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Photosynthetic response of monospecific macroalgal stands to density


Richards, D and Hurd, CL and Pritchard, D and Wing, S and Hepburn, C, Photosynthetic response of monospecific macroalgal stands to density, Aquatic Biology, 13, (1) pp. 41-49. ISSN 1864-7782 (2011) [Refereed Article]

Copyright Statement

Copyright 2011 Inter-Research

DOI: doi:10.3354/ab00349


Photosynthesis by benthic marine macroalgae makes an important contribution to the productivity of coastal seas. Quantification of photosynthesis and productivity of macroalgal assemblages is therefore important in understanding ecosystem functioning in coastal seas and providing realistic values for coastal productivity in global models. Estimates of macroalgal productivity are often based on the photosynthetic characteristics of thallus pieces or whole thalli, and not on those of communities. Such methods may overestimate rates of productivity as they do not account for neighborhood shading effects that may reduce photosynthetic rates in macroalgal stands that typically have high densities. In order to determine whether productivity estimates based on individuals differ from those based on communities, a controlled laboratory experiment was conducted with 3 dominant sub-canopy macroalgal species (Cystophora scalaris, Xiphophora gladiata and Undaria pinnatifida) from southern New Zealand. Photosynthetic parameters (initial slope of the photosynthesis vs. irradiance [P–E] curve α, saturation irradiance Ek, maximum rate of photosynthesis Pmax and darkrespiration Rd) were obtained via P–E experiments using a custom-built respirometry chamber for a range of densities that corresponded to the minimum, average and maximum densities of these species in the field. A 5 to 7-fold decrease in Pmax was observed when the density of the algal stand was above 1 ind. m–2. Rd and α were also lower in communities than for individuals. Results illustrate that estimates based on single specimens substantially overestimate productivity and we recommend that the densities used in experiments reflect those observed in the field.

Item Details

Item Type:Refereed Article
Keywords:Primary production, seaweed, photosynthesis, seaweed density
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Phycology (incl. marine grasses)
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Adaptation to climate change
Objective Field:Ecosystem adaptation to climate change
UTAS Author:Hurd, CL (Professor Catriona Hurd)
ID Code:91471
Year Published:2011
Web of Science® Times Cited:21
Deposited By:IMAS Research and Education Centre
Deposited On:2014-05-20
Last Modified:2017-10-31

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