THE DEMOGRAPHY AND INTERACTIONS OF ECKLONIA RADIATA IN SOUTHERN NEW ZEALAhTD A thesis submitted to the University of Canterbury for the degree of Doctor of Philosophy by Howard Royston Lees 2001 - Not an herb which carpeted the ground, not a branch which clothed the trees, was either broken or bent, nor did they extend horizontally; all stretched up to the surface of the ocean. Not a filament, not a ribbon, however thin they might be, but kept as straight as a rod of iron. The fuci and llianas grew in rigid perpendicular lines, due to the density of the element which had produced them. Motionless yet, when bent to one side by the hand, they directly resumed their former position. Truly it was the region of perpendicularity! - Jules Verne Twenty Thousand Leagues Under the Sea Chapter XVI - A Submarine Forest I:: 1\ DO '1lln? 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It ••••• ClI •••••• ,IIt •••••••••• a'.... a ••••••••••••••••••••••••••••••••• l 1.1 General Introduction to Thesis ............................................................................................. 2 1.2 Thesis Outline ...................................................................................................................... 5 1.3 Study Organism ............................... ,., ..... ,......... ,... ,.............................................................. 6 1.4 Study Sites ............................................................................................................................ 8 1.5 Plates .................................................................................................................................. 11 Chapter 2: General Demography . ..,O ••• CI •••• e •••••••• o •••••••••••••••••• o." ••• o ••••••••• 'u, •••• 01t1J •• oooo •••• oo ••••••• 12 2.1 Introduction ........................................................................................................................ 13 2.2 Methods .............................................................................................................................. 15 2.2.1 Sampling Methods ......................................................................................................... 15 2.2.1.1 Taggedplants ........................................................................................................ 15 2.2.1.2 Destructive Sanlpling ............................................................................................ 16 2.2.1.3 Randorll Transects ................................................................................................. 16 2.2.1.4 Recruitnlent ........................................................................................................... 17 2.2.2 Derivations ..................................................................................................................... 17 2.2.2.1 Derivation ofEcklonia Growth Rates ................................................................... 17 2.2.2.2 Derivation ofEcklonia Age (non-destructive) ....................................................... 17 2.2.2.3 Derivation of Biomass (non-destructive) .............................................................. 19 2.2.2.4 Derivation of Reproductive Output ....................................................................... 20 2.2.2.5 Derivation of Productivity ..................................................................................... 20 2.2.2.6 Transition Matrices ............................................................................................... 21 2.2.2.7 Life and Fertility Tables ........................................................................................ 22 2.2.3 Analysis ......................................................................................................................... 22 2.2.4 Definitions ...................................................................................................................... 22 2.3 Results ................................................................................................................................ 23 2.3.1 Spatial Patterns in Morphology, Biomass, and Density ................................................. 23 2.3.2 Temporal Patterns in Morphology, Biomass, and Density ............................................ 24 2.3.3 Growth ........................................................................................................................... 26 2.3.4 Survival .......................................................................................................................... 29 2.3.5 Reproduction and Recruitment ...................................................................................... 31 2.3.6 Stable Size-Distributions ............................................................................................... 33 2.3.7 Stable Age-Distributions ................................................................................................ 37 2.4 Discussion .......................................................................................................................... 40 Chapter 3: Canopy InteractiollS O •••••• IHII •• OIIIO •• OO •• "."' ••••• O •• IUO •••••••••• illG ••• 1HIQe ••• OD.OCH'I\IIIIO •••••••••• 000.00." .. 49 3.1 Introduction ........................................................................................................................ 50 3.2 Methods .............................................................................................................................. 52 3.2.1 Series I - Orthogonal Canopy Removals ....................................................................... 53 3.2.2 Series II Macrocystis Canopy Removal. ..................................................................... 54 3.2.3 Series III Substrate Clearances ................................................................................... 54 3.2.4 Environmental Parameters ........................................................................................... .. 3.2.5 Analysis ,........................................................................................................................ 55 3.3 Results .................................................................... ,........................................................... 57 3.3.1 Series Ia Orthogonal Canopy Removal ....................................................................... 57 3.3.1.1 Recruitment ........................................................................................................... 57 3.3.1.2 Juvenile Abundance ............................................................................................... 58 3.3.1.3 Growth ................................................................................................................... 60 3.3.1.4 Mortality ................................................................................................................ 63 Contents ii 3.3.1.5 Mature Ecklonia Abundance ................................................................................. 63 3.3.2 Series Ib Recovery of Ecklonia following canopy removaL ...................................... 64 3.3.3 Series II - Macrocystis Surface Canopy Removal ......................................................... 65 3.3.3.1 Recruitnlent ........................................................................................................... 65 3.3.3.2 Growth. .................................................................................................................. 65 3.3.3.3 Juvenile Abundance.......................................................................... ..................... 66 3.3.3.4 Mature Ecklonia Abundance ................................................................................. 67 3.3.3.5 MOltality ................................................................................................................ 68 3.3.4 Abundance of Other Algae within Series I & II ............................................................ 68 3.3.4.1 Cape Three Points ................................................................................................. 70 3.3.4.2 Tory Channel. ........................................................................................................ 70 3.3.5 Series III - Substrate Clearances .................................................................................... 71 3.3.6 Light ............................................................................................................................... 74 3.3.7 Sediment ........................................................................................................................ 74 3.3.8 Temperature & Rainfall ................................................................................................