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Kurt S Tande - One of the best experts on this subject based on the ideXlab platform.

  • secondary production at the polar front barents sea august 2007
    Journal of Marine Systems, 2014
    Co-Authors: Sunnje Linnea Basedow, Meng Zhou, Kurt S Tande
    Abstract:

    Abstract To investigate spatial patterns of secondary production we sampled four core hydrographical regions of the Polar Front in the Barents Sea (Arctic Water, ArW; Polar Front Water, PFW; Atlantic Water, AtW; and Melt Water, MW) by towing an undulating Instrument Platform along a transect crossing the front from August 8–9, 2007. Sensors mounted on the Platform provided data on the hydrography (CTD), fluorescence (Fluorometer, F) and zooplankton abundance in the size range between 0.1 and 30 mm (Laser Optical Plankton Counter, LOPC). These continuous, biophysical data with high-spatial resolution were supplemented by discrete water and zooplankton net samples at stations for sensor calibrations. After in depth quality assessments of the biophysical data, estimates were made of the vital rates based on biovolume spectrum theory. Five size groups were distinguished from the LOPC data: small (S), mainly Oithona spp. and the appendicularian Fritillaria sp.; medium (M), mainly Pseudocalanus spp. and Calanus spp. CI–CIII; large (L), mainly Calanus spp. CIV–CV; and extra large (XL and 2XL), juvenile and adult euphausids. Size groups were further divided based on transparency of organisms. Vital rates based on the biophysical in situ data in combination with biovolume spectrum theories agreed generally well with data from empirical and numerical models in the literature. ArW was characterised by subsurface maxima of chlorophyll a (chl a), and an estimated population growth of ca. 13 mg C m− 3 d− 1 for CI–CIII Calanus spp. and some older Pseudocalanus within the chl a maxima. Frontal waters were characterised by low chl a concentrations, but high abundances and production (around 1 g C m− 3 d− 1) of small copepods (Oithona spp.) and appendicularians (Fritillaria sp.). The estimated production of small-size zooplankton was an order of magnitude higher than the production of all other size groups combined, including large copepods. The high loss rates (− 166 to − 271 mg C m− 3 d− 1) of small zooplankton may contribute a substantial amount of carbon to the benthos and to pelagic predators such as young capelin. AtW was the most productive water mass, with surface chl a maxima and an estimated population growth of 134 mg C m− 3 d− 1 for small zooplankton, 3.6 mg C m− 3 d− 1 for medium-sized copepods and 0.9 mg C m− 3 d− 1 for CIV–CVI Calanus. For those Calanus spp. in the surface layer, the estimated specific mortality rates were up to − 0.35 d− 1, partly due to high predation pressure by hydrozoans and chaetognaths.

  • biovolume spectrum theories applied spatial patterns of trophic levels within a mesozooplankton community at the polar front
    Journal of Plankton Research, 2010
    Co-Authors: Sunnje Linnea Basedow, Kurt S Tande, Meng Zhou
    Abstract:

    Three-dimensional data on the mesoscale distribution of hydrography and mesozooplankton were collected at the Polar Front, northwestern Barents Sea, in spring 2008 (29 April–15 May) using a combination of multinet and towed Instrument Platform equipped with Laser Optical Plankton Counter, fluorometer and CTD. Trophic levels (TLs) within the zooplankton community (whole community and size-separated) were analysed for three consecutive periods using biovolume spectrum theory, which proved to be a powerful tool in the physically and biologically variable frontal system. Trophic structure was highly variable in time and across the Polar Front, but was mostly related to the phytoplankton bloom (as determined by fluorescence). High TLs of 5.5 within the zooplankton community were observed outside bloom situations (mostly in Atlantic Water) and were likely due to increased omnivory of Calanus spp., which dominated the large zooplankton size group that had a lower TL (2.2) during the bloom than outside blooms (max. TL 5.6). A strong input of herbivorous barnacle nauplii (Cirripedia) into the upper layer (35 000 ind. m−3 in net samples) substantially decreased mean TL in the marginal ice zone. Differences in TL estimates based on biovolume spectrum theory and other methods (stable isotopes, lipid markers, dietary analyses) are discussed.

