New Zealand Journal of Marine and Freshwater Research abstracts
Microphytobenthic communities of subtidal locations in New Zealand:
taxonomy, biomass, production, and food-web implications
PAUL A. GILLESPIE
PAUL D. MAXWELL*
LESLEY L. RHODES
Cawthron Institute
Private Bag 2
Nelson, New Zealand
email: paul@cawthron.org.nz
*Present address: c/- Okoki Rd, RD 45, Urenui, Taranaki, New
Zealand.
Abstract Diatom mats dominated by large sigmoid, raphid
species of the genus Gyrosigma (Naviculaceae) and, in some instances,
the tube-former, Berkeleya rutilans (Naviculaceae) were observed in the
semi-enclosed coastal waters (depths 6-20 m) of Tory Channel, Marlborough
Sounds, New Zealand. The latter species, not previously observed in New
Zealand, is generally associated with intertidal environments where light
intensities are relatively higher than subtidal locations. Its presence
imparted a filamentous nature to the mat that may play a role in maintaining
the integrity of the sediment/water interface. Sediment chlorophyll a
concentrations ranged from c. 20 to 200 mg m-2.
Microphytobenthic (MPB) contributions to the total (benthic + planktonic)
chlorophyll a equated to 92, 89, and 84% at depths of 8, 16, and
20 m, respectively. Oxygen production in intact cores often exceeded
consumption (e.g., by up to 2.5 mmol
m-2 h-1) under near-in situ
conditions of light (8-30 umol m-2 s-1). The feeding
strategies of major components of the benthic macroinvertebrate fauna were used
to identify possible pathways for utilisation of MPB production. MPB
communities of more exposed subtidal locations in Tasman Bay were generally
less dense and comprised of different species dominated by Pleurosigma
amara and/or Paralia marina. We conclude that microalgal communities
inhabiting the soft sediments in these regions can provide an important
contribution to the benthic food web.
Keywords microphytobenthos; subtidal sediments;
Gyrosigma; Pleurosigma; Berkeleya; Paralia;
chlorophyll a; primary production; oxygen; food-web
M98065
Received 15 September 1998; accepted 22 September
1999
PDF file of entire paper: medium quality (2779K); (scanned from paper original: notes about this process)
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