New Zealand Journal of Marine and Freshwater Research abstracts
Growth and reproductive phenology of the kelp Lessonia variegata in central
New Zealand
Anne-Maree Schwarz1,*
Ian Hawes1,*
Wendy Nelson2
Neil Andrew2,†
1National Institute of Water and Atmospheric
Research Limited
P.O. Box 11 115
Hamilton, New Zealand
email: a.schwarz@cgiar.org
2National Institute of Water and Atmospheric
Research Limited
P.O. Box 14 901
Wellington, New Zealand.
*Present address: The WorldFish Center, P.O. Box 77, Gizo, Western Province,
Solomon Islands.
†Present address: The WorldFish Center, P.O. Box 500, GPO, Penang, Malaysia.
Abstract A field study of Lessonia variegata growing
in depths of 8–10 m on the south coast of Wellington, New Zealand investigated
morphometric and biomass indices measured on destructively harvested entire algae,
rates of blade elongation measured in situ using a blade hole punch
technique, and timing of fertility over a 2-year period. Blade fertility was
estimated using a fertility score based on the visual appearance of the reproductive
tissue. Lessonia
variegata attained a maximum length of 154 cm, a density of 0.8 to 2.1
individuals m–2, and developed an areal biomass ranging from 1700 to 6000 g fresh weight
(FW) m–2. The highest proportion of fertile blades (up to 100% of sampled
blades) occurred during winter and the end of the fertile period coincided with
the onset of the longer days and warmer temperatures of summer. Blade elongation
occurred more rapidly in summer months (0.117 cm day–1, SE = 0.015) than
winter months (0.041 cm day–1, SE = 0.009). The slower winter blade elongation
rate meant that growth could not overcome tip ablation and average blade length
reduced from 51.5 cm (SE = 1.9) to 30.8 cm (SE = 1.7) between March and September
2003. Average blade length increased again over the following summer months to
40.7 cm (SE = 1.6). Blade biomass dominated total fresh weight biomass (average
64% of total). Two parameters that are relatively easily measured on live macroalgae in
situ, holdfast diameter and girth of all stipes collectively, predicted
total biomass with an r2 = 0.91, suggesting these could be useful
tools for assessment of this potentially harvestable resource on Wellington’s south
coast.
Keywords Phaeophyceae; Laminariales; morphometry; subtidal;
harvest
New Zealand Journal of Marine and Freshwater Research, 2006, Vol. 40:
273–284
0028–8330/06/4002–0273 © The Royal Society
of New Zealand 2006
M05051; Online publication date 10 April 2006. Received 10 August 2005;
accepted 29 January 2006
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