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The spatio-temporal dynamics of the size fractions and pigment spectra of phytoplankton assemblages in different coastal marine ecosystems.
No full textCarrying capacity of pelagic ecosystems of the Ross Sea (Antarctica) during summer: primary production processes and limiting factors.
No full textThe Ross Sea is one of the most productive areas of the Southern Ocean; seasonal variations in biomass accumulation and production are very pronounced. Highest values of primary production are recorded in austral spring till early summer. During summer primary production sharply decreases and micro-nutrients limitation as well as deepening of the upper mixed layer have been invoked as major factors limiting phytoplankton growth. During austral summer 1996 and 2001 two oceanographic cruises were carried out in the Ross Sea within the framework of the PNRA.
Primary production processes are presented for different environmental conditions during austral summer characterized by ice free waters and extensive ice coverage in offshore waters.
In extensive pack ice coverage, the average Chlorophyll a (Chla) concentration was about three times the values recorded under ice-free conditions but the primary production was relatively lower. In situ primary production and photosynthetic parameters over few days show that in most of the area high primary production values occurs only in the first five meter of the water column and within the melting pack-ice. Notwithstanding the some values of phytoplankton biomass, water column stability, similar irradiance levels, photosynthetic capacity was suppressed in deeper layer indicating a low carrying capacity of pelagic ecosystem. In contrast to a very high variability in phytoplankton biomass and primary production, photosynthetic parameters vary within narrow ranges.
Spatial and temporal distribution of biomass (Chla), in situ simulated primary production, photosynthetic parameters (PvsE) are presented in order to assess the carrying capacity and limiting factors of primary production of the Ross Sea, during austral summer, in different environmental conditions
Spatial patterns of photosynthetic pigments and primary production in a periantarctic ecosystem: the Strait of Magellan.
No full textSpatial patterns of photosynthetic pigments and primary production in a periantarctic ecosystem: the Strait of Magellan.
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LIGHT ENVIRONMENT AND SEASONAL DYNAMICS OF MICROALGAE IN THE ANNUAL SEA ICE AT TERRA NOVA BAY ROSS SEA
No full textWe investigated the physical conditions of the Spring pack ice environment at Terra Nova Bay to understand their influence on the structure and physiology of sympagic microalgae. Bio-optical methods were used to study the availability and spectral quality of solar radiation, both inside and underneath the ice cover. Pack ice thickness was around 2.5 m, with a temperature between -2 and -7°C. On average, only 1.4% of surface PAR penetrated to the bottom ice and less than 0.6% below platelet ice level. Surface UV-B radiation under the bottom ice was 0.20.4%. Biomass concentrations up to 2400 mg Chl a m-3, dominated
by two species of diatoms (Entomoneis kjellmannii and Nitschia cf. stellata), showed marked spatial and temporal patterns. Maximum values were in the platelet ice during the first half of November, and in the bottom ice two weeks later. Strong shade adaptation characteristics emerged clearly and explained the
relevant abundance of microalgae within the sea ice, with specific absorption coefficients (a*) as low as 0.005 m2 (mg Chl a)-1 and the photo-acclimation index (Ek) in the range of in situ irradiance. The biomass specific production values were low, around 0.120.13 mg C mg Chl a-1 h -1. The hypothesis suggesting
bottom ice colonization by platelet ice microalgae is supported here
Surface distribution of phytoplankton pigments along a latitudinal transect from New Zealand to the Continetal shelf of the Ross Sea (Antarctica).
No full textLIGHT ENVIRONMENT AND SEASONAL DYNAMICS OF MICROALGAE IN THE ANNUAL SEA ICE AT TERRA NOVA BAY ROSS SEA
No full textWe investigated the physical conditions of the Spring pack ice environment at Terra Nova Bay to understand their influence on the structure and physiology of sympagic microalgae. Bio-optical methods were used to study the availability and spectral quality of solar radiation, both inside and underneath the ice cover. Pack ice thickness was around 2.5 m, with a temperature between -2 and -7°C. On average, only 1.4% of surface PAR penetrated to the bottom ice and less than 0.6% below platelet ice level. Surface UV-B radiation under the bottom ice was 0.20.4%. Biomass concentrations up to 2400 mg Chl a m-3, dominated
by two species of diatoms (Entomoneis kjellmannii and Nitschia cf. stellata), showed marked spatial and temporal patterns. Maximum values were in the platelet ice during the first half of November, and in the bottom ice two weeks later. Strong shade adaptation characteristics emerged clearly and explained the
relevant abundance of microalgae within the sea ice, with specific absorption coefficients (a*) as low as 0.005 m2 (mg Chl a)-1 and the photo-acclimation index (Ek) in the range of in situ irradiance. The biomass specific production values were low, around 0.120.13 mg C mg Chl a-1 h -1. The hypothesis suggesting
bottom ice colonization by platelet ice microalgae is supported here
Marine strategy: spatio-temporal dynamics of phytoplankton assemblages in different coastal marine areas of the Adriatic Sea.
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