Aquatic Sciences Meeting, Albuquerque 2001

SS01 Submerged Aquatic Vegetation and the Water Column (Environmental Connections)

Date: Tuesday, February 13, 2001, Time: 2:45:00 PM

Location: Galisteo

Miller, H, L, The University of Texas Marine Science Institute, Port Aransas, USA, hmiller@utmsi.utexas.edu

Dunton, K, H, The University of Texas Marine Science Institute, Port Aransas, USA, dunton@utmsi.utexas.edu

Fredriksen, S, , The University of Oslo, Oslo, Norway, stein.fredriksen@bio.uio.no

Tang, E, P, Smithsonian Environmental Research Center, Edgewater, USA, tang@serc1.si.edu

PRIMARY PRODUCTION ESTIMATES IN SCANDINAVIAN KELP FORESTS USING A DIVING-PAM FLUOROMETER

The Walz Diving-PAM fluorometer offers the capability for a rapid, non-invasive, and in situ measurement of photosystem II electron transport in macrophytes. Laminaria hyperborea, the principle kelp along the Atlantic coast of Norway, was collected from three depth intervals (0, 5, 15 m relative to MLLW). For each thallus, oxygen evolution and effective quantum yield of photochemistry, deltaF/Fm', were measured simultaneously at nine light levels (0 to 2000 umol photons m-2 s-1), and the empirical relationship between photosynthesis and deltaF/Fm' was calculated using irradiance as the common variable. Pmax and Ik both decreased with attachment depth, which suggests physiological acclimation to the lower ambient irradiance at depth of attachment. Furthermore, deltaF/Fm' decreased with increasing PAR more rapidly in plants collected at deeper depths. Using a continuous record of underwater PAR at the collection site, daily photosynthesis was estimated for the resident kelp population. Production estimates were then compared with in situ deltaF/Fm' measurements taken at sequential times over several days. Results will be discussed in the context of the utility and applicability of PAM fluorescence as a measure of kelp primary production.

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Aquatic Sciences Meeting, Albuquerque 2001

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