Meng Zhou - One of the best experts on this subject based on the ideXlab platform.

  • secondary production at the polar front barents sea august 2007
    Journal of Marine Systems, 2014
    Co-Authors: Sunnje Linnea Basedow, Meng Zhou, Kurt S Tande
    Abstract:

    Abstract To investigate spatial patterns of secondary production we sampled four core hydrographical regions of the Polar Front in the Barents Sea (Arctic Water, ArW; Polar Front Water, PFW; Atlantic Water, AtW; and Melt Water, MW) by towing an undulating Instrument Platform along a transect crossing the front from August 8–9, 2007. Sensors mounted on the Platform provided data on the hydrography (CTD), fluorescence (Fluorometer, F) and zooplankton abundance in the size range between 0.1 and 30 mm (Laser Optical Plankton Counter, LOPC). These continuous, biophysical data with high-spatial resolution were supplemented by discrete water and zooplankton net samples at stations for sensor calibrations. After in depth quality assessments of the biophysical data, estimates were made of the vital rates based on biovolume spectrum theory. Five size groups were distinguished from the LOPC data: small (S), mainly Oithona spp. and the appendicularian Fritillaria sp.; medium (M), mainly Pseudocalanus spp. and Calanus spp. CI–CIII; large (L), mainly Calanus spp. CIV–CV; and extra large (XL and 2XL), juvenile and adult euphausids. Size groups were further divided based on transparency of organisms. Vital rates based on the biophysical in situ data in combination with biovolume spectrum theories agreed generally well with data from empirical and numerical models in the literature. ArW was characterised by subsurface maxima of chlorophyll a (chl a), and an estimated population growth of ca. 13 mg C m− 3 d− 1 for CI–CIII Calanus spp. and some older Pseudocalanus within the chl a maxima. Frontal waters were characterised by low chl a concentrations, but high abundances and production (around 1 g C m− 3 d− 1) of small copepods (Oithona spp.) and appendicularians (Fritillaria sp.). The estimated production of small-size zooplankton was an order of magnitude higher than the production of all other size groups combined, including large copepods. The high loss rates (− 166 to − 271 mg C m− 3 d− 1) of small zooplankton may contribute a substantial amount of carbon to the benthos and to pelagic predators such as young capelin. AtW was the most productive water mass, with surface chl a maxima and an estimated population growth of 134 mg C m− 3 d− 1 for small zooplankton, 3.6 mg C m− 3 d− 1 for medium-sized copepods and 0.9 mg C m− 3 d− 1 for CIV–CVI Calanus. For those Calanus spp. in the surface layer, the estimated specific mortality rates were up to − 0.35 d− 1, partly due to high predation pressure by hydrozoans and chaetognaths.

  • biovolume spectrum theories applied spatial patterns of trophic levels within a mesozooplankton community at the polar front
    Journal of Plankton Research, 2010
    Co-Authors: Sunnje Linnea Basedow, Kurt S Tande, Meng Zhou
    Abstract:

    Three-dimensional data on the mesoscale distribution of hydrography and mesozooplankton were collected at the Polar Front, northwestern Barents Sea, in spring 2008 (29 April–15 May) using a combination of multinet and towed Instrument Platform equipped with Laser Optical Plankton Counter, fluorometer and CTD. Trophic levels (TLs) within the zooplankton community (whole community and size-separated) were analysed for three consecutive periods using biovolume spectrum theory, which proved to be a powerful tool in the physically and biologically variable frontal system. Trophic structure was highly variable in time and across the Polar Front, but was mostly related to the phytoplankton bloom (as determined by fluorescence). High TLs of 5.5 within the zooplankton community were observed outside bloom situations (mostly in Atlantic Water) and were likely due to increased omnivory of Calanus spp., which dominated the large zooplankton size group that had a lower TL (2.2) during the bloom than outside blooms (max. TL 5.6). A strong input of herbivorous barnacle nauplii (Cirripedia) into the upper layer (35 000 ind. m−3 in net samples) substantially decreased mean TL in the marginal ice zone. Differences in TL estimates based on biovolume spectrum theory and other methods (stable isotopes, lipid markers, dietary analyses) are discussed.

