii
Chapter 5 ... 98
Texture analysis of Laminaria digitata (Phaeophyceae) thallus reveals toughness gradient along lamina ... 98
5.1 Abstract ... 98
5.2 Introduction ... 99
5.3 Material and methods ... 101
5.4 Results ... 107
5.5 Discussion ... 110
5.6 Acknowledgements ... 115
Chapter 6 ... 116
Dissolved inorganic phosphate uptake and corresponding dissolved inorganic nitrate uptake in the seaweed Palmaria palmata (Rhodophyceae): ecological and physiological aspects of nutrient availability. ... 116
6.1 Abstract ... 116
6.2 Introduction ... 117
6.3 Material and methods ... 120
6.4 Results ... 125
6.5 Discussion ... 134
6.6 Acknowledgements ... 141
Chapter 7 ... 142
‘Manual for nutrient uptake kinetics in seaweed cultivation’ ... 142
7.1 Offshore cultivation ... 142
7.2 Integrated multi-trophic aquaculture (IMTA) ... 145
7.3 Tank cultivation ... 148
7.4 Biofiltration ... 150
Chapter 8 ... 153
Synthesis ... 153
8.1 General findings ... 154
8.2 Innovative aspects / highlights of the thesis ... 159
8.3 Conclusions ... 160 8.4 Research outlook ... 161 References ... 164 Summary ... 191 Samenvatting ... 195 Acknowledgements ... 200
