Dissertation - HQ

More documents

Recommendations

Info

154 Oceanography vs. behaviour Figure 6.18 Swimming speeds of P. amboinensis larvae through time, along 100 optimal trajectories in each of the two environments. Maximum potential speed (curve) is compared to speed decisions actually chosen along the trajectories (dots). Most of the time, larvae do not swim (zero speeds are present during the whole larval phase). When they do, their speed is often much less than the maximum. Most swimming, in particular fast swimming events, occurs early in the larval phase. than to first be advected away passively and take advantage of their increased swimming abilities to later return to the recruitment area. 6.4.5 Effect of temperature Increased recruitment success The impact of swimming should be reinforced in warmer water, because swimming abilities develop faster (Figure 6.12, page 144). To investigate this hypothesis, the same type of comparison between optimal trajectories is performed. Table 6.3 summarises the effect of a 2ºC temperature increase in all configurations. While the percentage of successful (i.e. recruiting) trajectories is constant for P. amboinensis (whose swimming abilities are already sufficient to exploit the heterogeneities of the flow), the larvae of the cold-temperate species are more successful after the 2ºC increase. Figure 6.19 compares some trajectories of the cold temperate species in present conditions and after a 2ºC increase. In current situation, most larvae are advected away from the island, first as passive eggs, then as weak swimming larvae. After a 2ºC increase, the egg phase is shorter, swimming abilities develop faster, and some young larvae are able to swim down in the lee of the island. This allows them to be retained there for the remainder of the pelagic phase. Here again,
Oriented swimming and passive advection 155 Table 6.3 Effect of the a 2ºC increase in water temperature on the Pelagic Larval Duration, percentage of successful (i.e. self-recruiting) trajectories, recruitment rate, and mean distance from the starting location along the trajectory, for the coral reef fish P. amboinensis and a temperate fish, in the island and promontory (Prom.) environments. The reduction of PLD is computed after O’Connor et al. 37 . Coral-Reef Temperate present +2ºC present +2ºC PLD (d) 25 22.1 27 21.7 Island Prom. success (%) 95 95 45 48 recruitment rate × 10 3 1.9 2.2 0.092 0.28 mean dist (km) 17.1 18.5 18.1 20.1 success (%) 95 95 72 75 recruitment rate × 10 3 1.9 2.2 0.15 0.44 mean dist (km) 16.5 22.4 43.5 33.1 swimming early and swimming down seem to be key to enhancing self-recruitment. The rate of self-recruitment is estimated as PLD multiplied by daily mortality rate and success percentage (Table 6.3). The daily mortality rates are 0.22 for the perciform coral-reef fish, and 0.27 for the temperate fish (which would correspond to a gadiform species or to a measure of the mean between gadiform, pleuronectiform, and perciform temperate fishes) 232 and were adjusted for temperature after the 2ºC increase (mortality rates increase with temperature) 72,273 . For P. amboinensis the increase in recruitment rate is due to the shorter PLD that reduces the exposure of larvae to pelagic mortality. For the temperate larvae, however, the increase in recruitment rate is proportionally larger, both because the reduction in PLD is larger (5.3 d instead of 2.9 d – note the convexity of the curve in Figure 6.13, page 145) and because the mean percentage of success increases. In all cases, recruitment varies between roughly 10 -3 and 10 -5 . Eventually, as self-recruitment is higher, one may assume that larvae are retained more and stay closer to their release points on average. The mean radial distance between the release point and positions at each time step along the trajectory is computed for the successful trajectories among a hundred runs in each configuration. As Table 6.3 highlights, the expected result is only observed for the temperate species in the promontory configuration. In all other cases, the mean distance is actually larger after the 2ºC increase. This surprising result has two explanations. First, in present situation, some larvae may rapidly be entrained too far to self-recruit. After a 2ºC increase, their swimming abilities develop faster and, following the same initial trajectories, larvae may now be able to make it back to the island (or promontory) to recruit. The optimisation routine is only concerned with successful trajectories Higher self-recruitment but increased distance from release point Increased maximum distance
Page 3:
À mon étoile.
Page 6 and 7:
vi Résumé La plupart des organism
Page 8 and 9:
viii Abstract Most demersal marine
Page 10 and 11:
x Table des matières 1.3.3 Simple