Sunnje Linnea Basedow - One of the best experts on this subject based on the ideXlab platform.

  • secondary production at the polar front barents sea august 2007
    Journal of Marine Systems, 2014
    Co-Authors: Sunnje Linnea Basedow, Meng Zhou, Kurt S Tande
    Abstract:

    Abstract To investigate spatial patterns of secondary production we sampled four core hydrographical regions of the Polar Front in the Barents Sea (Arctic Water, ArW; Polar Front Water, PFW; Atlantic Water, AtW; and Melt Water, MW) by towing an undulating Instrument Platform along a transect crossing the front from August 8–9, 2007. Sensors mounted on the Platform provided data on the hydrography (CTD), fluorescence (Fluorometer, F) and zooplankton abundance in the size range between 0.1 and 30 mm (Laser Optical Plankton Counter, LOPC). These continuous, biophysical data with high-spatial resolution were supplemented by discrete water and zooplankton net samples at stations for sensor calibrations. After in depth quality assessments of the biophysical data, estimates were made of the vital rates based on biovolume spectrum theory. Five size groups were distinguished from the LOPC data: small (S), mainly Oithona spp. and the appendicularian Fritillaria sp.; medium (M), mainly Pseudocalanus spp. and Calanus spp. CI–CIII; large (L), mainly Calanus spp. CIV–CV; and extra large (XL and 2XL), juvenile and adult euphausids. Size groups were further divided based on transparency of organisms. Vital rates based on the biophysical in situ data in combination with biovolume spectrum theories agreed generally well with data from empirical and numerical models in the literature. ArW was characterised by subsurface maxima of chlorophyll a (chl a), and an estimated population growth of ca. 13 mg C m− 3 d− 1 for CI–CIII Calanus spp. and some older Pseudocalanus within the chl a maxima. Frontal waters were characterised by low chl a concentrations, but high abundances and production (around 1 g C m− 3 d− 1) of small copepods (Oithona spp.) and appendicularians (Fritillaria sp.). The estimated production of small-size zooplankton was an order of magnitude higher than the production of all other size groups combined, including large copepods. The high loss rates (− 166 to − 271 mg C m− 3 d− 1) of small zooplankton may contribute a substantial amount of carbon to the benthos and to pelagic predators such as young capelin. AtW was the most productive water mass, with surface chl a maxima and an estimated population growth of 134 mg C m− 3 d− 1 for small zooplankton, 3.6 mg C m− 3 d− 1 for medium-sized copepods and 0.9 mg C m− 3 d− 1 for CIV–CVI Calanus. For those Calanus spp. in the surface layer, the estimated specific mortality rates were up to − 0.35 d− 1, partly due to high predation pressure by hydrozoans and chaetognaths.

  • biovolume spectrum theories applied spatial patterns of trophic levels within a mesozooplankton community at the polar front
    Journal of Plankton Research, 2010
    Co-Authors: Sunnje Linnea Basedow, Kurt S Tande, Meng Zhou
    Abstract:

    Three-dimensional data on the mesoscale distribution of hydrography and mesozooplankton were collected at the Polar Front, northwestern Barents Sea, in spring 2008 (29 April–15 May) using a combination of multinet and towed Instrument Platform equipped with Laser Optical Plankton Counter, fluorometer and CTD. Trophic levels (TLs) within the zooplankton community (whole community and size-separated) were analysed for three consecutive periods using biovolume spectrum theory, which proved to be a powerful tool in the physically and biologically variable frontal system. Trophic structure was highly variable in time and across the Polar Front, but was mostly related to the phytoplankton bloom (as determined by fluorescence). High TLs of 5.5 within the zooplankton community were observed outside bloom situations (mostly in Atlantic Water) and were likely due to increased omnivory of Calanus spp., which dominated the large zooplankton size group that had a lower TL (2.2) during the bloom than outside blooms (max. TL 5.6). A strong input of herbivorous barnacle nauplii (Cirripedia) into the upper layer (35 000 ind. m−3 in net samples) substantially decreased mean TL in the marginal ice zone. Differences in TL estimates based on biovolume spectrum theory and other methods (stable isotopes, lipid markers, dietary analyses) are discussed.

