Benthic-pelagic exchange of microalgae at a tidal flat 2. Taxonomic analysis

• Published in: Marine ecology. Progress series (Halstenbek) Vol. 212; pp. 39 - 52
• Main Authors: Lucas, Cathy H., Banham, Clare, Holligan, Patrick M.
• Format: Journal Article
• Language: English
• Published: Oldendorf Inter-Research 08-03-2001
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Bacillariophyta; Biddulphia; Biological and medical sciences; Biomass; Brackish water ecosystems; Carbon; chlorophyll a; Coscinodiscus; Diatoms; Estuaries; Flumes; Fundamental and applied biological sciences. Psychology; Marine; Microalgae; Navicula; Nitzschia; Ocean floor; Phytoplankton; Pigments; Rhizosolenia; Sediments; Synecology; Netherlands; Europe; ANE, Netherlands, Zeeland, Westerschelde; Brackish water environment; Algae; Interspecific comparison; Estuaries; Environmental factor; Suspension; Flume; Pelagic zone; Heterokontophyta; Tide effect; Bacillariophyta; Spatial distribution; Vertical circulation; Seasonal variation; Phytoplankton; Flow velocity; Thallophyta; Ecological abundance; Benthic zone
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps212039

Benthic-pelagic exchange of diatoms over a tidal cycle has been examined using a combination of field measurements and annular flume experiments. The relative contribution of benthic and planktonic species to water-column abundance and biomass has been estimated using taxonomic counts, and cell volume to carbon conversions. In June, peaks in chlorophylla(chla) biomass occurred either side of the high-water slack period, which corresponded with increased abundance of benthic diatoms, as well as the large centric diatomCoscinodiscusspp. In numerical terms, benthic diatoms accounted for, on average, 15 to 42% of total diatom abundance over the flood-ebb period, whileCoscinodiscusspp. accounted for 12 to 17% in June and 3% in late August. Because of the large size of planktonic forms (e.g.,Coscinodiscusspp.,Rhizosoleniaspp.,Biddulphiaspp.) compared with the small benthicNitzschiaandNaviculaspecies, the contribution of benthic diatoms was significantly lower in terms of biomass. The average contribution of benthic diatoms to total diatom carbon was <1% in June, but up to 25% in late August. In contrast, the relative contribution ofCoscinodiscusspp. was ~90% in June and 73 to 80% in late August. The flume experiments confirmed that, in addition to increased benthic abundance in response to stepwise increases in current velocity, the large centric diatomCoscinodiscusspp. was also resuspended from sediments at high current velocities. At low current velocities, these cells rapidly sank to the seabed, the rate probably enhanced by deposition of sand grains out of the water column. Ecological implications related to water-column biomass and production, macro-infauna diet, and composition of benthic chlaare discussed.