Page 12 and 13:
xii Table des matières 6.2.3 Examp
Page 14 and 15:
xiv Liste des figures 4.6 Distribut
Page 17:
Liste des tableaux 1.1 Potential or
Page 20 and 21:
2 Introduction La survie des larves
Page 22 and 23:
4 Introduction Limitation par le re
Page 24 and 25:
6 Introduction Les courants déterm
Page 26 and 27:
8 Introduction où m est le taux de
Page 28 and 29:
10 Introduction biologique simple.
Page 30 and 31:
12 Introduction Le milieu lui-même
Page 32 and 33:
14 Introduction Figure I.6 Schémat
Page 34 and 35:
16 Introduction obstacles technique
Page 36 and 37:
18 Introduction Figure I.8 Prédict
Page 38 and 39:
20 Introduction I.5 La biologie des
Page 40 and 41:
22 Introduction du fonctionnement d
Page 42 and 43:
24 Introduction L’objectif de cet
Page 44 and 45:
26 Behaviour in models 1.1 Introduc
Page 46 and 47:
28 Behaviour in models Using mean p
Page 48 and 49:
30 Behaviour in models 1.3 Vertical
Page 50 and 51:
32 Behaviour in models . . . bring
Page 52 and 53:
34 Behaviour in models of measured
Page 54 and 55:
36 Behaviour in models Additive dis
Page 56 and 57:
38 Behaviour in models In situ stud
Page 58 and 59:
40 Behaviour in models Operational
Page 60 and 61:
42 Behaviour in models Effects on p
Page 62 and 63:
44 Behaviour in models begins is no
Page 64 and 65:
46 Behaviour in models 1.10 Conclus
Page 66 and 67:
48 Larvae orientation in situ Diver
Page 68 and 69:
50 Larvae orientation in situ . . .
Page 70 and 71:
52 Larvae orientation in situ optio
Page 72 and 73:
54 Larvae orientation in situ if >
Page 74 and 75:
56 Larvae orientation in situ Table
Page 76 and 77:
58 Larvae orientation in situ that
Page 78 and 79:
60 Larvae orientation in situ 2.A A
Page 80 and 81:
62 Behaviour of settling fishes at
Page 82 and 83:
Page 84 and 85:
Page 87 and 88:
Chapter 4 Biophysical correlates in
Page 89 and 90:
Methods 71 4.2 Methods 4.2.1 Sampli
Page 91 and 92:
Methods 73 Three rotations were com
Page 93 and 94:
Methods 75 test really focuses on w
Page 95 and 96:
Results 77 Figure 4.3 Mean of insta
Page 97 and 98:
Results 79 Figure 4.5 Perspective v
Page 99 and 100:
Results 81 Table 4.1 Abundances of
Page 101 and 102:
Results 83 Figure 4.8 Distribution
Page 103 and 104:
Results 85 Figure 4.10 Concentratio
Page 105 and 106:
Discussion 87 Figure 4.11 Compariso
Page 107 and 108:
Discussion 89 But the most likely e
Page 109 and 110:
Acknowledgements 91 This evidence a
Page 111 and 112:
Chapter 5 Ontogenetic vertical “m
Page 113 and 114:
The statistical analysis of vertica
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Methods 101 80, 55, 30 m (Figure 4.
Page 121 and 122: Methods 103 same station were likel
Page 123 and 124: Results 105 Figure 5.2 Univariate r
Page 125 and 126: Results 107 5.4.3 Ontogenetic shift
Page 127 and 128: Results 109 Figure 5.5 Violin plot
Page 129 and 130: Discussion 111 5.5 Discussion 5.5.1
Page 131 and 132: Discussion 113 expression of differ
Page 133 and 134: Chapter 6 Oceanography vs. behaviou
Page 135 and 136: Introduction 117 a good description
Page 137 and 138: A general modelling framework for l
Page 145 and 146: The balance between feeding and pre
Page 155 and 156: Oriented swimming and passive advec
Page 171: Oriented swimming and passive advec
Page 179 and 180: General discussion 161 such integra
Page 181 and 182: General discussion 163 6.5.2 Why se
Page 183 and 184: General discussion 165 such as the
Page 185 and 186: General discussion 167 energeticall
Page 187: Acknowledgements 169 Therefore: •
Page 190 and 191: 172 Conclusion Un environnement pé
Page 192 and 193: 174 Conclusion global sur la connec
Page 194 and 195: 176 Conclusion l’intérêt est po
Page 196 and 197: 178 Conclusion La différence entre
Page 198 and 199: 180 Conclusion Mieux décrire la di
Page 200 and 201: 182 Conclusion Comme tout comportem
Page 202 and 203: 184 Undescribed Chaetodonthidae Fig
Page 204 and 205: 186 Undescribed Chaetodonthidae Fig
Page 206 and 207: 188 Bibliographie [12] Cushing DH.
Page 208 and 209: 190 Bibliographie [39] Johnson MW.
Page 210 and 211: 192 Bibliographie [71] Paris CB, Co
Page 212 and 213: 194 Bibliographie [99] Lara MR. Mor
Page 214 and 215: 196 Bibliographie [127] Masuda R, S
Page 216 and 217: 198 Bibliographie [157] Holbrook SJ
Page 218 and 219: 200 Bibliographie [187] Bowen B, Ba
Page 220 and 221: 202 Bibliographie [218] Oxenford HA
Page 222 and 223:
204 Bibliographie [246] Wellington
Page 224 and 225:
206 Bibliographie [276] Sargent RC,
Page 226 and 227:
208 Bibliographie [308] Greenberg D
Page 228 and 229:
210 Remerciements solides pour ces
Page 230 and 231:
212 Remerciements tri des larves de
Page 232:
214 Remerciements Évidemment, tout
show all

Dissertation - HQ

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

Delete template?

Save as template?