Robert Pinkel - One of the best experts on this subject based on the ideXlab platform.

  • subharmonic energy transfer from the semidiurnal internal tide to near diurnal motions over kaena ridge hawaii
    Journal of Physical Oceanography, 2013
    Co-Authors: Oliver M T Sun, Robert Pinkel
    Abstract:

    AbstractNonlinear energy transfers from the semidiurnal internal tide to high-mode, near-diurnal motions are documented near Kaena Ridge, Hawaii, an energetic generation site for the baroclinic tide. Data were collected aboard the Research Floating Instrument Platform (FLIP) over a 35-day period during the fall of 2002, as part of the Hawaii Ocean Mixing Experiment (HOME) Nearfield program.Energy transfer terms for a PSI resonant interaction at midlatitude are identified and compared to those for near-inertial PSI close to the M2 critical latitude. Bispectral techniques are used to demonstrate significant energy transfers in the Nearfield, between the low-mode M2 internal tide and subharmonic waves with frequencies near M2/2 and vertical wavelengths of O(120 m). A novel prefilter is used to test the PSI wavenumber resonance condition, which requires the subharmonic waves to propagate in opposite vertical directions. Depth–time maps of the interactions, formed by directly estimating the energy transfer ter...

  • semidiurnal baroclinic wave momentum fluxes at kaena ridge hawaii
    Journal of Physical Oceanography, 2012
    Co-Authors: Luc Rainville, Robert Pinkel, Jody M Klymak
    Abstract:

    AbstractKaena Ridge, Hawaii, is a site of energetic conversion of the semidiurnal barotropic tide. Diffuse baroclinic wave beams emanate from the critical-slope regions near the ridge crest, directed upward and southward from the north flank of the ridge and upward and northward from the south flank. Here, the momentum fluxes associated with generation at the ridge are estimated. Continuous vertical profiles of density and velocity from 80 to 800 m were obtained from the Research Platform Floating Instrument Platform (FLIP) over the southern edge of the ridge, as an aspect of the Hawaii Ocean Mixing Experiment. Data are used to estimate the Reynolds stress, Eulerian buoyancy flux, and the combined Eliassen–Palm flux in the semidiurnal band. An upward–southward stress maximum of ~0.5 × 10−4 m2 s−2 appears at depths of 300–500 m, generally consistent with beam-like behavior. A strong off-ridge buoyancy flux (~0.3 × 10−4 m2 s−3) combines with large along-ridge Reynolds stresses to form an Eliassen–Palm flux ...

Jody M Klymak - One of the best experts on this subject based on the ideXlab platform.

  • semidiurnal baroclinic wave momentum fluxes at kaena ridge hawaii
    Journal of Physical Oceanography, 2012
    Co-Authors: Luc Rainville, Robert Pinkel, Jody M Klymak
    Abstract:

    AbstractKaena Ridge, Hawaii, is a site of energetic conversion of the semidiurnal barotropic tide. Diffuse baroclinic wave beams emanate from the critical-slope regions near the ridge crest, directed upward and southward from the north flank of the ridge and upward and northward from the south flank. Here, the momentum fluxes associated with generation at the ridge are estimated. Continuous vertical profiles of density and velocity from 80 to 800 m were obtained from the Research Platform Floating Instrument Platform (FLIP) over the southern edge of the ridge, as an aspect of the Hawaii Ocean Mixing Experiment. Data are used to estimate the Reynolds stress, Eulerian buoyancy flux, and the combined Eliassen–Palm flux in the semidiurnal band. An upward–southward stress maximum of ~0.5 × 10−4 m2 s−2 appears at depths of 300–500 m, generally consistent with beam-like behavior. A strong off-ridge buoyancy flux (~0.3 × 10−4 m2 s−3) combines with large along-ridge Reynolds stresses to form an Eliassen–Palm flux ...