University of Tasmania
Browse

File(s) under permanent embargo

Flow-induced morphological variations affect diffusion boundary-layer thickness of macrocystis pyrifera (Heterokontophyta, Laminariales)

journal contribution
posted on 2023-05-18, 00:51 authored by Catriona HurdCatriona Hurd, Pilditch, C
In slow mainstream flows (<4–6 cm Æ s)1), the transport of dissolved nutrients to seaweed blade surfaces is reduced due to the formation of thicker diffusion boundary layers (DBLs). The blade morphology of Macrocystis pyrifera (L.) C. Agardh varies with the hydrodynamic environment in which it grows; wave-exposed blades are narrow and thick with small surface corrugations (1 mm tall), whereas wave-sheltered blades are wider and thinner with large (2–5 cm) edge undulations. Within the surface corrugations of wave-exposed blades, the DBL thickness, measured using an O2 micro-optode, ranged from 0.67 to 0.80 mm and did not vary with mainstream velocities between 0.8 and 4.5 cm Æ s)1. At the corrugation apex, DBL thickness decreased with increasing seawater velocity, from 0.4 mm at 0.8 cm Æ s)1 to being undetectable at 4.5 cm Æ s)1. Results show how the wave-exposed blades trap fluid within the corrugations at their surface. For wavesheltered blades at 0.8 cm Æ s)1, a DBL thickness of 0.73 ± 0.31 mm within the edge undulation was 10- fold greater than at the undulation apex, while at 2.1 cm Æ s)1, DBL thicknesses were similar at <0.07 mm. Relative turbulence intensity was measured using an acoustic Doppler velocimeter (ADV), and overall, there was little evidence to support our hypothesis that the edge undulations of wave-sheltered blades increased turbulence intensity compared to wave-exposed blades. We discuss the positive and negative effects of thick DBLs at seaweed surfaces. Key index words: blade morphology; diffusion boundary layer; kelp; Macrocystis pyrifera; microoptode; oxygen profiles; turbulence intensity Abbreviations: ADV, acoustic Doppler velocimeter; DBL, diffusion boundary layer

History

Publication title

Journal of Phycology

Volume

47

Pagination

341-351

ISSN

0022-3646

Department/School

Institute for Marine and Antarctic Studies

Publisher

Blackwell Publishing Inc

Place of publication

350 Main St, Malden, USA, Ma, 02148

Rights statement

Copyright 2011 Phycological Society of America

Repository Status

  • Restricted

Socio-economic Objectives

Ecosystem adaptation to climate change

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC